Add support for custom taxation rules

src/pretix/base/migrations/0083_auto_20180228_2102.py

@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.10 on 2018-02-28 21:02
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('pretixbase', '0082_auto_20180222_0938'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='taxrule',
+            name='custom_rules',
+            field=models.TextField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='orderfee',
+            name='fee_type',
+            field=models.CharField(choices=[('payment', 'Payment fee'), ('shipping', 'Shipping fee'), ('service', 'Service fee'), ('other', 'Other fees')], max_length=100),
+        ),
+    ]

src/pretix/base/models/tax.py

@@ -1,3 +1,4 @@
+import json
 from decimal import Decimal
 
 from django.db import models
@@ -88,6 +89,7 @@ class TaxRule(LoggedModel):
         help_text=_('Your country of residence. This is the country the EU reverse charge rule will not apply in, '
                     'if configured above.'),
     )
+    custom_rules = models.TextField(blank=True, null=True)
 
     def allow_delete(self):
         from pretix.base.models.orders import OrderFee, OrderPosition
@@ -151,7 +153,27 @@ class TaxRule(LoggedModel):
             rate=self.rate, name=self.name
         )
 
+    def get_matching_rule(self, invoice_address):
+        rules = json.loads(self.custom_rules)
+        for r in rules:
+            if r['country'] == 'EU' and str(invoice_address.country) not in EU_COUNTRIES:
+                continue
+            if r['country'] not in ('ZZ', 'EU') and r['country'] != str(invoice_address.country):
+                continue
+            if r['address_type'] == 'individual' and invoice_address.is_business:
+                continue
+            if r['address_type'] in ('business', 'business_vat_id') and not invoice_address.is_business:
+                continue
+            if r['address_type'] == 'business_vat_id' and (not invoice_address.vat_id or not invoice_address.vat_id_validated):
+                continue
+            return r
+        return {'action': 'vat'}
+
     def is_reverse_charge(self, invoice_address):
+        if self.custom_rules:
+            rule = self.get_matching_rule(invoice_address)
+            return rule['action'] == 'reverse'
+
         if not self.eu_reverse_charge:
             return False
 
@@ -170,6 +192,10 @@ class TaxRule(LoggedModel):
         return False
 
     def tax_applicable(self, invoice_address):
+        if self.custom_rules:
+            rule = self.get_matching_rule(invoice_address)
+            return rule.get('action', 'vat') == 'vat'
+
         if not self.eu_reverse_charge:
             # No reverse charge rules? Always apply VAT!
             return True