better order_max handling

src/pretix/base/models/discount.py

@@ -23,7 +23,7 @@
 from collections import defaultdict
 from decimal import Decimal
 from itertools import groupby
-from math import ceil
+from math import ceil, inf
 from typing import Dict, Optional, Tuple
 
 from django.core.exceptions import ValidationError
@@ -268,7 +268,7 @@ class Discount(LoggedModel):
 
         if collect_potential_discounts is not None:
             for idx in condition_idx_group:
-                collect_potential_discounts[idx] = [(self, None, -1)]
+                collect_potential_discounts[idx] = [(self, inf, -1)]
 
     def _apply_min_count(self, positions, condition_idx_group, benefit_idx_group, result, collect_potential_discounts):
         if len(condition_idx_group) < self.condition_min_count:
@@ -321,7 +321,7 @@ class Discount(LoggedModel):
 
             if collect_potential_discounts is not None:
                 for idx in consume_idx:
-                    collect_potential_discounts[idx] = [(self, None, -1)]
+                    collect_potential_discounts[idx] = [(self, inf, -1)]
 
         for idx in benefit_idx:
             previous_price = positions[idx][LINE_PRICE_GROSS]

src/pretix/base/models/items.py

@@ -64,6 +64,7 @@ from django.utils.translation import gettext_lazy as _, pgettext_lazy
 from django_countries.fields import Country
 from django_scopes import ScopedManager
 from i18nfield.fields import I18nCharField, I18nTextField
+from math import inf
 
 from pretix.base.models.base import LoggedModel
 from pretix.base.models.fields import MultiStringField
@@ -160,6 +161,7 @@ class ItemCategory(LoggedModel):
         if self.cross_selling_condition == 'always':
             return self.items.all(), {}
         if self.cross_selling_condition == 'products':
+            # TODO set max_count for products with max_per_order
             match = set(match.pk for match in self.cross_selling_match_products.only('pk'))  # TODO prefetch this
             return (self.items.all(), {}) if any(pos.item.pk in match for pos in cart) else ([], {})
         if self.cross_selling_condition == 'discounts':
@@ -183,8 +185,19 @@ class ItemCategory(LoggedModel):
             # - max_count for product: sum up max_counts
             # - discount_rule for product: take first discount_rule
 
+            def discount_info(item, infos_for_item):
+                infos_for_item = list(infos_for_item)
+                return (
+                    item,
+                    min(
+                        sum(max_count for (item, discount_rule, max_count, i) in infos_for_item),
+                        (item.max_per_order - sum(1 for pos in cart if pos.item_id == item.pk)) if item.max_per_order else inf
+                    ),
+                    next(discount_rule for (item, discount_rule, max_count, i) in infos_for_item)
+                )
+
             grouped_by_item = [
-                (item, list(infos_for_item)) for item, infos_for_item in
+                discount_info(item, infos_for_item) for item, infos_for_item in
                 groupby(
                     sorted(
                         (
@@ -197,17 +210,11 @@ class ItemCategory(LoggedModel):
                     lambda tup: tup[0])
             ]
 
-            def sum_or_none(iter):
-                return functools.reduce(lambda x, y: None if x is None or y is None else x + y, iter, 0)
-
             my_item_pks = self.items.values_list('pk', flat=True)
             potential_discount_items = {
-                item.pk: (
-                    sum_or_none(max_count for (item, discount_rule, max_count, i) in infos_for_item),
-                    next(discount_rule for (item, discount_rule, max_count, i) in infos_for_item)
-                )
-                for item, infos_for_item in grouped_by_item
-                if item.pk in my_item_pks
+                item.pk: (max_count, discount_rule)
+                for item, max_count, discount_rule in grouped_by_item
+                if max_count > 0 and item.pk in my_item_pks and item.is_available()
             }
 
             return self.items.filter(pk__in=potential_discount_items), potential_discount_items

src/pretix/presale/checkoutflow.py

@@ -54,6 +54,7 @@ from django.utils.translation import (
 )
 from django.views.generic.base import TemplateResponseMixin
 from django_scopes import scopes_disabled
+from math import inf
 
 from pretix.base.models import Customer, Membership, Order
 from pretix.base.models.items import Question
@@ -665,7 +666,7 @@ class AddOnsStep(CartMixin, AsyncAction, TemplateFlowStep):
                 (max_count, discount_rule) = discount_info[item.pk]
 
                 # set item.order_max for benefit_only_apply_to_cheapest_n_matches discounted items
-                if max_count:
+                if max_count and max_count != inf:
                     item.order_max = min(item.order_max, max_count)
 
                 # calculate discounted price