Restructure our python module. A lot.

src/pretix/presale/views/event.py

@@ -0,0 +1,45 @@
+from django.db.models import Count
+from django.views.generic import TemplateView
+from pretix.presale.views import EventViewMixin, CartDisplayMixin
+
+
+class EventIndex(EventViewMixin, CartDisplayMixin, TemplateView):
+    template_name = "pretixpresale/event/index.html"
+
+    def get_context_data(self, **kwargs):
+        context = super().get_context_data(**kwargs)
+        # Fetch all items
+        items = self.request.event.items.all().select_related(
+            'category',  # for re-grouping
+        ).prefetch_related(
+            'properties',  # for .get_all_available_variations()
+            'quotas', 'variations__quotas'  # for .availability()
+        ).annotate(quotac=Count('quotas')).filter(
+            quotac__gt=0
+        ).order_by('category__position', 'category_id', 'name')
+
+        for item in items:
+            item.available_variations = sorted(item.get_all_available_variations(),
+                                               key=lambda vd: vd.ordered_values())
+            item.has_variations = (len(item.available_variations) != 1
+                                   or not item.available_variations[0].empty())
+            if not item.has_variations:
+                item.cached_availability = list(item.check_quotas())
+                item.cached_availability[1] = min(item.cached_availability[1],
+                                                  self.request.event.max_items_per_order)
+                item.price = item.available_variations[0]['price']
+            else:
+                for var in item.available_variations:
+                    var.cached_availability = list(var['variation'].check_quotas())
+                    var.cached_availability[1] = min(var.cached_availability[1],
+                                                     self.request.event.max_items_per_order)
+
+        # Regroup those by category
+        context['items_by_category'] = sorted([
+            # a group is a tuple of a category and a list of items
+            (cat, [i for i in items if i.category_id == cat.identity])
+            for cat in set([i.category for i in items])  # insert categories into a set for uniqueness
+        ], key=lambda group: (group[0].position, group[0].pk))  # a set is unsorted, so sort again by category
+
+        context['cart'] = self.get_cart()
+        return context