More docs and payments

doc/user/events/giftcards.rst

@@ -1,3 +1,8 @@
+.. spelling::
+
+   Warengutschein
+   Wertgutschein
+
 Gift cards
 ==========
 
@@ -9,6 +14,58 @@ Gift cards are very different feature than **vouchers**. The difference is:
 * Vouchers can be used to give a discount. When a voucher is used, the price of a ticket is reduced by the configured
   discount and sold at a lower price. They therefore reduce both revenue as well as taxes. Vouchers (in pretix) are
   always specific to a certain product in an order. Vouchers are usually not sold but given out as part of a
-  marketing campaign or to specific groups of people.
+  marketing campaign or to specific groups of people. Vouchers in pretix are bound to a specific event.
 
-* Gift cards are not a discount. If you buy a €20 ticket with a €10 gift card, it is still a €20 ticket and
+* Gift cards are not a discount, but rather a means of payment. If you buy a €20 ticket with a €10 gift card, it is
+  still a €20 ticket and will still count towards your revenue with €20. Gift cards are usually bought for the money
+  that they are worth. Gift cards in pretix can be used across events (and even organizers).
+
+Selling gift cards
+------------------
+
+Selling gift cards works like selling every other type of product in pretix: Create a new product, then head to
+"Additional settings" and select the option "This product is a gift card". Whenever someone buys this product and
+pays for it, a new gift card will be created.
+
+In this case, the gift card code corresponds to the "ticket secret" in the PDF ticket. Therefore, if selling gift cards,
+you can use ticket downloads just as with normal tickets and use our ticket editor to create beautiful gift certificates
+people can give to their loved ones.
+
+Of course, you can use pretix' flexible options to modify your product. For example, you can configure that the customer
+can freely choose the price of the gift card.
+
+.. note::
+
+   pretix currently does not support charging sales tax or VAT when selling gift cards, but instead charges VAT on
+   the full price when the gift card is redeemed. This is the correct behavior in Germany and some other countries for
+   gift cards which are not bound to a very specific service ("Warengutschein"), but instead to a monetary amount
+   ("Wertgutschein").
+
+.. note::
+
+   The ticket PDF will not contain the correct gift card code before the order has been paid, so we recommend not
+   selling gift cards in events where tickets are issued before payments arrive.
+
+
+Accepting gift cards
+--------------------
+
+All your events have have the payment provider "Gift card" enabled by default, but it will only show up in the ticket
+shop once the very first gift card has been issued on your organizer account. Of course, you can turn off gift card
+payments if you do not want them for a specific event.
+
+If gift card payments are enabled, buyers will be able to select "Gift card" as a payment method during checkout. If
+a gift card with a value less than the order total is used, the buyer will be asked to select a second payment method
+for the remaining payment. If a gift card with a value greater than the order total is used, the surplus amount
+remains on the gift card and can be used in a different purchase.
+
+If it possible to accept gift cards across organizer accounts. To do so, you need to have access to both organizer
+accounts. Then, you will see a configuration section at the bottom of the "Gift cards" page of your organizer settings
+where you can specify which gift cards should be accepted.
+
+Manually issuing or using gift cards
+------------------------------------
+
+Of course, you can also issue or redeem gift cards manually through our backend using the "Gift cards" menu item in your
+organizer profile or using our API. These gift cards will be tracked by pretix, but do not correspond to any purchase
+within pretix. You will therefore need to account for them in your books separately.

src/pretix/api/serializers/item.py

@@ -134,6 +134,17 @@ class ItemSerializer(I18nAwareModelSerializer):
         Item.clean_per_order(data.get('min_per_order'), data.get('max_per_order'))
         Item.clean_available(data.get('available_from'), data.get('available_until'))
 
+        if data.get('issue_giftcard'):
+            if data.get('tax_rule') and data.get('tax_rule').rate > 0:
+                raise ValidationError(
+                    _("Gift card products should not be associated with non-zero tax rates since sales tax will be "
+                      "applied when the gift card is redeemed.")
+                )
+            if data.get('admission'):
+                raise ValidationError(_(
+                    "Gift card products should not be admission products at the same time."
+                ))
+
         return data
 
     def validate_category(self, value):

src/pretix/control/forms/item.py

@@ -429,6 +429,13 @@ class ItemUpdateForm(I18nModelForm):
                     'tax_rule',
                     _("Gift card products should not be associated with non-zero tax rates since sales tax will be applied when the gift card is redeemed.")
                 )
+            if d['admission']:
+                self.add_error(
+                    'admission',
+                    _(
+                        "Gift card products should not be admission products at the same time."
+                    )
+                )
         return d
 
     class Meta: