Add tax splitting

pretix_servicefees/signals.py

@@ -1,17 +1,19 @@
+from collections import defaultdict
 from decimal import Decimal
-
-from django.urls import resolve, reverse
 from django.dispatch import receiver
 from django.http import HttpRequest
-from django.utils.translation import gettext_lazy as _, gettext, get_language
+from django.urls import resolve, reverse
+from django.utils.translation import get_language, gettext, gettext_lazy as _
 from pretix.base.decimal import round_decimal
-from pretix.base.models import Event, Order, TaxRule
+from pretix.base.models import CartPosition, Event, Order, TaxRule
 from pretix.base.models.orders import OrderFee
 from pretix.base.settings import settings_hierarkey
 from pretix.base.signals import order_fee_calculation
 from pretix.base.templatetags.money import money_filter
 from pretix.control.signals import nav_event_settings
-from pretix.presale.signals import fee_calculation_for_cart, front_page_top, order_meta_from_request
+from pretix.presale.signals import (
+    fee_calculation_for_cart, front_page_top, order_meta_from_request,
+)
 from pretix.presale.views import get_cart
 from pretix.presale.views.cart import cart_session
 
@@ -76,17 +78,52 @@ def get_fees(event, total, invoice_address, mod='', request=None, positions=[],
                 summed += fval
 
     if (fee_per_ticket or fee_abs or fee_percent) and total != Decimal('0.00'):
+        tax_rule_zero = TaxRule.zero()
         fee = round_decimal(fee_abs + total * (fee_percent / 100) + len(positions) * fee_per_ticket, event.currency)
-        tax_rule = event.settings.tax_rate_default or TaxRule.zero()
-        tax = tax_rule.tax(fee, invoice_address=invoice_address, base_price_is='gross')
-        return [OrderFee(
-            fee_type=OrderFee.FEE_TYPE_SERVICE,
-            internal_type='',
-            value=fee,
-            tax_rate=tax.rate,
-            tax_value=tax.tax,
-            tax_rule=tax_rule
-        )]
+        split_taxes = event.settings.get('service_fee_split_taxes', as_type=bool)
+        if split_taxes:
+            # split taxes based on products ordered
+            d = defaultdict(lambda: Decimal('0.00'))
+            for p in positions:
+                if isinstance(p, CartPosition):
+                    tr = p.item.tax_rule
+                else:
+                    tr = p.tax_rule
+                d[tr] += p.price - p.tax_value
+
+            base_values = sorted([tuple(t) for t in d.items()], key=lambda t: t[0].rate)
+            sum_base = sum(t[1] for t in base_values)
+            if sum_base:
+                fee_values = [(t[0], round_decimal(fee * t[1] / sum_base, event.currency))
+                              for t in base_values]
+                sum_fee = sum(t[1] for t in fee_values)
+
+                # If there are rounding differences, we fix them up, but always leaning to the benefit of the tax
+                # authorities
+                if sum_fee > fee:
+                    fee_values[0] = (fee_values[0][0], fee_values[0][1] + (fee - sum_fee))
+                elif sum_fee < fee:
+                    fee_values[-1] = (fee_values[-1][0], fee_values[-1][1] + (fee - sum_fee))
+            else:
+                fee_values = [(event.settings.tax_rate_default or tax_rule_zero, fee)]
+
+        else:
+            fee_values = [(event.settings.tax_rate_default or tax_rule_zero, fee)]
+
+        fees = []
+        for tax_rule, price in fee_values:
+            tax_rule = tax_rule or tax_rule_zero
+            tax = tax_rule.tax(price, invoice_address=invoice_address, base_price_is='gross')
+            fees.append(OrderFee(
+                fee_type=OrderFee.FEE_TYPE_SERVICE,
+                internal_type='',
+                value=price,
+                tax_rate=tax.rate,
+                tax_value=tax.tax,
+                tax_rule=tax_rule
+            ))
+        return fees
+
     return []
 
 
@@ -94,7 +131,9 @@ def get_fees(event, total, invoice_address, mod='', request=None, positions=[],
 def cart_fee(sender: Event, request: HttpRequest, invoice_address, total, **kwargs):
     mod = ''
     try:
-        from pretix_resellers.utils import ResellerException, get_reseller_and_user
+        from pretix_resellers.utils import (
+            ResellerException, get_reseller_and_user,
+        )
     except ImportError:
         pass
     else:
@@ -153,7 +192,9 @@ def front_page_top_recv(sender: Event, **kwargs):
 def order_meta_signal(sender: Event, request: HttpRequest, **kwargs):
     meta = {}
     try:
-        from pretix_resellers.utils import ResellerException, get_reseller_and_user
+        from pretix_resellers.utils import (
+            ResellerException, get_reseller_and_user,
+        )
     except ImportError:
         pass
     else:

pretix_servicefees/templates/pretix_servicefees/settings.html

@@ -14,6 +14,7 @@
             {% bootstrap_field form.service_fee_skip_free layout="control" %}
             {% bootstrap_field form.service_fee_abs addon_after=request.event.currency layout="control" %}
             {% bootstrap_field form.service_fee_percent addon_after="%" layout="control" %}
+            {% bootstrap_field form.service_fee_split_taxes layout="control" %}
             {% bootstrap_field form.service_fee_skip_if_gift_card layout="control" %}
         </fieldset>
         <fieldset>

pretix_servicefees/views.py

@@ -46,6 +46,11 @@ class ServiceFeeSettingsForm(SettingsForm):
         help_text=_('Note that regardless of this setting, a per-ticket fee will not be charged if the entire order is free.'),
         required=False
     )
+    service_fee_split_taxes = forms.BooleanField(
+        label=_('Split taxes proportionate to the tax rates and net values of the ordered products.'),
+        help_text=_('If not split based on ordered products, the tax rate falls back to the event’s base tax rate or no tax, if none is given.'),
+        required=False
+    )
 
     service_fee_abs_resellers = forms.DecimalField(
         label=_('Fixed fee per order'),