From 3eb4e84db43fbda035e92749d20ef98ee8aded8b Mon Sep 17 00:00:00 2001
From: Tobias Kunze <rixx@cutebit.de>
Date: Wed, 7 Sep 2016 00:33:27 +0200
Subject: [PATCH 1/4] Allow payment providers to supply invoice content

---
 .../0037_invoice_payment_provider_text.py     | 20 ++++++++++
 src/pretix/base/models/invoices.py            |  3 ++
 src/pretix/base/payment.py                    | 16 ++++++++
 src/pretix/base/services/invoices.py          | 40 +++++++++++--------
 4 files changed, 63 insertions(+), 16 deletions(-)
 create mode 100644 src/pretix/base/migrations/0037_invoice_payment_provider_text.py

diff --git a/src/pretix/base/migrations/0037_invoice_payment_provider_text.py b/src/pretix/base/migrations/0037_invoice_payment_provider_text.py
new file mode 100644
index 0000000000..9659a910ec
--- /dev/null
+++ b/src/pretix/base/migrations/0037_invoice_payment_provider_text.py
@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.9 on 2016-09-06 21:31
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0036_auto_20160902_0755'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='invoice',
+            name='payment_provider_text',
+            field=models.TextField(blank=True),
+        ),
+    ]
diff --git a/src/pretix/base/models/invoices.py b/src/pretix/base/models/invoices.py
index ec73130b77..b65b688f22 100644
--- a/src/pretix/base/models/invoices.py
+++ b/src/pretix/base/models/invoices.py
@@ -43,6 +43,8 @@ class Invoice(models.Model):
     :type introductory_text: str
     :param additional_text: Additional text for the invoice
     :type additional_text: str
+    :param payment_provider_text: A payment provider specific text
+    :type payment_provider_text: str
     :param footer_text: A footer text, displayed smaller and centered on every page
     :type footer_text: str
     :param file: The filename of the rendered invoice
@@ -59,6 +61,7 @@ class Invoice(models.Model):
     locale = models.CharField(max_length=50, default='en')
     introductory_text = models.TextField(blank=True)
     additional_text = models.TextField(blank=True)
+    payment_provider_text = models.TextField(blank=True)
     footer_text = models.TextField(blank=True)
     file = models.FileField(null=True, blank=True, upload_to=invoice_filename)
 
diff --git a/src/pretix/base/payment.py b/src/pretix/base/payment.py
index 3b8f636969..5abdfdae09 100644
--- a/src/pretix/base/payment.py
+++ b/src/pretix/base/payment.py
@@ -12,6 +12,7 @@ from django.template.loader import get_template
 from django.utils.translation import ugettext_lazy as _
 
 from pretix.base.decimal import round_decimal
+from pretix.base.i18n import I18nFormField, I18nTextarea, LazyI18nString
 from pretix.base.models import CartPosition, Event, Order, Quota
 from pretix.base.settings import SettingsSandbox
 from pretix.base.signals import register_payment_providers
@@ -134,6 +135,13 @@ class BasePaymentProvider:
                              'above!'),
                  required=False
              )),
+            ('_invoice_text',
+             I18nFormField(
+                 label=_('Text on invoices'),
+                 help_text=_('Will be printed just below the payment figures and above the closing text on invoices.'),
+                 required=False,
+                 widget=I18nTextarea,
+             )),
         ])
 
     def settings_content_render(self, request: HttpRequest) -> str:
@@ -144,6 +152,14 @@ class BasePaymentProvider:
         """
         pass
 
