Fix #526 -- Add a webhook system (#1073)

- [x] Data model
- [x] UI
- [x] Fire hooks
- [x] Unit tests
- [x] Display logs
- [x] API to modify hooks
- [x] Documentation
- [x] More hooks!

src/pretix/api/views/checkin.py

@@ -244,7 +244,9 @@ class CheckinListPositionViewSet(viewsets.ReadOnlyModelViewSet):
                 ignore_unpaid=ignore_unpaid,
                 nonce=nonce,
                 datetime=dt,
-                questions_supported=self.request.data.get('questions_supported', True)
+                questions_supported=self.request.data.get('questions_supported', True),
+                user=self.request.user,
+                auth=self.request.auth,
             )
         except RequiredQuestionsError as e:
             return Response({

src/pretix/api/views/webhooks.py

@@ -0,0 +1,49 @@
+from rest_framework import viewsets
+
+from pretix.api.models import WebHook
+from pretix.api.serializers.webhooks import WebHookSerializer
+from pretix.helpers.dicts import merge_dicts
+
+
+class WebHookViewSet(viewsets.ModelViewSet):
+    serializer_class = WebHookSerializer
+    queryset = WebHook.objects.none()
+    permission = 'can_change_organizer_settings'
+    write_permission = 'can_change_organizer_settings'
+
+    def get_queryset(self):
+        return self.request.organizer.webhooks.prefetch_related('listeners')
+
+    def get_serializer_context(self):
+        ctx = super().get_serializer_context()
+        ctx['organizer'] = self.request.organizer
+        return ctx
+
+    def perform_create(self, serializer):
+        inst = serializer.save(organizer=self.request.organizer)
+        self.request.organizer.log_action(
+            'pretix.webhook.created',
+            user=self.request.user,
+            auth=self.request.auth,
+            data=merge_dicts(self.request.data, {'id': inst.pk})
+        )
+
+    def perform_update(self, serializer):
+        inst = serializer.save(organizer=self.request.organizer)
+        self.request.organizer.log_action(
+            'pretix.webhook.changed',
+            user=self.request.user,
+            auth=self.request.auth,
+            data=merge_dicts(self.request.data, {'id': serializer.instance.pk})
+        )
+        return inst
+
+    def perform_destroy(self, instance):
+        self.request.organizer.log_action(
+            'pretix.webhook.changed',
+            user=self.request.user,
+            auth=self.request.auth,
+            data={'id': instance.pk, 'enabled': False}
+        )
+        instance.enabled = False
+        instance.save(update_fields=['enabled'])