Bump version

Update from Weblate.

.readthedocs.requirements.txt

@@ -1,2 +1 @@
--r src/requirements/py34.txt
 -r doc/requirements.txt

.travis.sh

@@ -15,13 +15,13 @@ if [ "$PRETIX_CONFIG_FILE" == "tests/travis_postgres.cfg" ]; then
 fi
 
 if [ "$1" == "style" ]; then
-	XDG_CACHE_HOME=/cache pip3 install -Ur src/requirements.txt -r src/requirements/dev.txt -r src/requirements/py34.txt
+	XDG_CACHE_HOME=/cache pip3 install -Ur src/requirements.txt -r src/requirements/dev.txt
 	cd src
     flake8 .
     isort -c -rc -df .
 fi
 if [ "$1" == "doctests" ]; then
-	XDG_CACHE_HOME=/cache pip3 install -Ur doc/requirements.txt -r src/requirements/py34.txt
+	XDG_CACHE_HOME=/cache pip3 install -Ur doc/requirements.txt
 	cd doc
 	make doctest
 fi
@@ -39,21 +39,21 @@ if [ "$1" == "translation-spelling" ]; then
 	potypo
 fi
 if [ "$1" == "tests" ]; then
-	pip3 install -r src/requirements.txt -Ur src/requirements/dev.txt -r src/requirements/py34.txt pytest-xdist
+	pip3 install -r src/requirements.txt -Ur src/requirements/dev.txt pytest-xdist
 	cd src
 	python manage.py check
 	make all compress
 	py.test --reruns 5 -n 2 tests
 fi
 if [ "$1" == "tests-cov" ]; then
-	pip3 install -r src/requirements.txt -Ur src/requirements/dev.txt -r src/requirements/py34.txt
+	pip3 install -r src/requirements.txt -Ur src/requirements/dev.txt
 	cd src
 	python manage.py check
 	make all compress
 	coverage run -m py.test --reruns 5 tests && codecov
 fi
 if [ "$1" == "plugins" ]; then
-	pip3 install -r src/requirements.txt -Ur src/requirements/dev.txt -r src/requirements/py34.txt
+	pip3 install -r src/requirements.txt -Ur src/requirements/dev.txt
 	cd src
 	python setup.py develop
 	make all compress

.travis.yml

@@ -18,20 +18,10 @@ matrix:
       env: JOB=tests-cov PRETIX_CONFIG_FILE=tests/travis_postgres.cfg
     - python: 3.6
       env: JOB=style
-    - python: 3.4
-      env: JOB=tests PRETIX_CONFIG_FILE=tests/travis_sqlite.cfg
     - python: 3.5
       env: JOB=tests PRETIX_CONFIG_FILE=tests/travis_sqlite.cfg
-    - python: 3.4
-      env: JOB=tests PRETIX_CONFIG_FILE=tests/travis_mysql.cfg
-    - python: 3.5
-      env: JOB=tests PRETIX_CONFIG_FILE=tests/travis_mysql.cfg
     - python: 3.6
       env: JOB=tests PRETIX_CONFIG_FILE=tests/travis_mysql.cfg
-    - python: 3.4
-      env: JOB=tests PRETIX_CONFIG_FILE=tests/travis_postgres.cfg
-    - python: 3.5
-      env: JOB=tests PRETIX_CONFIG_FILE=tests/travis_postgres.cfg
     - python: 3.6
       env: JOB=tests PRETIX_CONFIG_FILE=tests/travis_postgres.cfg
     - python: 3.6

doc/admin/config.rst

@@ -53,6 +53,10 @@ Example::
     A comma-separated list of plugins that are enabled by default for all new events.
     Defaults to ``pretix.plugins.sendmail,pretix.plugins.statistics``.
 
+``plugins_exclude``
+    A comma-separated list of plugins that are not available even though they are installed.
+    Defaults to an empty string.
+
 ``cookie_domain``
     The cookie domain to be set. Defaults to ``None``.
 

doc/admin/installation/manual_smallscale.rst

@@ -121,8 +121,7 @@ command if you're running PostgreSQL::
 
     (venv)$ pip3 install "pretix[mysql]" gunicorn
 
-If you are running Python 3.4, you also need to ``pip3 install typing``. This is not required on 3.5 or newer.
-You can find out your Python version using ``python -V``.
+Note that you need Python 3.5 or newer. You can find out your Python version using ``python -V``.
 
 We also need to create a data directory::
 

doc/api/resources/carts.rst

@@ -0,0 +1,258 @@
+.. _rest-carts:
+
+Cart positions
+==============
+
+The API provides limited access to the cart position data model. This API currently only allows creating and deleting
+cart positions to reserve quota.
+
+Cart position resource
+----------------------
+
+The cart position resource contains the following public fields:
+
+.. rst-class:: rest-resource-table
+
+===================================== ========================== =======================================================
+Field                                 Type                       Description
+===================================== ========================== =======================================================
+id                                    integer                    Internal ID of the cart position
+cart_id                               string                     Identifier of the cart this belongs to. Needs to end
+                                                                 in "@api" for API-created positions.
+datetime                              datetime                   Time of creation
+expires                               datetime                   The cart position will expire at this time and no longer block quota
+item                                  integer                    ID of the item
+variation                             integer                    ID of the variation (or ``null``)
+price                                 money (string)             Price of this position
+attendee_name                         string                     Specified attendee name for this position (or ``null``)
+attendee_email                        string                     Specified attendee email address for this position (or ``null``)
+voucher                               integer                    Internal ID of the voucher used for this position (or ``null``)
+addon_to                              integer                    Internal ID of the position this position is an add-on for (or ``null``)
+subevent                              integer                    ID of the date inside an event series this position belongs to (or ``null``).
+answers                               list of objects            Answers to user-defined questions
+├ question                            integer                    Internal ID of the answered question
+├ answer                              string                     Text representation of the answer
+├ question_identifier                 string                     The question's ``identifier`` field
+├ options                             list of integers           Internal IDs of selected option(s)s (only for choice types)
+└ option_identifiers                  list of strings            The ``identifier`` fields of the selected option(s)s
+===================================== ========================== =======================================================
+
+.. versionchanged:: 1.17
+
+   This resource has been added.
+
+
+Cart position endpoints
+-----------------------
+
+.. http:get:: /api/v1/organizers/(organizer)/events/(event)/cartpositions/
+
+   Returns a list of API-created cart positions.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      GET /api/v1/organizers/bigevents/events/sampleconf/cartpositions/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+      X-Page-Generated: 2017-12-01T10:00:00Z
+
+      {
+        "count": 1,
+        "next": null,
+        "previous": null,
+        "results": [
+          {
+            "id": 1,
+            "cart_id": "XwokV8FojQviD9jhtDzKvHFdlLRNMhlfo3cNjGbuK6MUTQDT@api",
+            "item": 1,
+            "variation": null,
+            "price": "23.00",
+            "attendee_name": null,
+            "attendee_email": null,
+            "voucher": null,
+            "addon_to": null,
+            "subevent": null,
+            "datetime": "2018-06-11T10:00:00Z",
+            "expires": "2018-06-11T10:00:00Z",
+            "includes_tax": true,
+            "answers": []
+          }
+        ]
+      }
+
+   :query integer page: The page number in case of a multi-page result set, default is 1
+   :statuscode 200: no error
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+
+.. http:get:: /api/v1/organizers/(organizer)/events/(event)/cartpositions/(id)/
+
+   Returns information on one cart position, identified by its internal ID.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      GET /api/v1/organizers/bigevents/events/sampleconf/cartpositions/1/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "id": 1,
+        "cart_id": "XwokV8FojQviD9jhtDzKvHFdlLRNMhlfo3cNjGbuK6MUTQDT@api",
+        "item": 1,
+        "variation": null,
+        "price": "23.00",
+        "attendee_name": null,
+        "attendee_email": null,
+        "voucher": null,
+        "addon_to": null,
+        "subevent": null,
+        "datetime": "2018-06-11T10:00:00Z",
+        "expires": "2018-06-11T10:00:00Z",
+        "includes_tax": true,
+        "answers": []
+      }
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param id: The ``id`` field of the position to fetch
+   :statuscode 200: no error
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested cart position does not exist.
+
+.. http:post:: /api/v1/organizers/(organizer)/events/(event)/cartpositions/
+
+   Creates a new cart position.
+
+   .. warning:: This endpoint is considered **experimental**. It might change at any time without prior notice.
+
+   .. warning::
+
+       This endpoint is intended for advanced users. It is not designed to be used to build your own shop frontend.
+       There is a lot that it does not or can not do, and you will need to be careful using it.
+       It allows to bypass many of the restrictions imposed when creating a cart through the
+       regular shop.
+
+       Specifically, this endpoint currently
+
+       * does not validate if products are only to be sold in a specific time frame
+
+       * does not validate if the event's ticket sales are already over or haven't started
+
+       * does not support add-on products at the moment
+
+       * does not check or calculate prices but believes any prices you send
+
+       * does not support the redemption of vouchers
+
+       * does not prevent you from buying items that can only be bought with a voucher
+
+       * does not support file upload questions
+
+   You can supply the following fields of the resource:
+
+   * ``cart_id`` (optional, needs to end in ``@api``)
+   * ``item``
+   * ``variation`` (optional)
+   * ``price``
+   * ``attendee_name`` (optional)
+   * ``attendee_email`` (optional)
+   * ``subevent`` (optional)
+   * ``expires`` (optional)
+   * ``includes_tax`` (optional)
+   * ``answers``
+
+      * ``question``
+      * ``answer``
+      * ``options``
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      POST /api/v1/organizers/bigevents/events/sampleconf/cartpositions/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+      Content: application/json
+
+      {
+        "item": 1,
+        "variation": null,
+        "price": "23.00",
+        "attendee_name": "Peter",
+        "attendee_email": null,
+        "answers": [
+          {
+            "question": 1,
+            "answer": "23",
+            "options": []
+          }
+        ],
+        "subevent": null
+      }
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 201 Created
+      Vary: Accept
+      Content-Type: application/json
+
+      (Full cart position resource, see above.)
+
+   :param organizer: The ``slug`` field of the organizer of the event to create a position for
+   :param event: The ``slug`` field of the event to create a position for
+   :statuscode 201: no error
+   :statuscode 400: The item could not be created due to invalid submitted data or lack of quota.
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to create this
+         order.
+
+.. http:delete:: /api/v1/organizers/(organizer)/events/(event)/cartpositions/(id)/
+
+   Deletes a cart position, identified by its internal ID.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      DELETE /api/v1/organizers/bigevents/events/sampleconf/cartpositions/1/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 204 No Content
+      Vary: Accept
+      Content-Type: application/json
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param id: The ``id`` field of the position to delete
+   :statuscode 200: no error
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested cart position does not exist.

doc/api/resources/checkinlists.rst

@@ -332,6 +332,10 @@ Order position endpoints
 
    The ``.../redeem/`` endpoint has been added.
 
+.. versionchanged:: 2.0
+
+   The order positions endpoint has been extended by the filter queries ``voucher`` and ``voucher__code``.
+
 .. http:get:: /api/v1/organizers/(organizer)/events/(event)/checkinlists/(list)/positions/
 
    Returns a list of all order positions within a given event. The result is the same as
@@ -422,6 +426,8 @@ Order position endpoints
    :query integer addon_to: Only return positions that are add-ons to the position with the given ID.
    :query integer addon_to__in: Only return positions that are add-ons to one of the positions with the given
                                       comma-separated IDs.
+   :query string voucher: Only return positions with a specific voucher.
+   :query string voucher__code: Only return positions with a specific voucher code.
    :param organizer: The ``slug`` field of the organizer to fetch
    :param event: The ``slug`` field of the event to fetch
    :param list: The ID of the check-in list to look for

doc/api/resources/index.rst

@@ -20,3 +20,4 @@ Resources and endpoints
    vouchers
    checkinlists
    waitinglist
+   carts

doc/api/resources/items.rst

@@ -59,6 +59,9 @@ checkin_attention                     boolean                    If ``True``, th
                                                                  a product is being scanned.
 original_price                        money (string)             An original price, shown for comparison, not used
                                                                  for price calculations.
+require_approval                      boolean                    If ``True``, orders with this product will need to be
+                                                                 approved by the event organizer before they can be
+                                                                 paid.
 has_variations                        boolean                    Shows whether or not this item has variations.
 variations                            list of objects            A list with one object for each variation of this item.
                                                                  Can be empty. Only writable during creation,
@@ -96,7 +99,11 @@ addons                                list of objects            Definition of a
 
 .. versionchanged:: 1.16
 
-   The field ``internal_name`` and ``original_price`` fields have been added.
+   The ``internal_name`` and ``original_price`` fields have been added.
+
+.. versionchanged:: 2.0
+
+   The field ``require_approval`` has been added.
 
 Notes
 -----
@@ -160,6 +167,7 @@ Endpoints
             "max_per_order": null,
             "checkin_attention": false,
             "has_variations": false,
+            "require_approval": false,
             "variations": [
               {
                  "value": {"en": "Student"},
@@ -244,6 +252,7 @@ Endpoints
         "max_per_order": null,
         "checkin_attention": false,
         "has_variations": false,
+        "require_approval": false,
         "variations": [
           {
              "value": {"en": "Student"},
@@ -308,6 +317,7 @@ Endpoints
         "min_per_order": null,
         "max_per_order": null,
         "checkin_attention": false,
+        "require_approval": false,
         "variations": [
           {
              "value": {"en": "Student"},
@@ -361,6 +371,7 @@ Endpoints
         "max_per_order": null,
         "checkin_attention": false,
         "has_variations": true,
+        "require_approval": false,
         "variations": [
           {
              "value": {"en": "Student"},
@@ -445,6 +456,7 @@ Endpoints
         "max_per_order": null,
         "checkin_attention": false,
         "has_variations": true,
+        "require_approval": false,
         "variations": [
           {
              "value": {"en": "Student"},

doc/api/resources/orders.rst

@@ -32,8 +32,8 @@ email                                 string                     The customer em
 locale                                string                     The locale used for communication with this customer
 datetime                              datetime                   Time of order creation
 expires                               datetime                   The order will expire, if it is still pending by this time
-payment_date                          date                       Date of payment receipt
-payment_provider                      string                     Payment provider used for this order
+payment_date                          date                       **DEPRECATED AND INACCURATE** Date of payment receipt
+payment_provider                      string                     **DEPRECATED AND INACCURATE** Payment provider used for this order
 total                                 money (string)             Total value of this order
 comment                               string                     Internal comment on this order
 checkin_attention                     boolean                    If ``True``, the check-in app should show a warning
@@ -74,6 +74,12 @@ downloads                             list of objects            List of ticket
                                                                  download options.
 ├ output                              string                     Ticket output provider (e.g. ``pdf``, ``passbook``)
 └ url                                 string                     Download URL
+require_approval                      boolean                    If ``True`` and the order is pending, this order
+                                                                 needs approval by an organizer before it can
+                                                                 continue. If ``True`` and the order is canceled,
+                                                                 this order has been denied by the event organizer.
+payments                              list of objects            List of payment processes (see below)
+refunds                               list of objects            List of refund processes (see below)
 last_modified                         datetime                   Last modification of this object
 ===================================== ========================== =======================================================
 
@@ -108,6 +114,12 @@ last_modified                         datetime                   Last modificati
    The attributes ``order.last_modified`` as well as the corresponding filters to the resource have been added.
    An endpoint for order creation as well as ``…/mark_refunded/`` has been added.
 
+.. versionchanged:: 2.0
+
+   The ``order.payment_date`` and ``order.payment_provider`` attributes have been deprecated in favor of the new
+   nested ``payments`` and ``refunds`` resources, but will still be served and removed in 2.2. The ``require_approval``
+   attribute has been added, as have been the ``…/approve/`` and ``…/deny/`` endpoints.
+
 .. _order-position-resource:
 
 Order position resource
@@ -167,9 +179,53 @@ pdf_data                              object                     Data object req
 
   The attributes ``pseudonymization_id`` and ``pdf_data`` have been added.
 
+.. _order-payment-resource:
 
-Order endpoints
----------------
+Order payment resource
+----------------------
+
+.. rst-class:: rest-resource-table
+
+===================================== ========================== =======================================================
+Field                                 Type                       Description
+===================================== ========================== =======================================================
+local_id                              integer                    Internal ID of this payment, starts at 1 for every order
+state                                 string                     Payment state, one of ``created``, ``pending``, ``confirmed``, ``canceled``, ``pending``, ``failed``, or ``refunded``
+amount                                money (string)             Payment amount
+created                               datetime                   Date and time of creation of this payment
+payment_date                          datetime                   Date and time of completion of this payment (or ``null``)
+provider                              string                     Identification string of the payment provider
+===================================== ========================== =======================================================
+
+.. versionchanged:: 2.0
+
+  This resource has been added.
+
+.. _order-payment-resource:
+
+Order refund resource
+---------------------
+
+.. rst-class:: rest-resource-table
+
+===================================== ========================== =======================================================
+Field                                 Type                       Description
+===================================== ========================== =======================================================
+local_id                              integer                    Internal ID of this payment, starts at 1 for every order
+state                                 string                     Payment state, one of ``created``, ``transit``, ``external``, ``canceled``, ``failed``, or ``done``
+source                                string                     How this refund has been created, one of ``buyer``, ``admin``, or ``external``
+amount                                money (string)             Payment amount
+created                               datetime                   Date and time of creation of this payment
+payment_date                          datetime                   Date and time of completion of this payment (or ``null``)
+provider                              string                     Identification string of the payment provider
+===================================== ========================== =======================================================
+
+.. versionchanged:: 2.0
+
+  This resource has been added.
+
+List of all orders
+------------------
 
 .. versionchanged:: 1.15
 
@@ -216,6 +272,7 @@ Order endpoints
             "total": "23.00",
             "comment": "",
             "checkin_attention": false,
+            "require_approval": false,
             "invoice_address": {
                 "last_modified": "2017-12-01T10:00:00Z",
                 "is_business": True,
@@ -275,7 +332,18 @@ Order endpoints
                 "output": "pdf",
                 "url": "https://pretix.eu/api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/download/pdf/"
               }
-            ]
+            ],
+            "payments": [
+              {
+                "local_id": 1,
+                "state": "confirmed",
+                "amount": "23.00",
+                "created": "2017-12-01T10:00:00Z",
+                "payment_date": "2017-12-04T12:13:12Z",
+                "provider": "banktransfer"
+              }
+            ],
+            "refunds": []
           }
         ]
       }
@@ -285,6 +353,8 @@ Order endpoints
                            ``status``. Default: ``datetime``
    :query string code: Only return orders that match the given order code
    :query string status: Only return orders in the given order status (see above)
+   :query boolean require_approval: If set to ``true`` or ``false``, only categories with this value for the field
+                                    ``require_approval`` will be returned.
    :query string email: Only return orders created with the given email address
    :query string locale: Only return orders with the given customer locale
    :query datetime modified_since: Only return orders that have changed since the given date
@@ -296,6 +366,9 @@ Order endpoints
    :statuscode 401: Authentication failure
    :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
 
+Fetching individual orders
+--------------------------
+
 .. http:get:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/
 
    Returns information on one order, identified by its order code.
@@ -331,6 +404,7 @@ Order endpoints
         "total": "23.00",
         "comment": "",
         "checkin_attention": false,
+        "require_approval": false,
         "invoice_address": {
             "last_modified": "2017-12-01T10:00:00Z",
             "company": "Sample company",
@@ -390,7 +464,18 @@ Order endpoints
             "output": "pdf",
             "url": "https://pretix.eu/api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/download/pdf/"
           }
-        ]
+        ],
+        "payments": [
+          {
+            "local_id": 1,
+            "state": "confirmed",
+            "amount": "23.00",
+            "created": "2017-12-01T10:00:00Z",
+            "payment_date": "2017-12-04T12:13:12Z",
+            "provider": "banktransfer"
+          }
+        ],
+        "refunds": []
       }
 
    :param organizer: The ``slug`` field of the organizer to fetch
@@ -401,6 +486,9 @@ Order endpoints
    :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
    :statuscode 404: The requested order does not exist.
 
+Order ticket download
+---------------------
+
 .. http:get:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/download/(output)/
 
    Download tickets for an order, identified by its order code. Depending on the chosen output, the response might
@@ -442,6 +530,9 @@ Order endpoints
    :statuscode 409: The file is not yet ready and will now be prepared. Retry the request after waiting for a few
                           seconds.
 
+Creating orders
+---------------
+
 .. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/
 
    Creates a new order.
@@ -487,18 +578,23 @@ Order endpoints
 
    * ``code`` (optional)
    * ``status`` (optional) – Defaults to pending for non-free orders and paid for free orders. You can only set this to
-     ``"n"`` for pending or ``"p"`` for paid. If you create a paid order, the ``order_paid`` signal will **not** be
-     sent out to plugins and no email will be sent. If you want that behavior, create an unpaid order and then call
-     the ``mark_paid`` API method.
+     ``"n"`` for pending or ``"p"`` for paid. We will create a payment object for this order either in state ``created``
+     or in state ``confirmed``, depending on this value. If you create a paid order, the ``order_paid`` signal will
+     **not** be sent out to plugins and no email will be sent. If you want that behavior, create an unpaid order and
+     then call the ``mark_paid`` API method.
+   * ``consume_carts`` (optional) – A list of cart IDs. All cart positions with these IDs will be deleted if the
+     order creation is successful. Any quotas that become free by this operation will be credited to your order
+     creation.
    * ``email``
    * ``locale``
    * ``payment_provider`` – The identifier of the payment provider set for this order. This needs to be an existing
-     payment provider. You should use ``"free"`` for free orders.
-   * ``payment_info`` (optional) – You can pass a nested JSON object that will be set as the internal ``payment_info``
-     value of the order. How this value is handled is up to the payment provider and you should only use this if you
-     know the specific payment provider in detail. Please keep in mind that the payment provider will not be called
-     to do anything about this (i.e. if you pass a bank account to a debit provider, *no* charge will be created),
-     this is just informative in case you *handled the payment already*.
+     payment provider. You should use ``"free"`` for free orders, and we strongly advise to use ``"manual"`` for all
+     orders you create as paid.
+   * ``payment_info`` (optional) – You can pass a nested JSON object that will be set as the internal ``info``
+     value of the payment object that will be created. How this value is handled is up to the payment provider and you
+     should only use this if you know the specific payment provider in detail. Please keep in mind that the payment
+     provider will not be called to do anything about this (i.e. if you pass a bank account to a debit provider, *no*
+     charge will be created), this is just informative in case you *handled the payment already*.
    * ``comment`` (optional)
    * ``checkin_attention`` (optional)
    * ``invoice_address`` (optional)
@@ -580,11 +676,11 @@ Order endpoints
           {
             "positionid": 1,
             "item": 1,
-            "variation": None,
+            "variation": null,
             "price": "23.00",
             "attendee_name": "Peter",
-            "attendee_email": None,
-            "addon_to": None,
+            "attendee_email": null,
+            "addon_to": null,
             "answers": [
               {
                 "question": 1,
@@ -592,7 +688,7 @@ Order endpoints
                 "options": []
               }
             ],
-            "subevent": None
+            "subevent": null
           }
         ],
       }
@@ -615,6 +711,9 @@ Order endpoints
    :statuscode 403: The requested organizer/event does not exist **or** you have no permission to create this
          order.
 
+Order state operations
+----------------------
+
 .. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/mark_paid/
 
    Marks a pending or expired order as successfully paid.
@@ -849,9 +948,88 @@ Order endpoints
    :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
    :statuscode 404: The requested order does not exist.
 
+.. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/approve/
 
-Order position endpoints
-------------------------
+   Approve an order that is pending approval.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      POST /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/approve/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "code": "ABC12",
+        "status": "n",
+        "require_approval": false,
+        ...
+      }
+
+   :param organizer: The ``slug`` field of the organizer to modify
+   :param event: The ``slug`` field of the event to modify
+   :param code: The ``code`` field of the order to modify
+   :statuscode 200: no error
+   :statuscode 400: The order cannot be approved, likely because the current order status does not allow it.
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order does not exist.
+   :statuscode 409: The server was unable to acquire a lock and could not process your request. You can try again after a short waiting period.
+
+.. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/deny/
+
+   Marks an order that is pending approval as denied.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      POST /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/deny/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+      Content-Type: text/json
+
+      {
+          "send_email": true,
+          "comment": "You're not a business customer!"
+      }
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "code": "ABC12",
+        "status": "c",
+        "require_approval": true,
+        ...
+      }
+
+   :param organizer: The ``slug`` field of the organizer to modify
+   :param event: The ``slug`` field of the event to modify
+   :param code: The ``code`` field of the order to modify
+   :statuscode 200: no error
+   :statuscode 400: The order cannot be marked as denied since the current order status does not allow it.
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order does not exist.
+
+
+List of all order positions
+---------------------------
 
 .. versionchanged:: 1.15
 
@@ -859,6 +1037,11 @@ Order position endpoints
    ``order__status__in``, ``subevent__in``, ``addon_to__in`` and ``search``. The search for attendee names and order
    codes is now case-insensitive.
 
+.. versionchanged:: 2.0
+
+   The order positions endpoint has been extended by the filter queries ``voucher``, ``voucher__code`` and
+   ``pseudonymization_id``.
+
 .. http:get:: /api/v1/organizers/(organizer)/events/(event)/orderpositions/
 
    Returns a list of all order positions within a given event.
@@ -940,6 +1123,7 @@ Order position endpoints
    :query string attendee_name: Only return positions with the given value in the attendee_name field. Also, add-on
                                 products positions are shown if they refer to an attendee with the given name.
    :query string secret: Only return positions with the given ticket secret.
+   :query string pseudonymization_id: Only return positions with the given pseudonymization ID.
    :query string order__status: Only return positions with the given order status.
    :query string order__status__in: Only return positions with one the given comma-separated order status.
    :query boolean has_checkin: If set to ``true`` or ``false``, only return positions that have or have not been
@@ -949,12 +1133,17 @@ Order position endpoints
    :query integer addon_to: Only return positions that are add-ons to the position with the given ID.
    :query integer addon_to__in: Only return positions that are add-ons to one of the positions with the given
                                 comma-separated IDs.
+   :query string voucher: Only return positions with a specific voucher.
+   :query string voucher__code: Only return positions with a specific voucher code.
    :param organizer: The ``slug`` field of the organizer to fetch
    :param event: The ``slug`` field of the event to fetch
    :statuscode 200: no error
    :statuscode 401: Authentication failure
    :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
 
+Fetching individual positions
+-----------------------------
+
 .. http:get:: /api/v1/organizers/(organizer)/events/(event)/orderpositions/(id)/
 
    Returns information on one order position, identified by its internal ID.
@@ -1023,6 +1212,9 @@ Order position endpoints
    :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
    :statuscode 404: The requested order position does not exist.
 
+Order position ticket download
+------------------------------
+
 .. http:get:: /api/v1/organizers/(organizer)/events/(event)/orderpositions/(id)/download/(output)/
 
    Download tickets for one order position, identified by its internal ID.
@@ -1064,3 +1256,507 @@ Order position endpoints
    :statuscode 404: The requested order position or download provider does not exist.
    :statuscode 409: The file is not yet ready and will now be prepared. Retry the request after waiting for a few
                     seconds.
+
+Manipulating individual positions
+---------------------------------
+
+.. http:delete:: /api/v1/organizers/(organizer)/events/(event)/orderpositions/(id)/
+
+   Deletes an order position, identified by its internal ID.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      DELETE /api/v1/organizers/bigevents/events/sampleconf/orderpositions/23442/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 204 No Content
+      Vary: Accept
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param id: The ``id`` field of the order position to delete
+   :statuscode 204: no error
+   :statuscode 400: This position cannot be deleted (e.g. last position in order)
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order position does not exist.
+
+
+Order payment endpoints
+-----------------------
+
+.. versionchanged:: 2.0
+
+  These endpoints have been added.
+
+.. http:get:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/payments/
+
+   Returns a list of all payments for an order.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      GET /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/payments/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "count": 1,
+        "next": null,
+        "previous": null,
+        "results": [
+          {
+            "local_id": 1,
+            "state": "confirmed",
+            "amount": "23.00",
+            "created": "2017-12-01T10:00:00Z",
+            "payment_date": "2017-12-04T12:13:12Z",
+            "provider": "banktransfer"
+          }
+        ]
+      }
+
+   :query integer page: The page number in case of a multi-page result set, default is 1
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param order: The ``code`` field of the order to fetch
+   :statuscode 200: no error
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order does not exist.
+
+.. http:get:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/payments/(local_id)/
+
+   Returns information on one payment, identified by its order-local ID.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      GET /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/payments/1/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "local_id": 1,
+        "state": "confirmed",
+        "amount": "23.00",
+        "created": "2017-12-01T10:00:00Z",
+        "payment_date": "2017-12-04T12:13:12Z",
+        "provider": "banktransfer"
+      }
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param code: The ``code`` field of the order to fetch
+   :param local_id: The ``local_id`` field of the payment to fetch
+   :statuscode 200: no error
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order or payment does not exist.
+
+.. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/payments/(local_id)/confirm/
+
+   Marks a payment as confirmed. Only allowed in states ``pending`` and ``created``.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      POST /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/payments/1/confirm/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+      Content-Type: application/json
+
+      {"force": false}
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "local_id": 1,
+        "state": "confirmed",
+        ...
+      }
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param code: The ``code`` field of the order to fetch
+   :param local_id: The ``local_id`` field of the payment to modify
+   :statuscode 200: no error
+   :statuscode 400: Invalid request or payment state
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order or payment does not exist.
+
+.. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/payments/(local_id)/cancel/
+
+   Marks a payment as canceled. Only allowed in states ``pending`` and ``created``.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      POST /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/payments/1/cancel/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "local_id": 1,
+        "state": "canceled",
+        ...
+      }
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param code: The ``code`` field of the order to fetch
+   :param local_id: The ``local_id`` field of the payment to modify
+   :statuscode 200: no error
+   :statuscode 400: Invalid request or payment state
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order or payment does not exist.
+
+.. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/payments/(local_id)/refund/
+
+   Create and execute a manual refund. Only available in ``confirmed`` state. Returns a refund resource, not
+   a payment resource!
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      POST /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/payments/1/refund/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+      Content-Type: application/json
+
+      {
+        "amount": "23.00",
+        "mark_refunded": false
+      }
+
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "local_id": 1,
+        "source": "admin",
+        "state": "done",
+        ...
+      }
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param code: The ``code`` field of the order to fetch
+   :param local_id: The ``local_id`` field of the payment to modify
+   :statuscode 200: no error
+   :statuscode 400: Invalid request, payment state, or operation not supported by the payment provider
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order or payment does not exist.
+
+
+Order refund endpoints
+----------------------
+
+.. versionchanged:: 2.0
+
+  These endpoints have been added.
+
+.. http:get:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/refunds/
+
+   Returns a list of all refunds for an order.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      GET /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/refunds/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "count": 1,
+        "next": null,
+        "previous": null,
+        "results": [
+          {
+            "local_id": 1,
+            "state": "done",
+            "source": "admin",
+            "amount": "23.00",
+            "payment": 1,
+            "created": "2017-12-01T10:00:00Z",
+            "execution_date": "2017-12-04T12:13:12Z",
+            "provider": "banktransfer"
+          }
+        ]
+      }
+
+   :query integer page: The page number in case of a multi-page result set, default is 1
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param order: The ``code`` field of the order to fetch
+   :statuscode 200: no error
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order does not exist.
+
+.. http:get:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/refunds/(local_id)/
+
+   Returns information on one refund, identified by its order-local ID.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      GET /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/refunds/1/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "local_id": 1,
+        "state": "done",
+        "source": "admin",
+        "amount": "23.00",
+        "payment": 1,
+        "created": "2017-12-01T10:00:00Z",
+        "execution_date": "2017-12-04T12:13:12Z",
+        "provider": "banktransfer"
+      }
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param code: The ``code`` field of the order to fetch
+   :param local_id: The ``local_id`` field of the refund to fetch
+   :statuscode 200: no error
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order or refund does not exist.
+
+.. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/refunds/
+
+   Creates a refund manually.
+
+   .. warning:: We recommend to only use this endpoint for refunds with payment provider ``manual``. This endpoint also
+                does not check for mismatching amounts etc. Be careful!
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      POST /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/refunds/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+      Content-Type: application/json
+
+      {
+        "state": "created",
+        "source": "admin",
+        "amount": "23.00",
+        "payment": 1,
+        "execution_date": null,
+        "provider": "manual",
+        "mark_refunded": false
+      }
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 201 Created
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "local_id": 1,
+        "state": "created",
+        "source": "admin",
+        "amount": "23.00",
+        "payment": 1,
+        "created": "2017-12-01T10:00:00Z",
+        "execution_date": null,
+        "provider": "manual"
+      }
+
+   :query integer page: The page number in case of a multi-page result set, default is 1
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param order: The ``code`` field of the order to fetch
+   :statuscode 200: no error
+   :statuscode 400: Invalid data supplied
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order does not exist.
+
+.. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/refunds/(local_id)/done/
+
+   Marks a refund as completed. Only allowed in states ``transit`` and ``created``.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      POST /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/refunds/1/done/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "local_id": 1,
+        "state": "done",
+        ....
+      }
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param code: The ``code`` field of the order to fetch
+   :param local_id: The ``local_id`` field of the refund to modify
+   :statuscode 200: no error
+   :statuscode 400: Invalid request or refund state
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order or refund does not exist.
+
+.. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/refunds/(local_id)/process/
+
+   Acts on an external refund, either marks the order as refunded or pending. Only allowed in state ``external``.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      POST /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/refunds/1/done/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+      Content-Type: application/json
+
+      {"mark_refunded": false}
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "local_id": 1,
+        "state": "done",
+        ....
+      }
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param code: The ``code`` field of the order to fetch
+   :param local_id: The ``local_id`` field of the refund to modify
+   :statuscode 200: no error
+   :statuscode 400: Invalid request or refund state
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order or refund does not exist.
+
+.. http:post:: /api/v1/organizers/(organizer)/events/(event)/orders/(code)/refunds/(local_id)/cancel/
+
+   Marks a refund as canceled. Only allowed in states ``transit``, ``external``, and ``created``.
+
+   **Example request**:
+
+   .. sourcecode:: http
+
+      POST /api/v1/organizers/bigevents/events/sampleconf/orders/ABC12/refunds/1/cancel/ HTTP/1.1
+      Host: pretix.eu
+      Accept: application/json, text/javascript
+
+   **Example response**:
+
+   .. sourcecode:: http
+
+      HTTP/1.1 200 OK
+      Vary: Accept
+      Content-Type: application/json
+
+      {
+        "local_id": 1,
+        "state": "canceled",
+        ....
+      }
+
+   :param organizer: The ``slug`` field of the organizer to fetch
+   :param event: The ``slug`` field of the event to fetch
+   :param code: The ``code`` field of the order to fetch
+   :param local_id: The ``local_id`` field of the refund to modify
+   :statuscode 200: no error
+   :statuscode 400: Invalid request or refund state
+   :statuscode 401: Authentication failure
+   :statuscode 403: The requested organizer/event does not exist **or** you have no permission to view this resource.
+   :statuscode 404: The requested order or refund does not exist.

doc/development/api/customview.rst

@@ -64,7 +64,7 @@ Similarly, there is ``organizer_permission_required`` and ``OrganizerPermissionR
 event-related views, there is also a signal that allows you to add the view to the event navigation like this::
 
 
-    from django.core.urlresolvers import resolve, reverse
+    from django.urls import resolve, reverse
     from django.dispatch import receiver
     from django.utils.translation import ugettext_lazy as _
     from pretix.control.signals import nav_event

doc/development/api/email.rst

@@ -0,0 +1,109 @@
+.. highlight:: python
+   :linenothreshold: 5
+
+Writing an HTML e-mail renderer plugin
+======================================
+
+An email renderer class controls how the HTML part of e-mails sent by pretix is built.
+The creation of such a plugin is very similar to creating an export output.
+
+Please read :ref:`Creating a plugin <pluginsetup>` first, if you haven't already.
+
+Output registration
+-------------------
+
+The email HTML renderer API does not make a lot of usage from signals, however, it
+does use a signal to get a list of all available email renderers. Your plugin
+should listen for this signal and return the subclass of ``pretix.base.email.BaseHTMLMailRenderer``
+that we'll provide in this plugin::
+
+    from django.dispatch import receiver
+
+    from pretix.base.signals import register_html_mail_renderers
+
+
+    @receiver(register_html_mail_renderers, dispatch_uid="renderer_custom")
+    def register_mail_renderers(sender, **kwargs):
+        from .email import MyMailRenderer
+        return MyMailRenderer
+
+
+The renderer class
+------------------
+
+.. class:: pretix.base.email.BaseHTMLMailRenderer
+
+   The central object of each email renderer is the subclass of ``BaseHTMLMailRenderer``.
+
+   .. py:attribute:: BaseHTMLMailRenderer.event
+
+      The default constructor sets this property to the event we are currently
+      working for.
+
+   .. autoattribute:: identifier
+
+      This is an abstract attribute, you **must** override this!
+
+   .. autoattribute:: verbose_name
+
+      This is an abstract attribute, you **must** override this!
+
+   .. autoattribute:: thumbnail_filename
+
+      This is an abstract attribute, you **must** override this!
+
+   .. autoattribute:: is_available
+
+   .. automethod:: render
+
+      This is an abstract method, you **must** implement this!
+
+Helper class for template-base renderers
+----------------------------------------
+
+The email renderer that ships with pretix is based on Django templates to generate HTML.
+In case you also want to render emails based on a template, we provided a ready-made base
+class ``TemplateBasedMailRenderer`` that you can re-use to perform the following steps:
+
+* Convert the body text and the signature to HTML using our markdown renderer
+
+* Render the template
+
+* Call `inlinestyler`_ to convert all ``<style>`` style sheets to inline ``style=""``
+  attributes for better compatibility
+
+To use it, you just need to implement some variables::
+
+    class ClassicMailRenderer(TemplateBasedMailRenderer):
+        verbose_name = _('pretix default')
+        identifier = 'classic'
+        thumbnail_filename = 'pretixbase/email/thumb.png'
+        template_name = 'pretixbase/email/plainwrapper.html'
+
+The template is passed the following context variables:
+
+``site``
+   Name of the pretix installation (``settings.PRETIX_INSTANCE_NAME``)
+
+``site_url``
+   Root URL of the pretix installation (``settings.SITE_URL``)
+
+``body``
+   The body as markdown (render with ``{{ body|safe }}``)
+
+``subject``
+   The email subject
+
+``color``
+   The primary color of the event
+
+``event``
+   The ``Event`` object
+
+``signature`` (optional, only if configured)
+   The body as markdown (render with ``{{ signature|safe }}``)
+
+``order`` (optional, only if applicable)
+   The ``Order`` object
+
+.. _inlinestyler: https://pypi.org/project/inlinestyler/

doc/development/api/general.rst

@@ -48,7 +48,8 @@ Backend
 -------
 
 .. automodule:: pretix.control.signals
-   :members: nav_event, html_head, quota_detail_html, nav_topbar, nav_global, nav_organizer, nav_event_settings, order_info, event_settings_widget, oauth_application_registered
+   :members: nav_event, html_head, html_page_start, quota_detail_html, nav_topbar, nav_global, nav_organizer, nav_event_settings,
+   order_info, event_settings_widget, oauth_application_registered
 
 
 .. automodule:: pretix.base.signals

doc/development/api/index.rst

@@ -10,6 +10,8 @@ Contents:
    exporter
    ticketoutput
    payment
+   payment_2.0
+   email
    invoice
    shredder
    customview

doc/development/api/payment.rst

@@ -9,6 +9,10 @@ is very similar to creating an export output.
 
 Please read :ref:`Creating a plugin <pluginsetup>` first, if you haven't already.
 
+.. warning:: We changed our payment provider API a lot in pretix 2.x. Our documentation page on :ref:`payment2.0`
+             might be insightful even if you do not have a payment provider to port, as it outlines the rationale
+             behind the current design.
+
 Provider registration
 ---------------------
 
@@ -31,7 +35,7 @@ that the plugin will provide::
 The provider class
 ------------------
 
-.. class:: pretix.base.payment.BasePaymentProvider
+.. py:class:: pretix.base.payment.BasePaymentProvider
 
    The central object of each payment provider is the subclass of ``BasePaymentProvider``.
 
@@ -54,58 +58,62 @@ The provider class
 
       This is an abstract attribute, you **must** override this!
 
-   .. autoattribute:: is_enabled
+   .. autoattribute:: public_name
 
-   .. automethod:: calculate_fee
+   .. autoattribute:: is_enabled
 
    .. autoattribute:: settings_form_fields
 
    .. automethod:: settings_content_render
 
-   .. automethod:: render_invoice_text
+   .. automethod:: is_allowed
 
    .. automethod:: payment_form_render
 
    .. automethod:: payment_form
 
-   .. automethod:: is_allowed
-
    .. autoattribute:: payment_form_fields
 
-   .. automethod:: checkout_prepare
-
    .. automethod:: payment_is_valid_session
 
+   .. automethod:: checkout_prepare
+
    .. automethod:: checkout_confirm_render
 
       This is an abstract method, you **must** override this!
 
-   .. automethod:: payment_perform
+   .. automethod:: execute_payment
+
+   .. automethod:: calculate_fee
 
    .. automethod:: order_pending_mail_render
 
-   .. automethod:: order_pending_render
+   .. automethod:: payment_pending_render
 
-      This is an abstract method, you **must** override this!
+   .. autoattribute:: abort_pending_allowed
+
+   .. automethod:: render_invoice_text
 
    .. automethod:: order_change_allowed
 
    .. automethod:: order_can_retry
 
-   .. automethod:: order_prepare
+   .. automethod:: payment_prepare
 
-   .. automethod:: order_paid_render
+   .. automethod:: payment_control_render
 
-   .. automethod:: order_control_render
+   .. automethod:: payment_refund_supported
 
-   .. automethod:: order_control_refund_render
+   .. automethod:: payment_partial_refund_supported
 
-   .. automethod:: order_control_refund_perform
-
-   .. automethod:: is_implicit
+   .. automethod:: execute_refund
 
    .. automethod:: shred_payment_info
 
+   .. autoattribute:: is_implicit
+
+   .. autoattribute:: is_meta
+
 
 Additional views
 ----------------

doc/development/api/payment_2.0.rst

@@ -0,0 +1,129 @@
+.. highlight:: python
+   :linenothreshold: 5
+
+.. _`payment2.0`:
+
+Porting a payment provider from pretix 1.x to pretix 2.x
+========================================================
+
+In pretix 2.x, we changed large parts of the payment provider API. This documentation details the changes we made
+and shows you how you can make an existing pretix 1.x payment provider compatible with pretix 2.x
+
+Conceptual overview
+-------------------
+
+In pretix 1.x, an order was always directly connected to a payment provider for the full life of an order. As long as
+an order was unpaid, this could still be changed in some cases, but once an order was paid, no changes to the payment
+provider were possible any more. Additionally, the internal state of orders allowed orders only to be fully paid or
+not paid at all. This leads to a couple of consequences:
+
+* Payment-related functions (like "execute payment" or "do a refund") always operated on full orders.
+
+* Changing the total of an order was basically impossible once an order was paid, since there was no concept of
+  partial payments or partial refunds.
+
+* Payment provider plugins needed to take complicated steps to detect cases that require human intervention, like e.g.
+
+  * An order has expired, no quota is left to revive it, but a payment has been received
+
+  * A payment has been received for a canceled order
+
+  * A payment has been received for an order that has already been paid with a different payment method
+
+  * An external payment service notified us of a refund/dispute
+
+  We noticed that we copied and repeated large portions of code in all our official payment provider plugins, just
+  to deal with some of these cases.
+
+* Sometimes, there is the need to mark an order as refunded within pretix, without automatically triggering a refund
+  with an external API. Every payment method needed to implement a user interface for this independently.
+
+* If a refund was not possible automatically, there was no way user to track which payments actually have been refunded
+  manually and which are still left to do.
+
+* When the payment with one payment provider failed and the user changed to a different payment provider, all
+  information about the first payment was lost from the order object and could only be retrieved from order log data,
+  which also made it hard to design a data shredder API to get rid of this data.
+
+In pretix 2.x, we introduced two new models, :py:class:`OrderPayment <pretix.base.models.OrderPayment>` and
+:py:class:`OrderRefund <pretix.base.models.OrderRefund>`. Each instance of these is connected to an order and
+represents one single attempt to pay or refund a specific amount of money. Each one of these has an individual state,
+can individually fail or succeed, and carries an amount variable that can differ from the order total.
+
+This has the following advantages:
+
+* The system can now detect orders that are over- or underpaid, independent of the payment providers in use.
+
+* Therefore, we can now allow partial payments, partial refunds, and changing paid orders, and automatically detect
+  the cases listed above and notify the user.
+
+Payment providers now interact with those payment and refund objects more than with orders.
+
+Your to-do list
+---------------
+
+Payment processing
+""""""""""""""""""
+
+* The method ``BasePaymentProvider.order_pending_render`` has been removed and replaced by a new
+  ``BasePaymentProvider.payment_pending_render(request, payment)`` method that is passed an ``OrderPayment``
+  object instead of an ``Order``.
+
+* The method ``BasePaymentProvider.payment_form_render`` now receives a new ``total`` parameter.
+
+* The method ``BasePaymentProvider.payment_perform`` has been removed and replaced by a new method
+  ``BasePaymentProvider.execute_payment(request, payment)`` that is passed an ``OrderPayment``
+  object instead of an ``Order``.
+
+* The function ``pretix.base.services.mark_order_paid`` has been removed, instead call ``payment.confirm()``
+  on a pending ``OrderPayment`` object. If no further payments are required for this order, this will also
+  mark the order as paid automatically. Note that ``payment.confirm()`` can still throw a ``QuotaExceededException``,
+  however it will still mark the payment as complete (not the order!), so you should catch this exception and
+  inform the user, but not abort the transaction.
+
+* A new property ``BasePaymentProvider.abort_pending_allowed`` has been introduced. Only if set, the user will
+  be able to retry a payment or switch the payment method when the order currently has a payment object in
+  state ``"pending"``. This replaces ``BasePaymentProvider.order_can_retry``, which no longer exists.
+
+* The methods ``BasePaymentProvider.retry_prepare`` and ``BasePaymentProvider.order_prepare`` have both been
+  replaced by a new method ``BasePaymentProvider.payment_prepare(request, payment)`` that is passed an ``OrderPayment``
+  object instead of an ``Order``. **Keep in mind that this payment object might have an amount property that
+  differs from the order total, if the order is already partially paid.**
+
+* The method ``BasePaymentProvider.order_paid_render`` has been removed.
+
+* The method ``BasePaymentProvider.order_control_render`` has been removed and replaced by a new method
+  ``BasePaymentProvider.payment_control_render(request, payment)`` that is passed an ``OrderPayment``
+  object instead of an ``Order``.
+
+* There's no need to manually deal with excess payments or duplicate payments anymore, just setting the ``OrderPayment``
+  methods to the correct state will do the job.
+
+Creating refunds
+""""""""""""""""
+
+* The methods ``BasePaymentProvider.order_control_refund_render`` and ``BasePaymentProvider.order_control_refund_perform``
+  have been removed.
+
+* Two new boolean methods ``BasePaymentProvider.payment_refund_supported(payment)`` and ``BasePaymentProvider.payment_partial_refund_supported(payment)``
+  have been introduced. They should be set to return ``True`` if and only if the payment API allows to *automatically*
+  transfer the money back to the customer.
+
+* A new method ``BasePaymentProvider.execute_refund(refund)`` has been introduced. This method is called using a
+  ``OrderRefund`` object in ``"created"`` state and is expected to transfer the money back and confirm success with
+  calling ``refund.done()``. This will only ever be called if either ``BasePaymentProvider.payment_refund_supported(payment)``
+  or ``BasePaymentProvider.payment_partial_refund_supported(payment)`` return ``True``.
+
+Processing external refunds
+"""""""""""""""""""""""""""
+
+* If e.g. a webhook API notifies you that a payment has been disputed or refunded with the external API, you are
+  expected to call ``OrderPayment.create_external_refund(self, amount, execution_date, info='{}')`` on this payment.
+  This will create and return an appropriate ``OrderRefund`` object and send out a notification. However, it will not
+  mark the order as refunded, but will ask the event organizer for a decision.
+
+Data shredders
+""""""""""""""
+
+* The method ``BasePaymentProvider.shred_payment_info`` is no longer passed an order, but instead **either**
+  an ``OrderPayment`` **or** an ``OrderRefund``.

doc/development/implementation/models.rst

@@ -86,6 +86,15 @@ Carts and Orders
 .. autoclass:: pretix.base.models.OrderPosition
    :members:
 
+.. autoclass:: pretix.base.models.OrderFee
+   :members:
+
+.. autoclass:: pretix.base.models.OrderPayment
+   :members:
+
+.. autoclass:: pretix.base.models.OrderRefund
+   :members:
+
 .. autoclass:: pretix.base.models.CartPosition
    :members:
 

doc/development/setup.rst

@@ -18,7 +18,7 @@ External Dependencies
 ---------------------
 Your should install the following on your system:
 
-* Python 3.4 or newer
+* Python 3.5 or newer
 * ``pip`` for Python 3 (Debian package: ``python3-pip``)
 * ``python-dev`` for Python 3 (Debian package: ``python3-dev``)
 * ``libffi`` (Debian package: ``libffi-dev``)
@@ -54,10 +54,6 @@ The first thing you need are all the main application's dependencies::
     cd src/
     pip3 install -r requirements.txt -r requirements/dev.txt
 
-If you are working with Python 3.4, you will also need (you can skip this for Python 3.5+)::
-
-    pip3 install -r requirements/py34.txt
-
 Next, you need to copy the SCSS files from the source folder to the STATIC_ROOT directory::
 
     python manage.py collectstatic --noinput
@@ -122,13 +118,15 @@ for example, to check for any errors in any staged files when committing::
     export GIT_WORK_TREE=../
     export GIT_DIR=../.git
     source ../env/bin/activate  # Adjust to however you activate your virtual environment
-    for file in $(git diff --cached --name-only | grep -E '\.py$')
+    for file in $(git diff --cached --name-only | grep -E '\.py$' | grep -Ev "migrations|mt940\.py|pretix/settings\.py|make_testdata\.py|testutils/settings\.py|tests/settings\.py|pretix/base/models/__init__\.py")
     do
+      echo $file
       git show ":$file" | flake8 - --stdin-display-name="$file" || exit 1 # we only want to lint the staged changes, not any un-staged changes
       git show ":$file" | isort -df --check-only - | grep ERROR && exit 1 || true
     done
 
 
+
 This keeps you from accidentally creating commits violating the style guide.
 
 Working with mails

doc/user/events/widget.rst

@@ -107,6 +107,13 @@ voucher's settings.
         </div>
     </noscript>
 
+Disabling the voucher input
+---------------------------
+
+If you want to disable voucher input in the widget, you can pass the ``disable-vouchers`` attribute::
+
+   <pretix-widget event="https://pretix.eu/demo/democon/" disable-vouchers></pretix-widget>
+
 pretix Button
 -------------
 
@@ -136,7 +143,7 @@ resources. Then, instead of the ``pretix-widget`` tag, use the ``pretix-button``
 As you can see, the ``pretix-button`` element takes an additional ``items`` attribute that specifies the items that
 should be added to the cart. The syntax of this attribute is ``item_ITEMID=1,item_ITEMID=2,variation_ITEMID_VARID=4``
 where ``ITEMID`` are the internal IDs of items to be added and ``VARID`` are the internal IDs of variations of those
-items, if the items have variations.
+items, if the items have variations. If you omit the ``items`` attribute, the general start page will be presented.
 
 Just as the widget, the button supports the optional attributes ``voucher`` and ``skip-ssl-check``.
 

readthedocs.yml

@@ -0,0 +1,6 @@
+
+build:
+  image: latest
+
+python:
+  version: 3.6

src/MANIFEST.in

@@ -8,6 +8,8 @@ recursive-include pretix/control/templates *
 recursive-include pretix/presale/templates *
 recursive-include pretix/plugins/banktransfer/templates *
 recursive-include pretix/plugins/banktransfer/static *
+recursive-include pretix/plugins/manualpayment/templates *
+recursive-include pretix/plugins/manualpayment/static *
 recursive-include pretix/plugins/paypal/templates *
 recursive-include pretix/plugins/pretixdroid/templates *
 recursive-include pretix/plugins/pretixdroid/static *

src/pretix/__init__.py

@@ -1 +1 @@
-__version__ = "1.16.0"
+__version__ = "2.0.0"

src/pretix/api/migrations/0001_initial.py

@@ -46,7 +46,7 @@ class Migration(migrations.Migration):
                 ('updated', models.DateTimeField(auto_now=True)),
                 ('name', models.CharField(max_length=255, verbose_name='Application name')),
                 ('redirect_uris', models.TextField(help_text='Allowed URIs list, space separated',
-                                                   validators=[oauth2_provider.validators.validate_uris],
+                                                   validators=[oauth2_provider.validators.URIValidator],
                                                    verbose_name='Redirection URIs')),
                 ('client_id',
                  models.CharField(db_index=True, default=oauth2_provider.generators.generate_client_id, max_length=100,

src/pretix/api/models.py

@@ -11,13 +11,13 @@ from oauth2_provider.models import (
     AbstractAccessToken, AbstractApplication, AbstractGrant,
     AbstractRefreshToken,
 )
-from oauth2_provider.validators import validate_uris
+from oauth2_provider.validators import URIValidator
 
 
 class OAuthApplication(AbstractApplication):
     name = models.CharField(verbose_name=_("Application name"), max_length=255, blank=False)
     redirect_uris = models.TextField(
-        blank=False, validators=[validate_uris],
+        blank=False, validators=[URIValidator],
         verbose_name=_("Redirection URIs"),
         help_text=_("Allowed URIs list, space separated")
     )

src/pretix/api/serializers/cart.py

@@ -0,0 +1,121 @@
+from datetime import timedelta
+
+from django.utils.crypto import get_random_string
+from django.utils.timezone import now
+from django.utils.translation import ugettext_lazy
+from rest_framework import serializers
+from rest_framework.exceptions import ValidationError
+
+from pretix.api.serializers.i18n import I18nAwareModelSerializer
+from pretix.api.serializers.order import (
+    AnswerCreateSerializer, AnswerSerializer,
+)
+from pretix.base.models import Quota
+from pretix.base.models.orders import CartPosition
+
+
+class CartPositionSerializer(I18nAwareModelSerializer):
+    answers = AnswerSerializer(many=True)
+
+    class Meta:
+        model = CartPosition
+        fields = ('id', 'cart_id', 'item', 'variation', 'price', 'attendee_name', 'attendee_email',
+                  'voucher', 'addon_to', 'subevent', 'datetime', 'expires', 'includes_tax',
+                  'answers',)
+
+
+class CartPositionCreateSerializer(I18nAwareModelSerializer):
+    answers = AnswerCreateSerializer(many=True, required=False)
+    expires = serializers.DateTimeField(required=False)
+
+    class Meta:
+        model = CartPosition
+        fields = ('cart_id', 'item', 'variation', 'price', 'attendee_name', 'attendee_email',
+                  'subevent', 'expires', 'includes_tax', 'answers',)
+
+    def create(self, validated_data):
+        answers_data = validated_data.pop('answers')
+        if not validated_data.get('cart_id'):
+            cid = "{}@api".format(get_random_string(48))
+            while CartPosition.objects.filter(cart_id=cid).exists():
+                cid = "{}@api".format(get_random_string(48))
+            validated_data['cart_id'] = cid
+
+        if not validated_data.get('expires'):
+            validated_data['expires'] = now() + timedelta(
+                minutes=self.context['event'].settings.get('reservation_time', as_type=int)
+            )
+
+        with self.context['event'].lock():
+            new_quotas = (validated_data.get('variation').quotas.filter(subevent=validated_data.get('subevent'))
+                          if validated_data.get('variation')
+                          else validated_data.get('item').quotas.filter(subevent=validated_data.get('subevent')))
+            if len(new_quotas) == 0:
+                raise ValidationError(
+                    ugettext_lazy('The product "{}" is not assigned to a quota.').format(
+                        str(validated_data.get('item'))
+                    )
+                )
+            for quota in new_quotas:
+                avail = quota.availability()
+                if avail[0] != Quota.AVAILABILITY_OK or (avail[1] is not None and avail[1] < 1):
+                    raise ValidationError(
+                        ugettext_lazy('There is not enough quota available on quota "{}" to perform '
+                                      'the operation.').format(
+                            quota.name
+                        )
+                    )
+            cp = CartPosition.objects.create(event=self.context['event'], **validated_data)
+
+        for answ_data in answers_data:
+            options = answ_data.pop('options')
+            answ = cp.answers.create(**answ_data)
+            answ.options.add(*options)
+        return cp
+
+    def validate_cart_id(self, cid):
+        if cid and not cid.endswith('@api'):
+            raise ValidationError('Cart ID should end in @api or be empty.')
+
+    def validate_item(self, item):
+        if item.event != self.context['event']:
+            raise ValidationError(
+                'The specified item does not belong to this event.'
+            )
+        if not item.active:
+            raise ValidationError(
+                'The specified item is not active.'
+            )
+        return item
+
+    def validate_subevent(self, subevent):
+        if self.context['event'].has_subevents:
+            if not subevent:
+                raise ValidationError(
+                    'You need to set a subevent.'
+                )
+            if subevent.event != self.context['event']:
+                raise ValidationError(
+                    'The specified subevent does not belong to this event.'
+                )
+        elif subevent:
+            raise ValidationError(
+                'You cannot set a subevent for this event.'
+            )
+        return subevent
+
+    def validate(self, data):
+        if data.get('item'):
+            if data.get('item').has_variations:
+                if not data.get('variation'):
+                    raise ValidationError('You should specify a variation for this item.')
+                else:
+                    if data.get('variation').item != data.get('item'):
+                        raise ValidationError(
+                            'The specified variation does not belong to the specified item.'
+                        )
+            elif data.get('variation'):
+                raise ValidationError(
+                    'You cannot specify a variation for this item.'
+                )
+        return data

src/pretix/api/serializers/item.py

@@ -79,7 +79,7 @@ class ItemSerializer(I18nAwareModelSerializer):
                   'position', 'picture', 'available_from', 'available_until',
                   'require_voucher', 'hide_without_voucher', 'allow_cancel',
                   'min_per_order', 'max_per_order', 'checkin_attention', 'has_variations',
-                  'variations', 'addons', 'original_price')
+                  'variations', 'addons', 'original_price', 'require_approval')
         read_only_fields = ('has_variations', 'picture')
 
     def get_serializer_context(self):

src/pretix/api/serializers/order.py

@@ -3,17 +3,21 @@ from collections import Counter
 from decimal import Decimal
 
 from django.utils.timezone import now
+from django.utils.translation import ugettext_lazy
 from django_countries.fields import Country
 from rest_framework import serializers
 from rest_framework.exceptions import ValidationError
+from rest_framework.relations import SlugRelatedField
 from rest_framework.reverse import reverse
 
 from pretix.api.serializers.i18n import I18nAwareModelSerializer
 from pretix.base.models import (
     Checkin, Invoice, InvoiceAddress, InvoiceLine, Order, OrderPosition,
-    Question, QuestionAnswer, Quota,
+    Question, QuestionAnswer,
+)
+from pretix.base.models.orders import (
+    CartPosition, OrderFee, OrderPayment, OrderRefund,
 )
-from pretix.base.models.orders import OrderFee
 from pretix.base.pdf import get_variables
 from pretix.base.signals import register_ticket_outputs
 
@@ -155,23 +159,61 @@ class OrderPositionSerializer(I18nAwareModelSerializer):
             self.fields.pop('pdf_data')
 
 
+class OrderPaymentTypeField(serializers.Field):
+    # TODO: Remove after pretix 2.2
+    def to_representation(self, instance: Order):
+        t = None
+        for p in instance.payments.all():
+            t = p.provider
+        return t
+
+
+class OrderPaymentDateField(serializers.DateField):
+    # TODO: Remove after pretix 2.2
+    def to_representation(self, instance: Order):
+        t = None
+        for p in instance.payments.all():
+            t = p.payment_date or t
+        if t:
+
+            return super().to_representation(t.date())
+
+
 class OrderFeeSerializer(I18nAwareModelSerializer):
     class Meta:
         model = OrderFee
         fields = ('fee_type', 'value', 'description', 'internal_type', 'tax_rate', 'tax_value', 'tax_rule')
 
 
+class OrderPaymentSerializer(I18nAwareModelSerializer):
+    class Meta:
+        model = OrderPayment
+        fields = ('local_id', 'state', 'amount', 'created', 'payment_date', 'provider')
+
+
+class OrderRefundSerializer(I18nAwareModelSerializer):
+    payment = SlugRelatedField(slug_field='local_id', read_only=True)
+
+    class Meta:
+        model = OrderRefund
+        fields = ('local_id', 'state', 'source', 'amount', 'payment', 'created', 'execution_date', 'provider')
+
+
 class OrderSerializer(I18nAwareModelSerializer):
     invoice_address = InvoiceAddressSerializer()
     positions = OrderPositionSerializer(many=True)
     fees = OrderFeeSerializer(many=True)
     downloads = OrderDownloadsField(source='*')
+    payments = OrderPaymentSerializer(many=True)
+    refunds = OrderRefundSerializer(many=True)
+    payment_date = OrderPaymentDateField(source='*')
+    payment_provider = OrderPaymentTypeField(source='*')
 
     class Meta:
         model = Order
         fields = ('code', 'status', 'secret', 'email', 'locale', 'datetime', 'expires', 'payment_date',
                   'payment_provider', 'fees', 'total', 'comment', 'invoice_address', 'positions', 'downloads',
-                  'checkin_attention', 'last_modified')
+                  'checkin_attention', 'last_modified', 'payments', 'refunds', 'require_approval')
 
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
@@ -298,15 +340,15 @@ class OrderPositionCreateSerializer(I18nAwareModelSerializer):
         if data.get('item'):
             if data.get('item').has_variations:
                 if not data.get('variation'):
-                    raise ValidationError('You should specify a variation for this item.')
+                    raise ValidationError({'variation': ['You should specify a variation for this item.']})
                 else:
                     if data.get('variation').item != data.get('item'):
                         raise ValidationError(
-                            'The specified variation does not belong to the specified item.'
+                            {'variation': ['The specified variation does not belong to the specified item.']}
                         )
             elif data.get('variation'):
                 raise ValidationError(
-                    'You cannot specify a variation for this item.'
+                    {'variation': ['You cannot specify a variation for this item.']}
                 )
         return data
 
@@ -340,11 +382,12 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
     comment = serializers.CharField(required=False, allow_blank=True)
     payment_provider = serializers.CharField(required=True)
     payment_info = CompatibleJSONField(required=False)
+    consume_carts = serializers.ListField(child=serializers.CharField(), required=False)
 
     class Meta:
         model = Order
         fields = ('code', 'status', 'email', 'locale', 'payment_provider', 'fees', 'comment',
-                  'invoice_address', 'positions', 'checkin_attention', 'payment_info')
+                  'invoice_address', 'positions', 'checkin_attention', 'payment_info', 'consume_carts')
 
     def validate_payment_provider(self, pp):
         if pp not in self.context['event'].get_payment_providers():
@@ -367,73 +410,140 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
             raise ValidationError(
                 'An order cannot be empty.'
             )
+        errs = [{} for p in data]
         if any([p.get('positionid') for p in data]):
             if not all([p.get('positionid') for p in data]):
-                raise ValidationError(
-                    'If you set position IDs manually, you need to do so for all positions.'
-                )
+                for i, p in enumerate(data):
+                    if not p.get('positionid'):
+                        errs[i]['positionid'] = [
+                            'If you set position IDs manually, you need to do so for all positions.'
+                        ]
+                raise ValidationError(errs)
 
             last_non_add_on = None
             last_posid = 0
 
-            for p in data:
+            for i, p in enumerate(data):
                 if p['positionid'] != last_posid + 1:
-                    raise ValidationError("Position IDs need to be consecutive.")
+                    errs[i]['positionid'] = [
+                        'Position IDs need to be consecutive.'
+                    ]
                 if p.get('addon_to') and p['addon_to'] != last_non_add_on:
-                    raise ValidationError("If you set addon_to, you need to make sure that the referenced "
-                                          "position ID exists and is transmitted directly before its add-ons.")
+                    errs[i]['addon_to'] = [
+                        "If you set addon_to, you need to make sure that the referenced "
+                        "position ID exists and is transmitted directly before its add-ons."
+                    ]
 
                 if not p.get('addon_to'):
                     last_non_add_on = p['positionid']
                 last_posid = p['positionid']
 
         elif any([p.get('addon_to') for p in data]):
-            raise ValidationError("If you set addon_to, you need to specify position IDs manually.")
+            errs = [
+                {'positionid': ["If you set addon_to on any position, you need to specify position IDs manually."]}
+                for p in data
+            ]
+
+        if any(errs):
+            raise ValidationError(errs)
         return data
 
     def create(self, validated_data):
         fees_data = validated_data.pop('fees') if 'fees' in validated_data else []
         positions_data = validated_data.pop('positions') if 'positions' in validated_data else []
+        payment_provider = validated_data.pop('payment_provider')
+        payment_info = validated_data.pop('payment_info', '{}')
+
         if 'invoice_address' in validated_data:
             ia = InvoiceAddress(**validated_data.pop('invoice_address'))
         else:
             ia = None
 
-        with self.context['event'].lock():
+        with self.context['event'].lock() as now_dt:
             quotadiff = Counter()
-            for pos_data in positions_data:
+
+            consume_carts = validated_data.pop('consume_carts', [])
+            delete_cps = []
+            quota_avail_cache = {}
+            if consume_carts:
+                for cp in CartPosition.objects.filter(event=self.context['event'], cart_id__in=consume_carts):
+                    quotas = (cp.variation.quotas.filter(subevent=cp.subevent)
+                              if cp.variation else cp.item.quotas.filter(subevent=cp.subevent))
+                    for quota in quotas:
+                        if quota not in quota_avail_cache:
+                            quota_avail_cache[quota] = list(quota.availability())
+                        if quota_avail_cache[quota][1] is not None:
+                            quota_avail_cache[quota][1] += 1
+                    if cp.expires > now_dt:
+                        quotadiff.subtract(quotas)
+                    delete_cps.append(cp)
+
+            errs = [{} for p in positions_data]
+
+            for i, pos_data in enumerate(positions_data):
                 new_quotas = (pos_data.get('variation').quotas.filter(subevent=pos_data.get('subevent'))
                               if pos_data.get('variation')
                               else pos_data.get('item').quotas.filter(subevent=pos_data.get('subevent')))
+                if len(new_quotas) == 0:
+                    errs[i]['item'] = [ugettext_lazy('The product "{}" is not assigned to a quota.').format(
+                        str(pos_data.get('item'))
+                    )]
+                else:
+                    for quota in new_quotas:
+                        if quota not in quota_avail_cache:
+                            quota_avail_cache[quota] = list(quota.availability())
+
+                        if quota_avail_cache[quota][1] is not None:
+                            quota_avail_cache[quota][1] -= 1
+                            if quota_avail_cache[quota][1] < 0:
+                                errs[i]['item'] = [
+                                    ugettext_lazy('There is not enough quota available on quota "{}" to perform the operation.').format(
+                                        quota.name
+                                    )
+                                ]
+
                 quotadiff.update(new_quotas)
 
-                for quota, diff in quotadiff.items():
-                    avail = quota.availability()
-                    if avail[0] != Quota.AVAILABILITY_OK or (avail[1] is not None and avail[1] < diff):
-                        raise ValidationError(
-                            'There is not enough quota available on quota "{}" to perform the operation.'.format(
-                                quota.name
-                            )
-                        )
+            if any(errs):
+                raise ValidationError({'positions': errs})
 
             order = Order(event=self.context['event'], **validated_data)
-            order.set_expires(subevents=[p['subevent'] for p in positions_data])
+            order.set_expires(subevents=[p.get('subevent') for p in positions_data])
             order.total = sum([p['price'] for p in positions_data]) + sum([f['value'] for f in fees_data], Decimal('0.00'))
-            if order.total == Decimal('0.00') and validated_data.get('status') != Order.STATUS_PAID:
-                order.payment_provider = 'free'
-                order.status = Order.STATUS_PAID
-            elif order.payment_provider == "free" and order.total != Decimal('0.00'):
-                raise ValidationError('You cannot use the "free" payment provider for non-free orders.')
-            if validated_data.get('status') == Order.STATUS_PAID:
-                order.payment_date = now()
+            order.meta_info = "{}"
             order.save()
+
+            if order.total == Decimal('0.00') and validated_data.get('status') != Order.STATUS_PAID:
+                order.status = Order.STATUS_PAID
+                order.save()
+                order.payments.create(
+                    amount=order.total, provider='free', state=OrderPayment.PAYMENT_STATE_CONFIRMED
+                )
+            elif payment_provider == "free" and order.total != Decimal('0.00'):
+                raise ValidationError('You cannot use the "free" payment provider for non-free orders.')
+            elif validated_data.get('status') == Order.STATUS_PAID:
+                order.payments.create(
+                    amount=order.total,
+                    provider=payment_provider,
+                    info=payment_info,
+                    payment_date=now(),
+                    state=OrderPayment.PAYMENT_STATE_CONFIRMED
+                )
+            elif payment_provider:
+                order.payments.create(
+                    amount=order.total,
+                    provider=payment_provider,
+                    info=payment_info,
+                    state=OrderPayment.PAYMENT_STATE_CREATED
+                )
+
             if ia:
                 ia.order = order
                 ia.save()
             pos_map = {}
             for pos_data in positions_data:
-                answers_data = pos_data.pop('answers')
-                addon_to = pos_data.pop('addon_to')
+                answers_data = pos_data.pop('answers', [])
+                addon_to = pos_data.pop('addon_to', None)
                 pos = OrderPosition(**pos_data)
                 pos.order = order
                 pos._calculate_tax()
@@ -442,9 +552,12 @@ class OrderCreateSerializer(I18nAwareModelSerializer):
                 pos.save()
                 pos_map[pos.positionid] = pos
                 for answ_data in answers_data:
-                    options = answ_data.pop('options')
+                    options = answ_data.pop('options', [])
                     answ = pos.answers.create(**answ_data)
                     answ.options.add(*options)
+
+            for cp in delete_cps:
+                cp.delete()
         for fee_data in fees_data:
             f = OrderFee(**fee_data)
             f.order = order
@@ -471,3 +584,27 @@ class InvoiceSerializer(I18nAwareModelSerializer):
                   'introductory_text', 'additional_text', 'payment_provider_text', 'footer_text', 'lines',
                   'foreign_currency_display', 'foreign_currency_rate', 'foreign_currency_rate_date',
                   'internal_reference')
+
+
+class OrderRefundCreateSerializer(I18nAwareModelSerializer):
+    payment = serializers.IntegerField(required=False, allow_null=True)
+    provider = serializers.CharField(required=True, allow_null=False, allow_blank=False)
+    info = CompatibleJSONField(required=False)
+
+    class Meta:
+        model = OrderRefund
+        fields = ('state', 'source', 'amount', 'payment', 'execution_date', 'provider', 'info')
+
+    def create(self, validated_data):
+        pid = validated_data.pop('payment', None)
+        if pid:
+            try:
+                p = self.context['order'].payments.get(local_id=pid)
+            except OrderPayment.DoesNotExist:
+                raise ValidationError('Unknown payment ID.')
+        else:
+            p = None
+
+        order = OrderRefund(order=self.context['order'], payment=p, **validated_data)
+        order.save()
+        return order

src/pretix/api/serializers/waitinglist.py

@@ -8,7 +8,7 @@ class WaitingListSerializer(I18nAwareModelSerializer):
 
     class Meta:
         model = WaitingListEntry
-        fields = ('id', 'created', 'email', 'voucher', 'item', 'variation', 'locale', 'subevent')
+        fields = ('id', 'created', 'email', 'voucher', 'item', 'variation', 'locale', 'subevent', 'priority')
         read_only_fields = ('id', 'created', 'voucher')
 
     def validate(self, data):

src/pretix/api/urls.py

@@ -4,6 +4,8 @@ from django.apps import apps
 from django.conf.urls import include, url
 from rest_framework import routers
 
+from pretix.api.views import cart
+
 from .views import (
     checkin, event, item, oauth, order, organizer, voucher, waitinglist,
 )
@@ -28,6 +30,7 @@ event_router.register(r'invoices', order.InvoiceViewSet)
 event_router.register(r'taxrules', event.TaxRuleViewSet)
 event_router.register(r'waitinglistentries', waitinglist.WaitingListViewSet)
 event_router.register(r'checkinlists', checkin.CheckinListViewSet)
+event_router.register(r'cartpositions', cart.CartPositionViewSet)
 
 checkinlist_router = routers.DefaultRouter()
 checkinlist_router.register(r'positions', checkin.CheckinListPositionViewSet)
@@ -39,6 +42,10 @@ item_router = routers.DefaultRouter()
 item_router.register(r'variations', item.ItemVariationViewSet)
 item_router.register(r'addons', item.ItemAddOnViewSet)
 
+order_router = routers.DefaultRouter()
+order_router.register(r'payments', order.PaymentViewSet)
+order_router.register(r'refunds', order.RefundViewSet)
+
 # Force import of all plugins to give them a chance to register URLs with the router
 for app in apps.get_app_configs():
     if hasattr(app, 'PretixPluginMeta'):
@@ -54,6 +61,7 @@ urlpatterns = [
         include(question_router.urls)),
     url(r'^organizers/(?P<organizer>[^/]+)/events/(?P<event>[^/]+)/checkinlists/(?P<list>[^/]+)/',
         include(checkinlist_router.urls)),
+    url(r'^organizers/(?P<organizer>[^/]+)/events/(?P<event>[^/]+)/orders/(?P<order>[^/]+)/', include(order_router.urls)),
     url(r"^oauth/authorize$", oauth.AuthorizationView.as_view(), name="authorize"),
     url(r"^oauth/token$", oauth.TokenView.as_view(), name="token"),
     url(r"^oauth/revoke_token$", oauth.RevokeTokenView.as_view(), name="revoke-token"),

src/pretix/api/views/cart.py

@@ -0,0 +1,46 @@
+from django.db import transaction
+from rest_framework import status, viewsets
+from rest_framework.filters import OrderingFilter
+from rest_framework.mixins import CreateModelMixin, DestroyModelMixin
+from rest_framework.response import Response
+
+from pretix.api.serializers.cart import (
+    CartPositionCreateSerializer, CartPositionSerializer,
+)
+from pretix.base.models import CartPosition
+
+
+class CartPositionViewSet(CreateModelMixin, DestroyModelMixin, viewsets.ReadOnlyModelViewSet):
+    serializer_class = CartPositionSerializer
+    queryset = CartPosition.objects.none()
+    filter_backends = (OrderingFilter,)
+    ordering = ('datetime',)
+    ordering_fields = ('datetime', 'cart_id')
+    lookup_field = 'id'
+    permission = 'can_view_orders'
+    write_permission = 'can_change_orders'
+
+    def get_queryset(self):
+        return CartPosition.objects.filter(
+            event=self.request.event,
+            cart_id__endswith="@api"
+        )
+
+    def get_serializer_context(self):
+        ctx = super().get_serializer_context()
+        ctx['event'] = self.request.event
+        return ctx
+
+    def create(self, request, *args, **kwargs):
+        serializer = CartPositionCreateSerializer(data=request.data, context=self.get_serializer_context())
+        serializer.is_valid(raise_exception=True)
+        with transaction.atomic():
+            self.perform_create(serializer)
+            cp = serializer.instance
+            serializer = CartPositionSerializer(cp, context=serializer.context)
+
+        headers = self.get_success_headers(serializer.data)
+        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
+
+    def perform_create(self, serializer):
+        serializer.save()

src/pretix/api/views/checkin.py

@@ -1,6 +1,7 @@
 from django.core.exceptions import ValidationError
 from django.db.models import Count, F, Max, OuterRef, Prefetch, Subquery
 from django.db.models.functions import Coalesce
+from django.http import Http404
 from django.shortcuts import get_object_or_404
 from django.utils.functional import cached_property
 from django.utils.timezone import now
@@ -32,7 +33,7 @@ class CheckinListViewSet(viewsets.ModelViewSet):
     serializer_class = CheckinListSerializer
     queryset = CheckinList.objects.none()
     filter_backends = (DjangoFilterBackend,)
-    filter_class = CheckinListFilter
+    filterset_class = CheckinListFilter
     permission = 'can_view_orders'
     write_permission = 'can_change_event_settings'
 