+    def render_invoice_text(self, order: Order) -> str:
+        """
+        This is called when an invoice for an order with this payment provider is generated.
+        The default implementation returns the content of the _invoice_text configuration
+        variable (an I18nString).
+        """
+        return self.settings.get('_invoice_text', as_type=LazyI18nString)
+
     @property
     def payment_form_fields(self) -> dict:
         """
diff --git a/src/pretix/base/services/invoices.py b/src/pretix/base/services/invoices.py
index c9dde9c6c1..4cd43972d9 100644
--- a/src/pretix/base/services/invoices.py
+++ b/src/pretix/base/services/invoices.py
@@ -33,6 +33,7 @@ def generate_cancellation(invoice: Invoice):
     cancellation.date = date.today()
     cancellation.refers = invoice
     cancellation.invoice_no = None
+    cancellation.payment_provider_text = ''
     cancellation.save()
     for line in invoice.lines.all():
         line.pk = None
@@ -48,15 +49,24 @@ def generate_cancellation(invoice: Invoice):
 @transaction.atomic
 def regenerate_invoice(invoice: Invoice):
     with language(invoice.locale):
+        responses = register_payment_providers.send(invoice.event)
+        for receiver, response in responses:
+            provider = response(invoice.event)
+            if provider.identifier == invoice.order.payment_provider:
+                payment_provider = provider
+                break
+
         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)
+        payment = payment_provider.render_invoice_text(invoice.order)
 
         invoice.introductory_text = str(introductory).replace('\n', '<br />')
-        invoice.additional_text = str(additional).replace('\n', '<br /')
+        invoice.additional_text = str(additional).replace('\n', '<br />')
         invoice.footer_text = str(footer)
+        invoice.payment_provider_text = str(payment).replace('\n', '<br />')
 
         try:
             addr_template = pgettext("invoice", """{i.company}
@@ -73,13 +83,6 @@ def regenerate_invoice(invoice: Invoice):
         invoice.file = None
         invoice.save()
 
-        responses = register_payment_providers.send(invoice.event)
-        for receiver, response in responses:
-            provider = response(invoice.event)
-            if provider.identifier == invoice.order.payment_provider:
-                payment_provider = provider
-                break
-
         invoice.lines.all().delete()
         for p in invoice.order.positions.all():
             desc = str(p.item.name)
@@ -110,16 +113,25 @@ def generate_invoice(order: Order):
             locale = order.locale
 
     with language(locale):
+        responses = register_payment_providers.send(order.event)
+        for receiver, response in responses:
+            provider = response(order.event)
+            if provider.identifier == order.payment_provider:
+                payment_provider = provider
+                break
+
         i = Invoice(order=order, event=order.event)
         i.invoice_from = order.event.settings.get('invoice_address_from')
 
         introductory = i.event.settings.get('invoice_introductory_text', as_type=LazyI18nString)
         additional = i.event.settings.get('invoice_additional_text', as_type=LazyI18nString)
         footer = i.event.settings.get('invoice_footer_text', as_type=LazyI18nString)
+        payment = payment_provider.render_invoice_text(i.order)
 
         i.introductory_text = str(introductory).replace('\n', '<br />')
-        i.additional_text = str(additional).replace('\n', '<br /')
+        i.additional_text = str(additional).replace('\n', '<br />')
         i.footer_text = str(footer)
+        i.payment_provider_text = str(payment).replace('\n', '<br />')
 
         try:
             addr_template = pgettext("invoice", """{i.company}
@@ -137,13 +149,6 @@ def generate_invoice(order: Order):
         i.locale = locale
         i.save()
 
-        responses = register_payment_providers.send(order.event)
-        for receiver, response in responses:
-            provider = response(order.event)
-            if provider.identifier == order.payment_provider:
-                payment_provider = provider
-                break
-
         for p in order.positions.all():
             desc = str(p.item.name)
             if p.variation:
@@ -362,6 +367,9 @@ def _invoice_generate_german(invoice, f):
 
     story.append(Spacer(1, 15 * mm))
 
+    if invoice.payment_provider_text:
+        story.append(Paragraph(invoice.payment_provider_text, styles['Normal']))
+
     if invoice.additional_text:
         story.append(Paragraph(invoice.additional_text, styles['Normal']))
         story.append(Spacer(1, 15 * mm))

From 65db55f21bba348bc3aeaca6f7ad4937eb2bcd04 Mon Sep 17 00:00:00 2001
From: Tobias Kunze <rixx@cutebit.de>
Date: Wed, 7 Sep 2016 00:50:10 +0200
Subject: [PATCH 2/4] Extract common code of generate_invoice and
 regenerate_invoice

Only change is that a regenerated invoice's date is updated to the
current date, which would seem to be better to me, anyways.
---
 src/pretix/base/services/invoices.py | 75 ++++++----------------------
 1 file changed, 14 insertions(+), 61 deletions(-)

diff --git a/src/pretix/base/services/invoices.py b/src/pretix/base/services/invoices.py
index 4cd43972d9..d5b848e7cb 100644
--- a/src/pretix/base/services/invoices.py
+++ b/src/pretix/base/services/invoices.py
@@ -47,8 +47,8 @@ def generate_cancellation(invoice: Invoice):
 
 
 @transaction.atomic
-def regenerate_invoice(invoice: Invoice):
-    with language(invoice.locale):
+def build_invoice(invoice, locale):
+    with language(locale):
         responses = register_payment_providers.send(invoice.event)
         for receiver, response in responses:
             provider = response(invoice.event)
@@ -81,9 +81,11 @@ def regenerate_invoice(invoice: Invoice):
             invoice.invoice_to = ""
 
         invoice.file = None
+        invoice.date = date.today()
+        invoice.locale = locale
         invoice.save()
-
         invoice.lines.all().delete()
+
         for p in invoice.order.positions.all():
             desc = str(p.item.name)
             if p.variation:
@@ -101,73 +103,24 @@ def regenerate_invoice(invoice: Invoice):
                 tax_rate=invoice.order.payment_fee_tax_rate
             )
 
-        invoice_pdf(invoice.pk)
+        return invoice
+
+
+def regenerate_invoice(invoice: Invoice):
+    invoice = build_invoice(invoice, invoice.locale)
+    invoice_pdf(invoice.pk)
     return invoice
 
 
-@transaction.atomic
 def generate_invoice(order: Order):
     locale = order.event.settings.get('invoice_language')
     if locale:
         if locale == '__user__':
             locale = order.locale
 
-    with language(locale):
-        responses = register_payment_providers.send(order.event)
-        for receiver, response in responses:
-            provider = response(order.event)
-            if provider.identifier == order.payment_provider:
-                payment_provider = provider
-                break
-
-        i = Invoice(order=order, event=order.event)
-        i.invoice_from = order.event.settings.get('invoice_address_from')
-
-        introductory = i.event.settings.get('invoice_introductory_text', as_type=LazyI18nString)
-        additional = i.event.settings.get('invoice_additional_text', as_type=LazyI18nString)
-        footer = i.event.settings.get('invoice_footer_text', as_type=LazyI18nString)
-        payment = payment_provider.render_invoice_text(i.order)
-
-        i.introductory_text = str(introductory).replace('\n', '<br />')
-        i.additional_text = str(additional).replace('\n', '<br />')
-        i.footer_text = str(footer)
-        i.payment_provider_text = str(payment).replace('\n', '<br />')
-
-        try:
-            addr_template = pgettext("invoice", """{i.company}
-{i.name}
-{i.street}
-{i.zipcode} {i.city}
-{i.country}""")
-            i.invoice_to = addr_template.format(i=order.invoice_address).strip()
-            if order.invoice_address.vat_id:
-                i.invoice_to += "\n" + pgettext("invoice", "VAT-ID: %s") % order.invoice_address.vat_id
-        except InvoiceAddress.DoesNotExist:
-            i.invoice_to = ""
-
-        i.date = date.today()
-        i.locale = locale
-        i.save()
-
-        for p in order.positions.all():
-            desc = str(p.item.name)
-            if p.variation:
-                desc += " - " + str(p.variation.value)
-            InvoiceLine.objects.create(
-                invoice=i, description=desc,
-                gross_value=p.price, tax_value=p.tax_value,
-                tax_rate=p.tax_rate
-            )
-
-        if order.payment_fee:
-            InvoiceLine.objects.create(
-                invoice=i, description=_('Payment via {method}').format(method=str(payment_provider.verbose_name)),
-                gross_value=order.payment_fee, tax_value=order.payment_fee_tax_value,
-                tax_rate=order.payment_fee_tax_rate
-            )
-
-        invoice_pdf(i.pk)
-    return i
+    invoice = build_invoice(Invoice(order=order, event=order.event), locale=locale)
+    invoice_pdf(invoice.pk)
+    return invoice
 
 
 def _invoice_get_stylesheet():

