Add support for reserved seating (#1228)

* Initial work on seating

* Add seat guids

* Add product_list_top

* CartAdd: Ignore item when a seat is passed

* Cart display

* product_list_top → render_seating_plan

* Render seating plan in voucher redemption

* Fix failing tests

* Add tests for extending cart positions with seats

* Add subevent_forms to docs

* Update schema, migrations

* Dealing with expired orders

* steps to order change

* Change order positions

* Allow to add seats

* tests for ocm

* Fix things after rebase

* Seating plans API

* Add more tests for cart behaviour

* Widget support

* Adjust widget tests

* Re-enable CSP

* Update schema

* Api: position.seat

* Add guid to word list

* API: (sub)event.seating_plan

* Vali fixes

* Fix api

* Fix reference in test

* Fix test for real

src/pretix/base/models/event.py

@@ -336,6 +336,8 @@ class Event(EventMixin, LoggedModel):
         verbose_name=_('Event series'),
         default=False
     )
+    seating_plan = models.ForeignKey('SeatingPlan', on_delete=models.PROTECT, null=True, blank=True,
+                                     related_name='events')
 
     objects = ScopedManager(organizer='organizer')
 
@@ -348,6 +350,26 @@ class Event(EventMixin, LoggedModel):
     def __str__(self):
         return str(self.name)
 
+    @property
+    def free_seats(self):
+        from .orders import CartPosition, Order, OrderPosition
+        return self.seats.annotate(
+            has_order=Exists(
+                OrderPosition.objects.filter(
+                    order__event=self,
+                    seat_id=OuterRef('pk'),
+                    order__status__in=[Order.STATUS_PENDING, Order.STATUS_PAID]
+                )
+            ),
+            has_cart=Exists(
+                CartPosition.objects.filter(
+                    event=self,
+                    seat_id=OuterRef('pk'),
+                    expires__gte=now()
+                )
+            )
+        ).filter(has_order=False, has_cart=False, blocked=False)
+
     @property
     def presale_has_ended(self):
         if self.has_subevents:
@@ -531,6 +553,24 @@ class Event(EventMixin, LoggedModel):
             for i in items:
                 cl.limit_products.add(item_map[i.pk])
 
+        if other.seating_plan:
+            if other.seating_plan.organizer_id == self.organizer_id:
+                self.seating_plan = other.seating_plan
+            else:
+                self.organizer.seating_plans.create(name=other.seating_plan.name, layout=other.seating_plan.layout)
+            self.save()
+
+        for m in other.seat_category_mappings.filter(subevent__isnull=True):
+            m.pk = None
+            m.event = self
+            m.product = item_map[m.product_id]
+            m.save()
+
+        for s in other.seats.filter(subevent__isnull=True):
+            s.pk = None
+            s.event = self
+            s.save()
+
         for s in other.settings._objects.all():
             s.object = self
             s.pk = None
@@ -874,6 +914,8 @@ class SubEvent(EventMixin, LoggedModel):
         null=True, blank=True,
         verbose_name=_("Frontpage text")
     )
+    seating_plan = models.ForeignKey('SeatingPlan', on_delete=models.PROTECT, null=True, blank=True,
+                                     related_name='subevents')
 
     items = models.ManyToManyField('Item', through='SubEventItem')
     variations = models.ManyToManyField('ItemVariation', through='SubEventItemVariation')
@@ -888,6 +930,28 @@ class SubEvent(EventMixin, LoggedModel):
     def __str__(self):
         return '{} - {}'.format(self.name, self.get_date_range_display())
 
+    @property
+    def free_seats(self):
+        from .orders import CartPosition, Order, OrderPosition
+        return self.seats.annotate(
+            has_order=Exists(
+                OrderPosition.objects.filter(
+                    order__event_id=self.event_id,
+                    subevent=self,
+                    seat_id=OuterRef('pk'),
+                    order__status__in=[Order.STATUS_PENDING, Order.STATUS_PAID]
+                )
+            ),
+            has_cart=Exists(
+                CartPosition.objects.filter(
+                    event_id=self.event_id,
+                    subevent=self,
+                    seat_id=OuterRef('pk'),
+                    expires__gte=now()
+                )
+            )
+        ).filter(has_order=False, has_cart=False, blocked=False)
+
     @cached_property
     def settings(self):
         return self.event.settings