@@ -175,13 +176,16 @@ class CheckinListPositionViewSet(viewsets.ReadOnlyModelViewSet):
         },
     }
 
-    filter_class = CheckinOrderPositionFilter
+    filterset_class = CheckinOrderPositionFilter
     permission = 'can_view_orders'
     write_permission = 'can_change_orders'
 
     @cached_property
     def checkinlist(self):
-        return get_object_or_404(CheckinList, event=self.request.event, pk=self.kwargs.get("list"))
+        try:
+            return get_object_or_404(CheckinList, event=self.request.event, pk=self.kwargs.get("list"))
+        except ValueError:
+            raise Http404()
 
     def get_queryset(self):
         cqs = Checkin.objects.filter(

src/pretix/api/views/event.py

@@ -129,7 +129,7 @@ class SubEventViewSet(ConditionalListView, viewsets.ReadOnlyModelViewSet):
     serializer_class = SubEventSerializer
     queryset = ItemCategory.objects.none()
     filter_backends = (DjangoFilterBackend, filters.OrderingFilter)
-    filter_class = SubEventFilter
+    filterset_class = SubEventFilter
 
     def get_queryset(self):
         return self.request.event.subevents.prefetch_related(

src/pretix/api/views/item.py

@@ -41,7 +41,7 @@ class ItemViewSet(ConditionalListView, viewsets.ModelViewSet):
     filter_backends = (DjangoFilterBackend, OrderingFilter)
     ordering_fields = ('id', 'position')
     ordering = ('position', 'id')
-    filter_class = ItemFilter
+    filterset_class = ItemFilter
     permission = 'can_change_items'
     write_permission = 'can_change_items'
 
@@ -207,7 +207,7 @@ class ItemCategoryViewSet(ConditionalListView, viewsets.ModelViewSet):
     serializer_class = ItemCategorySerializer
     queryset = ItemCategory.objects.none()
     filter_backends = (DjangoFilterBackend, OrderingFilter)
-    filter_class = ItemCategoryFilter
+    filterset_class = ItemCategoryFilter
     ordering_fields = ('id', 'position')
     ordering = ('position', 'id')
     permission = 'can_change_items'
@@ -261,7 +261,7 @@ class QuestionViewSet(ConditionalListView, viewsets.ModelViewSet):
     serializer_class = QuestionSerializer
     queryset = Question.objects.none()
     filter_backends = (DjangoFilterBackend, OrderingFilter)
-    filter_class = QuestionFilter
+    filterset_class = QuestionFilter
     ordering_fields = ('id', 'position')
     ordering = ('position', 'id')
     permission = 'can_change_items'
@@ -359,7 +359,7 @@ class QuotaViewSet(ConditionalListView, viewsets.ModelViewSet):
     serializer_class = QuotaSerializer
     queryset = Quota.objects.none()
     filter_backends = (DjangoFilterBackend, OrderingFilter,)
-    filter_class = QuotaFilter
+    filterset_class = QuotaFilter
     ordering_fields = ('id', 'size')
     ordering = ('id',)
     permission = 'can_change_items'

src/pretix/api/views/order.py

@@ -6,9 +6,10 @@ from django.db import transaction
 from django.db.models import Q
 from django.db.models.functions import Concat
 from django.http import FileResponse
+from django.shortcuts import get_object_or_404
 from django.utils.timezone import make_aware, now
 from django_filters.rest_framework import DjangoFilterBackend, FilterSet
-from rest_framework import serializers, status, viewsets
+from rest_framework import mixins, serializers, status, viewsets
 from rest_framework.decorators import detail_route
 from rest_framework.exceptions import (
     APIException, NotFound, PermissionDenied, ValidationError,
@@ -19,20 +20,23 @@ from rest_framework.response import Response
 
 from pretix.api.models import OAuthAccessToken
 from pretix.api.serializers.order import (
-    InvoiceSerializer, OrderCreateSerializer, OrderPositionSerializer,
-    OrderSerializer,
+    InvoiceSerializer, OrderCreateSerializer, OrderPaymentSerializer,
+    OrderPositionSerializer, OrderRefundCreateSerializer,
+    OrderRefundSerializer, OrderSerializer,
 )
 from pretix.base.models import (
-    Invoice, Order, OrderPosition, Quota, TeamAPIToken,
+    Invoice, Order, OrderPayment, OrderPosition, OrderRefund, Quota,
+    TeamAPIToken,
 )
+from pretix.base.payment import PaymentException
 from pretix.base.services.invoices import (
     generate_cancellation, generate_invoice, invoice_pdf, invoice_qualified,
     regenerate_invoice,
 )
 from pretix.base.services.mail import SendMailException
 from pretix.base.services.orders import (
-    OrderError, cancel_order, extend_order, mark_order_expired,
-    mark_order_paid, mark_order_refunded,
+    OrderChangeManager, OrderError, approve_order, cancel_order, deny_order,
+    extend_order, mark_order_expired, mark_order_refunded,
 )
 from pretix.base.services.tickets import (
     get_cachedticket_for_order, get_cachedticket_for_position,
@@ -41,14 +45,14 @@ from pretix.base.signals import order_placed, register_ticket_outputs
 
 
 class OrderFilter(FilterSet):
-    email = django_filters.CharFilter(name='email', lookup_expr='iexact')
-    code = django_filters.CharFilter(name='code', lookup_expr='iexact')
-    status = django_filters.CharFilter(name='status', lookup_expr='iexact')
-    modified_since = django_filters.IsoDateTimeFilter(name='last_modified', lookup_expr='gte')
+    email = django_filters.CharFilter(field_name='email', lookup_expr='iexact')
+    code = django_filters.CharFilter(field_name='code', lookup_expr='iexact')
+    status = django_filters.CharFilter(field_name='status', lookup_expr='iexact')
+    modified_since = django_filters.IsoDateTimeFilter(field_name='last_modified', lookup_expr='gte')
 
     class Meta:
         model = Order
-        fields = ['code', 'status', 'email', 'locale']
+        fields = ['code', 'status', 'email', 'locale', 'require_approval']
 
 
 class OrderViewSet(CreateModelMixin, viewsets.ReadOnlyModelViewSet):
@@ -57,7 +61,7 @@ class OrderViewSet(CreateModelMixin, viewsets.ReadOnlyModelViewSet):
     filter_backends = (DjangoFilterBackend, OrderingFilter)
     ordering = ('datetime',)
     ordering_fields = ('datetime', 'code', 'status')
-    filter_class = OrderFilter
+    filterset_class = OrderFilter
     lookup_field = 'code'
     permission = 'can_view_orders'
     write_permission = 'can_change_orders'
@@ -70,7 +74,7 @@ class OrderViewSet(CreateModelMixin, viewsets.ReadOnlyModelViewSet):
     def get_queryset(self):
         return self.request.event.orders.prefetch_related(
             'positions', 'positions__checkins', 'positions__item', 'positions__answers', 'positions__answers__options',
-            'positions__answers__question', 'fees'
+            'positions__answers__question', 'fees', 'payments', 'refunds', 'refunds__payment'
         ).select_related(
             'invoice_address'
         )
@@ -122,14 +126,33 @@ class OrderViewSet(CreateModelMixin, viewsets.ReadOnlyModelViewSet):
         order = self.get_object()
 
         if order.status in (Order.STATUS_PENDING, Order.STATUS_EXPIRED):
+
+            ps = order.pending_sum
             try:
-                mark_order_paid(
-                    order, manual=True,
-                    user=request.user if request.user.is_authenticated else None,
-                    auth=request.auth,
+                p = order.payments.get(
+                    state__in=(OrderPayment.PAYMENT_STATE_PENDING, OrderPayment.PAYMENT_STATE_CREATED),
+                    provider='manual',
+                    amount=ps
                 )
+            except OrderPayment.DoesNotExist:
+                order.payments.filter(state__in=(OrderPayment.PAYMENT_STATE_PENDING,
+                                                 OrderPayment.PAYMENT_STATE_CREATED)) \
+                    .update(state=OrderPayment.PAYMENT_STATE_CANCELED)
+                p = order.payments.create(
+                    state=OrderPayment.PAYMENT_STATE_CREATED,
+                    provider='manual',
+                    amount=ps,
+                    fee=None
+                )
+
+            try:
+                p.confirm(auth=self.request.auth,
+                          user=self.request.user if request.user.is_authenticated else None,
+                          count_waitinglist=False)
             except Quota.QuotaExceededException as e:
                 return Response({'detail': str(e)}, status=status.HTTP_400_BAD_REQUEST)
+            except PaymentException as e:
+                return Response({'detail': str(e)}, status=status.HTTP_400_BAD_REQUEST)
             except SendMailException:
                 pass
 
@@ -159,6 +182,42 @@ class OrderViewSet(CreateModelMixin, viewsets.ReadOnlyModelViewSet):
         )
         return self.retrieve(request, [], **kwargs)
 
+    @detail_route(methods=['POST'])
+    def approve(self, request, **kwargs):
+        send_mail = request.data.get('send_email', True)
+
+        order = self.get_object()
+        try:
+            approve_order(
+                order,
+                user=request.user if request.user.is_authenticated else None,
+                auth=request.auth if isinstance(request.auth, (TeamAPIToken, OAuthAccessToken)) else None,
+                send_mail=send_mail,
+            )
+        except Quota.QuotaExceededException as e:
+            return Response({'detail': str(e)}, status=status.HTTP_400_BAD_REQUEST)
+        except OrderError as e:
+            return Response({'detail': str(e)}, status=status.HTTP_400_BAD_REQUEST)
+        return self.retrieve(request, [], **kwargs)
+
+    @detail_route(methods=['POST'])
+    def deny(self, request, **kwargs):
+        send_mail = request.data.get('send_email', True)
+        comment = request.data.get('comment', '')
+
+        order = self.get_object()
+        try:
+            deny_order(
+                order,
+                user=request.user if request.user.is_authenticated else None,
+                auth=request.auth if isinstance(request.auth, (TeamAPIToken, OAuthAccessToken)) else None,
+                send_mail=send_mail,
+                comment=comment,
+            )
+        except OrderError as e:
+            return Response({'detail': str(e)}, status=status.HTTP_400_BAD_REQUEST)
+        return self.retrieve(request, [], **kwargs)
+
     @detail_route(methods=['POST'])
     def mark_pending(self, request, **kwargs):
         order = self.get_object()
@@ -170,7 +229,6 @@ class OrderViewSet(CreateModelMixin, viewsets.ReadOnlyModelViewSet):
             )
 
         order.status = Order.STATUS_PENDING
-        order.payment_manual = True
         order.save()
         order.log_action(
             'pretix.event.order.unpaid',
@@ -285,7 +343,7 @@ class OrderViewSet(CreateModelMixin, viewsets.ReadOnlyModelViewSet):
 
 
 class OrderPositionFilter(FilterSet):
-    order = django_filters.CharFilter(name='order', lookup_expr='code__iexact')
+    order = django_filters.CharFilter(field_name='order', lookup_expr='code__iexact')
     has_checkin = django_filters.rest_framework.BooleanFilter(method='has_checkin_qs')
     attendee_name = django_filters.CharFilter(method='attendee_name_qs')
     search = django_filters.CharFilter(method='search_qs')
@@ -313,18 +371,22 @@ class OrderPositionFilter(FilterSet):
             'secret': ['exact'],
             'order__status': ['exact', 'in'],
             'addon_to': ['exact', 'in'],
-            'subevent': ['exact', 'in']
+            'subevent': ['exact', 'in'],
+            'pseudonymization_id': ['exact'],
+            'voucher__code': ['exact'],
+            'voucher': ['exact'],
         }
 
 
-class OrderPositionViewSet(viewsets.ReadOnlyModelViewSet):
+class OrderPositionViewSet(mixins.DestroyModelMixin, viewsets.ReadOnlyModelViewSet):
     serializer_class = OrderPositionSerializer
     queryset = OrderPosition.objects.none()
     filter_backends = (DjangoFilterBackend, OrderingFilter)
     ordering = ('order__datetime', 'positionid')
     ordering_fields = ('order__code', 'order__datetime', 'positionid', 'attendee_name', 'order__status',)
-    filter_class = OrderPositionFilter
+    filterset_class = OrderPositionFilter
     permission = 'can_view_orders'
+    write_permission = 'can_change_orders'
 
     def get_queryset(self):
         return OrderPosition.objects.filter(order__event=self.request.event).prefetch_related(
@@ -365,11 +427,232 @@ class OrderPositionViewSet(viewsets.ReadOnlyModelViewSet):
             )
             return resp
 
+    def perform_destroy(self, instance):
+        try:
+            ocm = OrderChangeManager(
+                instance.order,
+                user=self.request.user if self.request.user.is_authenticated else None,
+                auth=self.request.auth,
+                notify=False
+            )
+            ocm.cancel(instance)
+            ocm.commit()
+        except OrderError as e:
+            raise ValidationError(str(e))
+        except Quota.QuotaExceededException as e:
+            raise ValidationError(str(e))
+
+
+class PaymentViewSet(viewsets.ReadOnlyModelViewSet):
+    serializer_class = OrderPaymentSerializer
+    queryset = OrderPayment.objects.none()
+    permission = 'can_view_orders'
+    write_permission = 'can_change_orders'
+    lookup_field = 'local_id'
+
+    def get_queryset(self):
+        order = get_object_or_404(Order, code=self.kwargs['order'], event=self.request.event)
+        return order.payments.all()
+
+    @detail_route(methods=['POST'])
+    def confirm(self, request, **kwargs):
+        payment = self.get_object()
+        force = request.data.get('force', False)
+
+        if payment.state not in (OrderPayment.PAYMENT_STATE_PENDING, OrderPayment.PAYMENT_STATE_CREATED):
+            return Response({'detail': 'Invalid state of payment'}, status=status.HTTP_400_BAD_REQUEST)
+
+        try:
+            payment.confirm(user=self.request.user if self.request.user.is_authenticated else None,
+                            auth=self.request.auth,
+                            count_waitinglist=False,
+                            force=force)
+        except Quota.QuotaExceededException as e:
+            return Response({'detail': str(e)}, status=status.HTTP_400_BAD_REQUEST)
+        except PaymentException as e:
+            return Response({'detail': str(e)}, status=status.HTTP_400_BAD_REQUEST)
+        except SendMailException:
+            pass
+        return self.retrieve(request, [], **kwargs)
+
+    @detail_route(methods=['POST'])
+    def refund(self, request, **kwargs):
+        payment = self.get_object()
+        amount = serializers.DecimalField(max_digits=10, decimal_places=2).to_internal_value(
+            request.data.get('amount', str(payment.amount))
+        )
+        mark_refunded = request.data.get('mark_refunded', False)
+
+        if payment.state != OrderPayment.PAYMENT_STATE_CONFIRMED:
+            return Response({'detail': 'Invalid state of payment.'}, status=status.HTTP_400_BAD_REQUEST)
+
+        full_refund_possible = payment.payment_provider.payment_refund_supported(payment)
+        partial_refund_possible = payment.payment_provider.payment_partial_refund_supported(payment)
+        available_amount = payment.amount - payment.refunded_amount
+
+        if amount <= 0:
+            return Response({'amount': ['Invalid refund amount.']}, status=status.HTTP_400_BAD_REQUEST)
+        if amount > available_amount:
+            return Response(
+                {'amount': ['Invalid refund amount, only {} are available to refund.'.format(available_amount)]},
+                status=status.HTTP_400_BAD_REQUEST)
+        if amount != payment.amount and not partial_refund_possible:
+            return Response({'amount': ['Partial refund not available for this payment method.']},
+                            status=status.HTTP_400_BAD_REQUEST)
+        if amount == payment.amount and not full_refund_possible:
+            return Response({'amount': ['Full refund not available for this payment method.']},
+                            status=status.HTTP_400_BAD_REQUEST)
+        r = payment.order.refunds.create(
+            payment=payment,
+            source=OrderRefund.REFUND_SOURCE_ADMIN,
+            state=OrderRefund.REFUND_STATE_CREATED,
+            amount=amount,
+            provider=payment.provider
+        )
+
+        try:
+            r.payment_provider.execute_refund(r)
+        except PaymentException as e:
+            r.state = OrderRefund.REFUND_STATE_FAILED
+            r.save()
+            return Response({'detail': 'External error: {}'.format(str(e))},
+                            status=status.HTTP_400_BAD_REQUEST)
+        else:
+            payment.order.log_action('pretix.event.order.refund.created', {
+                'local_id': r.local_id,
+                'provider': r.provider,
+            }, user=self.request.user if self.request.user.is_authenticated else None, auth=self.request.auth)
+            if payment.order.pending_sum > 0:
+                if mark_refunded:
+                    mark_order_refunded(payment.order,
+                                        user=self.request.user if self.request.user.is_authenticated else None,
+                                        auth=self.request.auth)
+                else:
+                    payment.order.status = Order.STATUS_PENDING
+                    payment.order.set_expires(
+                        now(),
+                        payment.order.event.subevents.filter(
+                            id__in=payment.order.positions.values_list('subevent_id', flat=True))
+                    )
+                    payment.order.save()
+            return Response(OrderRefundSerializer(r).data, status=status.HTTP_200_OK)
+
+    @detail_route(methods=['POST'])
+    def cancel(self, request, **kwargs):
+        payment = self.get_object()
+
+        if payment.state not in (OrderPayment.PAYMENT_STATE_PENDING, OrderPayment.PAYMENT_STATE_CREATED):
+            return Response({'detail': 'Invalid state of payment'}, status=status.HTTP_400_BAD_REQUEST)
+
+        with transaction.atomic():
+            payment.state = OrderPayment.PAYMENT_STATE_CANCELED
+            payment.save()
+            payment.order.log_action('pretix.event.order.payment.canceled', {
+                'local_id': payment.local_id,
+                'provider': payment.provider,
+            }, user=self.request.user if self.request.user.is_authenticated else None, auth=self.request.auth)
+        return self.retrieve(request, [], **kwargs)
+
+
+class RefundViewSet(CreateModelMixin, viewsets.ReadOnlyModelViewSet):
+    serializer_class = OrderRefundSerializer
+    queryset = OrderRefund.objects.none()
+    permission = 'can_view_orders'
+    write_permission = 'can_change_orders'
+    lookup_field = 'local_id'
+
+    def get_queryset(self):
+        order = get_object_or_404(Order, code=self.kwargs['order'], event=self.request.event)
+        return order.refunds.all()
+
+    @detail_route(methods=['POST'])
+    def cancel(self, request, **kwargs):
+        refund = self.get_object()
+
+        if refund.state not in (OrderRefund.REFUND_STATE_CREATED, OrderRefund.REFUND_STATE_TRANSIT,
+                                OrderRefund.REFUND_STATE_EXTERNAL):
+            return Response({'detail': 'Invalid state of refund'}, status=status.HTTP_400_BAD_REQUEST)
+
+        with transaction.atomic():
+            refund.state = OrderRefund.REFUND_STATE_CANCELED
+            refund.save()
+            refund.order.log_action('pretix.event.order.refund.canceled', {
+                'local_id': refund.local_id,
+                'provider': refund.provider,
+            }, user=self.request.user if self.request.user.is_authenticated else None, auth=self.request.auth)
+        return self.retrieve(request, [], **kwargs)
+
+    @detail_route(methods=['POST'])
+    def process(self, request, **kwargs):
+        refund = self.get_object()
+
+        if refund.state != OrderRefund.REFUND_STATE_EXTERNAL:
+            return Response({'detail': 'Invalid state of refund'}, status=status.HTTP_400_BAD_REQUEST)
+
+        refund.done(user=self.request.user if self.request.user.is_authenticated else None, auth=self.request.auth)
+        if request.data.get('mark_refunded', False):
+            mark_order_refunded(refund.order, user=self.request.user if self.request.user.is_authenticated else None,
+                                auth=self.request.auth)
+        else:
+            refund.order.status = Order.STATUS_PENDING
+            refund.order.set_expires(
+                now(),
+                refund.order.event.subevents.filter(
+                    id__in=refund.order.positions.values_list('subevent_id', flat=True))
+            )
+            refund.order.save()
+        return self.retrieve(request, [], **kwargs)
+
+    @detail_route(methods=['POST'])
+    def done(self, request, **kwargs):
+        refund = self.get_object()
+
+        if refund.state not in (OrderRefund.REFUND_STATE_CREATED, OrderRefund.REFUND_STATE_TRANSIT):
+            return Response({'detail': 'Invalid state of refund'}, status=status.HTTP_400_BAD_REQUEST)
+
+        refund.done(user=self.request.user if self.request.user.is_authenticated else None, auth=self.request.auth)
+        return self.retrieve(request, [], **kwargs)
+
+    def get_serializer_context(self):
+        ctx = super().get_serializer_context()
+        ctx['order'] = get_object_or_404(Order, code=self.kwargs['order'], event=self.request.event)
+        return ctx
+
+    def create(self, request, *args, **kwargs):
+        mark_refunded = request.data.pop('mark_refunded', False)
+        serializer = OrderRefundCreateSerializer(data=request.data, context=self.get_serializer_context())
+        serializer.is_valid(raise_exception=True)
+        with transaction.atomic():
+            self.perform_create(serializer)
+            r = serializer.instance
+            serializer = OrderRefundSerializer(r, context=serializer.context)
+
+            r.order.log_action(
+                'pretix.event.order.refund.created', {
+                    'local_id': r.local_id,
+                    'provider': r.provider,
+                },
+                user=request.user if request.user.is_authenticated else None,
+                auth=request.auth
+            )
+            if mark_refunded:
+                mark_order_refunded(
+                    r.order,
+                    user=request.user if request.user.is_authenticated else None,
+                    auth=(request.auth if request.auth else None),
+                )
+
+        headers = self.get_success_headers(serializer.data)
+        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)
+
+    def perform_create(self, serializer):
+        serializer.save()
+
 
 class InvoiceFilter(FilterSet):
     refers = django_filters.CharFilter(method='refers_qs')
     number = django_filters.CharFilter(method='nr_qs')
-    order = django_filters.CharFilter(name='order', lookup_expr='code__iexact')
+    order = django_filters.CharFilter(field_name='order', lookup_expr='code__iexact')
 
     def refers_qs(self, queryset, name, value):
         return queryset.annotate(
@@ -396,7 +679,7 @@ class InvoiceViewSet(viewsets.ReadOnlyModelViewSet):
     filter_backends = (DjangoFilterBackend, OrderingFilter)
     ordering = ('nr',)
     ordering_fields = ('nr', 'date')
-    filter_class = InvoiceFilter
+    filterset_class = InvoiceFilter
     permission = 'can_view_orders'
     lookup_url_kwarg = 'number'
     lookup_field = 'nr'

src/pretix/api/views/organizer.py

@@ -12,7 +12,7 @@ class OrganizerViewSet(viewsets.ReadOnlyModelViewSet):
     lookup_url_kwarg = 'organizer'
 
     def get_queryset(self):
-        if self.request.user.is_authenticated():
+        if self.request.user.is_authenticated:
             if self.request.user.has_active_staff_session(self.request.session.session_key):
                 return Organizer.objects.all()
             elif isinstance(self.request.auth, OAuthAccessToken):

src/pretix/api/views/voucher.py

@@ -34,7 +34,7 @@ class VoucherViewSet(viewsets.ModelViewSet):
     filter_backends = (DjangoFilterBackend, OrderingFilter)
     ordering = ('id',)
     ordering_fields = ('id', 'code', 'max_usages', 'valid_until', 'value')
-    filter_class = VoucherFilter
+    filterset_class = VoucherFilter
     permission = 'can_view_vouchers'
     write_permission = 'can_change_vouchers'
 

src/pretix/api/views/waitinglist.py

@@ -28,7 +28,7 @@ class WaitingListViewSet(viewsets.ModelViewSet):
     filter_backends = (DjangoFilterBackend, OrderingFilter)
     ordering = ('created',)
     ordering_fields = ('id', 'created', 'email', 'item')
-    filter_class = WaitingListFilter
+    filterset_class = WaitingListFilter
     permission = 'can_view_orders'
     write_permission = 'can_change_orders'
 

src/pretix/base/__init__.py

@@ -12,6 +12,7 @@ class PretixBaseConfig(AppConfig):
         from . import exporters  # NOQA
         from . import invoice  # NOQA
         from . import notifications  # NOQA
+        from . import email  # NOQA
         from .services import auth, export, mail, tickets, cart, orders, invoices, cleanup, update_check, quotas, notifications  # NOQA
 
         try:

src/pretix/base/email.py

@@ -1,7 +1,18 @@
 import logging
 from smtplib import SMTPRecipientsRefused, SMTPSenderRefused
 
+import bleach
+import markdown
+from django.conf import settings
 from django.core.mail.backends.smtp import EmailBackend
+from django.dispatch import receiver
+from django.template.loader import get_template
+from django.utils.translation import ugettext_lazy as _
+from inlinestyler.utils import inline_css
+
+from pretix.base.models import Event, Order
+from pretix.base.signals import register_html_mail_renderers
+from pretix.base.templatetags.rich_text import markdown_compile
 
 logger = logging.getLogger('pretix.base.email')
 
@@ -24,3 +35,103 @@ class CustomSMTPBackend(EmailBackend):
                 raise SMTPRecipientsRefused(senderrs)
         finally:
             self.close()
+
+
+class BaseHTMLMailRenderer:
+    """
+    This is the base class for all HTML e-mail renderers.
+    """
+
+    def __init__(self, event: Event):
+        self.event = event
+
+    def __str__(self):
+        return self.identifier
+
+    def render(self, plain_body: str, plain_signature: str, subject: str, order: Order=None) -> str:
+        """
+        This method should generate the HTML part of the email.
+
+        :param plain_body: The body of the email in plain text.
+        :param plain_signature: The signature with event organizer contact details in plain text.
+        :param subject: The email subject.
+        :param order: The order if this email is connected to one, otherwise ``None``.
+        :return: An HTML string
+        """
+        raise NotImplementedError()
+
+    @property
+    def verbose_name(self) -> str:
+        """
+        A human-readable name for this renderer. This should be short but self-explanatory.
+        """
+        raise NotImplementedError()  # NOQA
+
+    @property
+    def identifier(self) -> str:
+        """
+        A short and unique identifier for this renderer.
+        This should only contain lowercase letters and in most cases will be the same as your package name or prefixed
+        with your package name.
+        """
+        raise NotImplementedError()  # NOQA
+
+    @property
+    def thumbnail_filename(self) -> str:
+        """
+        A file name discoverable in the static file storage that contains a preview of your renderer. This should
+        be with aspect resolution 4:3.
+        """
+        raise NotImplementedError()  # NOQA
+
+    @property
+    def is_available(self) -> bool:
+        """
+        This renderer will only be available if this returns ``True``. You can use this to limit this renderer
+        to certain events. Defaults to ``True``.
+        """
+        return True
+
+
+class TemplateBasedMailRenderer(BaseHTMLMailRenderer):
+
+    @property
+    def template_name(self):
+        raise NotImplemented
+
+    def render(self, plain_body: str, plain_signature: str, subject: str, order: Order) -> str:
+        body_md = bleach.linkify(markdown_compile(plain_body))
+        htmlctx = {
+            'site': settings.PRETIX_INSTANCE_NAME,
+            'site_url': settings.SITE_URL,
+            'body': body_md,
+            'subject': str(subject),
+            'color': '#8E44B3'
+        }
+        if self.event:
+            htmlctx['event'] = self.event
+            htmlctx['color'] = self.event.settings.primary_color
+
+        if plain_signature:
+            signature_md = plain_signature.replace('\n', '<br>\n')
+            signature_md = bleach.linkify(bleach.clean(markdown.markdown(signature_md), tags=bleach.ALLOWED_TAGS + ['p', 'br']))
+            htmlctx['signature'] = signature_md
+
+        if order:
+            htmlctx['order'] = order
+
+        tpl = get_template(self.template_name)
+        body_html = inline_css(tpl.render(htmlctx))
+        return body_html
+
+
+class ClassicMailRenderer(TemplateBasedMailRenderer):
+    verbose_name = _('pretix default')
+    identifier = 'classic'
+    thumbnail_filename = 'pretixbase/email/thumb.png'
+    template_name = 'pretixbase/email/plainwrapper.html'
+
+
+@receiver(register_html_mail_renderers, dispatch_uid="pretixbase_email_renderers")
+def base_renderers(sender, **kwargs):
+    return [ClassicMailRenderer]

src/pretix/base/exporters/invoices.py

@@ -5,9 +5,12 @@ from zipfile import ZipFile
 
 import dateutil.parser
 from django import forms
+from django.db.models import Exists, OuterRef, Q
 from django.dispatch import receiver
 from django.utils.translation import ugettext_lazy as _
 
+from pretix.base.models import OrderPayment
+
 from ..exporter import BaseExporter
 from ..services.invoices import invoice_pdf_task
 from ..signals import register_data_exporters
@@ -21,7 +24,14 @@ class InvoiceExporter(BaseExporter):
         qs = self.event.invoices.filter(shredded=False)
 
         if form_data.get('payment_provider'):
-            qs = qs.filter(order__payment_provider=form_data.get('payment_provider'))
+            qs = qs.annotate(
+                has_payment_with_provider=Exists(
+                    OrderPayment.objects.filter(
+                        Q(order=OuterRef('pk')) & Q(provider=form_data.get('payment_provider'))
+                    )
+                )
+            )
+            qs = qs.filter(has_payment_with_provider=1)
 
         if form_data.get('date_from'):
             date_value = form_data.get('date_from')
@@ -84,10 +94,10 @@ class InvoiceExporter(BaseExporter):
                          (k, v.verbose_name) for k, v in self.event.get_payment_providers().items()
                      ],
                      required=False,
-                     help_text=_('Only include invoices for orders that are currently set to this payment provider. '
-                                 'Note that this might include some invoices of other payment providers or misses '
-                                 'some invoices if the payment provider of an order has been changed and a new invoice '
-                                 'has been generated.')
+                     help_text=_('Only include invoices for orders that have at least one payment attempt '
+                                 'with this payment provider. '
+                                 'Note that this might include some invoices of orders which in the end have been '
+                                 'fully or partially paid with a different provider.')
                  )),
             ]
         )

src/pretix/base/exporters/orderlist.py

@@ -5,13 +5,13 @@ from decimal import Decimal
 import pytz
 from defusedcsv import csv
 from django import forms
-from django.db.models import Sum
+from django.db.models import DateTimeField, Max, OuterRef, Subquery, Sum
 from django.dispatch import receiver
 from django.utils.formats import localize
 from django.utils.translation import ugettext as _, ugettext_lazy
 
 from pretix.base.models import InvoiceAddress, Order, OrderPosition
-from pretix.base.models.orders import OrderFee
+from pretix.base.models.orders import OrderFee, OrderPayment, OrderRefund
 
 from ..exporter import BaseExporter
 from ..signals import register_data_exporters
@@ -55,7 +55,19 @@ class OrderListExporter(BaseExporter):
         tz = pytz.timezone(self.event.settings.timezone)
         writer = csv.writer(output, quoting=csv.QUOTE_NONNUMERIC, delimiter=",")
 
-        qs = self.event.orders.all().select_related('invoice_address').prefetch_related('invoices')
+        p_date = OrderPayment.objects.filter(
+            order=OuterRef('pk'),
+            state__in=(OrderPayment.PAYMENT_STATE_CONFIRMED, OrderPayment.PAYMENT_STATE_REFUNDED),
+            payment_date__isnull=False
+        ).values('order').annotate(
+            m=Max('payment_date')
+        ).values(
+            'm'
+        ).order_by()
+
+        qs = self.event.orders.annotate(
+            payment_date=Subquery(p_date, output_field=DateTimeField())
+        ).select_related('invoice_address').prefetch_related('invoices')
         if form_data['paid_only']:
             qs = qs.filter(status=Order.STATUS_PAID)
         tax_rates = self._get_all_tax_rates(qs)
@@ -63,7 +75,7 @@ class OrderListExporter(BaseExporter):
         headers = [
             _('Order code'), _('Order total'), _('Status'), _('Email'), _('Order date'),
             _('Company'), _('Name'), _('Address'), _('ZIP code'), _('City'), _('Country'), _('VAT ID'),
-            _('Payment date'), _('Payment type'), _('Fees'), _('Order locale')
+            _('Date of last payment'), _('Fees'), _('Order locale')
         ]
 
         for tr in tax_rates:
@@ -77,11 +89,6 @@ class OrderListExporter(BaseExporter):
 
         writer.writerow(headers)
 
-        provider_names = {
-            k: v.verbose_name
-            for k, v in self.event.get_payment_providers().items()
-        }
-
         full_fee_sum_cache = {
             o['order__id']: o['grosssum'] for o in
             OrderFee.objects.values('tax_rate', 'order__id').order_by().annotate(grosssum=Sum('value'))
@@ -114,7 +121,8 @@ class OrderListExporter(BaseExporter):
                     order.invoice_address.street,
                     order.invoice_address.zipcode,
                     order.invoice_address.city,
-                    order.invoice_address.country if order.invoice_address.country else order.invoice_address.country_old,
+                    order.invoice_address.country if order.invoice_address.country else
+                    order.invoice_address.country_old,
                     order.invoice_address.vat_id,
                 ]
             except InvoiceAddress.DoesNotExist:
@@ -122,14 +130,14 @@ class OrderListExporter(BaseExporter):
 
             row += [
                 order.payment_date.astimezone(tz).strftime('%Y-%m-%d') if order.payment_date else '',
-                provider_names.get(order.payment_provider, order.payment_provider),
                 localize(full_fee_sum_cache.get(order.id) or Decimal('0.00')),
                 order.locale,
             ]
 
             for tr in tax_rates:
                 taxrate_values = sum_cache.get((order.id, tr), {'grosssum': Decimal('0.00'), 'taxsum': Decimal('0.00')})
-                fee_taxrate_values = fee_sum_cache.get((order.id, tr), {'grosssum': Decimal('0.00'), 'taxsum': Decimal('0.00')})
+                fee_taxrate_values = fee_sum_cache.get((order.id, tr),
+                                                       {'grosssum': Decimal('0.00'), 'taxsum': Decimal('0.00')})
 
                 row += [
                     localize(taxrate_values['grosssum'] + fee_taxrate_values['grosssum']),
@@ -144,6 +152,77 @@ class OrderListExporter(BaseExporter):
         return '{}_orders.csv'.format(self.event.slug), 'text/csv', output.getvalue().encode("utf-8")
 
 
+class PaymentListExporter(BaseExporter):
+    identifier = 'paymentlistcsv'
+    verbose_name = ugettext_lazy('List of payments and refunds (CSV)')
+
+    @property
+    def export_form_fields(self):
+        return OrderedDict(
+            [
+                ('successful_only',
+                 forms.BooleanField(
+                     label=_('Only successful payments'),
+                     initial=True,
+                     required=False
+                 )),
+            ]
+        )
+
+    def render(self, form_data: dict):
+        output = io.StringIO()
+        tz = pytz.timezone(self.event.settings.timezone)
+        writer = csv.writer(output, quoting=csv.QUOTE_NONNUMERIC, delimiter=",")
+
+        provider_names = {
+            k: v.verbose_name
+            for k, v in self.event.get_payment_providers().items()
+        }
+
+        payments = OrderPayment.objects.filter(
+            order__event=self.event,
+        ).order_by('created')
+        refunds = OrderRefund.objects.filter(
+            order__event=self.event
+        ).order_by('created')
+
+        if form_data['successful_only']:
+            payments = payments.filter(
+                state__in=(OrderPayment.PAYMENT_STATE_CONFIRMED, OrderPayment.PAYMENT_STATE_REFUNDED),
+            )
+            refunds = refunds.filter(
+                state=OrderRefund.REFUND_STATE_DONE,
+            )
+
+        objs = sorted(list(payments) + list(refunds), key=lambda o: o.created)
+
+        headers = [
+            _('Order'), _('Payment ID'), _('Creation date'), _('Completion date'), _('Status'),
+            _('Amount'), _('Payment method')
+        ]
+        writer.writerow(headers)
+
+        for obj in objs:
+            if isinstance(obj, OrderPayment) and obj.payment_date:
+                d2 = obj.payment_date.astimezone(tz).date().strftime('%Y-%m-%d')
+            elif isinstance(obj, OrderRefund) and obj.execution_date:
+                d2 = obj.execution_date.astimezone(tz).date().strftime('%Y-%m-%d')
+            else:
+                d2 = ''
+            row = [
+                obj.order.code,
+                obj.full_id,
+                obj.created.astimezone(tz).date().strftime('%Y-%m-%d'),
+                d2,
+                obj.get_state_display(),
+                localize(obj.amount * (-1 if isinstance(obj, OrderRefund) else 1)),
+                provider_names.get(obj.provider, obj.provider)
+            ]
+            writer.writerow(row)
+
+        return '{}_payments.csv'.format(self.event.slug), 'text/csv', output.getvalue().encode("utf-8")
+
+
 class QuotaListExporter(BaseExporter):
     identifier = 'quotalistcsv'
     verbose_name = ugettext_lazy('Quota availabilities (CSV)')
@@ -180,6 +259,11 @@ def register_orderlist_exporter(sender, **kwargs):
     return OrderListExporter
 
 
+@receiver(register_data_exporters, dispatch_uid="exporter_paymentlist")
+def register_paymentlist_exporter(sender, **kwargs):
+    return PaymentListExporter
+
+
 @receiver(register_data_exporters, dispatch_uid="exporter_quotalist")
 def register_quotalist_exporter(sender, **kwargs):
     return QuotaListExporter

src/pretix/base/forms/auth.py

@@ -39,7 +39,7 @@ class LoginForm(forms.Form):
         password = self.cleaned_data.get('password')
 
         if email and password:
-            self.user_cache = authenticate(email=email.lower(), password=password)
+            self.user_cache = authenticate(request=self.request, email=email.lower(), password=password)
             if self.user_cache is None:
                 raise forms.ValidationError(
                     self.error_messages['invalid_login'],
@@ -180,12 +180,4 @@ class PasswordForgotForm(forms.Form):
         super().__init__(*args, **kwargs)
 
     def clean_email(self):
-        email = self.cleaned_data['email']
-        try:
-            self.cleaned_data['user'] = User.objects.get(email=email)
-            return email
-        except User.DoesNotExist:
-            raise forms.ValidationError(
-                _("We are unable to find a user matching the data you provided."),
-                code='unknown_user'
-            )
+        return self.cleaned_data['email']

src/pretix/base/forms/questions.py

@@ -199,6 +199,16 @@ class BaseInvoiceAddressForm(forms.ModelForm):
 
             if event.settings.invoice_name_required:
                 self.fields['name'].required = True
+        elif event.settings.invoice_address_company_required:
+            self.initial['is_business'] = True
+
+            self.fields['is_business'].widget = BusinessBooleanRadio(require_business=True)
+            self.fields['company'].required = True
+            self.fields['company'].widget.is_required = True
+            self.fields['company'].widget.attrs['required'] = 'required'
+            del self.fields['company'].widget.attrs['data-display-dependency']
+            if 'vat_id' in self.fields:
+                del self.fields['vat_id'].widget.attrs['data-display-dependency']
         else:
             self.fields['company'].widget.attrs['data-required-if'] = '#id_is_business_1'
             self.fields['name'].widget.attrs['data-required-if'] = '#id_is_business_0'

src/pretix/base/forms/widgets.py

@@ -110,14 +110,22 @@ class SplitDateTimePickerWidget(forms.SplitDateTimeWidget):
 
 
 class BusinessBooleanRadio(forms.RadioSelect):
-    def __init__(self, attrs=None):
-        choices = (
-            ('individual', _('Individual customer')),
-            ('business', _('Business customer')),
-        )
+    def __init__(self, require_business=False, attrs=None):
+        self.require_business = require_business
+        if self.require_business:
+            choices = (
+                ('business', _('Business customer')),
+            )
+        else:
+            choices = (
+                ('individual', _('Individual customer')),
+                ('business', _('Business customer')),
+            )
         super().__init__(attrs, choices)
 
     def format_value(self, value):
+        if self.require_business:
+            return 'business'
         try:
             return {True: 'business', False: 'individual'}[value]
         except KeyError:
@@ -125,6 +133,8 @@ class BusinessBooleanRadio(forms.RadioSelect):
 
     def value_from_datadict(self, data, files, name):
         value = data.get(name)
+        if self.require_business:
+            return True
         return {
             'business': True,
             True: True,

src/pretix/base/invoice.py

@@ -184,10 +184,15 @@ class BaseReportlabInvoiceRenderer(BaseInvoiceRenderer):
 
 class ThumbnailingImageReader(ImageReader):
     def resize(self, width, height, dpi):
+        if width is None:
+            width = height * self._image.size[0] / self._image.size[1]
+        if height is None:
+            height = width * self._image.size[1] / self._image.size[0]
         self._image.thumbnail(
             size=(int(width * dpi / 72), int(height * dpi / 72)),
             resample=BICUBIC
         )
+        return width, height
 
 
 class ClassicInvoiceRenderer(BaseReportlabInvoiceRenderer):
@@ -204,6 +209,18 @@ class ClassicInvoiceRenderer(BaseReportlabInvoiceRenderer):
 
         canvas.restoreState()
 
+    def _draw_invoice_to(self, canvas):
+        p = Paragraph(self.invoice.invoice_to.strip().replace('\n', '<br />\n'), style=self.stylesheet['Normal'])
+        p.wrapOn(canvas, 85 * mm, 50 * mm)
+        p_size = p.wrap(85 * mm, 50 * mm)
+        p.drawOn(canvas, 25 * mm, (297 - 52) * mm - p_size[1])
+
+    def _draw_invoice_from(self, canvas):
+        p = Paragraph(self.invoice.invoice_from.strip().replace('\n', '<br />\n'), style=self.stylesheet['Normal'])
+        p.wrapOn(canvas, 70 * mm, 50 * mm)
+        p_size = p.wrap(70 * mm, 50 * mm)
+        p.drawOn(canvas, 25 * mm, (297 - 17) * mm - p_size[1])
+
     def _on_first_page(self, canvas: Canvas, doc):
         canvas.setCreator('pretix.eu')
         canvas.setTitle(pgettext('invoice', 'Invoice {num}').format(num=self.invoice.number))
@@ -220,20 +237,14 @@ class ClassicInvoiceRenderer(BaseReportlabInvoiceRenderer):
         textobject.textLine(pgettext('invoice', 'Invoice from').upper())
         canvas.drawText(textobject)
 
-        p = Paragraph(self.invoice.invoice_from.strip().replace('\n', '<br />\n'), style=self.stylesheet['Normal'])
-        p.wrapOn(canvas, 70 * mm, 50 * mm)
-        p_size = p.wrap(70 * mm, 50 * mm)
-        p.drawOn(canvas, 25 * mm, (297 - 17) * mm - p_size[1])
+        self._draw_invoice_from(canvas)
 
         textobject = canvas.beginText(25 * mm, (297 - 50) * mm)
         textobject.setFont('OpenSansBd', 8)
         textobject.textLine(pgettext('invoice', 'Invoice to').upper())
         canvas.drawText(textobject)
 
-        p = Paragraph(self.invoice.invoice_to.strip().replace('\n', '<br />\n'), style=self.stylesheet['Normal'])
-        p.wrapOn(canvas, 85 * mm, 50 * mm)
-        p_size = p.wrap(85 * mm, 50 * mm)
-        p.drawOn(canvas, 25 * mm, (297 - 52) * mm - p_size[1])
+        self._draw_invoice_to(canvas)
 
         textobject = canvas.beginText(125 * mm, (297 - 38) * mm)
         textobject.setFont('OpenSansBd', 8)

src/pretix/base/management/commands/rebuild.py

@@ -8,10 +8,10 @@ class Command(BaseCommand):
     help = "Rebuild static files and language files"
 
     def handle(self, *args, **options):
-        call_command('compilemessages', verbosity=1, interactive=False)
-        call_command('compilejsi18n', verbosity=1, interactive=False)
+        call_command('compilemessages', verbosity=1)
+        call_command('compilejsi18n', verbosity=1)
         call_command('collectstatic', verbosity=1, interactive=False)
-        call_command('compress', verbosity=1, interactive=False)
+        call_command('compress', verbosity=1)
         try:
             gs = GlobalSettingsObject()
             del gs.settings.update_check_last

src/pretix/base/middleware.py

@@ -3,8 +3,8 @@ from urllib.parse import urlsplit
 
 import pytz
 from django.conf import settings
-from django.core.urlresolvers import get_script_prefix
 from django.http import HttpRequest, HttpResponse
+from django.urls import get_script_prefix
 from django.utils import timezone, translation
 from django.utils.cache import patch_vary_headers
 from django.utils.deprecation import MiddlewareMixin
@@ -172,6 +172,12 @@ class SecurityMiddleware(MiddlewareMixin):
             return resp
 
         resp['X-XSS-Protection'] = '1'
+
+        # We just need to have a P3P, not matter whats in there
+        # https://blogs.msdn.microsoft.com/ieinternals/2013/09/17/a-quick-look-at-p3p/
+        # https://github.com/pretix/pretix/issues/765
+        resp['P3P'] = 'CP=\"ALL DSP COR CUR ADM TAI OUR IND COM NAV INT\"'
+
         h = {
             'default-src': ["{static}"],
             'script-src': ['{static}', 'https://checkout.stripe.com', 'https://js.stripe.com'],

src/pretix/base/migrations/0077_auto_20171124_1629_squashed_0088_auto_20180328_1217.py

@@ -0,0 +1,424 @@
+# Generated by Django 2.0.8 on 2018-09-11 14:50
+
+import django.core.validators
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+from django.db.models import F
+from django.db.models.functions import Concat
+from django.utils.crypto import get_random_string
+from django.utils.translation import ugettext as _
+
+import pretix.base.models.auth
+import pretix.base.validators
+from pretix.base.i18n import language
+
+
+def create_checkin_lists(apps, schema_editor):
+    Event = apps.get_model('pretixbase', 'Event')
+    Checkin = apps.get_model('pretixbase', 'Checkin')
+    EventSettingsStore = apps.get_model('pretixbase', 'Event_SettingsStore')
+    for e in Event.objects.all():
+        locale = EventSettingsStore.objects.filter(object=e, key='locale').first()
+        if locale:
+            locale = locale.value
+        else:
+            locale = settings.LANGUAGE_CODE
+
+        if e.has_subevents:
+            for se in e.subevents.all():
+                with language(locale):
+                    cl = e.checkin_lists.create(name=se.name, subevent=se, all_products=True)
+                Checkin.objects.filter(position__subevent=se, position__order__event=e).update(list=cl)
+        else:
+            with language(locale):
+                cl = e.checkin_lists.create(name=_('Default list'), all_products=True)
+            Checkin.objects.filter(position__order__event=e).update(list=cl)
+
+
+def set_full_invoice_no(app, schema_editor):
+    Invoice = app.get_model('pretixbase', 'Invoice')
+    Invoice.objects.all().update(
+        full_invoice_no=Concat(F('prefix'), F('invoice_no'))
+    )
+
+
+def set_position(apps, schema_editor):
+    Question = apps.get_model('pretixbase', 'Question')
+    for q in Question.objects.all():
+        for i, option in enumerate(q.options.all()):
+            option.position = i
+            option.save()
+
+
+def set_is_staff(apps, schema_editor):
+    User = apps.get_model('pretixbase', 'User')
+    User.objects.filter(is_superuser=True).update(is_staff=True)
+
+
+def set_identifiers(apps, schema_editor):
+    Question = apps.get_model('pretixbase', 'Question')
+    QuestionOption = apps.get_model('pretixbase', 'QuestionOption')
+
+    for q in Question.objects.select_related('event'):
+        if not q.identifier:
+            charset = list('ABCDEFGHJKLMNPQRSTUVWXYZ3789')
+            while True:
+                code = get_random_string(length=8, allowed_chars=charset)
+                if not Question.objects.filter(event=q.event, identifier=code).exists():
+                    q.identifier = code
+                    q.save()
+                    break
+
+    for q in QuestionOption.objects.select_related('question', 'question__event'):
+        if not q.identifier:
+            charset = list('ABCDEFGHJKLMNPQRSTUVWXYZ3789')
+            while True:
+                code = get_random_string(length=8, allowed_chars=charset)
+                if not QuestionOption.objects.filter(question__event=q.question.event, identifier=code).exists():
+                    q.identifier = code
+                    q.save()
+                    break
+
+
+class Migration(migrations.Migration):
+    replaces = [('pretixbase', '0077_auto_20171124_1629'), ('pretixbase', '0078_auto_20171206_1603'),
+                ('pretixbase', '0079_auto_20180115_0855'), ('pretixbase', '0080_question_ask_during_checkin'),
+                ('pretixbase', '0081_auto_20180220_1031'), ('pretixbase', '0082_auto_20180222_0938'),
+                ('pretixbase', '0083_auto_20180228_2102'), ('pretixbase', '0084_questionoption_position'),
+                ('pretixbase', '0085_auto_20180312_1119'), ('pretixbase', '0086_auto_20180320_1219'),
+                ('pretixbase', '0087_auto_20180317_1952'), ('pretixbase', '0088_auto_20180328_1217')]
+
+    dependencies = [
+        ('pretixbase', '0076_orderfee_squashed_0082_invoiceaddress_internal_reference'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='event',
+            name='slug',
+            field=models.SlugField(
+                help_text='Should be short, only contain lowercase letters, numbers, dots, and dashes, and must be '
+                          'unique among your events. We recommend some kind of abbreviation or a date with less than '
+                          '10 characters that can be easily remembered, but you can also choose to use a random '
+                          'value. This will be used in URLs, order codes, invoice numbers, and bank transfer '
+                          'references.',
+                validators=[django.core.validators.RegexValidator(
+                    message='The slug may only contain letters, numbers, dots and dashes.', regex='^[a-zA-Z0-9.-]+$'),
+                    pretix.base.validators.EventSlugBlacklistValidator()], verbose_name='Short form'),
+        ),
+        migrations.AlterField(
+            model_name='eventmetaproperty',
+            name='name',
+            field=models.CharField(db_index=True,
+                                   help_text='Can not contain spaces or special characters except underscores',
+                                   max_length=50, validators=[django.core.validators.RegexValidator(
+                    message='The property name may only contain letters, numbers and underscores.',
+                    regex='^[a-zA-Z0-9_]+$')], verbose_name='Name'),
+        ),
+        migrations.AlterField(
+            model_name='organizer',
+            name='slug',
+            field=models.SlugField(
+                help_text='Should be short, only contain lowercase letters, numbers, dots, and dashes. Every slug can '
+                          'only be used once. This is being used in URLs to refer to your organizer accounts and your'
+                          ' events.',
+                validators=[django.core.validators.RegexValidator(
+                    message='The slug may only contain letters, numbers, dots and dashes.', regex='^[a-zA-Z0-9.-]+$'),
+                    pretix.base.validators.OrganizerSlugBlacklistValidator()], verbose_name='Short form'),
+        ),
+        migrations.CreateModel(
+            name='CheckinList',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('name', models.CharField(max_length=190)),
+                ('all_products',
+                 models.BooleanField(default=True, verbose_name='All products (including newly created ones)')),
+                ('event', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='checkin_lists',
+                                            to='pretixbase.Event')),
+                ('subevent', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE,
+                                               to='pretixbase.SubEvent', verbose_name='Date')),
+                ('limit_products',
+                 models.ManyToManyField(blank=True, to='pretixbase.Item', verbose_name='Limit to products')),
+            ],
+        ),
+        migrations.AddField(
+            model_name='checkin',
+            name='list',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT,
+                                    related_name='checkins', to='pretixbase.CheckinList'),
+        ),
+        migrations.RunPython(
+            code=create_checkin_lists,
+            reverse_code=django.db.migrations.operations.special.RunPython.noop,
+        ),
+        migrations.AlterField(
+            model_name='checkin',
+            name='list',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='checkins',
+                                    to='pretixbase.CheckinList'),
+        ),
+        migrations.CreateModel(
+            name='NotificationSetting',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('action_type', models.CharField(max_length=255)),
+                ('method', models.CharField(choices=[('mail', 'E-mail')], max_length=255)),
+                ('event', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE,
+                                            to='pretixbase.Event')),
+                ('user', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL)),
+                ('enabled', models.BooleanField(default=True)),
+            ],
+        ),
+        migrations.AlterUniqueTogether(
+            name='notificationsetting',
+            unique_together={('user', 'action_type', 'event', 'method')},
+        ),
+        migrations.AddField(
+            model_name='logentry',
+            name='visible',
+            field=models.BooleanField(default=True),
+        ),
+        migrations.AlterField(
+            model_name='notificationsetting',
+            name='event',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE,
+                                    related_name='notification_settings', to='pretixbase.Event'),
+        ),
+        migrations.AlterField(
+            model_name='notificationsetting',
+            name='user',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='notification_settings',
+                                    to=settings.AUTH_USER_MODEL),
+        ),
+        migrations.AddField(
+            model_name='user',
+            name='notifications_send',
+            field=models.BooleanField(default=True, help_text='If turned off, you will not get any notifications.',
+                                      verbose_name='Receive notifications according to my settings below'),
+        ),
+        migrations.AddField(
+            model_name='user',
+            name='notifications_token',
+            field=models.CharField(default=pretix.base.models.auth.generate_notifications_token, max_length=255),
+        ),
+        migrations.AddField(
+            model_name='invoice',
+            name='full_invoice_no',
+            field=models.CharField(db_index=True, default='', max_length=190),
+            preserve_default=False,
+        ),
+        migrations.AlterField(
+            model_name='question',
+            name='type',
+            field=models.CharField(
+                choices=[('N', 'Number'), ('S', 'Text (one line)'), ('T', 'Multiline text'), ('B', 'Yes/No'),
+                         ('C', 'Choose one from a list'), ('M', 'Choose multiple from a list'), ('F', 'File upload'),
+                         ('D', 'Date'), ('H', 'Time'), ('W', 'Date and time')], max_length=5,
+                verbose_name='Question type'),
+        ),
+        migrations.RunPython(
+            code=set_full_invoice_no,
+            reverse_code=django.db.migrations.operations.special.RunPython.noop,
+        ),
+        migrations.AddField(
+            model_name='question',
+            name='ask_during_checkin',
+            field=models.BooleanField(default=False,
+                                      help_text='This will only work if you handle your check-in with pretixdroid 1.8 '
+                                                'or '
+                                                'newer or pretixdesk 0.2 or newer.',
+                                      verbose_name='Ask during check-in instead of in the ticket buying process'),
+        ),
+        migrations.AddField(
+            model_name='checkinlist',
+            name='include_pending',
+            field=models.BooleanField(default=False,
+                                      help_text='With this option, people will be able to check in even if the order '
+                                                'have '
+                                                'not been paid. This only works with pretixdesk 0.3.0 or newer or '
+                                                'pretixdroid 1.9 or newer.',
+                                      verbose_name='Include pending orders'),
+        ),
+        migrations.AlterField(
+            model_name='event',
+            name='presale_end',
+            field=models.DateTimeField(blank=True,
+                                       help_text='Optional. No products will be sold after this date. If you do not '
+                                                 'set '
+                                                 'this value, the presale will end after the end date of your event.',
+                                       null=True, verbose_name='End of presale'),
+        ),
+        migrations.AlterField(
+            model_name='logentry',
+            name='event',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL,
+                                    to='pretixbase.Event'),
+        ),
+        migrations.AlterField(
+            model_name='subevent',
+            name='presale_end',
+            field=models.DateTimeField(blank=True,
+                                       help_text='Optional. No products will be sold after this date. If you do not '
+                                                 'set '
+                                                 'this value, the presale will end after the end date of your event.',
+                                       null=True, verbose_name='End of presale'),
+        ),
+        migrations.AlterField(
+            model_name='user',
+            name='require_2fa',
+            field=models.BooleanField(default=False, verbose_name='Two-factor authentification is required to log in'),
+        ),
+        migrations.AddField(
+            model_name='order',
+            name='checkin_attention',
+            field=models.BooleanField(default=False,
+                                      help_text='If you set this, the check-in app will show a visible warning that '
+                                                'tickets of this order require special attention. This will not show '
+                                                'any '
+                                                'details or custom message, so you need to brief your check-in staff '
+                                                'how '
+                                                'to handle these cases.',
+                                      verbose_name='Requires special attention'),
+        ),
+        migrations.AddField(
+            model_name='taxrule',
+            name='custom_rules',
+            field=models.TextField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='orderfee',
+            name='fee_type',
+            field=models.CharField(
+                choices=[('payment', 'Payment fee'), ('shipping', 'Shipping fee'), ('service', 'Service fee'),
+                         ('other', 'Other fees')], max_length=100),
+        ),
+        migrations.AlterModelOptions(
+            name='questionoption',
+            options={'ordering': ('position', 'id'), 'verbose_name': 'Question option',
+                     'verbose_name_plural': 'Question options'},
+        ),
+        migrations.AddField(
+            model_name='questionoption',
+            name='position',
+            field=models.IntegerField(default=0),
+        ),
+        migrations.AlterField(
+            model_name='question',
+            name='position',
+            field=models.PositiveIntegerField(default=0, verbose_name='Position'),
+        ),
+        migrations.RunPython(
+            code=set_position,
+            reverse_code=django.db.migrations.operations.special.RunPython.noop,
+        ),
+        migrations.AddField(
+            model_name='question',
+            name='identifier',
+            field=models.CharField(default='', max_length=190),
+            preserve_default=False,
+        ),
+        migrations.AddField(
+            model_name='questionoption',
+            name='identifier',
+            field=models.CharField(default='', max_length=190),
+            preserve_default=False,
+        ),
+        migrations.AlterField(
+            model_name='user',
+            name='locale',
+            field=models.CharField(
+                choices=[('en', 'English'), ('de', 'German'), ('de-informal', 'German (informal)'), ('nl', 'Dutch'),
+                         ('da', 'Danish'), ('pt-br', 'Portuguese (Brazil)')], default='en', max_length=50,
+                verbose_name='Language'),
+        ),
+        migrations.RunPython(
+            code=set_identifiers,
+            reverse_code=django.db.migrations.operations.special.RunPython.noop,
+        ),
+        migrations.AlterField(
+            model_name='cachedcombinedticket',
+            name='file',
+            field=models.FileField(blank=True, max_length=255, null=True,
+                                   upload_to=pretix.base.models.orders.cachedcombinedticket_name),
+        ),
+        migrations.AlterField(
+            model_name='cachedticket',
+            name='file',
+            field=models.FileField(blank=True, max_length=255, null=True,
+                                   upload_to=pretix.base.models.orders.cachedticket_name),
+        ),
+        migrations.AlterField(
+            model_name='invoice',
+            name='file',
+            field=models.FileField(blank=True, max_length=255, null=True,
+                                   upload_to=pretix.base.models.invoices.invoice_filename),
+        ),
+        migrations.AlterField(
+            model_name='question',
+            name='identifier',
+            field=models.CharField(
+                help_text='You can enter any value here to make it easier to match the data with other sources. If '
+                          'you do '
+                          'not input one, we will generate one automatically.',
+                max_length=190, verbose_name='Internal identifier'),
+        ),
+        migrations.AlterField(
+            model_name='questionanswer',
+            name='file',
+            field=models.FileField(blank=True, max_length=255, null=True,
+                                   upload_to=pretix.base.models.orders.answerfile_name),
+        ),
+        migrations.RunPython(
+            code=set_is_staff,
+            reverse_code=django.db.migrations.operations.special.RunPython.noop,
+        ),
+        migrations.RemoveField(
+            model_name='user',
+            name='is_superuser',
+        ),
+        migrations.CreateModel(
+            name='StaffSession',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('date_start', models.DateTimeField(auto_now_add=True)),
+                ('date_end', models.DateTimeField(blank=True, null=True)),
+                ('session_key', models.CharField(max_length=255)),
+                ('comment', models.TextField()),
+            ],
+        ),
+        migrations.CreateModel(
+            name='StaffSessionAuditLog',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('datetime', models.DateTimeField(auto_now_add=True)),
+                ('url', models.CharField(max_length=255)),
+                ('session', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='logs',
+                                              to='pretixbase.StaffSession')),
+                ('impersonating', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE,
+                                                    to=settings.AUTH_USER_MODEL)),
+                ('method', models.CharField(default='GET', max_length=255)),
+            ],
+            options={
+                'ordering': ('datetime',),
+            },
+        ),
+        migrations.AddField(
+            model_name='staffsession',
+            name='user',
+            field=models.ForeignKey(default=None, on_delete=django.db.models.deletion.CASCADE,
+                                    to=settings.AUTH_USER_MODEL),
+            preserve_default=False,
+        ),
+        migrations.AlterModelOptions(
+            name='staffsession',
+            options={'ordering': ('date_start',)},
+        ),
+        migrations.AlterField(
+            model_name='item',
+            name='picture',
+            field=models.ImageField(blank=True, max_length=255, null=True,
+                                    upload_to=pretix.base.models.items.itempicture_upload_to,
+                                    verbose_name='Product picture'),
+        ),
+    ]

src/pretix/base/migrations/0089_auto_20180315_1322.py

@@ -9,6 +9,7 @@ class Migration(migrations.Migration):
 
     dependencies = [
         ('pretixbase', '0088_auto_20180328_1217'),
+        ('pretixapi', '0001_initial')
     ]
 
     operations = [

src/pretix/base/migrations/0090_auto_20180509_0917_squashed_0095_auto_20180604_1129.py

@@ -0,0 +1,85 @@
+# Generated by Django 2.0.8 on 2018-09-11 14:54
+
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+from django.utils.crypto import get_random_string
+
+
+def set_pids(apps, schema_editor):
+    OrderPosition = apps.get_model('pretixbase', 'OrderPosition')  # noqa
+    taken = set()
+    charset = list('ABCDEFGHJKLMNPQRSTUVWXYZ3789')
+    for op in OrderPosition.objects.iterator():
+        while True:
+            code = get_random_string(length=10, allowed_chars=charset)
+            if code not in taken:
+                op.pseudonymization_id = code
+                taken.add(code)
+                break
+        op.save(update_fields=['pseudonymization_id'])
+
+
+class Migration(migrations.Migration):
+    replaces = [('pretixbase', '0090_auto_20180509_0917'), ('pretixbase', '0091_auto_20180513_1641'),
+                ('pretixbase', '0092_auto_20180511_1224'), ('pretixbase', '0093_auto_20180528_1432'),
+                ('pretixbase', '0094_auto_20180604_1119'), ('pretixbase', '0095_auto_20180604_1129')]
+
+    dependencies = [
+        ('pretixbase', '0089_auto_20180315_1322'),
+        ('pretixapi', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='item',
+            name='internal_name',
+            field=models.CharField(blank=True,
+                                   help_text='If you set this, this will be used instead of the public name in the '
+                                             'backend.',
+                                   max_length=255, null=True, verbose_name='Internal name'),
+        ),
+        migrations.AddField(
+            model_name='itemcategory',
+            name='internal_name',
+            field=models.CharField(blank=True,
+                                   help_text='If you set this, this will be used instead of the public name in the '
+                                             'backend.',
+                                   max_length=255, null=True, verbose_name='Internal name'),
+        ),
+        migrations.AddField(
+            model_name='order',
+            name='last_modified',
+            field=models.DateTimeField(auto_now=True, db_index=True),
+        ),
+        migrations.AddField(
+            model_name='item',
+            name='original_price',
+            field=models.DecimalField(blank=True, decimal_places=2,
+                                      help_text='If set, this will be displayed next to the current price to show '
+                                                'that the current price is a discounted one. This is just a cosmetic '
+                                                'setting and will not actually impact pricing.',
+                                      max_digits=7, null=True, verbose_name='Original price'),
+        ),
+        migrations.AddField(
+            model_name='orderposition',
+            name='pseudonymization_id',
+            field=models.CharField(db_index=True, max_length=16, null=True, unique=True),
+        ),
+        migrations.RunPython(
+            code=set_pids,
+            reverse_code=django.db.migrations.operations.special.RunPython.noop,
+        ),
+        migrations.AlterField(
+            model_name='orderposition',
+            name='pseudonymization_id',
+            field=models.CharField(db_index=True, default='', max_length=16, unique=True),
+            preserve_default=False,
+        ),
+        migrations.AddField(
+            model_name='logentry',
+            name='oauth_application',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT,
+                                    to=settings.OAUTH2_PROVIDER_APPLICATION_MODEL),
+        ),
+    ]

src/pretix/base/migrations/0096_auto_20180722_0801.py

@@ -0,0 +1,81 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.13 on 2018-07-22 08:01
+from __future__ import unicode_literals
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0095_auto_20180604_1129'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='OrderPayment',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('local_id', models.PositiveIntegerField()),
+                ('state', models.CharField(choices=[('created', 'created'), ('pending', 'pending'), ('confirmed', 'confirmed'), ('canceled', 'canceled'), ('failed', 'failed'), ('refunded', 'refunded')], max_length=190)),
+                ('amount', models.DecimalField(decimal_places=2, max_digits=10, verbose_name='Amount')),
+                ('created', models.DateTimeField(auto_now_add=True)),
+                ('payment_date', models.DateTimeField(blank=True, null=True)),
+                ('provider', models.CharField(blank=True, max_length=255, null=True, verbose_name='Payment provider')),
+                ('info', models.TextField(blank=True, null=True, verbose_name='Payment information')),
+                ('migrated', models.BooleanField(default=False)),
+            ],
+            options={
+                'ordering': ('local_id',),
+            },
+        ),
+        migrations.CreateModel(
+            name='OrderRefund',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('local_id', models.PositiveIntegerField()),
+                ('state', models.CharField(choices=[('external', 'started externally'), ('created', 'created'), ('transit', 'in transit'), ('done', 'done'), ('failed', 'failed'), ('canceled', 'canceled')], max_length=190)),
+                ('source', models.CharField(choices=[('admin', 'Organizer'), ('buyer', 'Customer'), ('external', 'External')], max_length=190)),
+                ('amount', models.DecimalField(decimal_places=2, max_digits=10, verbose_name='Amount')),
+                ('created', models.DateTimeField(auto_now_add=True)),
+                ('execution_date', models.DateTimeField(blank=True, null=True)),
+                ('provider', models.CharField(blank=True, max_length=255, null=True, verbose_name='Payment provider')),
+                ('info', models.TextField(blank=True, null=True, verbose_name='Payment information')),
+                ('order', models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='refunds', to='pretixbase.Order', verbose_name='Order')),
+                ('payment', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT, related_name='refunds', to='pretixbase.OrderPayment')),
+            ],
+            options={
+                'ordering': ('local_id',),
+            },
+        ),
+        migrations.AlterModelOptions(
+            name='quota',
+            options={'ordering': ('name',), 'verbose_name': 'Quota', 'verbose_name_plural': 'Quotas'},
+        ),
+        migrations.AlterField(
+            model_name='orderfee',
+            name='fee_type',
+            field=models.CharField(choices=[('payment', 'Payment fee'), ('shipping', 'Shipping fee'), ('service', 'Service fee'), ('other', 'Other fees'), ('giftcard', 'Gift card')], max_length=100),
+        ),
+        migrations.AlterField(
+            model_name='team',
+            name='can_change_organizer_settings',
+            field=models.BooleanField(default=False, help_text='Someone with this setting can get access to most data of all of your events, i.e. via privacy reports, so be careful who you add to this team!', verbose_name='Can change organizer settings'),
+        ),
+        migrations.AlterField(
+            model_name='user',
+            name='require_2fa',
+            field=models.BooleanField(default=False, verbose_name='Two-factor authentication is required to log in'),
+        ),
+        migrations.AddField(
+            model_name='orderpayment',
+            name='fee',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='payments', to='pretixbase.OrderFee'),
+        ),
+        migrations.AddField(
+            model_name='orderpayment',
+            name='order',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='payments', to='pretixbase.Order', verbose_name='Order'),
+        ),
+    ]

src/pretix/base/migrations/0097_auto_20180722_0804.py

@@ -0,0 +1,118 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.13 on 2018-07-22 08:04
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+def create_payments(apps, schema_editor):
+    Order = apps.get_model('pretixbase', 'Order')  # noqa
+    OrderPayment = apps.get_model('pretixbase', 'OrderPayment')  # noqa
+    OrderRefund = apps.get_model('pretixbase', 'OrderRefund')  # noqa
+    payments = []
+    refunds = []
+    for o in Order.objects.filter(payments__isnull=True).iterator():
+        if o.status == 'n' or o.status == 'e':
+            payments.append(OrderPayment(
+                local_id=1,
+                state='created',
+                amount=o.total,
+                order=o,
+                provider=o.payment_provider,
+                info=o.payment_info,
+                migrated=True,
+                fee=o.fees.filter(fee_type="payment", internal_type=o.payment_provider).first(),
+            ))
+            pass
+        elif o.status == 'p':
+            payments.append(OrderPayment(
+                local_id=1,
+                state='confirmed',
+                amount=o.total,
+                order=o,
+                provider=o.payment_provider,
+                payment_date=o.payment_date,
+                info=o.payment_info,
+                migrated=True,
+                fee=o.fees.filter(fee_type="payment", internal_type=o.payment_provider).first(),
+            ))
+        elif o.status == 'r':
+            p = OrderPayment.objects.create(
+                local_id=1,
+                state='refunded',
+                amount=o.total,
+                order=o,
+                provider=o.payment_provider,
+                payment_date=o.payment_date,
+                info=o.payment_info,
+                migrated=True,
+                fee=o.fees.filter(fee_type="payment", internal_type=o.payment_provider).first(),
+            )
+            refunds.append(OrderRefund(
+                local_id=1,
+                state='done',
+                amount=o.total,
+                order=o,
+                provider=o.payment_provider,
+                info=o.payment_info,
+                source='admin',
+                payment=p
+            ))
+        elif o.status == 'c':
+            payments.append(OrderPayment(
+                local_id=1,
+                state='canceled',
+                amount=o.total,
+                order=o,
+                provider=o.payment_provider,
+                payment_date=o.payment_date,
+                info=o.payment_info,
+                migrated=True,
+                fee=o.fees.filter(fee_type="payment", internal_type=o.payment_provider).first(),
+            ))
+
+        if len(payments) > 500:
+            OrderPayment.objects.bulk_create(payments)
+            payments.clear()
+        if len(refunds) > 500:
+            OrderRefund.objects.bulk_create(refunds)
+            refunds.clear()
+    if len(payments) > 0:
+        OrderPayment.objects.bulk_create(payments)
+    if len(refunds) > 0:
+        OrderRefund.objects.bulk_create(refunds)
+
+
+def notifications(apps, schema_editor):
+    NotificationSetting = apps.get_model('pretixbase', 'NotificationSetting')
+    for n in NotificationSetting.objects.filter(action_type='pretix.event.action_required'):
+        n.pk = None
+        n.action_type = 'pretix.event.order.refund.created.externally'
+        n.save()
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ('pretixbase', '0096_auto_20180722_0801'),
+    ]
+
+    operations = [
+        migrations.RunPython(create_payments, migrations.RunPython.noop),
+        migrations.RunPython(notifications, migrations.RunPython.noop),
+        migrations.RemoveField(
+            model_name='order',
+            name='payment_date',
+        ),
+        migrations.RemoveField(
+            model_name='order',
+            name='payment_info',
+        ),
+        migrations.RemoveField(
+            model_name='order',
+            name='payment_manual',
+        ),
+        migrations.RemoveField(
+            model_name='order',
+            name='payment_provider',
+        ),
+    ]

src/pretix/base/migrations/0098_auto_20180731_1243.py

@@ -0,0 +1,56 @@
+# Generated by Django 2.0.7 on 2018-07-31 12:43
+
+import django.core.validators
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+
+import pretix.base.validators
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0097_auto_20180722_0804'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='logentry',
+            options={'ordering': ('-datetime', '-id')},
+        ),
+        migrations.AlterField(
+            model_name='orderpayment',
+            name='fee',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='payments', to='pretixbase.OrderFee'),
+        ),
+        migrations.AlterField(
+            model_name='organizer',
+            name='slug',
+            field=models.SlugField(help_text='Should be short, only contain lowercase letters, numbers, dots, and dashes. Every slug can only be used once. This is being used in URLs to refer to your organizer accounts and your events.', unique=True, validators=[django.core.validators.RegexValidator(message='The slug may only contain letters, numbers, dots and dashes.', regex='^[a-zA-Z0-9.-]+$'), pretix.base.validators.OrganizerSlugBlacklistValidator()], verbose_name='Short form'),
+        ),
+        migrations.AlterField(
+            model_name='staffsession',
+            name='user',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, to=settings.AUTH_USER_MODEL),
+        ),
+        migrations.AlterField(
+            model_name='staffsessionauditlog',
+            name='impersonating',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT, to=settings.AUTH_USER_MODEL),
+        ),
+        migrations.AlterField(
+            model_name='staffsessionauditlog',
+            name='session',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='logs', to='pretixbase.StaffSession'),
+        ),
+        migrations.AlterField(
+            model_name='user',
+            name='locale',
+            field=models.CharField(choices=[('en', 'English'), ('de', 'German'), ('de-informal', 'German (informal)'), ('nl', 'Dutch'), ('da', 'Danish'), ('tr', 'Turkish'), ('pt-br', 'Portuguese (Brazil)')], default='en', max_length=50, verbose_name='Language'),
+        ),
+        migrations.AlterUniqueTogether(
+            name='event',
+            unique_together={('organizer', 'slug')},
+        ),
+    ]

src/pretix/base/migrations/0098_auto_20180731_1243_squashed_0100_item_require_approval.py