From 988dfc32a38e43b6d2e28fab6692a0ffef4db91d Mon Sep 17 00:00:00 2001
From: Tobias Kunze <rixx@cutebit.de>
Date: Wed, 7 Sep 2016 15:03:06 +0200
Subject: [PATCH 3/4] Use @transaction.atomic instead of @transaction.atomic()

---
 doc/development/implementation/logging.rst |  4 ++--
 src/pretix/base/services/locking.py        |  2 +-
 src/pretix/base/services/orders.py         |  2 +-
 src/pretix/control/views/event.py          | 14 ++++++-------
 src/pretix/control/views/item.py           | 24 +++++++++++-----------
 src/pretix/control/views/vouchers.py       |  8 ++++----
 6 files changed, 27 insertions(+), 27 deletions(-)

diff --git a/doc/development/implementation/logging.rst b/doc/development/implementation/logging.rst
index f68efd9471..5c9c8a3bbd 100644
--- a/doc/development/implementation/logging.rst
+++ b/doc/development/implementation/logging.rst
@@ -29,7 +29,7 @@ Logging form actions
 A very common use case is to log the changes to a model that have been done in a ``ModelForm``. In this case,
 we generally use a custom ``form_valid`` method on our ``FormView`` that looks like this::
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         if form.has_changed():
             self.request.event.log_action('pretix.event.changed', user=self.request.user, data={
@@ -40,7 +40,7 @@ we generally use a custom ``form_valid`` method on our ``FormView`` that looks l
 
 It gets a little bit more complicated if your form allows file uploads::
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         if form.has_changed():
             self.request.event.log_action(
diff --git a/src/pretix/base/services/locking.py b/src/pretix/base/services/locking.py
index ebdf5ca5a3..565df6ed23 100644
--- a/src/pretix/base/services/locking.py
+++ b/src/pretix/base/services/locking.py
@@ -80,7 +80,7 @@ def lock_event_db(event):
     raise EventLock.LockTimeoutException()
 
 
-@transaction.atomic()
+@transaction.atomic
 def release_event_db(event):
     if not hasattr(event, '_lock') or not event._lock:
         raise EventLock.LockReleaseException('Lock is not owned by this thread')
diff --git a/src/pretix/base/services/orders.py b/src/pretix/base/services/orders.py
index a1ec0d91fa..cdb2ca0731 100644
--- a/src/pretix/base/services/orders.py
+++ b/src/pretix/base/services/orders.py
@@ -258,7 +258,7 @@ def _check_positions(event: Event, now_dt: datetime, positions: List[CartPositio
         raise OrderError(err)
 
 
-@transaction.atomic()
+@transaction.atomic
 def _create_order(event: Event, email: str, positions: List[CartPosition], now_dt: datetime,
                   payment_provider: BasePaymentProvider, locale: str=None):
     total = sum([c.price for c in positions])
diff --git a/src/pretix/control/views/event.py b/src/pretix/control/views/event.py
index 6842d6f174..c621648c90 100644
--- a/src/pretix/control/views/event.py
+++ b/src/pretix/control/views/event.py
@@ -57,7 +57,7 @@ class EventUpdate(EventPermissionRequiredMixin, UpdateView):
         context['sform'] = self.sform
         return context
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         self.sform.save()
         if self.sform.has_changed():
@@ -187,7 +187,7 @@ class PaymentSettings(EventPermissionRequiredMixin, TemplateView, SingleObjectMi
         context['providers'] = self.provider_forms
         return self.render_to_response(context)
 
-    @transaction.atomic()
+    @transaction.atomic
     def post(self, request, *args, **kwargs):
         self.object = self.get_object()
         success = self.sform.is_valid()
@@ -234,7 +234,7 @@ class EventSettingsFormView(EventPermissionRequiredMixin, FormView):
         kwargs['obj'] = self.request.event
         return kwargs
 