@@ -0,0 +1,82 @@
+# Generated by Django 2.0.8 on 2018-09-11 14:54
+
+import django.core.validators
+import django.db.models.deletion
+from django.conf import settings
+from django.db import migrations, models
+
+import pretix.base.validators
+
+
+class Migration(migrations.Migration):
+
+    replaces = [('pretixbase', '0098_auto_20180731_1243'), ('pretixbase', '0099_auto_20180807_0841'), ('pretixbase', '0100_item_require_approval')]
+
+    dependencies = [
+        ('pretixbase', '0097_auto_20180722_0804'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='logentry',
+            options={'ordering': ('-datetime', '-id')},
+        ),
+        migrations.AlterField(
+            model_name='orderpayment',
+            name='fee',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='payments', to='pretixbase.OrderFee'),
+        ),
+        migrations.AlterField(
+            model_name='organizer',
+            name='slug',
+            field=models.SlugField(help_text='Should be short, only contain lowercase letters, numbers, dots, and dashes. Every slug can only be used once. This is being used in URLs to refer to your organizer accounts and your events.', unique=True, validators=[django.core.validators.RegexValidator(message='The slug may only contain letters, numbers, dots and dashes.', regex='^[a-zA-Z0-9.-]+$'), pretix.base.validators.OrganizerSlugBlacklistValidator()], verbose_name='Short form'),
+        ),
+        migrations.AlterField(
+            model_name='staffsession',
+            name='user',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, to=settings.AUTH_USER_MODEL),
+        ),
+        migrations.AlterField(
+            model_name='staffsessionauditlog',
+            name='impersonating',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.PROTECT, to=settings.AUTH_USER_MODEL),
+        ),
+        migrations.AlterField(
+            model_name='staffsessionauditlog',
+            name='session',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.PROTECT, related_name='logs', to='pretixbase.StaffSession'),
+        ),
+        migrations.AlterField(
+            model_name='user',
+            name='locale',
+            field=models.CharField(choices=[('en', 'English'), ('de', 'German'), ('de-informal', 'German (informal)'), ('nl', 'Dutch'), ('da', 'Danish'), ('tr', 'Turkish'), ('pt-br', 'Portuguese (Brazil)')], default='en', max_length=50, verbose_name='Language'),
+        ),
+        migrations.AlterUniqueTogether(
+            name='event',
+            unique_together={('organizer', 'slug')},
+        ),
+        migrations.AlterModelOptions(
+            name='waitinglistentry',
+            options={'ordering': ('-priority', 'created'), 'verbose_name': 'Waiting list entry', 'verbose_name_plural': 'Waiting list entries'},
+        ),
+        migrations.AddField(
+            model_name='waitinglistentry',
+            name='priority',
+            field=models.IntegerField(default=0),
+        ),
+        migrations.AlterField(
+            model_name='waitinglistentry',
+            name='voucher',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='waitinglistentries', to='pretixbase.Voucher', verbose_name='Assigned voucher'),
+        ),
+        migrations.AddField(
+            model_name='item',
+            name='require_approval',
+            field=models.BooleanField(default=False, help_text='If this product is part of an order, the order will be put into an "approval" state and will need to be confirmed by you before it can be paid and completed. You can use this e.g. for discounted tickets that are only available to specific groups.', verbose_name='Buying this product requires approval.'),
+        ),
+        migrations.AddField(
+            model_name='order',
+            name='require_approval',
+            field=models.BooleanField(default=False),
+        ),
+    ]

src/pretix/base/migrations/0099_auto_20180807_0841.py

@@ -0,0 +1,28 @@
+# Generated by Django 2.1 on 2018-08-07 08:41
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0098_auto_20180731_1243'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='waitinglistentry',
+            options={'ordering': ('-priority', 'created'), 'verbose_name': 'Waiting list entry', 'verbose_name_plural': 'Waiting list entries'},
+        ),
+        migrations.AddField(
+            model_name='waitinglistentry',
+            name='priority',
+            field=models.IntegerField(default=0),
+        ),
+        migrations.AlterField(
+            model_name='waitinglistentry',
+            name='voucher',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, related_name='waitinglistentries', to='pretixbase.Voucher', verbose_name='Assigned voucher'),
+        ),
+    ]

src/pretix/base/migrations/0100_item_require_approval.py

@@ -0,0 +1,23 @@
+# Generated by Django 2.1 on 2018-08-09 15:17
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0099_auto_20180807_0841'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='item',
+            name='require_approval',
+            field=models.BooleanField(default=False, help_text='If this product is part of an order, the order will be put into an "approval" state and will need to be confirmed by you before it can be paid and completed. You can use this e.g. for discounted tickets that are only available to specific groups.', verbose_name='Buying this product requires approval.'),
+        ),
+        migrations.AddField(
+            model_name='order',
+            name='require_approval',
+            field=models.BooleanField(default=False),
+        ),
+    ]

src/pretix/base/models/__init__.py

@@ -15,9 +15,9 @@ from .log import LogEntry
 from .notifications import NotificationSetting
 from .orders import (
     AbstractPosition, CachedCombinedTicket, CachedTicket, CartPosition,
-    InvoiceAddress, Order, OrderPosition, QuestionAnswer,
-    cachedcombinedticket_name, cachedticket_name, generate_position_secret,
-    generate_secret,
+    InvoiceAddress, Order, OrderFee, OrderPayment, OrderPosition, OrderRefund,
+    QuestionAnswer, cachedcombinedticket_name, cachedticket_name,
+    generate_position_secret, generate_secret,
 )
 from .organizer import (
     Organizer, Organizer_SettingsStore, Team, TeamAPIToken, TeamInvite,

src/pretix/base/models/auth.py

@@ -340,7 +340,7 @@ class User(AbstractBaseUser, PermissionsMixin, LoggingMixin):
 
 
 class StaffSession(models.Model):
-    user = models.ForeignKey('User')
+    user = models.ForeignKey('User', on_delete=models.PROTECT)
     date_start = models.DateTimeField(auto_now_add=True)
     date_end = models.DateTimeField(null=True, blank=True)
     session_key = models.CharField(max_length=255)
@@ -351,11 +351,11 @@ class StaffSession(models.Model):
 
 
 class StaffSessionAuditLog(models.Model):
-    session = models.ForeignKey('StaffSession', related_name='logs')
+    session = models.ForeignKey('StaffSession', related_name='logs', on_delete=models.PROTECT)
     datetime = models.DateTimeField(auto_now_add=True)
     url = models.CharField(max_length=255)
     method = models.CharField(max_length=255)
-    impersonating = models.ForeignKey('User', null=True, blank=True)
+    impersonating = models.ForeignKey('User', null=True, blank=True, on_delete=models.PROTECT)
 
     class Meta:
         ordering = ('datetime',)

src/pretix/base/models/checkin.py

@@ -8,12 +8,12 @@ from pretix.base.models import LoggedModel
 
 
 class CheckinList(LoggedModel):
-    event = models.ForeignKey('Event', related_name='checkin_lists')
+    event = models.ForeignKey('Event', related_name='checkin_lists', on_delete=models.CASCADE)
     name = models.CharField(max_length=190)
     all_products = models.BooleanField(default=True, verbose_name=_("All products (including newly created ones)"))
     limit_products = models.ManyToManyField('Item', verbose_name=_("Limit to products"), blank=True)
     subevent = models.ForeignKey('SubEvent', null=True, blank=True,
-                                 verbose_name=pgettext_lazy('subevent', 'Date'))
+                                 verbose_name=pgettext_lazy('subevent', 'Date'), on_delete=models.CASCADE)
     include_pending = models.BooleanField(verbose_name=pgettext_lazy('checkin', 'Include pending orders'),
                                           default=False,
                                           help_text=_('With this option, people will be able to check in even if the '
@@ -157,7 +157,7 @@ class Checkin(models.Model):
     """
     A check-in object is created when a person enters the event.
     """
-    position = models.ForeignKey('pretixbase.OrderPosition', related_name='checkins')
+    position = models.ForeignKey('pretixbase.OrderPosition', related_name='checkins', on_delete=models.CASCADE)
     datetime = models.DateTimeField(default=now)
     nonce = models.CharField(max_length=190, null=True, blank=True)
     list = models.ForeignKey(

src/pretix/base/models/event.py

@@ -19,7 +19,6 @@ from django.utils.timezone import make_aware, now
 from django.utils.translation import ugettext_lazy as _
 from i18nfield.fields import I18nCharField, I18nTextField
 
-from pretix.base.email import CustomSMTPBackend
 from pretix.base.models.base import LoggedModel
 from pretix.base.reldate import RelativeDateWrapper
 from pretix.base.validators import EventSlugBlacklistValidator
@@ -265,6 +264,7 @@ class Event(EventMixin, LoggedModel):
         verbose_name = _("Event")
         verbose_name_plural = _("Events")
         ordering = ("date_from", "name")
+        unique_together = (('organizer', 'slug'),)
 
     def __str__(self):
         return str(self.name)
@@ -326,6 +326,8 @@ class Event(EventMixin, LoggedModel):
         Returns an email server connection, either by using the system-wide connection
         or by returning a custom one based on the event's settings.
         """
+        from pretix.base.email import CustomSMTPBackend
+
         if self.settings.smtp_use_custom or force_custom:
             return CustomSMTPBackend(host=self.settings.smtp_host,
                                      port=self.settings.smtp_port,
@@ -450,10 +452,8 @@ class Event(EventMixin, LoggedModel):
                     if int(s.value) in tax_map:
                         s.value = tax_map.get(int(s.value)).pk
                         s.save()
-                    else:
-                        s.delete()
                 except ValueError:
-                    s.delete()
+                    pass
             else:
                 s.save()
 
@@ -480,6 +480,31 @@ class Event(EventMixin, LoggedModel):
 
         return OrderedDict(sorted(providers.items(), key=lambda v: str(v[1].verbose_name)))
 
+    def get_html_mail_renderer(self):
+        """
+        Returns the currently selected HTML email renderer
+        """
+        return self.get_html_mail_renderers()[
+            self.settings.mail_html_renderer
+        ]
+
+    def get_html_mail_renderers(self) -> dict:
+        """
+        Returns a dictionary of initialized HTML email renderers mapped by their identifiers.
+        """
+        from ..signals import register_html_mail_renderers
+
+        responses = register_html_mail_renderers.send(self)
+        renderers = {}
+        for receiver, response in responses:
+            if not isinstance(response, list):
+                response = [response]
+            for p in response:
+                pp = p(self)
+                if pp.is_available:
+                    renderers[pp.identifier] = pp
+        return renderers
+
     def get_invoice_renderers(self) -> dict:
         """
         Returns a dictionary of initialized invoice renderers mapped by their identifiers.
@@ -551,7 +576,12 @@ class Event(EventMixin, LoggedModel):
                 | Q(date_to__gte=now())
             )
         )  # order_by doesn't make sense with I18nField
-        return sorted(subevs, key=attrgetter(*orderfields))
+        for f in reversed(orderfields):
+            if f.startswith('-'):
+                subevs = sorted(subevs, key=attrgetter(f[1:]), reverse=True)
+            else:
+                subevs = sorted(subevs, key=attrgetter(f))
+        return subevs
 
     @property
     def meta_data(self):
@@ -563,7 +593,7 @@ class Event(EventMixin, LoggedModel):
     def has_payment_provider(self):
         result = False
         for provider in self.get_payment_providers().values():
-            if provider.is_enabled and provider.identifier not in ('free', 'boxoffice'):
+            if provider.is_enabled and provider.identifier not in ('free', 'boxoffice', 'offsetting'):
                 result = True
                 break
         return result

src/pretix/base/models/invoices.py

@@ -64,14 +64,14 @@ class Invoice(models.Model):
     :param file: The filename of the rendered invoice
     :type file: File
     """
-    order = models.ForeignKey('Order', related_name='invoices', db_index=True)
+    order = models.ForeignKey('Order', related_name='invoices', db_index=True, on_delete=models.CASCADE)
     organizer = models.ForeignKey('Organizer', related_name='invoices', db_index=True, on_delete=models.PROTECT)
-    event = models.ForeignKey('Event', related_name='invoices', db_index=True)
+    event = models.ForeignKey('Event', related_name='invoices', db_index=True, on_delete=models.CASCADE)
     prefix = models.CharField(max_length=160, db_index=True)
     invoice_no = models.CharField(max_length=19, db_index=True)
     full_invoice_no = models.CharField(max_length=190, db_index=True)
     is_cancellation = models.BooleanField(default=False)
-    refers = models.ForeignKey('Invoice', related_name='refered', null=True, blank=True)
+    refers = models.ForeignKey('Invoice', related_name='refered', null=True, blank=True, on_delete=models.CASCADE)
     invoice_from = models.TextField()
     invoice_to = models.TextField()
     date = models.DateField(default=today)
@@ -175,7 +175,7 @@ class InvoiceLine(models.Model):
     :param tax_name: The name of the applied tax rate
     :type tax_name: str
     """
-    invoice = models.ForeignKey('Invoice', related_name='lines')
+    invoice = models.ForeignKey('Invoice', related_name='lines', on_delete=models.CASCADE)
     position = models.PositiveIntegerField(default=0)
     description = models.TextField()
     gross_value = models.DecimalField(max_digits=10, decimal_places=2)

src/pretix/base/models/items.py

@@ -193,6 +193,8 @@ class Item(LoggedModel):
     :type checkin_attention: bool
     :param original_price: The item's "original" price. Will not be used for any calculations, will just be shown.
     :type original_price: decimal.Decimal
+    :param require_approval: If set to ``True``, orders containing this product can only be processed and paid after approved by an administrator
+    :type require_approval: bool
     """
 
     event = models.ForeignKey(
@@ -280,6 +282,13 @@ class Item(LoggedModel):
         help_text=_('To buy this product, the user needs a voucher that applies to this product '
                     'either directly or via a quota.')
     )
+    require_approval = models.BooleanField(
+        verbose_name=_('Buying this product requires approval'),
+        default=False,
+        help_text=_('If this product is part of an order, the order will be put into an "approval" state and '
+                    'will need to be confirmed by you before it can be paid and completed. You can use this e.g. for '
+                    'discounted tickets that are only available to specific groups.'),
+    )
     hide_without_voucher = models.BooleanField(
         verbose_name=_('This product will only be shown if a voucher matching the product is redeemed.'),
         default=False,
@@ -447,7 +456,8 @@ class ItemVariation(models.Model):
     """
     item = models.ForeignKey(
         Item,
-        related_name='variations'
+        related_name='variations',
+        on_delete=models.CASCADE
     )
     value = I18nCharField(
         max_length=255,
@@ -562,12 +572,14 @@ class ItemAddOn(models.Model):
     """
     base_item = models.ForeignKey(
         Item,
-        related_name='addons'
+        related_name='addons',
+        on_delete=models.CASCADE
     )
     addon_category = models.ForeignKey(
         ItemCategory,
         related_name='addon_to',
-        verbose_name=_('Category')
+        verbose_name=_('Category'),
+        on_delete=models.CASCADE
     )
     min_count = models.PositiveIntegerField(
         default=0,
@@ -679,7 +691,8 @@ class Question(LoggedModel):
 
     event = models.ForeignKey(
         Event,
-        related_name="questions"
+        related_name="questions",
+        on_delete=models.CASCADE
     )
     question = I18nTextField(
         verbose_name=_("Question")
@@ -831,7 +844,7 @@ class Question(LoggedModel):
 
 
 class QuestionOption(models.Model):
-    question = models.ForeignKey('Question', related_name='options')
+    question = models.ForeignKey('Question', related_name='options', on_delete=models.CASCADE)
     identifier = models.CharField(max_length=190)
     answer = I18nCharField(verbose_name=_('Answer'))
     position = models.IntegerField(default=0)

src/pretix/base/models/log.py

@@ -52,7 +52,7 @@ class LogEntry(models.Model):
     all = models.Manager()
 
     class Meta:
-        ordering = ('-datetime',)
+        ordering = ('-datetime', '-id')
 
     def display(self):
         from ..signals import logentry_display
@@ -66,10 +66,13 @@ class LogEntry(models.Model):
     def display_object(self):
         from . import Order, Voucher, Quota, Item, ItemCategory, Question, Event, TaxRule, SubEvent
 
-        if self.content_type.model_class() is Event:
-            return ''
+        try:
+            if self.content_type.model_class() is Event:
+                return ''
 
-        co = self.content_object
+            co = self.content_object
+        except:
+            return ''
         a_map = None
         a_text = None
 

src/pretix/base/models/orders.py

@@ -1,5 +1,6 @@
 import copy
 import json
+import logging
 import os
 import string
 from datetime import datetime, time, timedelta
@@ -9,8 +10,11 @@ from typing import Any, Dict, List, Union
 import dateutil
 import pytz
 from django.conf import settings
-from django.db import models
-from django.db.models import F, Sum
+from django.db import models, transaction
+from django.db.models import (
+    Case, Exists, F, Max, OuterRef, Q, Subquery, Sum, Value, When,
+)
+from django.db.models.functions import Coalesce
 from django.db.models.signals import post_delete
 from django.dispatch import receiver
 from django.urls import reverse
@@ -31,6 +35,8 @@ from .base import LoggedModel
 from .event import Event, SubEvent
 from .items import Item, ItemVariation, Question, QuestionOption, Quota
 
+logger = logging.getLogger(__name__)
+
 
 def generate_secret():
     return get_random_string(length=16, allowed_chars=string.ascii_lowercase + string.digits)
@@ -76,18 +82,14 @@ class Order(LoggedModel):
     :type datetime: datetime
     :param expires: The date until this order has to be paid to guarantee the fulfillment
     :type expires: datetime
-    :param payment_date: The date of the payment completion (null if not yet paid)
-    :type payment_date: datetime
-    :param payment_provider: The payment provider selected by the user
-    :type payment_provider: str
-    :param payment_info: Arbitrary information stored by the payment provider
-    :type payment_info: str
     :param total: The total amount of the order, including the payment fee
     :type total: decimal.Decimal
     :param comment: An internal comment that will only be visible to staff, and never displayed to the user
     :type comment: str
     :param download_reminder_sent: A field to indicate whether a download reminder has been sent.
     :type download_reminder_sent: boolean
+    :param require_approval: If set to ``True``, this order is pending approval by an organizer
+    :type require_approval: bool
     :param meta_info: Additional meta information on the order, JSON-encoded.
     :type meta_info: str
     """
@@ -119,7 +121,8 @@ class Order(LoggedModel):
     event = models.ForeignKey(
         Event,
         verbose_name=_("Event"),
-        related_name="orders"
+        related_name="orders",
+        on_delete=models.CASCADE
     )
     email = models.EmailField(
         null=True, blank=True,
@@ -136,23 +139,6 @@ class Order(LoggedModel):
     expires = models.DateTimeField(
         verbose_name=_("Expiration date")
     )
-    payment_date = models.DateTimeField(
-        verbose_name=_("Payment date"),
-        null=True, blank=True
-    )
-    payment_provider = models.CharField(
-        null=True, blank=True,
-        max_length=255,
-        verbose_name=_("Payment provider")
-    )
-    payment_info = models.TextField(
-        verbose_name=_("Payment information"),
-        null=True, blank=True
-    )
-    payment_manual = models.BooleanField(
-        verbose_name=_("Payment state was manually modified"),
-        default=False
-    )
     total = models.DecimalField(
         decimal_places=2, max_digits=10,
         verbose_name=_("Total amount")
@@ -183,6 +169,9 @@ class Order(LoggedModel):
     last_modified = models.DateTimeField(
         auto_now=True, db_index=True
     )
+    require_approval = models.BooleanField(
+        default=False
+    )
 
     class Meta:
         verbose_name = _("Order")
@@ -199,6 +188,84 @@ class Order(LoggedModel):
         except TypeError:
             return None
 
+    @property
+    def payment_refund_sum(self):
+        payment_sum = self.payments.filter(
+            state__in=(OrderPayment.PAYMENT_STATE_CONFIRMED, OrderPayment.PAYMENT_STATE_REFUNDED)
+        ).aggregate(s=Sum('amount'))['s'] or Decimal('0.00')
+        refund_sum = self.refunds.filter(
+            state__in=(OrderRefund.REFUND_STATE_DONE, OrderRefund.REFUND_STATE_TRANSIT,
+                       OrderRefund.REFUND_STATE_CREATED)
+        ).aggregate(s=Sum('amount'))['s'] or Decimal('0.00')
+        return payment_sum - refund_sum
+
+    @property
+    def pending_sum(self):
+        total = self.total
+        if self.status in (Order.STATUS_REFUNDED, Order.STATUS_CANCELED):
+            total = 0
+        payment_sum = self.payments.filter(
+            state__in=(OrderPayment.PAYMENT_STATE_CONFIRMED, OrderPayment.PAYMENT_STATE_REFUNDED)
+        ).aggregate(s=Sum('amount'))['s'] or Decimal('0.00')
+        refund_sum = self.refunds.filter(
+            state__in=(OrderRefund.REFUND_STATE_DONE, OrderRefund.REFUND_STATE_TRANSIT,
+                       OrderRefund.REFUND_STATE_CREATED)
+        ).aggregate(s=Sum('amount'))['s'] or Decimal('0.00')
+        return total - payment_sum + refund_sum
+
+    @classmethod
+    def annotate_overpayments(cls, qs):
+        payment_sum = OrderPayment.objects.filter(
+            state__in=(OrderPayment.PAYMENT_STATE_CONFIRMED, OrderPayment.PAYMENT_STATE_REFUNDED),
+            order=OuterRef('pk')
+        ).order_by().values('order').annotate(s=Sum('amount')).values('s')
+        refund_sum = OrderRefund.objects.filter(
+            state__in=(OrderRefund.REFUND_STATE_DONE, OrderRefund.REFUND_STATE_TRANSIT,
+                       OrderRefund.REFUND_STATE_CREATED),
+            order=OuterRef('pk')
+        ).order_by().values('order').annotate(s=Sum('amount')).values('s')
+        external_refund = OrderRefund.objects.filter(
+            state=OrderRefund.REFUND_STATE_EXTERNAL,
+            order=OuterRef('pk')
+        )
+        pending_refund = OrderRefund.objects.filter(
+            state__in=(OrderRefund.REFUND_STATE_CREATED, OrderRefund.REFUND_STATE_TRANSIT),
+            order=OuterRef('pk')
+        )
+
+        qs = qs.annotate(
+            payment_sum=Subquery(payment_sum, output_field=models.DecimalField(decimal_places=2, max_digits=10)),
+            refund_sum=Subquery(refund_sum, output_field=models.DecimalField(decimal_places=2, max_digits=10)),
+            has_external_refund=Exists(external_refund),
+            has_pending_refund=Exists(pending_refund),
+        ).annotate(
+            pending_sum_t=F('total') - Coalesce(F('payment_sum'), 0) + Coalesce(F('refund_sum'), 0),
+            pending_sum_rc=-1 * Coalesce(F('payment_sum'), 0) + Coalesce(F('refund_sum'), 0),
+        ).annotate(
+            is_overpaid=Case(
+                When(~Q(status__in=(Order.STATUS_REFUNDED, Order.STATUS_CANCELED)) & Q(pending_sum_t__lt=0),
+                     then=Value('1')),
+                When(Q(status__in=(Order.STATUS_REFUNDED, Order.STATUS_CANCELED)) & Q(pending_sum_rc__lt=0),
+                     then=Value('1')),
+                default=Value('0'),
+                output_field=models.IntegerField()
+            ),
+            is_pending_with_full_payment=Case(
+                When(Q(status__in=(Order.STATUS_EXPIRED, Order.STATUS_PENDING)) & Q(pending_sum_t__lte=0)
+                     & Q(require_approval=False),
+                     then=Value('1')),
+                default=Value('0'),
+                output_field=models.IntegerField()
+            ),
+            is_underpaid=Case(
+                When(Q(status=Order.STATUS_PAID) & Q(pending_sum_t__gt=0),
+                     then=Value('1')),
+                default=Value('0'),
+                output_field=models.IntegerField()
+            )
+        )
+        return qs
+
     @property
     def full_code(self):
         """
@@ -377,7 +444,10 @@ class Order(LoggedModel):
                                "payment settings is over."),
             'late': _("The payment can not be accepted as it the order is expired and you configured that no late "
                       "payments should be accepted in the payment settings."),
+            'require_approval': _('This order is not yet approved by the event organizer.')
         }
+        if self.require_approval:
+            return error_messages['require_approval']
         term_last = self.payment_term_last
         if term_last:
             if now() > term_last:
@@ -425,7 +495,8 @@ class Order(LoggedModel):
 
     def send_mail(self, subject: str, template: Union[str, LazyI18nString],
                   context: Dict[str, Any]=None, log_entry_type: str='pretix.event.order.email.sent',
-                  user: User=None, headers: dict=None, sender: str=None, invoices: list=None):
+                  user: User=None, headers: dict=None, sender: str=None, invoices: list=None,
+                  auth=None):
         """
         Sends an email to the user that placed this order. Basically, this method does two things:
 
@@ -450,7 +521,7 @@ class Order(LoggedModel):
         with language(self.locale):
             recipient = self.email
             try:
-                email_content = render_mail(template, context)[0]
+                email_content = render_mail(template, context)
                 mail(
                     recipient, subject, template, context,
                     self.event, self.locale, self, headers, sender,
@@ -462,6 +533,7 @@ class Order(LoggedModel):
                 self.log_action(
                     log_entry_type,
                     user=user,
+                    auth=auth,
                     data={
                         'subject': subject,
                         'message': email_content,
@@ -499,14 +571,14 @@ class QuestionAnswer(models.Model):
     """
     orderposition = models.ForeignKey(
         'OrderPosition', null=True, blank=True,
-        related_name='answers'
+        related_name='answers', on_delete=models.CASCADE
     )
     cartposition = models.ForeignKey(
         'CartPosition', null=True, blank=True,
-        related_name='answers'
+        related_name='answers', on_delete=models.CASCADE
     )
     question = models.ForeignKey(
-        Question, related_name='answers'
+        Question, related_name='answers', on_delete=models.CASCADE
     )
     options = models.ManyToManyField(
         QuestionOption, related_name='answers', blank=True
@@ -654,7 +726,7 @@ class AbstractPosition(models.Model):
         help_text=_("Empty, if this product is not an admission ticket")
     )
     voucher = models.ForeignKey(
-        'Voucher', null=True, blank=True
+        'Voucher', null=True, blank=True, on_delete=models.CASCADE
     )
     addon_to = models.ForeignKey(
         'self', null=True, blank=True, on_delete=models.CASCADE, related_name='addons'
@@ -711,10 +783,441 @@ class AbstractPosition(models.Model):
                 else self.variation.quotas.filter(subevent=self.subevent))
 
 
+class OrderPayment(models.Model):
+    """
+    Represents a payment or payment attempt for an order.
+
+
+    :param id: A globally unique ID for this payment
+    :type id:
+    :param local_id: An ID of this payment, counting from one for every order independently.
+    :type local_id: int
+    :param state: The state of the payment, one of ``created``, ``pending``, ``confirmed``, ``failed``,
+      ``canceled``, or ``refunded``.
+    :type state: str
+    :param amount: The payment amount
+    :type amount: Decimal
+    :param order: The order that is paid
+    :type order: Order
+    :param created: The creation time of this record
+    :type created: datetime
+    :param payment_date: The completion time of this payment
+    :type payment_date: datetime
+    :param provider: The payment provider in use
+    :type provider: str
+    :param info: Provider-specific meta information (in JSON format)
+    :type info: str
+    :param fee: The ``OrderFee`` object used to track the fee for this order.
+    :type fee: pretix.base.models.OrderFee
+    """
+    PAYMENT_STATE_CREATED = 'created'
+    PAYMENT_STATE_PENDING = 'pending'
+    PAYMENT_STATE_CONFIRMED = 'confirmed'
+    PAYMENT_STATE_FAILED = 'failed'
+    PAYMENT_STATE_CANCELED = 'canceled'
+    PAYMENT_STATE_REFUNDED = 'refunded'
+
+    PAYMENT_STATES = (
+        (PAYMENT_STATE_CREATED, pgettext_lazy('payment_state', 'created')),
+        (PAYMENT_STATE_PENDING, pgettext_lazy('payment_state', 'pending')),
+        (PAYMENT_STATE_CONFIRMED, pgettext_lazy('payment_state', 'confirmed')),
+        (PAYMENT_STATE_CANCELED, pgettext_lazy('payment_state', 'canceled')),
+        (PAYMENT_STATE_FAILED, pgettext_lazy('payment_state', 'failed')),
+        (PAYMENT_STATE_REFUNDED, pgettext_lazy('payment_state', 'refunded')),
+    )
+    local_id = models.PositiveIntegerField()
+    state = models.CharField(
+        max_length=190, choices=PAYMENT_STATES
+    )
+    amount = models.DecimalField(
+        decimal_places=2, max_digits=10,
+        verbose_name=_("Amount")
+    )
+    order = models.ForeignKey(
+        Order,
+        verbose_name=_("Order"),
+        related_name='payments',
+        on_delete=models.PROTECT
+    )
+    created = models.DateTimeField(
+        auto_now_add=True
+    )
+    payment_date = models.DateTimeField(
+        null=True, blank=True
+    )
+    provider = models.CharField(
+        null=True, blank=True,
+        max_length=255,
+        verbose_name=_("Payment provider")
+    )
+    info = models.TextField(
+        verbose_name=_("Payment information"),
+        null=True, blank=True
+    )
+    fee = models.ForeignKey(
+        'OrderFee',
+        null=True, blank=True, related_name='payments', on_delete=models.SET_NULL
+    )
+    migrated = models.BooleanField(default=False)
+
+    class Meta:
+        ordering = ('local_id',)
+
+    @property
+    def info_data(self):
+        """
+        This property allows convenient access to the data stored in the ``info``
+        attribute by automatically encoding and decoding the content as JSON.
+        """
+        return json.loads(self.info) if self.info else {}
+
+    @info_data.setter
+    def info_data(self, d):
+        self.info = json.dumps(d)
+
+    @cached_property
+    def payment_provider(self):
+        """
+        Cached access to an instance of the payment provider in use.
+        """
+        return self.order.event.get_payment_providers().get(self.provider)
+
+    def confirm(self, count_waitinglist=True, send_mail=True, force=False, user=None, auth=None, mail_text=''):
+        """
+        Marks the payment as complete. If possible, this also marks the order as paid if no further
+        payment is required
+
+        :param count_waitinglist: Whether, when calculating quota, people on the waiting list should be taken into
+                                  consideration (default: ``True``).
+        :type count_waitinglist: boolean
+        :param force: Whether this payment should be marked as paid even if no remaining
+                      quota is available (default: ``False``).
+        :type force: boolean
+        :param send_mail: Whether an email should be sent to the user about this event (default: ``True``).
+        :type send_mail: boolean
+        :param user: The user who performed the change
+        :param auth: The API auth token that performed the change
+        :param mail_text: Additional text to be included in the email
+        :type mail_text: str
+        :raises Quota.QuotaExceededException: if the quota is exceeded and ``force`` is ``False``
+        """
+        from pretix.base.signals import order_paid
+        from pretix.base.services.invoices import generate_invoice, invoice_qualified
+        from pretix.base.services.mail import SendMailException
+        from pretix.multidomain.urlreverse import build_absolute_uri
+
+        self.state = self.PAYMENT_STATE_CONFIRMED
+        self.payment_date = now()
+        self.save()
+
+        self.order.log_action('pretix.event.order.payment.confirmed', {
+            'local_id': self.local_id,
+            'provider': self.provider,
+        }, user=user, auth=auth)
+
+        if self.order.status == Order.STATUS_PAID:
+            return
+
+        payment_sum = self.order.payments.filter(
+            state__in=(self.PAYMENT_STATE_CONFIRMED, self.PAYMENT_STATE_REFUNDED)
+        ).aggregate(s=Sum('amount'))['s'] or Decimal('0.00')
+        refund_sum = self.order.refunds.filter(
+            state__in=(OrderRefund.REFUND_STATE_DONE, OrderRefund.REFUND_STATE_TRANSIT,
+                       OrderRefund.REFUND_STATE_CREATED)
+        ).aggregate(s=Sum('amount'))['s'] or Decimal('0.00')
+        if payment_sum - refund_sum < self.order.total:
+            return
+
+        with self.order.event.lock():
+            can_be_paid = self.order._can_be_paid(count_waitinglist=count_waitinglist)
+            if not force and can_be_paid is not True:
+                raise Quota.QuotaExceededException(can_be_paid)
+            self.order.status = Order.STATUS_PAID
+            self.order.save()
+
+            self.order.log_action('pretix.event.order.paid', {
+                'provider': self.provider,
+                'info': self.info,
+                'date': self.payment_date,
+                'force': force
+            }, user=user, auth=auth)
+            order_paid.send(self.order.event, order=self.order)
+
+        invoice = None
+        if invoice_qualified(self.order):
+            invoices = self.order.invoices.filter(is_cancellation=False).count()
+            cancellations = self.order.invoices.filter(is_cancellation=True).count()
+            gen_invoice = (
+                (invoices == 0 and self.order.event.settings.get('invoice_generate') in ('True', 'paid')) or
+                0 < invoices <= cancellations
+            )
+            if gen_invoice:
+                invoice = generate_invoice(
+                    self.order,
+                    trigger_pdf=not send_mail or not self.order.event.settings.invoice_email_attachment
+                )
+
+        if send_mail:
+            with language(self.order.locale):
+                try:
+                    invoice_name = self.order.invoice_address.name
+                    invoice_company = self.order.invoice_address.company
+                except InvoiceAddress.DoesNotExist:
+                    invoice_name = ""
+                    invoice_company = ""
+                email_template = self.order.event.settings.mail_text_order_paid
+                email_context = {
+                    'event': self.order.event.name,
+                    'url': build_absolute_uri(self.order.event, 'presale:event.order', kwargs={
+                        'order': self.order.code,
+                        'secret': self.order.secret
+                    }),
+                    'downloads': self.order.event.settings.get('ticket_download', as_type=bool),
+                    'invoice_name': invoice_name,
+                    'invoice_company': invoice_company,
+                    'payment_info': mail_text
+                }
+                email_subject = _('Payment received for your order: %(code)s') % {'code': self.order.code}
+                try:
+                    self.order.send_mail(
+                        email_subject, email_template, email_context,
+                        'pretix.event.order.email.order_paid', user,
+                        invoices=[invoice] if invoice and self.order.event.settings.invoice_email_attachment else []
+                    )
+                except SendMailException:
+                    logger.exception('Order paid email could not be sent')
+
+    @property
+    def refunded_amount(self):
+        """
+        The sum of all refund amounts in ``done``, ``transit``, or ``created`` states associated
+        with this payment.
+        """
+        return self.refunds.filter(
+            state__in=(OrderRefund.REFUND_STATE_DONE, OrderRefund.REFUND_STATE_TRANSIT,
+                       OrderRefund.REFUND_STATE_CREATED)
+        ).aggregate(s=Sum('amount'))['s'] or Decimal('0.00')
+
+    @property
+    def full_id(self):
+        """
+        The full human-readable ID of this payment, constructed by the order code and the ``local_id``
+        field with ``-P-`` in between.
+        :return:
+        """
+        return '{}-P-{}'.format(self.order.code, self.local_id)
+
+    def save(self, *args, **kwargs):
+        if not self.local_id:
+            self.local_id = (self.order.payments.aggregate(m=Max('local_id'))['m'] or 0) + 1
+        super().save(*args, **kwargs)
+
+    def create_external_refund(self, amount=None, execution_date=None, info='{}'):
+        """
+        This should be called to create an OrderRefund object when a refund has triggered
+        by an external source, e.g. when a credit card payment has been refunded by the
+        credit card provider.
+
+        :param amount: Amount to refund. If not given, the full payment amount will be used.
+        :type amount: Decimal
+        :param execution_date: Date of the refund. Defaults to the current time.
+        :type execution_date: datetime
+        :param info: Additional information, defaults to ``"{}"``.
+        :type info: str
+        :return: OrderRefund
+        """
+        r = self.order.refunds.create(
+            state=OrderRefund.REFUND_STATE_EXTERNAL,
+            source=OrderRefund.REFUND_SOURCE_EXTERNAL,
+            amount=amount if amount is not None else self.amount,
+            order=self.order,
+            payment=self,
+            execution_date=execution_date or now(),
+            provider=self.provider,
+            info=info
+        )
+        self.order.log_action('pretix.event.order.refund.created.externally', {
+            'local_id': r.local_id,
+            'provider': r.provider,
+        })
+        return r
+
+
+class OrderRefund(models.Model):
+    """
+    Represents a refund or refund attempt for an order.
+
+    :param id: A globally unique ID for this refund
+    :type id:
+    :param local_id: An ID of this refund, counting from one for every order independently.
+    :type local_id: int
+    :param state: The state of the refund, one of ``created``, ``transit``, ``external``, ``canceled``,
+      ``failed``, or ``done``.
+    :type state: str
+    :param source: How this refund was started, one of ``buyer``, ``admin``, or ``external``.
+    :param amount: The refund amount
+    :type amount: Decimal
+    :param order: The order that is refunded
+    :type order: Order
+    :param created: The creation time of this record
+    :type created: datetime
+    :param execution_date: The completion time of this refund
+    :type execution_date: datetime
+    :param provider: The payment provider in use
+    :type provider: str
+    :param info: Provider-specific meta information in JSON format
+    :type info: dict
+    """
+    # REFUND_STATE_REQUESTED = 'requested'
+    # REFUND_STATE_APPROVED = 'approved'
+    REFUND_STATE_EXTERNAL = 'external'
+    REFUND_STATE_TRANSIT = 'transit'
+    REFUND_STATE_DONE = 'done'
+    # REFUND_STATE_REJECTED = 'rejected'
+    REFUND_STATE_CANCELED = 'canceled'
+    REFUND_STATE_CREATED = 'created'
+    REFUND_STATE_FAILED = 'failed'
+
+    REFUND_STATES = (
+        # (REFUND_STATE_REQUESTED, pgettext_lazy('refund_state', 'requested')),
+        # (REFUND_STATE_APPROVED, pgettext_lazy('refund_state', 'approved')),
+        (REFUND_STATE_EXTERNAL, pgettext_lazy('refund_state', 'started externally')),
+        (REFUND_STATE_CREATED, pgettext_lazy('refund_state', 'created')),
+        (REFUND_STATE_TRANSIT, pgettext_lazy('refund_state', 'in transit')),
+        (REFUND_STATE_DONE, pgettext_lazy('refund_state', 'done')),
+        (REFUND_STATE_FAILED, pgettext_lazy('refund_state', 'failed')),
+        # (REFUND_STATE_REJECTED, pgettext_lazy('refund_state', 'rejected')),
+        (REFUND_STATE_CANCELED, pgettext_lazy('refund_state', 'canceled')),
+    )
+
+    REFUND_SOURCE_BUYER = 'buyer'
+    REFUND_SOURCE_ADMIN = 'admin'
+    REFUND_SOURCE_EXTERNAL = 'external'
+
+    REFUND_SOURCES = (
+        (REFUND_SOURCE_ADMIN, pgettext_lazy('refund_source', 'Organizer')),
+        (REFUND_SOURCE_BUYER, pgettext_lazy('refund_source', 'Customer')),
+        (REFUND_SOURCE_EXTERNAL, pgettext_lazy('refund_source', 'External')),
+    )
+
+    local_id = models.PositiveIntegerField()
+    state = models.CharField(
+        max_length=190, choices=REFUND_STATES
+    )
+    source = models.CharField(
+        max_length=190, choices=REFUND_SOURCES
+    )
+    amount = models.DecimalField(
+        decimal_places=2, max_digits=10,
+        verbose_name=_("Amount")
+    )
+    order = models.ForeignKey(
+        Order,
+        verbose_name=_("Order"),
+        related_name='refunds',
+        on_delete=models.PROTECT
+    )
+    payment = models.ForeignKey(
+        OrderPayment,
+        null=True, blank=True,
+        related_name='refunds',
+        on_delete=models.PROTECT
+    )
+    created = models.DateTimeField(
+        auto_now_add=True
+    )
+    execution_date = models.DateTimeField(
+        null=True, blank=True
+    )
+    provider = models.CharField(
+        null=True, blank=True,
+        max_length=255,
+        verbose_name=_("Payment provider")
+    )
+    info = models.TextField(
+        verbose_name=_("Payment information"),
+        null=True, blank=True
+    )
+
+    class Meta:
+        ordering = ('local_id',)
+
+    @property
+    def info_data(self):
+        """
+        This property allows convenient access to the data stored in the ``info``
+        attribute by automatically encoding and decoding the content as JSON.
+        """
+        return json.loads(self.info) if self.info else {}
+
+    @info_data.setter
+    def info_data(self, d):
+        self.info = json.dumps(d)
+
+    @cached_property
+    def payment_provider(self):
+        """
+        Cached access to an instance of the payment provider in use.
+        """
+        return self.order.event.get_payment_providers().get(self.provider)
+
+    @transaction.atomic
+    def done(self, user=None, auth=None):
+        """
+        Marks the refund as complete. This does not modify the state of the order.
+
+        :param user: The user who performed the change
+        :param user: The API auth token that performed the change
+        """
+        self.state = self.REFUND_STATE_DONE
+        self.execution_date = self.execution_date or now()
+        self.save()
+
+        self.order.log_action('pretix.event.order.refund.done', {
+            'local_id': self.local_id,
+            'provider': self.provider,
+        }, user=user, auth=auth)
+
+        if self.payment and self.payment.refunded_amount >= self.payment.amount:
+            self.payment.state = OrderPayment.PAYMENT_STATE_REFUNDED
+            self.payment.save(update_fields=['state'])
+
+    @property
+    def full_id(self):
+        """
+        The full human-readable ID of this refund, constructed by the order code and the ``local_id``
+        field with ``-R-`` in between.
+        :return:
+        """
+        return '{}-R-{}'.format(self.order.code, self.local_id)
+
+    def save(self, *args, **kwargs):
+        if not self.local_id:
+            self.local_id = (self.order.refunds.aggregate(m=Max('local_id'))['m'] or 0) + 1
+        super().save(*args, **kwargs)
+
+
 class OrderFee(models.Model):
     """
-    An OrderFee objet represents a fee that is added to the order total independently of
+    An OrderFee object represents a fee that is added to the order total independently of
     the actual positions. This might for example be a payment or a shipping fee.
+
+    :param value: Gross price of this fee
+    :type value: Decimal
+    :param order: Order this fee is charged with
+    :type order: Order
+    :param fee_type: The type of the fee, currently ``payment``, ``shipping``, ``service``, ``giftcard``, or ``other``.
+    :type fee_type: str
+    :param description: A human-readable description of the fee
+    :type description: str
+    :param internal_type: An internal string to group fees by, e.g. the identifier string of a payment provider
+    :type internal_type: str
+    :param tax_rate: The tax rate applied to this fee
+    :type tax_rate: Decimal
+    :param tax_rule: The tax rule applied to this fee
+    :type tax_rule: TaxRule
+    :param tax_value: The tax amount included in the price
+    :type tax_value: Decimal
     """
     FEE_TYPE_PAYMENT = "payment"
     FEE_TYPE_SHIPPING = "shipping"
@@ -813,6 +1316,18 @@ class OrderPosition(AbstractPosition):
 
     :param order: The order this position is a part of
     :type order: Order
+    :param positionid: A local ID of this position, counted for each order individually
+    :type positionid: int
+    :param tax_rate: The tax rate applied to this position
+    :type tax_rate: Decimal
+    :param tax_rule: The tax rule applied to this position
+    :type tax_rule: TaxRule
+    :param tax_value: The tax amount included in the price
+    :type tax_value: Decimal
+    :param secret: The secret used for ticket QR codes
+    :type secret: str
+    :param pseudonymization_id: The QR code content for lead scanning
+    :type pseudonymization_id: str
     """
     positionid = models.PositiveIntegerField(default=1)
     order = models.ForeignKey(
@@ -956,7 +1471,8 @@ class CartPosition(AbstractPosition):
     """
     event = models.ForeignKey(
         Event,
-        verbose_name=_("Event")
+        verbose_name=_("Event"),
+        on_delete=models.CASCADE
     )
     cart_id = models.CharField(
         max_length=255, null=True, blank=True, db_index=True,
@@ -1000,7 +1516,7 @@ class CartPosition(AbstractPosition):
 
 class InvoiceAddress(models.Model):
     last_modified = models.DateTimeField(auto_now=True)
-    order = models.OneToOneField(Order, null=True, blank=True, related_name='invoice_address')
+    order = models.OneToOneField(Order, null=True, blank=True, related_name='invoice_address', on_delete=models.CASCADE)
     is_business = models.BooleanField(default=False, verbose_name=_('Business customer'))
     company = models.CharField(max_length=255, blank=True, verbose_name=_('Company name'))
     name = models.CharField(max_length=255, verbose_name=_('Full name'), blank=True)

src/pretix/base/models/organizer.py

@@ -42,6 +42,7 @@ class Organizer(LoggedModel):
             OrganizerSlugBlacklistValidator()
         ],
         verbose_name=_("Short form"),
+        unique=True
     )
 
     class Meta:

src/pretix/base/models/tax.py

@@ -60,7 +60,7 @@ EU_CURRENCIES = {
 
 
 class TaxRule(LoggedModel):
-    event = models.ForeignKey('Event', related_name='tax_rules')
+    event = models.ForeignKey('Event', related_name='tax_rules', on_delete=models.CASCADE)
     name = I18nCharField(
         verbose_name=_('Name'),
         help_text=_('Should be short, e.g. "VAT"'),

src/pretix/base/models/vouchers.py

@@ -137,14 +137,14 @@ class Voucher(LoggedModel):
     item = models.ForeignKey(
         Item, related_name='vouchers',
         verbose_name=_("Product"),
-        null=True, blank=True,
+        null=True, blank=True, on_delete=models.CASCADE,
         help_text=_(
             "This product is added to the user's cart if the voucher is redeemed."
         )
     )
     variation = models.ForeignKey(
         ItemVariation, related_name='vouchers',
-        null=True, blank=True,
+        null=True, blank=True, on_delete=models.CASCADE,
         verbose_name=_("Product variation"),
         help_text=_(
             "This variation of the product select above is being used."
@@ -152,7 +152,7 @@ class Voucher(LoggedModel):
     )
     quota = models.ForeignKey(
         Quota, related_name='quota',
-        null=True, blank=True,
+        null=True, blank=True, on_delete=models.CASCADE,
         verbose_name=_("Quota"),
         help_text=_(
             "If enabled, the voucher is valid for any product affected by this quota."

src/pretix/base/models/waitinglist.py

@@ -42,10 +42,12 @@ class WaitingListEntry(LoggedModel):
     voucher = models.ForeignKey(
         'Voucher',
         verbose_name=_("Assigned voucher"),
-        null=True, blank=True
+        null=True, blank=True,
+        related_name='waitinglistentries',
+        on_delete=models.CASCADE
     )
     item = models.ForeignKey(
-        Item, related_name='waitinglistentries',
+        Item, related_name='waitinglistentries', on_delete=models.CASCADE,
         verbose_name=_("Product"),
         help_text=_(
             "The product the user waits for."
@@ -53,7 +55,7 @@ class WaitingListEntry(LoggedModel):
     )
     variation = models.ForeignKey(
         ItemVariation, related_name='waitinglistentries',
-        null=True, blank=True,
+        null=True, blank=True, on_delete=models.CASCADE,
         verbose_name=_("Product variation"),
         help_text=_(
             "The variation of the product selected above."
@@ -63,11 +65,12 @@ class WaitingListEntry(LoggedModel):
         max_length=190,
         default='en'
     )
+    priority = models.IntegerField(default=0)
 
     class Meta:
         verbose_name = _("Waiting list entry")
         verbose_name_plural = _("Waiting list entries")
-        ordering = ['created']
+        ordering = ('-priority', 'created')
 
     def __str__(self):
         return '%s waits for %s' % (str(self.email), str(self.item))

src/pretix/base/notifications.py

@@ -229,6 +229,12 @@ def register_default_notification_types(sender, **kwargs):
             _('Order changed'),
             _('Order {order.code} has been changed.')
         ),
+        ParametrizedOrderNotificationType(
+            sender,
+            'pretix.event.order.refund.created.externally',
+            _('External refund of payment'),
+            _('An external refund for {order.code} has occurred.')
+        ),
         ParametrizedOrderNotificationType(
             sender,
             'pretix.event.order.refunded',

src/pretix/base/payment.py

@@ -1,3 +1,4 @@
+import json
 import logging
 from collections import OrderedDict
 from decimal import ROUND_HALF_UP, Decimal
@@ -6,20 +7,25 @@ from typing import Any, Dict, Union
 import pytz
 from django import forms
 from django.conf import settings
-from django.contrib import messages
+from django.core.exceptions import ImproperlyConfigured
 from django.dispatch import receiver
 from django.forms import Form
 from django.http import HttpRequest
 from django.template.loader import get_template
 from django.utils.timezone import now
 from django.utils.translation import pgettext_lazy, ugettext_lazy as _
-from i18nfield.forms import I18nFormField, I18nTextarea
+from i18nfield.forms import I18nFormField, I18nTextarea, I18nTextInput
 from i18nfield.strings import LazyI18nString
 
-from pretix.base.models import CartPosition, Event, Order, Quota
+from pretix.base.forms import PlaceholderValidator
+from pretix.base.models import (
+    CartPosition, Event, Order, OrderPayment, OrderRefund, Quota,
+)
 from pretix.base.reldate import RelativeDateField, RelativeDateWrapper
 from pretix.base.settings import SettingsSandbox
 from pretix.base.signals import register_payment_providers
+from pretix.base.templatetags.money import money_filter
+from pretix.base.templatetags.rich_text import rich_text
 from pretix.helpers.money import DecimalTextInput
 from pretix.presale.views import get_cart_total
 from pretix.presale.views.cart import get_or_create_cart_id
@@ -130,6 +136,16 @@ class BasePaymentProvider:
         """
         raise NotImplementedError()  # NOQA
 
+    @property
+    def abort_pending_allowed(self) -> bool:
+        """
+        Whether or not a user can abort a payment in pending start to switch to another
+        payment method. This returns ``False`` by default which is no guarantee that
+        aborting a pending payment can never happen, it just hides the frontend button
+        to avoid users accidentally committing double payments.
+        """
+        return False
+
     @property
     def settings_form_fields(self) -> dict:
         """
@@ -185,6 +201,28 @@ class BasePaymentProvider:
                  widget=I18nTextarea,
                  widget_kwargs={'attrs': {'rows': '2'}}
              )),
+            ('_total_min',
+             forms.DecimalField(
+                 label=_('Minimum order total'),
+                 help_text=_('This payment will be available only if the order total is equal to or exceeds the given '
+                             'value. The order total for this purpose may be computed without taking the fees imposed '
+                             'by this payment method into account.'),
+                 localize=True,
+                 required=False,
+                 decimal_places=places,
+                 widget=DecimalTextInput(places=places)
+             )),
+            ('_total_max',
+             forms.DecimalField(
+                 label=_('Maximum order total'),
+                 help_text=_('This payment will be available only if the order total is equal to or below the given '
+                             'value. The order total for this purpose may be computed without taking the fees imposed '
+                             'by this payment method into account.'),
+                 localize=True,
+                 required=False,
+                 decimal_places=places,
+                 widget=DecimalTextInput(places=places)
+             )),
             ('_fee_abs',
              forms.DecimalField(
                  label=_('Additional fee'),
@@ -304,20 +342,40 @@ class BasePaymentProvider:
 
         return True
 
-    def is_allowed(self, request: HttpRequest) -> bool:
+    def is_allowed(self, request: HttpRequest, total: Decimal=None) -> bool:
         """
         You can use this method to disable this payment provider for certain groups
         of users, products or other criteria. If this method returns ``False``, the
         user will not be able to select this payment method. This will only be called
         during checkout, not on retrying.
 
-        The default implementation checks for the _availability_date setting to be either unset or in the future.
-        """
-        return self._is_still_available(cart_id=get_or_create_cart_id(request))
+        The default implementation checks for the _availability_date setting to be either unset or in the future
+        and for the _total_max and _total_min requirements to be met.
 
-    def payment_form_render(self, request: HttpRequest) -> str:
+        :param total: The total value without the payment method fee, after taxes.
+
+        .. versionchanged:: 1.17.0
+
+           The ``total`` parameter has been added. For backwards compatibility, this method is called again
+           without this parameter if it raises a ``TypeError`` on first try.
         """
-        When the user selects this provider as his preferred payment method,
+        timing = self._is_still_available(cart_id=get_or_create_cart_id(request))
+        pricing = True
+
+        if (self.settings._total_max is not None or self.settings._total_min is not None) and total is None:
+            raise ImproperlyConfigured('This payment provider does not support maximum or minimum amounts.')
+
+        if self.settings._total_max is not None:
+            pricing = pricing and total <= Decimal(self.settings._total_max)
+
+        if self.settings._total_min is not None:
+            pricing = pricing and total >= Decimal(self.settings._total_min)
+
+        return timing and pricing
+
+    def payment_form_render(self, request: HttpRequest, total: Decimal) -> str:
+        """
+        When the user selects this provider as their preferred payment method,
         they will be shown the HTML you return from this method.
 
         The default implementation will call :py:meth:`checkout_form`
@@ -332,8 +390,8 @@ class BasePaymentProvider:
 
     def checkout_confirm_render(self, request) -> str:
         """
-        If the user has successfully filled in his payment data, they will be redirected
-        to a confirmation page which lists all details of his order for a final review.
+        If the user has successfully filled in their payment data, they will be redirected
+        to a confirmation page which lists all details of their order for a final review.
         This method should return the HTML which should be displayed inside the
         'Payment' box on this page.
 
@@ -342,11 +400,19 @@ class BasePaymentProvider:
         """
         raise NotImplementedError()  # NOQA
 
+    def payment_pending_render(self, request: HttpRequest, payment: OrderPayment) -> str:
+        """
+        Render customer-facing instructions on how to proceed with a pending payment
+
+        :return: HTML
+        """
+        return ""
+
     def checkout_prepare(self, request: HttpRequest, cart: Dict[str, Any]) -> Union[bool, str]:
         """
-        Will be called after the user selects this provider as his payment method.
+        Will be called after the user selects this provider as their payment method.
         If you provided a form to the user to enter payment data, this method should
-        at least store the user's input into his session.
+        at least store the user's input into their session.
 
         This method should return ``False`` if the user's input was invalid, ``True``
         if the input was valid and the frontend should continue with default behavior
@@ -361,7 +427,7 @@ class BasePaymentProvider:
         If your payment method requires you to redirect the user to an external provider,
         this might be the place to do so.
 
-        .. IMPORTANT:: If this is called, the user has not yet confirmed his or her order.
+        .. IMPORTANT:: If this is called, the user has not yet confirmed their order.
            You may NOT do anything which actually moves money.
 
         :param cart: This dictionary contains at least the following keys:
@@ -396,26 +462,29 @@ class BasePaymentProvider:
         """
         raise NotImplementedError()  # NOQA
 
-    def payment_perform(self, request: HttpRequest, order: Order) -> str:
+    def execute_payment(self, request: HttpRequest, payment: OrderPayment) -> str:
         """
         After the user has confirmed their purchase, this method will be called to complete
         the payment process. This is the place to actually move the money if applicable.
-        If you need any special  behavior,  you can return a string
+        You will be passed an :py:class:`pretix.base.models.OrderPayment` object that contains
+        the amount of money that should be paid.
+
+        If you need any special behavior, you can return a string
         containing the URL the user will be redirected to. If you are done with your process
         you should return the user to the order's detail page.
 
-        If the payment is completed, you should call ``pretix.base.services.orders.mark_order_paid(order, provider, info)``
-        with ``provider`` being your :py:attr:`identifier` and ``info`` being any string
-        you might want to store for later usage. Please note that ``mark_order_paid`` might
-        raise a ``Quota.QuotaExceededException`` if (and only if) the payment term of this
-        order is over and some of the items are sold out. You should use the exception message
-        to display a meaningful error to the user.
+        If the payment is completed, you should call ``payment.confirm()``. Please note that ``this`` might
+        raise a ``Quota.QuotaExceededException`` if (and only if) the payment term of this order is over and
+        some of the items are sold out. You should use the exception message to display a meaningful error
+        to the user.
 
         The default implementation just returns ``None`` and therefore leaves the
         order unpaid. The user will be redirected to the order's detail page by default.
 
         On errors, you should raise a ``PaymentException``.
+
         :param order: The order object
+        :param payment: An ``OrderPayment`` instance
         """
         return None
 
@@ -429,19 +498,6 @@ class BasePaymentProvider:
         """
         return ""
 
-    def order_pending_render(self, request: HttpRequest, order: Order) -> str:
-        """
-        If the user visits a detail page of an order which has not yet been paid but
-        this payment method was selected during checkout, this method will be called
-        to provide HTML content for the 'payment' box on the page.
-
-        It should contain instructions on how to continue with the payment process,
-        either in form of text or buttons/links/etc.
-
-        :param order: The order object
-        """
-        raise NotImplementedError()  # NOQA
-
     def order_change_allowed(self, order: Order) -> bool:
         """
         Will be called to check whether it is allowed to change the payment method of
@@ -451,33 +507,16 @@ class BasePaymentProvider:
 
         :param order: The order object
         """
+        ps = order.pending_sum
+        if self.settings._total_max is not None and ps > Decimal(self.settings._total_max):
+            return False
+
+        if self.settings._total_min is not None and ps < Decimal(self.settings._total_min):
+            return False
+
         return self._is_still_available(order=order)
 
-    def order_can_retry(self, order: Order) -> bool:
-        """
-        Will be called if the user views the detail page of an unpaid order to determine
-        whether the user should be presented with an option to retry the payment. The default
-        implementation always returns False.
-
-        If you want to enable retrials for your payment method, the best is to just return
-        ``self._is_still_available()`` from this method to disable it as soon as the method
-        gets disabled or the methods end date is reached.
-
-        The retry workflow is also used if a user switches to this payment method for an existing
-        order!
-
-        :param order: The order object
-        """
-        return False
-
-    def retry_prepare(self, request: HttpRequest, order: Order) -> Union[bool, str]:
-        """
-        Deprecated, use order_prepare instead
-        """
-        raise DeprecationWarning('retry_prepare is deprecated, use order_prepare instead')
-        return self.order_prepare(request, order)
-
-    def order_prepare(self, request: HttpRequest, order: Order) -> Union[bool, str]:
+    def payment_prepare(self, request: HttpRequest, payment: OrderPayment) -> Union[bool, str]:
         """
         Will be called if the user retries to pay an unpaid order (after the user filled in
         e.g. the form returned by :py:meth:`payment_form`) or if the user changes the payment
@@ -498,22 +537,9 @@ class BasePaymentProvider:
         else:
             return False
 
-    def order_paid_render(self, request: HttpRequest, order: Order) -> str:
+    def payment_control_render(self, request: HttpRequest, payment: OrderPayment) -> str:
         """
-        Will be called if the user views the detail page of a paid order which is
-        associated with this payment provider.
-
-        It should return HTML code which should be displayed to the user or None,
-        if there is nothing to say (like the default implementation does).
-
-        :param order: The order object
-        """
-        return None
-
-    def order_control_render(self, request: HttpRequest, order: Order) -> str:
-        """
-        Will be called if the *event administrator* views the detail page of an order
-        which is associated with this payment provider.
+        Will be called if the *event administrator* views the details of a payment.
 
         It should return HTML code containing information regarding the current payment
         status and, if applicable, next steps.
@@ -522,62 +548,44 @@ class BasePaymentProvider:
 
         :param order: The order object
         """
-        return _('Payment provider: %s' % self.verbose_name)
+        return ''
 
-    def order_control_refund_render(self, order: Order, request: HttpRequest=None) -> str:
+    def payment_refund_supported(self, payment: OrderPayment) -> bool:
         """
-        Will be called if the event administrator clicks an order's 'refund' button.
-        This can be used to display information *before* the order is being refunded.
-
-        It should return HTML code which should be displayed to the user. It should
-        contain information about to which extend the money will be refunded
-        automatically.
-
-        :param order: The order object
-        :param request: The HTTP request
-
-        .. versionchanged:: 1.6
-
-           The parameter ``request`` has been added.
+        Will be called to check if the provider supports automatic refunding for this
+        payment.
         """
-        return '<div class="alert alert-warning">%s</div>' % _('The money can not be automatically refunded, '
-                                                               'please transfer the money back manually.')
+        return False
 
-    def order_control_refund_perform(self, request: HttpRequest, order: Order) -> Union[bool, str]:
+    def payment_partial_refund_supported(self, payment: OrderPayment) -> bool:
         """
-        Will be called if the event administrator confirms the refund.
-
-        This should transfer the money back (if possible). You can return the URL the
-        user should be redirected to if you need special behavior or None to continue
-        with default behavior.
-
-        On failure, you should use Django's message framework to display an error message
-        to the user.
-
-        The default implementation sets the Order's state to refunded and shows a success
-        message.
-
-        :param request: The HTTP request
-        :param order: The order object
+        Will be called to check if the provider supports automatic partial refunding for this
+        payment.
         """
-        from pretix.base.services.orders import mark_order_refunded
+        return False
 
-        mark_order_refunded(order, user=request.user)
-        messages.success(request, _('The order has been marked as refunded. Please transfer the money '
-                                    'back to the buyer manually.'))
+    def execute_refund(self, refund: OrderRefund):
+        """
+        Will be called to execute an refund. Note that refunds have an amount property and can be partial.
 
-    def shred_payment_info(self, order: Order):
+        This should transfer the money back (if possible).
+        On success, you should call ``refund.done()``.
+        On failure, you should raise a PaymentException.
+        """
+        raise PaymentException(_('Automatic refunds are not supported by this payment provider.'))
+
+    def shred_payment_info(self, obj: Union[OrderPayment, OrderRefund]):
         """
         When personal data is removed from an event, this method is called to scrub payment-related data
-        from an order. By default, it removes all info from the ``payment_info`` attribute. You can override
+        from a payment or refund. By default, it removes all info from the ``info`` attribute. You can override
         this behavior if you want to retain attributes that are not personal data on their own, i.e. a
         reference to a transaction in an external system. You can also override this to scrub more data, e.g.
         data from external sources that is saved in LogEntry objects or other places.
 
         :param order: An order
         """
-        order.payment_info = None
-        order.save(update_fields=['payment_info'])
+        obj.info = '{}'
+        obj.save(update_fields=['info'])
 
 
 class PaymentException(Exception):
@@ -585,25 +593,13 @@ class PaymentException(Exception):
 
 
 class FreeOrderProvider(BasePaymentProvider):
-
-    @property
-    def is_implicit(self) -> bool:
-        return True
-
-    @property
-    def is_enabled(self) -> bool:
-        return True
-
-    @property
-    def identifier(self) -> str:
-        return "free"
+    is_implicit = True
+    is_enabled = True
+    identifier = "free"
 
     def checkout_confirm_render(self, request: HttpRequest) -> str:
         return _("No payment is required as this order only includes products which are free of charge.")
 
-    def order_pending_render(self, request: HttpRequest, order: Order) -> str:
-        pass
-
     def payment_is_valid_session(self, request: HttpRequest) -> bool:
         return True
 
@@ -611,10 +607,9 @@ class FreeOrderProvider(BasePaymentProvider):
     def verbose_name(self) -> str:
         return _("Free of charge")
 
-    def payment_perform(self, request: HttpRequest, order: Order):
-        from pretix.base.services.orders import mark_order_paid
+    def execute_payment(self, request: HttpRequest, payment: OrderPayment):
         try:
-            mark_order_paid(order, 'free', send_mail=False)
+            payment.confirm(send_mail=False)
         except Quota.QuotaExceededException as e:
             raise PaymentException(str(e))
 
@@ -622,32 +617,7 @@ class FreeOrderProvider(BasePaymentProvider):
     def settings_form_fields(self) -> dict:
         return {}
 
-    def order_control_refund_render(self, order: Order) -> str:
-        return ''
-
-    def order_control_refund_perform(self, request: HttpRequest, order: Order) -> Union[bool, str]:
-        """
-        Will be called if the event administrator confirms the refund.
-
-        This should transfer the money back (if possible). You can return the URL the
-        user should be redirected to if you need special behavior or None to continue
-        with default behavior.
-
-        On failure, you should use Django's message framework to display an error message
-        to the user.
-
-        The default implementation sets the Order's state to refunded and shows a success
-        message.
-
-        :param request: The HTTP request
-        :param order: The order object
-        """
-        from pretix.base.services.orders import mark_order_refunded
-
-        mark_order_refunded(order, user=request.user)
-        messages.success(request, _('The order has been marked as refunded.'))
-
-    def is_allowed(self, request: HttpRequest) -> bool:
+    def is_allowed(self, request: HttpRequest, total: Decimal=None) -> bool:
         from .services.cart import get_fees
 
         total = get_cart_total(request)
@@ -664,10 +634,9 @@ class BoxOfficeProvider(BasePaymentProvider):
     identifier = "boxoffice"
     verbose_name = _("Box office")
 
-    def payment_perform(self, request: HttpRequest, order: Order):
-        from pretix.base.services.orders import mark_order_paid
+    def execute_payment(self, request: HttpRequest, payment: OrderPayment):
         try:
-            mark_order_paid(order, 'boxoffice', send_mail=False)
+            payment.confirm(send_mail=False)
         except Quota.QuotaExceededException as e:
             raise PaymentException(str(e))
 
@@ -675,22 +644,139 @@ class BoxOfficeProvider(BasePaymentProvider):
     def settings_form_fields(self) -> dict:
         return {}
 
-    def order_control_refund_render(self, order: Order) -> str:
-        return ''
-
-    def order_control_refund_perform(self, request: HttpRequest, order: Order) -> Union[bool, str]:
-        from pretix.base.services.orders import mark_order_refunded
-
-        mark_order_refunded(order, user=request.user)
-        messages.success(request, _('The order has been marked as refunded.'))
-
-    def is_allowed(self, request: HttpRequest) -> bool:
+    def is_allowed(self, request: HttpRequest, total: Decimal=None) -> bool:
         return False
 
     def order_change_allowed(self, order: Order) -> bool:
         return False
 
 
+class ManualPayment(BasePaymentProvider):
+    identifier = 'manual'
+    verbose_name = _('Manual payment')
+
+    @property
+    def is_implicit(self):
+        return 'pretix.plugins.manualpayment' not in self.event.plugins
+
+    def is_allowed(self, request: HttpRequest, total: Decimal=None):
+        return 'pretix.plugins.manualpayment' in self.event.plugins and super().is_allowed(request, total)
+
+    def order_change_allowed(self, order: Order):
+        return 'pretix.plugins.manualpayment' in self.event.plugins and super().order_change_allowed(order)
+
+    @property
+    def public_name(self):
+        return str(self.settings.get('public_name', as_type=LazyI18nString))
+
+    @property
+    def settings_form_fields(self):
+        d = OrderedDict(
+            [
+                ('public_name', I18nFormField(
+                    label=_('Payment method name'),
+                    widget=I18nTextInput,
+                )),
+                ('checkout_description', I18nFormField(
+                    label=_('Payment process description during checkout'),
+                    help_text=_('This text will be shown during checkout when the user selects this payment method. '
+                                'It should give a short explanation on this payment method.'),
+                    widget=I18nTextarea,
+                )),
+                ('email_instructions', I18nFormField(
+                    label=_('Payment process description in order confirmation emails'),
+                    help_text=_('This text will be included for the {payment_info} placeholder in order confirmation '
+                                'mails. It should instruct the user on how to proceed with the payment. You can use'
+                                'the placeholders {order}, {total}, {currency} and {total_with_currency}'),
+                    widget=I18nTextarea,
+                    validators=[PlaceholderValidator(['{order}', '{total}', '{currency}', '{total_with_currency}'])],
+                )),
+                ('pending_description', I18nFormField(
+                    label=_('Payment process description for pending orders'),
+                    help_text=_('This text will be shown on the order confirmation page for pending orders. '
+                                'It should instruct the user on how to proceed with the payment. You can use'
+                                'the placeholders {order}, {total}, {currency} and {total_with_currency}'),
+                    widget=I18nTextarea,
+                    validators=[PlaceholderValidator(['{order}', '{total}', '{currency}', '{total_with_currency}'])],
+                )),
+            ] + list(super().settings_form_fields.items())
+        )
+        d.move_to_end('_enabled', last=False)
+        return d
+
+    def payment_form_render(self, request) -> str:
+        return rich_text(
+            str(self.settings.get('checkout_description', as_type=LazyI18nString))
+        )
+
+    def checkout_prepare(self, request, total):
+        return True
+
+    def payment_is_valid_session(self, request):
+        return True
+
+    def checkout_confirm_render(self, request):
+        return self.payment_form_render(request)
+
+    def format_map(self, order):
+        return {
+            'order': order.code,
+            'total': order.total,
+            'currency': self.event.currency,
+            'total_with_currency': money_filter(order.total, self.event.currency)
+        }
+
+    def order_pending_mail_render(self, order) -> str:
+        msg = str(self.settings.get('email_instructions', as_type=LazyI18nString)).format_map(self.format_map(order))
+        return msg
+
+    def order_pending_render(self, request, order) -> str:
+        return rich_text(
+            str(self.settings.get('pending_description', as_type=LazyI18nString)).format_map(self.format_map(order))
+        )
+
+
+class OffsettingProvider(BasePaymentProvider):
+    is_enabled = True
+    identifier = "offsetting"
+    verbose_name = _("Offsetting")
+    is_implicit = True
+
+    def execute_payment(self, request: HttpRequest, payment: OrderPayment):
+        try:
+            payment.confirm()
+        except Quota.QuotaExceededException as e:
+            raise PaymentException(str(e))
+
+    def execute_refund(self, refund: OrderRefund):
+        code = refund.info_data['orders'][0]
+        try:
+            order = Order.objects.get(code=code, event__organizer=self.event.organizer)
+        except Order.DoesNotExist:
+            raise PaymentException(_('You entered an order that could not be found.'))
+        p = order.payments.create(
+            state=OrderPayment.PAYMENT_STATE_PENDING,
+            amount=refund.amount,
+            payment_date=now(),
+            provider='offsetting',
+            info=json.dumps({'orders': [refund.order.code]})
+        )
+        p.confirm()
+
+    @property
+    def settings_form_fields(self) -> dict:
+        return {}
+
+    def is_allowed(self, request: HttpRequest, total: Decimal=None) -> bool:
+        return False
+
+    def order_change_allowed(self, order: Order) -> bool:
+        return False
+
+    def payment_control_render(self, request: HttpRequest, payment: OrderPayment) -> str:
+        return _('Balanced against orders: %s' % ', '.join(payment.info_data['orders']))
+
+
 @receiver(register_payment_providers, dispatch_uid="payment_free")
 def register_payment_provider(sender, **kwargs):
-    return [FreeOrderProvider, BoxOfficeProvider]
+    return [FreeOrderProvider, BoxOfficeProvider, OffsettingProvider, ManualPayment]

src/pretix/base/pdf.py

@@ -24,6 +24,7 @@ from reportlab.pdfbase.ttfonts import TTFont
 from reportlab.pdfgen.canvas import Canvas
 from reportlab.platypus import Paragraph
 
+from pretix.base.invoice import ThumbnailingImageReader
 from pretix.base.models import Order, OrderPosition
 from pretix.base.signals import layout_text_variables
 from pretix.base.templatetags.money import money_filter
@@ -210,6 +211,22 @@ class Renderer:
             if 'bolditalic' in styles:
                 pdfmetrics.registerFont(TTFont(family + ' B I', finders.find(styles['bolditalic']['truetype'])))
 
+    def _draw_poweredby(self, canvas: Canvas, op: OrderPosition, o: dict):
+        content = o.get('content', 'dark')
+        img = finders.find('pretixpresale/pdf/powered_by_pretix_{}.png'.format(content))
+
+        ir = ThumbnailingImageReader(img)
+        try:
+            width, height = ir.resize(None, float(o['size']) * mm, 300)
+        except:
+            logger.exception("Can not resize image")
+            pass
+        canvas.drawImage(ir,
+                         float(o['left']) * mm, float(o['bottom']) * mm,
+                         width=width, height=height,
+                         preserveAspectRatio=True, anchor='n',
+                         mask='auto')
+
     def _draw_barcodearea(self, canvas: Canvas, op: OrderPosition, o: dict):
         content = o.get('content', 'secret')
         if content == 'secret':
@@ -284,6 +301,8 @@ class Renderer:
                 self._draw_barcodearea(canvas, op, o)
             elif o['type'] == "textarea":
                 self._draw_textarea(canvas, op, order, o)
+            elif o['type'] == "poweredby":
+                self._draw_poweredby(canvas, op, o)
         canvas.showPage()
 
     def render_background(self, buffer, title=_('Ticket')):

src/pretix/base/plugins.py

@@ -2,6 +2,7 @@ from enum import Enum
 from typing import List
 
 from django.apps import apps
+from django.conf import settings
 
 
 class PluginType(Enum):
@@ -26,5 +27,7 @@ def get_all_plugins() -> List[type]:
             meta = app.PretixPluginMeta
             meta.module = app.name
             meta.app = app
+            if app.name in settings.PRETIX_PLUGINS_EXCLUDE:
+                continue
             plugins.append(meta)
     return plugins

src/pretix/base/reldate.py

@@ -104,7 +104,7 @@ class RelativeDateWrapper:
                 timeparts = parts[2].split(':')
                 time = datetime.time(hour=int(timeparts[0]), minute=int(timeparts[1]), second=int(timeparts[2]))
             data = RelativeDate(
-                days_before=int(parts[1]),
+                days_before=int(parts[1] or 0),
                 base_date_name=parts[3],
                 time=time
             )

src/pretix/base/services/cart.py

@@ -17,9 +17,9 @@ from pretix.base.models import (
 from pretix.base.models.event import SubEvent
 from pretix.base.models.orders import OrderFee
 from pretix.base.models.tax import TAXED_ZERO, TaxedPrice, TaxRule
-from pretix.base.services.async import ProfiledTask
 from pretix.base.services.locking import LockTimeoutException
 from pretix.base.services.pricing import get_price
+from pretix.base.services.tasks import ProfiledTask
 from pretix.base.templatetags.rich_text import rich_text
 from pretix.celery_app import app
 from pretix.presale.signals import (
@@ -64,6 +64,10 @@ error_messages = {
     'price_too_high': _('The entered price is to high.'),
     'voucher_invalid': _('This voucher code is not known in our database.'),
     'voucher_redeemed': _('This voucher code has already been used the maximum number of times allowed.'),
+    'voucher_redeemed_cart': _('This voucher code is currently locked since it is already contained in a cart. This '
+                               'might mean that someone else is redeeming this voucher right now, or that you tried '
+                               'to redeem it before but did not complete the checkout process. You can try to use it '
+                               'again in %d minutes.'),
     'voucher_redeemed_partial': _('This voucher code can only be redeemed %d more times.'),
     'voucher_double': _('You already used this voucher code. Remove the associated line from your '
                         'cart if you want to use it for a different product.'),
@@ -232,11 +236,17 @@ class CartManager:
     def _get_price(self, item: Item, variation: Optional[ItemVariation],
                    voucher: Optional[Voucher], custom_price: Optional[Decimal],
                    subevent: Optional[SubEvent], cp_is_net: bool=None):
-        return get_price(
-            item, variation, voucher, custom_price, subevent,
-            custom_price_is_net=cp_is_net if cp_is_net is not None else self.event.settings.display_net_prices,
-            invoice_address=self.invoice_address
-        )
+        try:
+            return get_price(
+                item, variation, voucher, custom_price, subevent,
+                custom_price_is_net=cp_is_net if cp_is_net is not None else self.event.settings.display_net_prices,
+                invoice_address=self.invoice_address
+            )
+        except ValueError as e:
+            if str(e) == 'price_too_high':
+                raise CartError(error_messages['price_too_high'])
+            else:
+                raise e
 
     def extend_expired_positions(self):
         expired = self.positions.filter(expires__lte=self.now_dt).select_related(
@@ -491,6 +501,7 @@ class CartManager:
 
     def _get_voucher_availability(self):
         vouchers_ok = {}
+        self._voucher_depend_on_cart = set()
         for voucher, count in self._voucher_use_diff.items():
             voucher.refresh_from_db()
 
@@ -503,7 +514,10 @@ class CartManager:
             ).exclude(pk__in=[
                 op.position.voucher_id for op in self._operations if isinstance(op, self.ExtendOperation)
             ])
-            v_avail = voucher.max_usages - voucher.redeemed - redeemed_in_carts.count()
+            cart_count = redeemed_in_carts.count()
+            v_avail = voucher.max_usages - voucher.redeemed - cart_count
+            if cart_count > 0:
+                self._voucher_depend_on_cart.add(voucher)
             vouchers_ok[voucher] = v_avail
 
         return vouchers_ok
@@ -574,7 +588,10 @@ class CartManager:
                     err = err or error_messages['in_part']
 
                 if voucher_available_count < 1:
-                    err = err or error_messages['voucher_redeemed']
+                    if op.voucher in self._voucher_depend_on_cart:
+                        err = err or error_messages['voucher_redeemed_cart'] % self.event.settings.reservation_time
+                    else:
+                        err = err or error_messages['voucher_redeemed']
                 elif voucher_available_count < requested_count:
                     err = err or error_messages['voucher_redeemed_partial'] % voucher_available_count
 

src/pretix/base/services/checkin.py

@@ -116,10 +116,13 @@ def perform_checkin(op: OrderPosition, clist: CheckinList, given_answers: dict,
             require_answers
         )
     else:
-        ci, created = Checkin.objects.get_or_create(position=op, list=clist, defaults={
-            'datetime': dt,
-            'nonce': nonce,
-        })
+        try:
+            ci, created = Checkin.objects.get_or_create(position=op, list=clist, defaults={
+                'datetime': dt,
+                'nonce': nonce,
+            })
+        except Checkin.MultipleObjectsReturned:
+            ci, created = Checkin.objects.filter(position=op, list=clist).last(), False
 
     if created or (nonce and nonce == ci.nonce):
         if created:

src/pretix/base/services/export.py

@@ -5,7 +5,7 @@ from django.utils.timezone import override
 
 from pretix.base.i18n import language
 from pretix.base.models import CachedFile, Event, cachedfile_name
-from pretix.base.services.async import ProfiledTask
+from pretix.base.services.tasks import ProfiledTask
 from pretix.base.signals import register_data_exporters
 from pretix.celery_app import app
 

src/pretix/base/services/invoices.py

@@ -1,4 +1,3 @@
-import copy
 import json
 import logging
 import urllib.error
@@ -18,29 +17,35 @@ from django.utils.translation import pgettext, ugettext as _
 from i18nfield.strings import LazyI18nString
 
 from pretix.base.i18n import language
-from pretix.base.models import Invoice, InvoiceAddress, InvoiceLine, Order
+from pretix.base.models import (
+    Invoice, InvoiceAddress, InvoiceLine, Order, OrderPayment,
+)
 from pretix.base.models.tax import EU_CURRENCIES
-from pretix.base.services.async import TransactionAwareTask
+from pretix.base.services.tasks import TransactionAwareTask
 from pretix.base.settings import GlobalSettingsObject
 from pretix.base.signals import periodic_task
 from pretix.celery_app import app
 from pretix.helpers.database import rolledback_transaction
+from pretix.helpers.models import modelcopy
 
 logger = logging.getLogger(__name__)
 