-    @transaction.atomic()
+    @transaction.atomic
     def post(self, request, *args, **kwargs):
         form = self.get_form()
         if form.is_valid():
@@ -279,7 +279,7 @@ class DisplaySettings(EventSettingsFormView):
             'event': self.request.event.slug
         })
 
-    @transaction.atomic()
+    @transaction.atomic
     def post(self, request, *args, **kwargs):
         form = self.get_form()
         if form.is_valid():
@@ -314,7 +314,7 @@ class MailSettings(EventSettingsFormView):
             'event': self.request.event.slug
         })
 
-    @transaction.atomic()
+    @transaction.atomic
     def post(self, request, *args, **kwargs):
         form = self.get_form()
         if form.is_valid():
@@ -374,7 +374,7 @@ class TicketSettings(EventPermissionRequiredMixin, FormView):
         form.prepare_fields()
         return form
 
-    @transaction.atomic()
+    @transaction.atomic
     def post(self, request, *args, **kwargs):
         success = True
         for provider in self.provider_forms:
@@ -470,7 +470,7 @@ class EventPermissions(EventPermissionRequiredMixin, TemplateView):
         ctx['add_form'] = self.add_form
         return ctx
 
-    @transaction.atomic()
+    @transaction.atomic
     def post(self, *args, **kwargs):
         if self.formset.is_valid() and self.add_form.is_valid():
             if self.add_form.has_changed():
diff --git a/src/pretix/control/views/item.py b/src/pretix/control/views/item.py
index 3a5d278da2..d817c7e6f2 100644
--- a/src/pretix/control/views/item.py
+++ b/src/pretix/control/views/item.py
@@ -99,7 +99,7 @@ class CategoryDelete(EventPermissionRequiredMixin, DeleteView):
         except ItemCategory.DoesNotExist:
             raise Http404(_("The requested product category does not exist."))
 
-    @transaction.atomic()
+    @transaction.atomic
     def delete(self, request, *args, **kwargs):
         self.object = self.get_object()
         for item in self.object.items.all():
@@ -134,7 +134,7 @@ class CategoryUpdate(EventPermissionRequiredMixin, UpdateView):
         except ItemCategory.DoesNotExist:
             raise Http404(_("The requested product category does not exist."))
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         messages.success(self.request, _('Your changes have been saved.'))
         if form.has_changed():
@@ -165,7 +165,7 @@ class CategoryCreate(EventPermissionRequiredMixin, CreateView):
             'event': self.request.event.slug,
         })
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         form.instance.event = self.request.event
         messages.success(self.request, _('The new category has been created.'))
@@ -299,7 +299,7 @@ class QuestionDelete(EventPermissionRequiredMixin, DeleteView):
         context['dependent'] = list(self.get_object().items.all())
         return context
 
-    @transaction.atomic()
+    @transaction.atomic
     def delete(self, request, *args, **kwargs):
         self.object = self.get_object()
         success_url = self.get_success_url()
@@ -390,7 +390,7 @@ class QuestionUpdate(EventPermissionRequiredMixin, QuestionMixin, UpdateView):
         except Question.DoesNotExist:
             raise Http404(_("The requested question does not exist."))
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         if form.cleaned_data.get('type') in ('M', 'C'):
             if not self.save_formset(self.get_object()):
@@ -433,7 +433,7 @@ class QuestionCreate(EventPermissionRequiredMixin, QuestionMixin, CreateView):
     def get_object(self, **kwargs):
         return None
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         if form.cleaned_data.get('type') in ('M', 'C'):
             if not self.formset.is_valid():
@@ -480,7 +480,7 @@ class QuotaEditorMixin:
             item.field = self.get_form(QuotaForm)['item_%s' % item.id]
         return context
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         res = super().form_valid(form)
         items = self.object.items.all()
@@ -516,7 +516,7 @@ class QuotaCreate(EventPermissionRequiredMixin, QuotaEditorMixin, CreateView):
             'event': self.request.event.slug,
         })
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         form.instance.event = self.request.event
         messages.success(self.request, _('The new quota has been created.'))
@@ -540,7 +540,7 @@ class QuotaUpdate(EventPermissionRequiredMixin, QuotaEditorMixin, UpdateView):
         except Quota.DoesNotExist:
             raise Http404(_("The requested quota does not exist."))
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         messages.success(self.request, _('Your changes have been saved.'))
         if form.has_changed():
@@ -577,7 +577,7 @@ class QuotaDelete(EventPermissionRequiredMixin, DeleteView):
         context['dependent'] = list(self.get_object().items.all())
         return context
 