 
 @transaction.atomic
 def build_invoice(invoice: Invoice) -> Invoice:
-    with language(invoice.locale):
-        payment_provider = invoice.event.get_payment_providers().get(invoice.order.payment_provider)
+    lp = invoice.order.payments.last()
+    open_payment = None
+    if lp and lp.state not in (OrderPayment.PAYMENT_STATE_CONFIRMED, OrderPayment.PAYMENT_STATE_REFUNDED):
+        open_payment = lp
 
+    with language(invoice.locale):
         invoice.invoice_from = invoice.event.settings.get('invoice_address_from')
 
         introductory = invoice.event.settings.get('invoice_introductory_text', as_type=LazyI18nString)
         additional = invoice.event.settings.get('invoice_additional_text', as_type=LazyI18nString)
         footer = invoice.event.settings.get('invoice_footer_text', as_type=LazyI18nString)
-        if payment_provider:
-            payment = payment_provider.render_invoice_text(invoice.order)
+        if open_payment and open_payment.payment_provider:
+            payment = open_payment.payment_provider.render_invoice_text(invoice.order)
         else:
             payment = ""
 
@@ -166,7 +171,7 @@ def build_cancellation(invoice: Invoice):
 
 
 def generate_cancellation(invoice: Invoice, trigger_pdf=True):
-    cancellation = copy.copy(invoice)
+    cancellation = modelcopy(invoice)
     cancellation.pk = None
     cancellation.invoice_no = None
     cancellation.prefix = None
@@ -232,7 +237,7 @@ def invoice_pdf_task(invoice: int):
 
 
 def invoice_qualified(order: Order):
-    if order.total == Decimal('0.00'):
+    if order.total == Decimal('0.00') or order.require_approval:
         return False
     return True
 

src/pretix/base/services/mail.py

@@ -2,22 +2,19 @@ import logging
 from email.utils import formataddr
 from typing import Any, Dict, List, Union
 
-import bleach
 import cssutils
-import markdown
 from celery import chain
 from django.conf import settings
 from django.core.mail import EmailMultiAlternatives, get_connection
 from django.template.loader import get_template
 from django.utils.translation import ugettext as _
 from i18nfield.strings import LazyI18nString
-from inlinestyler.utils import inline_css
 
+from pretix.base.email import ClassicMailRenderer
 from pretix.base.i18n import language
 from pretix.base.models import Event, Invoice, InvoiceAddress, Order
 from pretix.base.services.invoices import invoice_pdf_task
 from pretix.base.signals import email_filter
-from pretix.base.templatetags.rich_text import markdown_compile
 from pretix.celery_app import app
 from pretix.multidomain.urlreverse import build_absolute_uri
 
@@ -88,7 +85,8 @@ def mail(email: str, subject: str, template: Union[str, LazyI18nString],
                     'invoice_name': '',
                     'invoice_company': ''
                 })
-        body, body_md = render_mail(template, context)
+        renderer = ClassicMailRenderer(None)
+        content_plain = body_plain = render_mail(template, context)
         subject = str(subject).format_map(context)
         sender = sender or (event.settings.get('mail_from') if event else settings.MAIL_FROM)
         if event:
@@ -97,23 +95,20 @@ def mail(email: str, subject: str, template: Union[str, LazyI18nString],
             sender = formataddr((settings.PRETIX_INSTANCE_NAME, sender))
 
         subject = str(subject)
-        body_plain = body
-
-        htmlctx = {
-            'site': settings.PRETIX_INSTANCE_NAME,
-            'site_url': settings.SITE_URL,
-            'body': body_md,
-            'color': '#8E44B3'
-        }
+        signature = ""
 
+        bcc = []
         if event:
-            htmlctx['event'] = event
-            htmlctx['color'] = event.settings.primary_color
+            renderer = event.get_html_mail_renderer()
+            if event.settings.mail_bcc:
+                bcc.append(event.settings.mail_bcc)
 
             if event.settings.mail_from == settings.DEFAULT_FROM_EMAIL and event.settings.contact_mail and not headers.get('Reply-To'):
                 headers['Reply-To'] = event.settings.contact_mail
 
             prefix = event.settings.get('mail_prefix')
+            if prefix and prefix.startswith('[') and prefix.endswith(']'):
+                prefix = prefix[1:-1]
             if prefix:
                 subject = "[%s] %s" % (prefix, subject)
 
@@ -122,9 +117,6 @@ def mail(email: str, subject: str, template: Union[str, LazyI18nString],
             signature = str(event.settings.get('mail_text_signature'))
             if signature:
                 signature = signature.format(event=event.name)
-                signature_md = signature.replace('\n', '<br>\n')
-                signature_md = bleach.linkify(bleach.clean(markdown.markdown(signature_md), tags=bleach.ALLOWED_TAGS + ['p', 'br']))
-                htmlctx['signature'] = signature_md
                 body_plain += signature
                 body_plain += "\r\n\r\n-- \r\n"
 
@@ -132,7 +124,6 @@ def mail(email: str, subject: str, template: Union[str, LazyI18nString],
                 body_plain += _(
                     "You are receiving this email because you placed an order for {event}."
                 ).format(event=event.name)
-                htmlctx['order'] = order
                 body_plain += "\r\n"
                 body_plain += _(
                     "You can view your order details at the following URL:\n{orderurl}."
@@ -146,11 +137,15 @@ def mail(email: str, subject: str, template: Union[str, LazyI18nString],
                 )
             body_plain += "\r\n"
 
-        tpl = get_template('pretixbase/email/plainwrapper.html')
-        body_html = tpl.render(htmlctx)
+        try:
+            body_html = renderer.render(content_plain, signature, str(subject), order)
+        except:
+            logger.exception('Could not render HTML body')
+            body_html = None
 
         send_task = mail_send_task.si(
             to=[email],
+            bcc=bcc,
             subject=subject,
             body=body_plain,
             html=body_html,
@@ -176,7 +171,7 @@ def mail_send_task(*args, to: List[str], subject: str, body: str, html: str, sen
                    order: int=None) -> bool:
     email = EmailMultiAlternatives(subject, body, sender, to=to, bcc=bcc, headers=headers)
     if html is not None:
-        email.attach_alternative(inline_css(html), "text/html")
+        email.attach_alternative(html, "text/html")
     if invoices:
         invoices = Invoice.objects.filter(pk__in=invoices)
         for inv in invoices:
@@ -219,5 +214,4 @@ def render_mail(template, context):
     else:
         tpl = get_template(template)
         body = tpl.render(context)
-    body_md = bleach.linkify(markdown_compile(body))
-    return body, body_md
+    return body

src/pretix/base/services/notifications.py

@@ -1,11 +1,12 @@
 from django.conf import settings
 from django.template.loader import get_template
+from inlinestyler.utils import inline_css
 
 from pretix.base.i18n import language
 from pretix.base.models import LogEntry, NotificationSetting, User
 from pretix.base.notifications import Notification, get_all_notification_types
-from pretix.base.services.async import ProfiledTask, TransactionAwareTask
 from pretix.base.services.mail import mail_send_task
+from pretix.base.services.tasks import ProfiledTask, TransactionAwareTask
 from pretix.celery_app import app
 from pretix.helpers.urls import build_absolute_uri
 
@@ -91,7 +92,7 @@ def send_notification_mail(notification: Notification, user: User):
     }
 
     tpl_html = get_template('pretixbase/email/notification.html')
-    body_html = tpl_html.render(ctx)
+    body_html = inline_css(tpl_html.render(ctx))
     tpl_plain = get_template('pretixbase/email/notification.txt')
     body_plain = tpl_plain.render(ctx)
 

src/pretix/base/services/orders.py

@@ -1,4 +1,3 @@
-import copy
 import json
 import logging
 from collections import Counter, namedtuple
@@ -13,6 +12,7 @@ from django.db import transaction
 from django.db.models import F, Max, Q, Sum
 from django.dispatch import receiver
 from django.utils.formats import date_format
+from django.utils.functional import cached_property
 from django.utils.timezone import now
 from django.utils.translation import ugettext as _
 
@@ -21,29 +21,29 @@ from pretix.base.i18n import (
     LazyCurrencyNumber, LazyDate, LazyLocaleException, LazyNumber, language,
 )
 from pretix.base.models import (
-    CartPosition, Event, Item, ItemVariation, Order, OrderPosition, Quota,
-    User, Voucher,
+    CartPosition, Event, Item, ItemVariation, Order, OrderPayment,
+    OrderPosition, Quota, User, Voucher,
 )
 from pretix.base.models.event import SubEvent
 from pretix.base.models.orders import (
-    CachedCombinedTicket, CachedTicket, InvoiceAddress, OrderFee,
+    CachedCombinedTicket, CachedTicket, InvoiceAddress, OrderFee, OrderRefund,
     generate_position_secret, generate_secret,
 )
 from pretix.base.models.organizer import TeamAPIToken
 from pretix.base.models.tax import TaxedPrice
 from pretix.base.payment import BasePaymentProvider
-from pretix.base.services.async import ProfiledTask
 from pretix.base.services.invoices import (
     generate_cancellation, generate_invoice, invoice_qualified,
 )
 from pretix.base.services.locking import LockTimeoutException
 from pretix.base.services.mail import SendMailException
 from pretix.base.services.pricing import get_price
+from pretix.base.services.tasks import ProfiledTask
 from pretix.base.signals import (
-    allow_ticket_download, order_fee_calculation, order_paid, order_placed,
-    periodic_task,
+    allow_ticket_download, order_fee_calculation, order_placed, periodic_task,
 )
 from pretix.celery_app import app
+from pretix.helpers.models import modelcopy
 from pretix.multidomain.urlreverse import build_absolute_uri
 
 error_messages = {
@@ -79,99 +79,8 @@ error_messages = {
 logger = logging.getLogger(__name__)
 
 
-def mark_order_paid(order: Order, provider: str=None, info: str=None, date: datetime=None, manual: bool=None,
-                    force: bool=False, send_mail: bool=True, user: User=None, mail_text='',
-                    count_waitinglist=True, auth=None) -> Order:
-    """
-    Marks an order as paid. This sets the payment provider, info and date and returns
-    the order object.
-
-    :param provider: The payment provider that marked this as paid
-    :type provider: str
-    :param info: The information to store in order.payment_info
-    :type info: str
-    :param date: The date the payment was received (if you pass ``None``, the current
-                 time will be used).
-    :type date: datetime
-    :param force: Whether this payment should be marked as paid even if no remaining
-                  quota is available (default: ``False``).
-    :type force: boolean
-    :param send_mail: Whether an email should be sent to the user about this event (default: ``True``).
-    :type send_mail: boolean
-    :param user: The user that performed the change
-    :param mail_text: Additional text to be included in the email
-    :type mail_text: str
-    :raises Quota.QuotaExceededException: if the quota is exceeded and ``force`` is ``False``
-    """
-    if order.status == Order.STATUS_PAID:
-        return order
-
-    with order.event.lock() as now_dt:
-        can_be_paid = order._can_be_paid(count_waitinglist=count_waitinglist)
-        if not force and can_be_paid is not True:
-            raise Quota.QuotaExceededException(can_be_paid)
-        order.payment_provider = provider or order.payment_provider
-        order.payment_info = info or order.payment_info
-        order.payment_date = date or now_dt
-        if manual is not None:
-            order.payment_manual = manual
-        order.status = Order.STATUS_PAID
-        order.save()
-
-    order.log_action('pretix.event.order.paid', {
-        'provider': provider,
-        'info': info,
-        'date': date or now_dt,
-        'manual': manual,
-        'force': force
-    }, user=user, auth=auth)
-    order_paid.send(order.event, order=order)
-
-    invoice = None
-    if invoice_qualified(order):
-        invoices = order.invoices.filter(is_cancellation=False).count()
-        cancellations = order.invoices.filter(is_cancellation=True).count()
-        gen_invoice = (
-            (invoices == 0 and order.event.settings.get('invoice_generate') in ('True', 'paid')) or
-            0 < invoices <= cancellations
-        )
-        if gen_invoice:
-            invoice = generate_invoice(
-                order,
-                trigger_pdf=not send_mail or not order.event.settings.invoice_email_attachment
-            )
-
-    if send_mail:
-        with language(order.locale):
-            try:
-                invoice_name = order.invoice_address.name
-                invoice_company = order.invoice_address.company
-            except InvoiceAddress.DoesNotExist:
-                invoice_name = ""
-                invoice_company = ""
-            email_template = order.event.settings.mail_text_order_paid
-            email_context = {
-                'event': order.event.name,
-                'url': build_absolute_uri(order.event, 'presale:event.order', kwargs={
-                    'order': order.code,
-                    'secret': order.secret
-                }),
-                'downloads': order.event.settings.get('ticket_download', as_type=bool),
-                'invoice_name': invoice_name,
-                'invoice_company': invoice_company,
-                'payment_info': mail_text
-            }
-            email_subject = _('Payment received for your order: %(code)s') % {'code': order.code}
-            try:
-                order.send_mail(
-                    email_subject, email_template, email_context,
-                    'pretix.event.order.email.order_paid', user,
-                    invoices=[invoice] if invoice and order.event.settings.invoice_email_attachment else []
-                )
-            except SendMailException:
-                logger.exception('Order paid email could not be sent')
-
-    return order
+def mark_order_paid(*args, **kwargs):
+    raise NotImplementedError("This method is no longer supported since pretix 1.17.")
 
 
 def extend_order(order: Order, new_date: datetime, force: bool=False, user: User=None, auth=None):
@@ -215,7 +124,7 @@ def extend_order(order: Order, new_date: datetime, force: bool=False, user: User
 
 
 @transaction.atomic
-def mark_order_refunded(order, user=None, api_token=None):
+def mark_order_refunded(order, user=None, auth=None, api_token=None):
     """
     Mark this order as refunded. This sets the payment status and returns the order object.
     :param order: The order to change
@@ -229,7 +138,7 @@ def mark_order_refunded(order, user=None, api_token=None):
         order.status = Order.STATUS_REFUNDED
         order.save()
 
-    order.log_action('pretix.event.order.refunded', user=user, api_token=api_token)
+    order.log_action('pretix.event.order.refunded', user=user, auth=auth or api_token)
     i = order.invoices.filter(is_cancellation=False).last()
     if i:
         generate_cancellation(i)
@@ -260,6 +169,142 @@ def mark_order_expired(order, user=None, auth=None):
     return order
 
 
+@transaction.atomic
+def approve_order(order, user=None, send_mail: bool=True, auth=None):
+    """
+    Mark this order as approved
+    :param order: The order to change
+    :param user: The user that performed the change
+    """
+    if not order.require_approval or not order.status == Order.STATUS_PENDING:
+        raise OrderError(_('This order is not pending approval.'))
+
+    order.require_approval = False
+    order.set_expires(now(), order.event.subevents.filter(id__in=[p.subevent_id for p in order.positions.all()]))
+    order.save()
+
+    order.log_action('pretix.event.order.approved', user=user, auth=auth)
+    if order.total == Decimal('0.00'):
+        p = order.payments.create(
+            state=OrderPayment.PAYMENT_STATE_CREATED,
+            provider='free',
+            amount=0,
+            fee=None
+        )
+        try:
+            p.confirm(send_mail=False, count_waitinglist=False, user=user, auth=auth)
+        except Quota.QuotaExceededException:
+            raise OrderError(error_messages['unavailable'])
+
+    invoice = order.invoices.last()  # Might be generated by plugin already
+    if order.event.settings.get('invoice_generate') == 'True' and invoice_qualified(order):
+        if not invoice:
+            generate_invoice(
+                order,
+                trigger_pdf=not order.event.settings.invoice_email_attachment or not order.email
+            )
+            # send_mail will trigger PDF generation later
+
+    if send_mail:
+        try:
+            invoice_name = order.invoice_address.name
+            invoice_company = order.invoice_address.company
+        except InvoiceAddress.DoesNotExist:
+            invoice_name = ""
+            invoice_company = ""
+
+        with language(order.locale):
+            if order.total == Decimal('0.00'):
+                email_template = order.event.settings.mail_text_order_free
+                email_subject = _('Order approved and confirmed: %(code)s') % {'code': order.code}
+            else:
+                email_template = order.event.settings.mail_text_order_approved
+                email_subject = _('Order approved and awaiting payment: %(code)s') % {'code': order.code}
+
+            email_context = {
+                'total': LazyNumber(order.total),
+                'currency': order.event.currency,
+                'total_with_currency': LazyCurrencyNumber(order.total, order.event.currency),
+                'date': LazyDate(order.expires),
+                'event': order.event.name,
+                'url': build_absolute_uri(order.event, 'presale:event.order', kwargs={
+                    'order': order.code,
+                    'secret': order.secret
+                }),
+                'invoice_name': invoice_name,
+                'invoice_company': invoice_company,
+            }
+            try:
+                order.send_mail(
+                    email_subject, email_template, email_context,
+                    'pretix.event.order.email.order_approved', user
+                )
+            except SendMailException:
+                logger.exception('Order approved email could not be sent')
+
+    return order.pk
+
+
+@transaction.atomic
+def deny_order(order, comment='', user=None, send_mail: bool=True, auth=None):
+    """
+    Mark this order as canceled
+    :param order: The order to change
+    :param user: The user that performed the change
+    """
+    if not order.require_approval or not order.status == Order.STATUS_PENDING:
+        raise OrderError(_('This order is not pending approval.'))
+
+    with order.event.lock():
+        order.status = Order.STATUS_CANCELED
+        order.save()
+
+    order.log_action('pretix.event.order.denied', user=user, auth=auth, data={
+        'comment': comment
+    })
+    i = order.invoices.filter(is_cancellation=False).last()
+    if i:
+        generate_cancellation(i)
+
+    for position in order.positions.all():
+        if position.voucher:
+            Voucher.objects.filter(pk=position.voucher.pk).update(redeemed=F('redeemed') - 1)
+
+    if send_mail:
+        try:
+            invoice_name = order.invoice_address.name
+            invoice_company = order.invoice_address.company
+        except InvoiceAddress.DoesNotExist:
+            invoice_name = ""
+            invoice_company = ""
+        email_template = order.event.settings.mail_text_order_denied
+        email_context = {
+            'total': LazyNumber(order.total),
+            'currency': order.event.currency,
+            'total_with_currency': LazyCurrencyNumber(order.total, order.event.currency),
+            'date': LazyDate(order.expires),
+            'event': order.event.name,
+            'url': build_absolute_uri(order.event, 'presale:event.order', kwargs={
+                'order': order.code,
+                'secret': order.secret
+            }),
+            'comment': comment,
+            'invoice_name': invoice_name,
+            'invoice_company': invoice_company,
+        }
+        with language(order.locale):
+            email_subject = _('Order denied: %(code)s') % {'code': order.code}
+            try:
+                order.send_mail(
+                    email_subject, email_template, email_context,
+                    'pretix.event.order.email.order_denied', user
+                )
+            except SendMailException:
+                logger.exception('Order denied email could not be sent')
+
+    return order.pk
+
+
 @transaction.atomic
 def _cancel_order(order, user=None, send_mail: bool=True, api_token=None, oauth_application=None):
     """
@@ -433,21 +478,26 @@ def _get_fees(positions: List[CartPosition], payment_provider: BasePaymentProvid
               meta_info: dict, event: Event):
     fees = []
     total = sum([c.price for c in positions])
-    payment_fee = payment_provider.calculate_fee(total)
+    if payment_provider:
+        payment_fee = payment_provider.calculate_fee(total)
+    else:
+        payment_fee = 0
+    pf = None
     if payment_fee:
-        fees.append(OrderFee(fee_type=OrderFee.FEE_TYPE_PAYMENT, value=payment_fee,
-                             internal_type=payment_provider.identifier))
+        pf = OrderFee(fee_type=OrderFee.FEE_TYPE_PAYMENT, value=payment_fee,
+                      internal_type=payment_provider.identifier)
+        fees.append(pf)
 
     for recv, resp in order_fee_calculation.send(sender=event, invoice_address=address, total=total,
                                                  meta_info=meta_info, positions=positions):
         fees += resp
-    return fees
+    return fees, pf
 
 
 def _create_order(event: Event, email: str, positions: List[CartPosition], now_dt: datetime,
                   payment_provider: BasePaymentProvider, locale: str=None, address: InvoiceAddress=None,
                   meta_info: dict=None):
-    fees = _get_fees(positions, payment_provider, address, meta_info, event)
+    fees, pf = _get_fees(positions, payment_provider, address, meta_info, event)
     total = sum([c.price for c in positions]) + sum([c.value for c in fees])
 
     with transaction.atomic():
@@ -458,8 +508,8 @@ def _create_order(event: Event, email: str, positions: List[CartPosition], now_d
             datetime=now_dt,
             locale=locale,
             total=total,
-            payment_provider=payment_provider.identifier,
             meta_info=json.dumps(meta_info or {}),
+            require_approval=any(p.item.require_approval for p in positions)
         )
         order.set_expires(now_dt, event.subevents.filter(id__in=[p.subevent_id for p in positions]))
         order.save()
@@ -479,6 +529,14 @@ def _create_order(event: Event, email: str, positions: List[CartPosition], now_d
                 fee.tax_rule = None  # TODO: deprecate
             fee.save()
 
+        if payment_provider:
+            order.payments.create(
+                state=OrderPayment.PAYMENT_STATE_CREATED,
+                provider=payment_provider.identifier,
+                amount=total,
+                fee=pf
+            )
+
         OrderPosition.transform_cart_positions(positions, order)
         order.log_action('pretix.event.order.placed')
         if meta_info:
@@ -493,9 +551,12 @@ def _perform_order(event: str, payment_provider: str, position_ids: List[str],
                    email: str, locale: str, address: int, meta_info: dict=None):
 
     event = Event.objects.get(id=event)
-    pprov = event.get_payment_providers().get(payment_provider)
-    if not pprov:
-        raise OrderError(error_messages['internal'])
+    if payment_provider:
+        pprov = event.get_payment_providers().get(payment_provider)
+        if not pprov:
+            raise OrderError(error_messages['internal'])
+    else:
+        pprov = None
 
     if email == settings.PRETIX_EMAIL_NONE_VALUE:
         email = None
@@ -528,7 +589,10 @@ def _perform_order(event: str, payment_provider: str, position_ids: List[str],
             # send_mail will trigger PDF generation later
 
     if order.email:
-        if order.payment_provider == 'free':
+        if order.require_approval:
+            email_template = event.settings.mail_text_order_placed_require_approval
+            log_entry = 'pretix.event.order.email.order_placed_require_approval'
+        elif payment_provider == 'free':
             email_template = event.settings.mail_text_order_free
             log_entry = 'pretix.event.order.email.order_free'
         else:
@@ -541,6 +605,12 @@ def _perform_order(event: str, payment_provider: str, position_ids: List[str],
         except InvoiceAddress.DoesNotExist:
             invoice_name = ""
             invoice_company = ""
+
+        if pprov:
+            payment_info = str(pprov.order_pending_mail_render(order))
+        else:
+            payment_info = None
+
         email_context = {
             'total': LazyNumber(order.total),
             'currency': event.currency,
@@ -551,7 +621,7 @@ def _perform_order(event: str, payment_provider: str, position_ids: List[str],
                 'order': order.code,
                 'secret': order.secret
             }),
-            'payment_info': str(pprov.order_pending_mail_render(order)),
+            'payment_info': payment_info,
             'invoice_name': invoice_name,
             'invoice_company': invoice_company,
         }
@@ -572,7 +642,8 @@ def _perform_order(event: str, payment_provider: str, position_ids: List[str],
 def expire_orders(sender, **kwargs):
     eventcache = {}
 
-    for o in Order.objects.filter(expires__lt=now(), status=Order.STATUS_PENDING).select_related('event'):
+    for o in Order.objects.filter(expires__lt=now(), status=Order.STATUS_PENDING,
+                                  require_approval=False).select_related('event'):
         expire = eventcache.get(o.event.pk, None)
         if expire is None:
             expire = o.event.settings.get('payment_term_expire_automatically', as_type=bool)
@@ -646,29 +717,29 @@ def send_download_reminders(sender, **kwargs):
             if not all([r for rr, r in allow_ticket_download.send(e, order=o)]):
                 continue
 
-            o.download_reminder_sent = True
-            o.save()
-            email_template = e.settings.mail_text_download_reminder
-            email_context = {
-                'event': o.event.name,
-                'url': build_absolute_uri(o.event, 'presale:event.order', kwargs={
-                    'order': o.code,
-                    'secret': o.secret
-                }),
-            }
-            email_subject = _('Your ticket is ready for download: %(code)s') % {'code': o.code}
-            try:
-                o.send_mail(
-                    email_subject, email_template, email_context,
-                    'pretix.event.order.email.download_reminder_sent'
-                )
-            except SendMailException:
-                logger.exception('Reminder email could not be sent')
+            with language(o.locale):
+                o.download_reminder_sent = True
+                o.save()
+                email_template = e.settings.mail_text_download_reminder
+                email_context = {
+                    'event': o.event.name,
+                    'url': build_absolute_uri(o.event, 'presale:event.order', kwargs={
+                        'order': o.code,
+                        'secret': o.secret
+                    }),
+                }
+                email_subject = _('Your ticket is ready for download: %(code)s') % {'code': o.code}
+                try:
+                    o.send_mail(
+                        email_subject, email_template, email_context,
+                        'pretix.event.order.email.download_reminder_sent'
+                    )
+                except SendMailException:
+                    logger.exception('Reminder email could not be sent')
 
 
 class OrderChangeManager:
     error_messages = {
-        'free_to_paid': _('You cannot change a free order to a paid order.'),
         'product_without_variation': _('You need to select a variation of the product.'),
         'quota': _('The quota {name} does not have enough capacity left to perform the operation.'),
         'quota_missing': _('There is no quota defined that allows this operation.'),
@@ -677,8 +748,6 @@ class OrderChangeManager:
         'not_pending_or_paid': _('Only pending or paid orders can be changed.'),
         'paid_to_free_exceeded': _('This operation would make the order free and therefore immediately paid, however '
                                    'no quota is available.'),
-        'paid_price_change': _('Currently, paid orders can only be changed in a way that does not change the total '
-                               'price of the order as partial payments or refunds are not yet supported.'),
         'addon_to_required': _('This is an add-on product, please select the base position it should be added to.'),
         'addon_invalid': _('The selected base position does not allow you to add this product as an add-on.'),
         'subevent_required': _('You need to choose a subevent for the new position.'),
@@ -691,9 +760,10 @@ class OrderChangeManager:
     SplitOperation = namedtuple('SplitOperation', ('position',))
     RegenerateSecretOperation = namedtuple('RegenerateSecretOperation', ('position',))
 
-    def __init__(self, order: Order, user, notify=True):
+    def __init__(self, order: Order, user=None, auth=None, notify=True):
         self.order = order
         self.user = user
+        self.auth = auth
         self.split_order = None
         self._committed = False
         self._totaldiff = 0
@@ -834,33 +904,44 @@ class OrderChangeManager:
             if avail[0] != Quota.AVAILABILITY_OK or (avail[1] is not None and avail[1] < diff):
                 raise OrderError(self.error_messages['quota'].format(name=quota.name))
 
-    def _check_free_to_paid(self):
-        if self.order.total == Decimal('0.00') and self._totaldiff > 0:
-            raise OrderError(self.error_messages['free_to_paid'])
-
     def _check_paid_price_change(self):
-        if self.order.status == Order.STATUS_PAID and self._totaldiff != 0:
-            raise OrderError(self.error_messages['paid_price_change'])
+        if self.order.status == Order.STATUS_PAID and self._totaldiff > 0:
+            self.order.status = Order.STATUS_PENDING
+            self.order.set_expires(
+                now(),
+                self.order.event.subevents.filter(id__in=self.order.positions.values_list('subevent_id', flat=True))
+            )
+            self.order.save()
+        elif self.order.status in (Order.STATUS_PENDING, Order.STATUS_EXPIRED) and self._totaldiff < 0:
+            if self.order.pending_sum <= Decimal('0.00'):
+                self.order.status = Order.STATUS_PAID
+                self.order.save()
 
     def _check_paid_to_free(self):
         if self.order.total == 0 and (self._totaldiff < 0 or (self.split_order and self.split_order.total > 0)):
             # if the order becomes free, mark it paid using the 'free' provider
             # this could happen if positions have been made cheaper or removed (_totaldiff < 0)
             # or positions got split off to a new order (split_order with positive total)
+            p = self.order.payments.create(
+                state=OrderPayment.PAYMENT_STATE_CREATED,
+                provider='free',
+                amount=0,
+                fee=None
+            )
             try:
-                mark_order_paid(
-                    self.order, 'free', send_mail=False, count_waitinglist=False,
-                    user=self.user
-                )
+                p.confirm(send_mail=False, count_waitinglist=False, user=self.user, auth=self.auth)
             except Quota.QuotaExceededException:
                 raise OrderError(self.error_messages['paid_to_free_exceeded'])
 
         if self.split_order and self.split_order.total == 0:
+            p = self.split_order.payments.create(
+                state=OrderPayment.PAYMENT_STATE_CREATED,
+                provider='free',
+                amount=0,
+                fee=None
+            )
             try:
-                mark_order_paid(
-                    self.split_order, 'free', send_mail=False, count_waitinglist=False,
-                    user=self.user
-                )
+                p.confirm(send_mail=False, count_waitinglist=False, user=self.user, auth=self.auth)
             except Quota.QuotaExceededException:
                 raise OrderError(self.error_messages['paid_to_free_exceeded'])
 
@@ -870,7 +951,7 @@ class OrderChangeManager:
 
         for op in self._operations:
             if isinstance(op, self.ItemOperation):
-                self.order.log_action('pretix.event.order.changed.item', user=self.user, data={
+                self.order.log_action('pretix.event.order.changed.item', user=self.user, auth=self.auth, data={
                     'position': op.position.pk,
                     'positionid': op.position.positionid,
                     'old_item': op.position.item.pk,
@@ -889,7 +970,7 @@ class OrderChangeManager:
                 op.position.tax_rule = op.item.tax_rule
                 op.position.save()
             elif isinstance(op, self.SubeventOperation):
-                self.order.log_action('pretix.event.order.changed.subevent', user=self.user, data={
+                self.order.log_action('pretix.event.order.changed.subevent', user=self.user, auth=self.auth, data={
                     'position': op.position.pk,
                     'positionid': op.position.positionid,
                     'old_subevent': op.position.subevent.pk,
@@ -904,7 +985,7 @@ class OrderChangeManager:
                 op.position.tax_rule = op.position.item.tax_rule
                 op.position.save()
             elif isinstance(op, self.PriceOperation):
-                self.order.log_action('pretix.event.order.changed.price', user=self.user, data={
+                self.order.log_action('pretix.event.order.changed.price', user=self.user, auth=self.auth, data={
                     'position': op.position.pk,
                     'positionid': op.position.positionid,
                     'old_price': op.position.price,
@@ -918,7 +999,7 @@ class OrderChangeManager:
                 op.position.save()
             elif isinstance(op, self.CancelOperation):
                 for opa in op.position.addons.all():
-                    self.order.log_action('pretix.event.order.changed.cancel', user=self.user, data={
+                    self.order.log_action('pretix.event.order.changed.cancel', user=self.user, auth=self.auth, data={
                         'position': opa.pk,
                         'positionid': opa.positionid,
                         'old_item': opa.item.pk,
@@ -926,7 +1007,7 @@ class OrderChangeManager:
                         'addon_to': opa.addon_to_id,
                         'old_price': opa.price,
                     })
-                self.order.log_action('pretix.event.order.changed.cancel', user=self.user, data={
+                self.order.log_action('pretix.event.order.changed.cancel', user=self.user, auth=self.auth, data={
                     'position': op.position.pk,
                     'positionid': op.position.positionid,
                     'old_item': op.position.item.pk,
@@ -943,7 +1024,7 @@ class OrderChangeManager:
                     positionid=nextposid, subevent=op.subevent
                 )
                 nextposid += 1
-                self.order.log_action('pretix.event.order.changed.add', user=self.user, data={
+                self.order.log_action('pretix.event.order.changed.add', user=self.user, auth=self.auth, data={
                     'position': pos.pk,
                     'item': op.item.pk,
                     'variation': op.variation.pk if op.variation else None,
@@ -959,7 +1040,7 @@ class OrderChangeManager:
                 op.position.save()
                 CachedTicket.objects.filter(order_position__order=self.order).delete()
                 CachedCombinedTicket.objects.filter(order=self.order).delete()
-                self.order.log_action('pretix.event.order.changed.secret', user=self.user, data={
+                self.order.log_action('pretix.event.order.changed.secret', user=self.user, auth=self.auth, data={
                     'position': op.position.pk,
                     'positionid': op.position.positionid,
                 })
@@ -974,12 +1055,12 @@ class OrderChangeManager:
         split_order.datetime = now()
         split_order.secret = generate_secret()
         split_order.save()
-        split_order.log_action('pretix.event.order.changed.split_from', user=self.user, data={
+        split_order.log_action('pretix.event.order.changed.split_from', user=self.user, auth=self.auth, data={
             'original_order': self.order.code
         })
 
         for op in split_positions:
-            self.order.log_action('pretix.event.order.changed.split', user=self.user, data={
+            self.order.log_action('pretix.event.order.changed.split', user=self.user, auth=self.auth, data={
                 'position': op.pk,
                 'positionid': op.positionid,
                 'old_item': op.item.pk,
@@ -992,7 +1073,7 @@ class OrderChangeManager:
             op.save()
 
         try:
-            ia = copy.copy(self.order.invoice_address)
+            ia = modelcopy(self.order.invoice_address)
             ia.pk = None
             ia.order = split_order
             ia.save()
@@ -1001,7 +1082,11 @@ class OrderChangeManager:
 
         split_order.total = sum([p.price for p in split_positions])
         if split_order.total != Decimal('0.00') and self.order.status != Order.STATUS_PAID:
-            payment_fee = self._get_payment_provider().calculate_fee(split_order.total)
+            pp = self._get_payment_provider()
+            if pp:
+                payment_fee = pp.calculate_fee(split_order.total)
+            else:
+                payment_fee = Decimal('0.00')
             fee = split_order.fees.get_or_create(fee_type=OrderFee.FEE_TYPE_PAYMENT, defaults={'value': 0})[0]
             fee.value = payment_fee
             fee._calculate_tax()
@@ -1012,7 +1097,7 @@ class OrderChangeManager:
             split_order.total += fee.value
 
         for fee in self.order.fees.exclude(fee_type=OrderFee.FEE_TYPE_PAYMENT):
-            new_fee = copy.copy(fee)
+            new_fee = modelcopy(fee)
             new_fee.pk = None
             new_fee.order = split_order
             split_order.total += new_fee.value
@@ -1020,41 +1105,89 @@ class OrderChangeManager:
 
         split_order.save()
 
+        if split_order.status == Order.STATUS_PAID:
+            split_order.payments.create(
+                state=OrderPayment.PAYMENT_STATE_CONFIRMED,
+                amount=split_order.total,
+                payment_date=now(),
+                provider='offsetting',
+                info=json.dumps({'orders': [self.order.code]})
+            )
+            self.order.refunds.create(
+                state=OrderRefund.REFUND_STATE_DONE,
+                amount=split_order.total,
+                execution_date=now(),
+                provider='offsetting',
+                info=json.dumps({'orders': [split_order.code]})
+            )
+
         if split_order.total != Decimal('0.00') and self.order.invoices.filter(is_cancellation=False).last():
             generate_invoice(split_order)
         return split_order
 
-    def _recalculate_total_and_payment_fee(self):
-        self.order.total = sum([p.price for p in self.order.positions.all()])
+    @cached_property
+    def open_payment(self):
+        lp = self.order.payments.last()
+        if lp and lp.state not in (OrderPayment.PAYMENT_STATE_CONFIRMED,
+                                   OrderPayment.PAYMENT_STATE_REFUNDED):
+            return lp
 
-        if self.order.status != Order.STATUS_PAID:
-            # Do not change payment fees of paid orders
-            payment_fee = Decimal('0.00')
-            if self.order.total != 0:
-                prov = self._get_payment_provider()
+    @cached_property
+    def completed_payment_sum(self):
+        payment_sum = self.order.payments.filter(
+            state__in=(OrderPayment.PAYMENT_STATE_CONFIRMED, OrderPayment.PAYMENT_STATE_REFUNDED)
+        ).aggregate(s=Sum('amount'))['s'] or Decimal('0.00')
+        refund_sum = self.order.refunds.filter(
+            state__in=(OrderRefund.REFUND_STATE_DONE, OrderRefund.REFUND_STATE_TRANSIT, OrderRefund.REFUND_STATE_DONE)
+        ).aggregate(s=Sum('amount'))['s'] or Decimal('0.00')
+        return payment_sum - refund_sum
+
+    def _recalculate_total_and_payment_fee(self):
+        total = sum([p.price for p in self.order.positions.all()]) + sum([f.value for f in self.order.fees.all()])
+        payment_fee = Decimal('0.00')
+        if self.open_payment:
+            current_fee = Decimal('0.00')
+            fee = None
+            if self.open_payment.fee:
+                fee = self.open_payment.fee
+                current_fee = self.open_payment.fee.value
+            total -= current_fee
+
+            if self.order.pending_sum - current_fee != 0:
+                prov = self.open_payment.payment_provider
                 if prov:
-                    payment_fee = prov.calculate_fee(self.order.total)
+                    payment_fee = prov.calculate_fee(total - self.completed_payment_sum)
 
             if payment_fee:
-                fee = self.order.fees.get_or_create(fee_type=OrderFee.FEE_TYPE_PAYMENT, defaults={'value': 0})[0]
+                fee = fee or OrderFee(fee_type=OrderFee.FEE_TYPE_PAYMENT, order=self.order)
                 fee.value = payment_fee
                 fee._calculate_tax()
                 fee.save()
-            else:
-                self.order.fees.filter(fee_type=OrderFee.FEE_TYPE_PAYMENT).delete()
+                if not self.open_payment.fee:
+                    self.open_payment.fee = fee
+                    self.open_payment.save()
+            elif fee:
+                fee.delete()
 