-    @transaction.atomic()
+    @transaction.atomic
     def delete(self, request, *args, **kwargs):
         self.object = self.get_object()
         success_url = self.get_success_url()
@@ -621,7 +621,7 @@ class ItemCreate(EventPermissionRequiredMixin, CreateView):
             'item': self.object.id,
         })
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         messages.success(self.request, _('Your changes have been saved.'))
         ret = super().form_valid(form)
@@ -655,7 +655,7 @@ class ItemUpdateGeneral(ItemDetailMixin, EventPermissionRequiredMixin, UpdateVie
             'item': self.get_object().id,
         })
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         messages.success(self.request, _('Your changes have been saved.'))
         if form.has_changed():
diff --git a/src/pretix/control/views/vouchers.py b/src/pretix/control/views/vouchers.py
index 66a3e3789d..2f1f502075 100644
--- a/src/pretix/control/views/vouchers.py
+++ b/src/pretix/control/views/vouchers.py
@@ -126,7 +126,7 @@ class VoucherDelete(EventPermissionRequiredMixin, DeleteView):
             return HttpResponseRedirect(self.get_success_url())
         return super().get(request, *args, **kwargs)
 
-    @transaction.atomic()
+    @transaction.atomic
     def delete(self, request, *args, **kwargs):
         self.object = self.get_object()
         success_url = self.get_success_url()
@@ -168,7 +168,7 @@ class VoucherUpdate(EventPermissionRequiredMixin, UpdateView):
         except Voucher.DoesNotExist:
             raise Http404(_("The requested voucher does not exist."))
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         messages.success(self.request, _('Your changes have been saved.'))
         if form.has_changed():
@@ -210,7 +210,7 @@ class VoucherCreate(EventPermissionRequiredMixin, CreateView):
         kwargs['instance'] = Voucher(event=self.request.event)
         return kwargs
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         form.instance.event = self.request.event
         messages.success(self.request, _('The new voucher has been created.'))
@@ -241,7 +241,7 @@ class VoucherBulkCreate(EventPermissionRequiredMixin, CreateView):
         kwargs['instance'] = Voucher(event=self.request.event)
         return kwargs
 
-    @transaction.atomic()
+    @transaction.atomic
     def form_valid(self, form):
         for o in form.save(self.request.event):
             o.log_action('pretix.voucher.added', data=form.cleaned_data, user=self.request.user)

From 55120fc4ea57900a6c666ad9da02e91dfb2dbfbf Mon Sep 17 00:00:00 2001
From: Tobias Kunze <rixx@cutebit.de>
Date: Wed, 7 Sep 2016 15:52:15 +0200
Subject: [PATCH 4/4] Proper regeneration behavior for cancellations

---
 doc/development/api/payment.rst      |  2 +
 src/pretix/base/payment.py           |  4 +-
 src/pretix/base/services/invoices.py | 66 +++++++++++++++++-----------
 3 files changed, 44 insertions(+), 28 deletions(-)

diff --git a/doc/development/api/payment.rst b/doc/development/api/payment.rst
index e9b95de938..870d58ebe2 100644
--- a/doc/development/api/payment.rst
+++ b/doc/development/api/payment.rst
@@ -62,6 +62,8 @@ The provider class
 
    .. automethod:: settings_content_render
 
+   .. automethod:: render_invoice_text
+
    .. automethod:: payment_form_render
 
    .. automethod:: payment_form
diff --git a/src/pretix/base/payment.py b/src/pretix/base/payment.py
index 5abdfdae09..e0ded320e5 100644
--- a/src/pretix/base/payment.py
+++ b/src/pretix/base/payment.py
@@ -156,9 +156,9 @@ class BasePaymentProvider:
         """
         This is called when an invoice for an order with this payment provider is generated.
         The default implementation returns the content of the _invoice_text configuration
-        variable (an I18nString).
+        variable (an I18nString), or an empty string if unconfigured.
         """
-        return self.settings.get('_invoice_text', as_type=LazyI18nString)
+        return self.settings.get('_invoice_text', as_type=LazyI18nString, default='')
 
     @property
     def payment_form_fields(self) -> dict:
diff --git a/src/pretix/base/services/invoices.py b/src/pretix/base/services/invoices.py
index d5b848e7cb..9099058f5b 100644
--- a/src/pretix/base/services/invoices.py
+++ b/src/pretix/base/services/invoices.py
@@ -26,29 +26,9 @@ from pretix.base.models import Invoice, InvoiceAddress, InvoiceLine, Order
 from pretix.base.signals import register_payment_providers
 
 
-def generate_cancellation(invoice: Invoice):
-    cancellation = copy.copy(invoice)
-    cancellation.pk = None
-    cancellation.is_cancellation = True
-    cancellation.date = date.today()
-    cancellation.refers = invoice
-    cancellation.invoice_no = None
-    cancellation.payment_provider_text = ''
-    cancellation.save()
-    for line in invoice.lines.all():
-        line.pk = None
-        line.invoice = cancellation
-        line.gross_value *= -1
-        line.tax_value *= -1
-        line.save()
-
-    invoice_pdf(cancellation.pk)
-    return cancellation
-
-
 @transaction.atomic
-def build_invoice(invoice, locale):
-    with language(locale):
+def build_invoice(invoice: Invoice) -> Invoice:
+    with language(invoice.locale):
         responses = register_payment_providers.send(invoice.event)
         for receiver, response in responses:
             provider = response(invoice.event)
@@ -81,8 +61,6 @@ def build_invoice(invoice, locale):
             invoice.invoice_to = ""
 
         invoice.file = None
-        invoice.date = date.today()
-        invoice.locale = locale
         invoice.save()
         invoice.lines.all().delete()
 
@@ -106,8 +84,38 @@ def build_invoice(invoice, locale):
         return invoice
 
 
+def build_cancellation(invoice: Invoice):
+    invoice.lines.all().delete()
+
+    for line in invoice.refers.lines.all():
+        line.pk = None
+        line.invoice = invoice
+        line.gross_value *= -1
+        line.tax_value *= -1
+        line.save()
+    return invoice
+
+
+def generate_cancellation(invoice: Invoice):
+    cancellation = copy.copy(invoice)
+    cancellation.pk = None
+    cancellation.invoice_no = None
+    cancellation.refers = invoice
+    cancellation.is_cancellation = True
+    cancellation.date = date.today()
+    cancellation.payment_provider_text = ''
+    cancellation.save()
+
+    cancellation = build_cancellation(cancellation)
+    invoice_pdf(cancellation.pk)
+    return cancellation
+
+
 def regenerate_invoice(invoice: Invoice):
-    invoice = build_invoice(invoice, invoice.locale)
+    if invoice.is_cancellation:
+        invoice = build_cancellation(invoice)
+    else:
+        invoice = build_invoice(invoice)
     invoice_pdf(invoice.pk)
     return invoice
 
@@ -118,7 +126,13 @@ def generate_invoice(order: Order):
         if locale == '__user__':
             locale = order.locale
 
-    invoice = build_invoice(Invoice(order=order, event=order.event), locale=locale)
+    invoice = Invoice(
+        order=order,
+        event=order.event,
+        date=date.today(),
+        locale=locale
+    )
+    invoice = build_invoice(invoice)
     invoice_pdf(invoice.pk)
     return invoice