-        self.order.total += sum([f.value for f in self.order.fees.all()])
+        self.order.total = total + payment_fee
         self.order.save()
 
     def _payment_fee_diff(self):
-        prov = self._get_payment_provider()
-        if self.order.status != Order.STATUS_PAID and prov:
-            # payment fees of paid orders do not change
-            old_fee = OrderFee.objects.filter(order=self.order, fee_type=OrderFee.FEE_TYPE_PAYMENT).aggregate(s=Sum('value'))['s'] or 0
-            new_total = sum([p.price for p in self.order.positions.all()]) + self._totaldiff
-            if new_total != 0:
-                new_fee = prov.calculate_fee(new_total)
-                self._totaldiff += new_fee - old_fee
+        total = self.order.total + self._totaldiff
+        if self.open_payment:
+            current_fee = Decimal('0.00')
+            if self.open_payment and self.open_payment.fee:
+                current_fee = self.open_payment.fee.value
+            total -= current_fee
+
+            # Do not change payment fees of paid orders
+            payment_fee = Decimal('0.00')
+            if self.order.pending_sum - current_fee != 0:
+                prov = self.open_payment.payment_provider
+                if prov:
+                    payment_fee = prov.calculate_fee(total - self.completed_payment_sum)
+
+                self._totaldiff += payment_fee - current_fee
 
     def _reissue_invoice(self):
         i = self.order.invoices.filter(is_cancellation=False).last()
@@ -1097,7 +1230,7 @@ class OrderChangeManager:
             try:
                 order.send_mail(
                     email_subject, email_template, email_context,
-                    'pretix.event.order.email.order_changed', self.user
+                    'pretix.event.order.email.order_changed', self.user, auth=self.auth
                 )
             except SendMailException:
                 logger.exception('Order changed email could not be sent')
@@ -1119,8 +1252,6 @@ class OrderChangeManager:
             with self.order.event.lock():
                 if self.order.status not in (Order.STATUS_PENDING, Order.STATUS_PAID):
                     raise OrderError(self.error_messages['not_pending_or_paid'])
-                self._check_free_to_paid()
-                self._check_paid_price_change()
                 self._check_quotas()
                 self._check_complete_cancel()
                 self._perform_operations()
@@ -1128,6 +1259,7 @@ class OrderChangeManager:
             self._reissue_invoice()
             self._clear_tickets_cache()
             self.order.touch()
+        self._check_paid_price_change()
         self._check_paid_to_free()
 
         if self.notify:
@@ -1143,9 +1275,12 @@ class OrderChangeManager:
             CachedCombinedTicket.objects.filter(order=self.split_order).delete()
 
     def _get_payment_provider(self):
-        pprov = self.order.event.get_payment_providers().get(self.order.payment_provider)
+        lp = self.order.payments.last()
+        if not lp:
+            return None
+        pprov = lp.payment_provider
         if not pprov:
-            raise OrderError(error_messages['internal'])
+            return None
         return pprov
 
 

src/pretix/base/services/shredder.py

@@ -11,7 +11,7 @@ from django.utils.timezone import now
 from django.utils.translation import ugettext_lazy as _
 
 from pretix.base.models import CachedFile, Event, cachedfile_name
-from pretix.base.services.async import ProfiledTask
+from pretix.base.services.tasks import ProfiledTask
 from pretix.base.shredder import ShredError
 from pretix.celery_app import app
 

src/pretix/base/services/stats.py

@@ -88,53 +88,40 @@ def order_overview(event: Event, subevent: SubEvent=None) -> Tuple[List[Tuple[It
         'item', 'variation', 'order__status'
     ).annotate(cnt=Count('id'), price=Sum('price'), tax_value=Sum('tax_value')).order_by()
 
-    num_canceled = {
-        (p['item'], p['variation']): (p['cnt'], p['price'], p['price'] - p['tax_value'])
-        for p in counters if p['order__status'] == Order.STATUS_CANCELED
+    states = {
+        'canceled': Order.STATUS_CANCELED,
+        'refunded': Order.STATUS_REFUNDED,
+        'paid': Order.STATUS_PAID,
+        'pending': Order.STATUS_PENDING,
+        'expired': Order.STATUS_EXPIRED,
     }
-    num_refunded = {
-        (p['item'], p['variation']): (p['cnt'], p['price'], p['price'] - p['tax_value'])
-        for p in counters if p['order__status'] == Order.STATUS_REFUNDED
-    }
-    num_paid = {
-        (p['item'], p['variation']): (p['cnt'], p['price'], p['price'] - p['tax_value'])
-        for p in counters if p['order__status'] == Order.STATUS_PAID
-    }
-    num_pending = {
-        (p['item'], p['variation']): (p['cnt'], p['price'], p['price'] - p['tax_value'])
-        for p in counters if p['order__status'] == Order.STATUS_PENDING
-    }
-    num_expired = {
-        (p['item'], p['variation']): (p['cnt'], p['price'], p['price'] - p['tax_value'])
-        for p in counters if p['order__status'] == Order.STATUS_EXPIRED
-    }
-    num_total = dictsum(num_pending, num_paid)
+    num = {}
+    for l, s in states.items():
+        num[l] = {
+            (p['item'], p['variation']): (p['cnt'], p['price'], p['price'] - p['tax_value'])
+            for p in counters if p['order__status'] == s
+        }
+
+    num['total'] = dictsum(num['pending'], num['paid'])
 
     for item in items:
         item.all_variations = list(item.variations.all())
         item.has_variations = (len(item.all_variations) > 0)
+        item.num = {}
         if item.has_variations:
             for var in item.all_variations:
                 variid = var.id
-                var.num_total = num_total.get((item.id, variid), (0, 0, 0))
-                var.num_pending = num_pending.get((item.id, variid), (0, 0, 0))
-                var.num_expired = num_expired.get((item.id, variid), (0, 0, 0))
-                var.num_canceled = num_canceled.get((item.id, variid), (0, 0, 0))
-                var.num_refunded = num_refunded.get((item.id, variid), (0, 0, 0))
-                var.num_paid = num_paid.get((item.id, variid), (0, 0, 0))
-            item.num_total = tuplesum(var.num_total for var in item.all_variations)
-            item.num_pending = tuplesum(var.num_pending for var in item.all_variations)
-            item.num_expired = tuplesum(var.num_expired for var in item.all_variations)
-            item.num_canceled = tuplesum(var.num_canceled for var in item.all_variations)
-            item.num_refunded = tuplesum(var.num_refunded for var in item.all_variations)
-            item.num_paid = tuplesum(var.num_paid for var in item.all_variations)
+                var.num = {}
+                for l in states.keys():
+                    var.num[l] = num[l].get((item.id, variid), (0, 0, 0))
+                var.num['total'] = num['total'].get((item.id, variid), (0, 0, 0))
+            for l in states.keys():
+                item.num[l] = tuplesum(var.num[l] for var in item.all_variations)
+            item.num['total'] = tuplesum(var.num['total'] for var in item.all_variations)
         else:
-            item.num_total = num_total.get((item.id, None), (0, 0, 0))
-            item.num_pending = num_pending.get((item.id, None), (0, 0, 0))
-            item.num_expired = num_expired.get((item.id, None), (0, 0, 0))
-            item.num_canceled = num_canceled.get((item.id, None), (0, 0, 0))
-            item.num_refunded = num_refunded.get((item.id, None), (0, 0, 0))
-            item.num_paid = num_paid.get((item.id, None), (0, 0, 0))
+            for l in states.keys():
+                item.num[l] = num[l].get((item.id, None), (0, 0, 0))
+            item.num['total'] = num['total'].get((item.id, None), (0, 0, 0))
 
     nonecat = ItemCategory(name=_('Uncategorized'))
     # Regroup those by category
@@ -151,12 +138,10 @@ def order_overview(event: Event, subevent: SubEvent=None) -> Tuple[List[Tuple[It
     )
 
     for c in items_by_category:
-        c[0].num_total = tuplesum(item.num_total for item in c[1])
-        c[0].num_pending = tuplesum(item.num_pending for item in c[1])
-        c[0].num_expired = tuplesum(item.num_expired for item in c[1])
-        c[0].num_canceled = tuplesum(item.num_canceled for item in c[1])
-        c[0].num_refunded = tuplesum(item.num_refunded for item in c[1])
-        c[0].num_paid = tuplesum(item.num_paid for item in c[1])
+        c[0].num = {}
+        for l in states.keys():
+            c[0].num[l] = tuplesum(item.num[l] for item in c[1])
+        c[0].num['total'] = tuplesum(item.num['total'] for item in c[1])
 
     # Payment fees
     payment_cat_obj = DummyObject()
@@ -170,27 +155,12 @@ def order_overview(event: Event, subevent: SubEvent=None) -> Tuple[List[Tuple[It
             'fee_type', 'internal_type', 'order__status'
         ).annotate(cnt=Count('id'), value=Sum('value'), tax_value=Sum('tax_value')).order_by()
 
-        num_canceled = {
-            (o['fee_type'], o['internal_type']): (o['cnt'], o['value'], o['value'] - o['tax_value'])
-            for o in counters if o['order__status'] == Order.STATUS_CANCELED
-        }
-        num_refunded = {
-            (o['fee_type'], o['internal_type']): (o['cnt'], o['value'], o['value'] - o['tax_value'])
-            for o in counters if o['order__status'] == Order.STATUS_REFUNDED
-        }
-        num_pending = {
-            (o['fee_type'], o['internal_type']): (o['cnt'], o['value'], o['value'] - o['tax_value'])
-            for o in counters if o['order__status'] == Order.STATUS_PENDING
-        }
-        num_expired = {
-            (o['fee_type'], o['internal_type']): (o['cnt'], o['value'], o['value'] - o['tax_value'])
-            for o in counters if o['order__status'] == Order.STATUS_EXPIRED
-        }
-        num_paid = {
-            (o['fee_type'], o['internal_type']): (o['cnt'], o['value'], o['value'] - o['tax_value'])
-            for o in counters if o['order__status'] == Order.STATUS_PAID
-        }
-        num_total = dictsum(num_pending, num_paid)
+        for l, s in states.items():
+            num[l] = {
+                (o['fee_type'], o['internal_type']): (o['cnt'], o['value'], o['value'] - o['tax_value'])
+                for o in counters if o['order__status'] == s
+            }
+        num['total'] = dictsum(num['pending'], num['paid'])
 
         provider_names = {
             k: v.verbose_name
@@ -198,7 +168,7 @@ def order_overview(event: Event, subevent: SubEvent=None) -> Tuple[List[Tuple[It
         }
         names = dict(OrderFee.FEE_TYPES)
 
-        for pprov, total in sorted(num_total.items(), key=lambda i: i[0]):
+        for pprov, total in sorted(num['total'].items(), key=lambda i: i[0]):
             ppobj = DummyObject()
             if pprov[0] == OrderFee.FEE_TYPE_PAYMENT:
                 ppobj.name = '{} - {}'.format(names[pprov[0]], provider_names.get(pprov[1], pprov[1]))
@@ -212,43 +182,29 @@ def order_overview(event: Event, subevent: SubEvent=None) -> Tuple[List[Tuple[It
                 ppobj.name = '{} - {}'.format(names[pprov[0]], name)
             ppobj.provider = pprov[1]
             ppobj.has_variations = False
-            ppobj.num_total = total
-            ppobj.num_canceled = num_canceled.get(pprov, (0, 0, 0))
-            ppobj.num_refunded = num_refunded.get(pprov, (0, 0, 0))
-            ppobj.num_expired = num_expired.get(pprov, (0, 0, 0))
-            ppobj.num_pending = num_pending.get(pprov, (0, 0, 0))
-            ppobj.num_paid = num_paid.get(pprov, (0, 0, 0))
+            ppobj.num = {}
+            for l in states.keys():
+                ppobj.num[l] = num[l].get(pprov, (0, 0, 0))
+            ppobj.num['total'] = total
             payment_items.append(ppobj)
 
-        payment_cat_obj.num_total = (
-            Dontsum(''), sum(i.num_total[1] for i in payment_items), sum(i.num_total[2] for i in payment_items)
-        )
-        payment_cat_obj.num_canceled = (
-            Dontsum(''), sum(i.num_canceled[1] for i in payment_items), sum(i.num_canceled[2] for i in payment_items)
-        )
-        payment_cat_obj.num_refunded = (
-            Dontsum(''), sum(i.num_refunded[1] for i in payment_items), sum(i.num_refunded[2] for i in payment_items)
-        )
-        payment_cat_obj.num_expired = (
-            Dontsum(''), sum(i.num_expired[1] for i in payment_items), sum(i.num_expired[2] for i in payment_items)
-        )
-        payment_cat_obj.num_pending = (
-            Dontsum(''), sum(i.num_pending[1] for i in payment_items), sum(i.num_pending[2] for i in payment_items)
-        )
-        payment_cat_obj.num_paid = (
-            Dontsum(''), sum(i.num_paid[1] for i in payment_items), sum(i.num_paid[2] for i in payment_items)
+        payment_cat_obj.num = {}
+        for l in states.keys():
+            payment_cat_obj.num[l] = (
+                Dontsum(''), sum(i.num[l][1] for i in payment_items), sum(i.num[l][2] for i in payment_items)
+            )
+        payment_cat_obj.num['total'] = (
+            Dontsum(''), sum(i.num['total'][1] for i in payment_items), sum(i.num['total'][2] for i in payment_items)
         )
         payment_cat = (payment_cat_obj, payment_items)
-
-        items_by_category.append(payment_cat)
+        any_payment = any(payment_cat_obj.num[s][1] for s in states.keys())
+        if any_payment:
+            items_by_category.append(payment_cat)
 
     total = {
-        'num_total': tuplesum(c.num_total for c, i in items_by_category),
-        'num_pending': tuplesum(c.num_pending for c, i in items_by_category),
-        'num_expired': tuplesum(c.num_expired for c, i in items_by_category),
-        'num_canceled': tuplesum(c.num_canceled for c, i in items_by_category),
-        'num_refunded': tuplesum(c.num_refunded for c, i in items_by_category),
-        'num_paid': tuplesum(c.num_paid for c, i in items_by_category)
+        'num': {'total': tuplesum(c.num['total'] for c, i in items_by_category)}
     }
+    for l in states.keys():
+        total['num'][l] = tuplesum(c.num[l] for c, i in items_by_category)
 
     return items_by_category, total

src/pretix/base/services/tickets.py

@@ -10,7 +10,7 @@ from pretix.base.models import (
     CachedCombinedTicket, CachedTicket, Event, InvoiceAddress, Order,
     OrderPosition,
 )
-from pretix.base.services.async import ProfiledTask
+from pretix.base.services.tasks import ProfiledTask
 from pretix.base.signals import register_ticket_outputs
 from pretix.celery_app import app
 from pretix.helpers.database import rolledback_transaction

src/pretix/base/services/waitinglist.py

@@ -4,7 +4,7 @@ from django.dispatch import receiver
 
 from pretix.base.models import Event, User, WaitingListEntry
 from pretix.base.models.waitinglist import WaitingListException
-from pretix.base.services.async import ProfiledTask
+from pretix.base.services.tasks import ProfiledTask
 from pretix.base.signals import periodic_task
 from pretix.celery_app import app
 
@@ -22,7 +22,9 @@ def assign_automatically(event_id: int, user_id: int=None, subevent_id: int=None
 
     qs = WaitingListEntry.objects.filter(
         event=event, voucher__isnull=True
-    ).select_related('item', 'variation').prefetch_related('item__quotas', 'variation__quotas').order_by('created')
+    ).select_related('item', 'variation').prefetch_related(
+        'item__quotas', 'variation__quotas'
+    ).order_by('-priority', 'created')
 
     if subevent_id and event.has_subevents:
         subevent = event.subevents.get(id=subevent_id)

src/pretix/base/settings.py

@@ -1,5 +1,6 @@
 import json
 from datetime import datetime
+from typing import Any
 
 from django.conf import settings
 from django.core.files import File
@@ -7,7 +8,6 @@ from django.db.models import Model
 from django.utils.translation import ugettext_noop
 from hierarkey.models import GlobalSettingsBase, Hierarkey
 from i18nfield.strings import LazyI18nString
-from typing import Any
 
 from pretix.base.models.tax import TaxRule
 from pretix.base.reldate import RelativeDateWrapper
@@ -57,6 +57,10 @@ DEFAULTS = {
         'default': 'False',
         'type': bool,
     },
+    'invoice_address_company_required': {
+        'default': 'False',
+        'type': bool,
+    },
     'invoice_address_vatid': {
         'default': 'False',
         'type': bool,
@@ -221,10 +225,18 @@ DEFAULTS = {
         'default': None,
         'type': LazyI18nString
     },
+    'mail_html_renderer': {
+        'default': 'classic',
+        'type': str
+    },
     'mail_prefix': {
         'default': None,
         'type': str
     },
+    'mail_bcc': {
+        'default': None,
+        'type': str
+    },
     'mail_from': {
         'default': settings.MAIL_FROM,
         'type': str
@@ -262,8 +274,22 @@ Your {event} team"""))
         'type': LazyI18nString,
         'default': LazyI18nString.from_gettext(ugettext_noop("""Hello,
 
-we successfully received your order for {event}. As you only ordered
-free products, no payment is required.
+your order for {event} was successful. As you only ordered free products,
+no payment is required.
+
+You can change your order details and view the status of your order at
+{url}
+
+Best regards,
+Your {event} team"""))
+    },
+    'mail_text_order_placed_require_approval': {
+        'type': LazyI18nString,
+        'default': LazyI18nString.from_gettext(ugettext_noop("""Hello,
+
+we successfully received your order for {event}. Since you ordered
+a product that requires approval by the event organizer, we ask you to
+be patient and wait for our next email.
 
 You can change your order details and view the status of your order at
 {url}
@@ -362,6 +388,37 @@ your order {code} for {event} has been canceled.
 You can view the details of your order at
 {url}
 
+Best regards,
+Your {event} team"""))
+    },
+    'mail_text_order_approved': {
+        'type': LazyI18nString,
+        'default': LazyI18nString.from_gettext(ugettext_noop("""Hello,
+
+we approved your order for {event} and will be happy to welcome you
+at our event.
+
+Please continue by paying for your order before {date}.
+
+You can select a payment method and perform the payment here:
+
+{url}
+
+Best regards,
+Your {event} team"""))
+    },
+    'mail_text_order_denied': {
+        'type': LazyI18nString,
+        'default': LazyI18nString.from_gettext(ugettext_noop("""Hello,
+
+unfortunately, we denied your order request for {event}.
+
+{comment}
+
+You can view the details of your order here:
+
+{url}
+
 Best regards,
 Your {event} team"""))
     },

src/pretix/base/shredder.py

@@ -15,8 +15,8 @@ from pretix.api.serializers.order import (
 from pretix.api.serializers.waitinglist import WaitingListSerializer
 from pretix.base.i18n import LazyLocaleException
 from pretix.base.models import (
-    CachedCombinedTicket, CachedTicket, Event, InvoiceAddress, OrderPosition,
-    QuestionAnswer,
+    CachedCombinedTicket, CachedTicket, Event, InvoiceAddress, OrderPayment,
+    OrderPosition, OrderRefund, QuestionAnswer,
 )
 from pretix.base.services.invoices import invoice_pdf_task
 from pretix.base.signals import register_data_shredders
@@ -331,10 +331,14 @@ class PaymentInfoShredder(BaseDataShredder):
     @transaction.atomic
     def shred_data(self):
         provs = self.event.get_payment_providers()
-        for o in self.event.orders.all():
-            pprov = provs.get(o.payment_provider)
+        for obj in OrderPayment.objects.filter(order__event=self.event):
+            pprov = provs.get(obj.provider)
             if pprov:
-                pprov.shred_payment_info(o)
+                pprov.shred_payment_info(obj)
+        for obj in OrderRefund.objects.filter(order__event=self.event):
+            pprov = provs.get(obj.provider)
+            if pprov:
+                pprov.shred_payment_info(obj)
 
 
 @receiver(register_data_shredders, dispatch_uid="shredders_builtin")

src/pretix/base/signals.py

@@ -42,7 +42,8 @@ class EventPluginSignal(django.dispatch.Signal):
                 searchpath, _ = searchpath.rsplit(".", 1)
 
         # Only fire receivers from active plugins and core modules
-        if core_module or (sender and app and app.name in sender.get_plugins()):
+        excluded = settings.PRETIX_PLUGINS_EXCLUDE
+        if core_module or (sender and app and app.name in sender.get_plugins() and app.name not in excluded):
             if not hasattr(app, 'compatibility_errors') or not app.compatibility_errors:
                 return True
         return False
@@ -124,6 +125,16 @@ subclass of pretix.base.payment.BasePaymentProvider or a list of these
 As with all event-plugin signals, the ``sender`` keyword argument will contain the event.
 """
 
+register_html_mail_renderers = EventPluginSignal(
+    providing_args=[]
+)
+"""
+This signal is sent out to get all known HTML email renderers. Receivers should return a
+subclass of pretix.base.email.BaseHTMLMailRenderer or a list of these
+
+As with all event-plugin signals, the ``sender`` keyword argument will contain the event.
+"""
+
 register_invoice_renderers = EventPluginSignal(
     providing_args=[]
 )

src/pretix/base/templates/403.html

@@ -10,4 +10,14 @@
         <a id='goback' href='#'>{% trans "Take a step back" %}</a>
         &middot; <a id='reload' href='#'>{% trans "Try again" %}</a>
     </p>
+    {% if request.user.is_staff and not staff_session %}
+        <form action="{% url 'control:user.sudo' %}?next={{ request.path|urlencode }}" method="post">
+            <p>
+                {% csrf_token %}
+                <button type="submit" class="btn btn-default" id="button-sudo">
+                    <i class="fa fa-id-card"></i> {% trans "Admin mode" %}
+                </button>
+            </p>
+        </form>
+    {% endif %}
 {% endblock %}

src/pretix/base/templates/404.html

@@ -9,4 +9,14 @@
     <p class="links">
         <a id='goback' href='#'>{% trans "Take a step back" %}</a>
     </p>
+    {% if request.user.is_staff and not staff_session %}
+        <form action="{% url 'control:user.sudo' %}?next={{ request.path|urlencode }}" method="post">
+            <p>
+                {% csrf_token %}
+                <button type="submit" class="btn btn-default" id="button-sudo">
+                    <i class="fa fa-id-card"></i> {% trans "Admin mode" %}
+                </button>
+            </p>
+        </form>
+    {% endif %}
 {% endblock %}

src/pretix/base/templates/error.html

@@ -1,6 +1,6 @@
 {% load compress %}
 {% load i18n %}
-{% load staticfiles %}
+{% load static %}
 <!DOCTYPE html>
 <html>
 <head>

src/pretix/base/templates/pretixbase/cachedfiles/pending.html

@@ -1,6 +1,6 @@
 {% load compress %}
 {% load i18n %}
-{% load staticfiles %}
+{% load static %}
 <!DOCTYPE html>
 <html>
 <head>

src/pretix/base/templates/pretixbase/email/base.html

@@ -5,163 +5,206 @@
 <head>
     <meta charset="utf-8">
     <meta name="viewport" content="width=device-width, user-scalable=false">
-</head>
-<style type="text/css">
-    body {
-        background-color: #e8e8e8;
-        background-position: top;
-        background-repeat: repeat-x;
-        font-family: "Open Sans", "OpenSans", "Helvetica Neue", Helvetica, Arial, sans-serif;
-        font-size: 14px;
-        line-height: 20px;
-        color: #333;
-        margin: 0;
-    }
-
-    .header h1 {
-        margin-top: 20px;
-        margin-bottom: 20px;
-    }
-
-    .header h1 a, .content h2 a, .content h3 a {
-        text-decoration: none;
-    }
-
-    .content h2, .content h3 {
-        margin-bottom: 20px;
-        margin-top: 10px;
-    }
-
-    a {
-        color: {{ color }};
-        font-weight: bold;
-    }
-
-    a:hover, a:focus {
-        color: {{ color }};
-        text-decoration: underline;
-    }
-
-    a:hover, a:active {
-        outline: 0;
-    }
-
-    p {
-        margin: 0 0 10px;
-
-        /* These are technically the same, but use both */
-        overflow-wrap: break-word;
-        word-wrap: break-word;
-
-        -ms-word-break: break-all;
-        /* This is the dangerous one in WebKit, as it breaks things wherever */
-        word-break: break-all;
-        /* Instead use this non-standard one: */
-        word-break: break-word;
-
-        /* Adds a hyphen where the word breaks, if supported (No Blink) */
-        -ms-hyphens: auto;
-        -moz-hyphens: auto;
-        -webkit-hyphens: auto;
-        hyphens: auto;
-    }
-
-    .footer {
-        padding: 10px;
-        text-align: center;
-        font-size: 12px;
-    }
-
-    .content {
-        padding: 8px 18px 8px;
-    }
-
-    ::selection {
-        background: {{ color }};
-        color: #FFF;
-    }
-
-    table.layout {
-        width: 90%;
-        max-width: 900px;
-        border-spacing: 0px;
-        border-collapse: separate;
-        margin: auto;
-    }
-
-    .content table {
-        width: 100%;
-    }
-
-    .content table td {
-        vertical-align: top;
-        text-align: left;
-        padding: 5px 0;
-    }
-    a.button {
-        display: inline-block;
-        padding: 10px 16px;
-        font-size: 14px;
-        line-height: 1.33333;
-        border: 1px solid #cccccc;
-        border-radius: 6px;
-        -webkit-border-radius: 6px;
-        -moz-border-radius: 6px;
-        margin: 5px;
-        text-decoration: none;
-        color: {{ color }};
-    }
-
-    @media (max-width: 480px) {
-        .header h1 {
-            font-size: 19px;
-            line-height: 24px;
-            margin: 0 9px 3px 0;
-            border-radius: 5px 5px;
-            -webkit-border-radius: 5px 5px;
-            -moz-border-radius: 5px 5px;
-        }
-
-        .header h1 a {
-            padding: 3px 9px;
-            display: block;
-        }
-
-        .header {
+    <style type="text/css">
+        body {
+            background-color: #eee;
+            background-position: top;
+            background-repeat: repeat-x;
+            font-family: "Open Sans", "OpenSans", "Helvetica Neue", Helvetica, Arial, sans-serif;
+            font-size: 14px;
+            line-height: 20px;
+            color: #333;
             margin: 0;
-            padding: 12px 0 8px;
+            padding-top: 20px;
         }
-    }
 
-    td.containertd {
-        background-color: #FFFFFF;
-        border: 1px solid #cccccc;
-    }
+        table.layout > tr > td {
+            background-color: white;
+            padding: 0;
+        }
 
-    {% block addcss %}{% endblock %}
-</style>
-<body>
-    <table class="layout">
+        table.layout > tr > td.header {
+            padding: 0 20px;
+            text-align: center;
+        }
+
+        .header h2 {
+            margin-top: 20px;
+            margin-bottom: 10px;
+            font-size: 22px;
+            line-height: 26px;
+        }
+
+        .header h1 {
+            margin-top: 0;
+            margin-bottom: 20px;
+            font-size: 26px;
+            line-height: 30px;
+        }
+
+        .header h2 a, .header h1 a, .content h2 a, .content h3 a {
+            text-decoration: none;
+        }
+
+        .content h2, .content h3 {
+            margin-bottom: 20px;
+            margin-top: 10px;
+        }
+
+        a {
+            color: {{ color }};
+            font-weight: bold;
+        }
+
+        a:hover, a:focus {
+            color: {{ color }};
+            text-decoration: underline;
+        }
+
+        a:hover, a:active {
+            outline: 0;
+        }
+
+        p {
+            margin: 0 0 10px;
+
+            /* These are technically the same, but use both */
+            overflow-wrap: break-word;
+            word-wrap: break-word;
+
+            -ms-word-break: break-all;
+            /* This is the dangerous one in WebKit, as it breaks things wherever */
+            word-break: break-all;
+            /* Instead use this non-standard one: */
+            word-break: break-word;
+
+            /* Adds a hyphen where the word breaks, if supported (No Blink) */
+            -ms-hyphens: auto;
+            -moz-hyphens: auto;
+            -webkit-hyphens: auto;
+            hyphens: auto;
+        }
+        p:last-child {
+            margin-bottom: 0;
+        }
+
+        .footer {
+            padding: 10px;
+            text-align: center;
+            font-size: 12px;
+        }
+
+        .content {
+            padding: 0 18px;
+        }
+
+        ::selection {
+            background: {{ color }};
+            color: #FFF;
+        }
+
+        table.layout {
+            width: 100%;
+            max-width: 600px;
+            border-spacing: 0px;
+            border-collapse: separate;
+            margin: auto;
+        }
+
+        img.wide {
+            width: 100%;
+            height: auto;
+        }
+
+        .content table {
+            width: 100%;
+        }
+
+        .content table td {
+            vertical-align: top;
+            text-align: left;
+            padding: 0;
+        }
+
+        a.button {
+            display: inline-block;
+            padding: 10px 16px;
+            font-size: 14px;
+            line-height: 1.33333;
+            border: 1px solid #cccccc;
+            border-radius: 6px;
+            -webkit-border-radius: 6px;
+            -moz-border-radius: 6px;
+            margin: 5px;
+            text-decoration: none;
+            color: {{ color }};
+        }
+
+        {% block addcss %}{% endblock %}
+    </style>
+    <!--[if mso]>
+        <style type="text/css">
+        body, table, td {
+            font-family: "Open Sans", "OpenSans", "Helvetica Neue", Helvetica, Arial, sans-serif !important;
+        }
+        </style>
+    <![endif]-->
+</head>
+<body align="center">
+    <!--[if gte mso 9]>
+    <table width="100%"><tr><td align="center">
+    <table width="600"><tr><td align="center"
+    <![endif]-->
+    <table class="layout" width="600" border="0" cellspacing="0">
+        <!--[if !mso]><!-- -->
         <tr>
-            <td class="header" background="">
-                {% if event %}
-                    <h1><a href="{% abseventurl event "presale:event.index" %}" target="_blank">{{ event.name }}</a></h1>
-                {% else %}
-                    <h1><a href="{{ site_url }}" target="_blank">{{ site }}</a></h1>
-                {% endif %}
+            <td>
+                <img class="wide" src="data:image/png;base64,
+                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"
+                style="max-height: 60px;">
             </td>
         </tr>
+        <!--<![endif]-->
+        <tr>
+            <td class="header" align="center">
+                <!--[if gte mso 9]>
+                    <table cellpadding="20"><tr><td align="center">
+                <![endif]-->
+                {% if event %}
+                    <h2><a href="{% abseventurl event "presale:event.index" %}" target="_blank">{{ event.name }}</a>
+                    </h2>
+                {% else %}
+                    <h2><a href="{{ site_url }}" target="_blank">{{ site }}</a></h2>
+                {% endif %}
+                {% block header %}
+                    <h1>{{ subject }}</h1>
+                {% endblock %}
+                <!--[if gte mso 9]>
+                    </td></tr></table>
+                <![endif]-->
+            </td>
+        </tr>
+        {% include "pretixbase/email/separator.html" %}
         {% block content %}
         {% endblock %}
+        <!--[if !mso]><!-- -->
         <tr>
-            <td class="footer">
-                <div>
-                    {% include "pretixbase/email/email_footer.html" %}
-                </div>
+            <td>
+                <br>
+                <img class="wide" src="data:image/png;base64,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"
+                style="max-height: 60px;">
             </td>
         </tr>
+        <!--<![endif]-->
     </table>
+    <div class="footer">
+        {% include "pretixbase/email/email_footer.html" %}
+    </div>
     <br/>
     <br/>
+    <!--[if gte mso 9]>
+    </td></tr></table>
+    </td></tr></table>
+    <![endif]-->
 </body>
 </html>

src/pretix/base/templates/pretixbase/email/notification.html

@@ -1,15 +1,20 @@
 {% extends "pretixbase/email/base.html" %}
 {% load eventurl %}
 {% load i18n %}
+{% block header %}
+    <h1>
+        {% if notification.url %}<a href="{{ notification.url }}">{% endif %}
+        {{ notification.title }}
+        {% if notification.url %}</a>{% endif %}
+    </h1>
+{% endblock %}
 {% block content %}
     <tr>
         <td class="containertd">
+            <!--[if gte mso 9]>
+                    <table cellpadding="20"><tr><td>
+            <![endif]-->
             <div class="content">
-                <h3>
-                    {% if notification.url %}<a href="{{ notification.url }}">{% endif %}
-                    {{ notification.title }}
-                    {% if notification.url %}</a>{% endif %}
-                </h3>
                 {% if notification.detail %}
                     <p>{{ notification.detail }}</p>
                 {% endif %}
@@ -35,10 +40,17 @@
                     </p>
                 {% endif %}
             </div>
+            <!--[if gte mso 9]>
+                    </td></tr></table>
+            <![endif]-->
         </td>
     </tr>
+    {% include "pretixbase/email/separator.html" %}
     <tr>
         <td class="containertd">
+            <!--[if gte mso 9]>
+                    <table cellpadding="20"><tr><td>
+            <![endif]-->
             <div class="content">
                 {% trans "You receive these emails based on your notification settings." %}<br>
                 <a href="{{ settings_url }}">
@@ -48,6 +60,9 @@
                     {% trans "Click here disable all notifications immediately." %}
                 </a>
             </div>
+            <!--[if gte mso 9]>
+                    </td></tr></table>
+            <![endif]-->
         </td>
     </tr>
 {% endblock %}

src/pretix/base/templates/pretixbase/email/plainwrapper.html

@@ -4,17 +4,24 @@
 {% block content %}
     <tr>
         <td class="containertd">
+            <!--[if gte mso 9]>
+                    <table cellpadding="20"><tr><td>
+                <![endif]-->
             <div class="content">
                 {{ body|safe }}
             </div>
+            <!--[if gte mso 9]>
+                    </td></tr></table>
+                <![endif]-->
         </td>
     </tr>
     {% if order %}
-        <tr>
-            <td class="gap"></td>
-        </tr>
+        {% include "pretixbase/email/separator.html" %}
         <tr>
             <td class="order containertd">
+                <!--[if gte mso 9]>
+                    <table cellpadding="20"><tr><td>
+                <![endif]-->
                 <div class="content">
                     {% trans "You are receiving this email because you placed an order for the following event:" %}<br>
                     <strong>{% trans "Event:" %}</strong> {{ event.name }}<br>
@@ -24,18 +31,25 @@
                         {% trans "View order details" %}
                     </a>
                 </div>
+                <!--[if gte mso 9]>
+                    </td></tr></table>
+                <![endif]-->
             </td>
         </tr>
     {% endif %}
 	{% if signature %}
-        <tr>
-            <td class="gap"></td>
-        </tr>
+        {% include "pretixbase/email/separator.html" %}
         <tr>
             <td class="order containertd">
+                <!--[if gte mso 9]>
+                    <table cellpadding="20"><tr><td>
+                <![endif]-->
                 <div class="content">
                     {{ signature | safe }}
                 </div>
+                <!--[if gte mso 9]>
+                    </td></tr></table>
+                <![endif]-->
             </td>
         </tr>
     {% endif %}

src/pretix/base/templates/pretixbase/email/separator.html

@@ -0,0 +1,15 @@
+<!--[if !mso]><!-- -->
+<tr>
+    <td>
+        <img class="wide" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAlgAAAAoBAMAAADQ9ZkHAAAAA3NCSVQICAjb4U/gAAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAGXRFWHRTb2Z0d2FyZQB3d3cuaW5rc2NhcGUub3Jnm+48GgAAAC1QTFRF7u7u7+/v8PDw8fHx8vLy9PT09fX19/f3+Pj4+fn5+vr6/Pz8/f39/v7+////BLnnfgAAAKJJREFUaN7t1cGtgUEARtFfQkREDypQihpUoIQXpahADUqRiIgINdjehcXbSTjf8s5mchYzw9P+vQEBLFiwYMGChQAWLFiwYMFCAAsWLFhfipX9pe/S1+nH9EX6OX2Wfk2fpN/TR73QMgeH9E36Nn2fvko/pc/TL+nT9Fv6OP0xvB8sWLA+g+XZ9hvCggULFiwEsGDBggULFgJYsGDBgvXzewGTOlWA3NB0eQAAAABJRU5ErkJggg=="
+            style="max-height: 40px;">
+    </td>
+</tr>
+<!--<![endif]-->
+<!--[if gte mso 9]>
+<tr>
+    <td background="white" style="background-color: white;">
+        <hr background="white" style="background-color: white;"/>
+    </td>
+</tr>
+<![endif]-->

src/pretix/base/templatetags/eventsignal.py

@@ -25,3 +25,22 @@ def eventsignal(event: Event, signame: str, **kwargs):
         if response:
             _html.append(response)
     return mark_safe("".join(_html))
+
+
+@register.simple_tag
+def signal(signame: str, request, **kwargs):
+    """
+    Send a signal and return the concatenated return values of all responses.
+
+    Usage::
+
+        {% signal request "path.to.signal" argument="value" ... %}
+    """
+    sigstr = signame.rsplit('.', 1)
+    sigmod = importlib.import_module(sigstr[0])
+    signal = getattr(sigmod, sigstr[1])
+    _html = []
+    for receiver, response in signal.send(request, **kwargs):
+        if response:
+            _html.append(response)
+    return mark_safe("".join(_html))

src/pretix/base/templatetags/rich_text.py

@@ -63,7 +63,7 @@ ALLOWED_PROTOCOLS = ['http', 'https', 'mailto', 'tel']
 
 def safelink_callback(attrs, new=False):
     url = attrs.get((None, 'href'), '/')
-    if not is_safe_url(url) and not url.startswith('mailto:') and not url.startswith('tel:'):
+    if not is_safe_url(url, allowed_hosts=None) and not url.startswith('mailto:') and not url.startswith('tel:'):
         signer = signing.Signer(salt='safe-redirect')
         attrs[None, 'href'] = reverse('redirect') + '?url=' + urllib.parse.quote(signer.sign(url))
         attrs[None, 'target'] = '_blank'

src/pretix/base/templatetags/urlreplace.py

@@ -15,6 +15,6 @@ def url_replace(request, *pairs):
                 if key in dict_:
                     del dict_[key]
             else:
-                dict_[key] = p
+                dict_[key] = str(p)
             key = None
     return dict_.urlencode(safe='[]')

src/pretix/base/ticketoutput.py

@@ -156,3 +156,10 @@ class BaseTicketOutput:
         The text on the download button in the frontend.
         """
         return _('Download ticket')
+
+    @property
+    def download_button_icon(self) -> str:
+        """
+        The Font Awesome icon on the download button in the frontend.
+        """
+        return 'fa-download'