Allow to use custom domains for some but not all events (Z#23153875) (#4627)

* Allow to use custom domains for some but not all events

* Update src/pretix/multidomain/urlreverse.py

* Apply suggestions from code review

Co-authored-by: Mira <weller@rami.io>

* Logging for domain config changes

---------

Co-authored-by: Mira <weller@rami.io>

src/pretix/control/forms/event.py

@@ -35,7 +35,7 @@
 # License for the specific language governing permissions and limitations under the License.
 
 from decimal import Decimal
-from urllib.parse import urlencode, urlparse
+from urllib.parse import urlencode
 from zoneinfo import ZoneInfo
 
 import pycountry
@@ -76,8 +76,10 @@ from pretix.control.forms import (
 )
 from pretix.control.forms.widgets import Select2
 from pretix.helpers.countries import CachedCountries
-from pretix.multidomain.models import KnownDomain
-from pretix.multidomain.urlreverse import build_absolute_uri
+from pretix.multidomain.models import AlternativeDomainAssignment, KnownDomain
+from pretix.multidomain.urlreverse import (
+    build_absolute_uri, get_organizer_domain,
+)
 from pretix.plugins.banktransfer.payment import BankTransfer
 from pretix.presale.style import get_fonts
 
@@ -363,14 +365,9 @@ class EventUpdateForm(I18nModelForm):
 
     def __init__(self, *args, **kwargs):
         self.change_slug = kwargs.pop('change_slug', False)
-        self.domain = kwargs.pop('domain', False)
 
         kwargs.setdefault('initial', {})
         self.instance = kwargs['instance']
-        if self.domain and self.instance:
-            initial_domain = self.instance.domains.first()
-            if initial_domain:
-                kwargs['initial'].setdefault('domain', initial_domain.domainname)
 
         super().__init__(*args, **kwargs)
         if not self.change_slug:
@@ -379,48 +376,54 @@ class EventUpdateForm(I18nModelForm):
         self.fields['location'].widget.attrs['placeholder'] = _(
             'Sample Conference Center\nHeidelberg, Germany'
         )
-        if self.domain:
+
+        try:
             self.fields['domain'] = forms.CharField(
                 max_length=255,
-                label=_('Custom domain'),
+                label=_('Domain'),
+                initial=self.instance.domain.domainname,
+                required=False,
+                disabled=True,
+                help_text=_('You can configure this in your organizer settings.')
+            )
+        except KnownDomain.DoesNotExist:
+            domain = get_organizer_domain(self.instance.organizer)
+            try:
+                current_domain_assignment = self.instance.alternative_domain_assignment
+            except AlternativeDomainAssignment.DoesNotExist:
+                current_domain_assignment = None
+            self.fields['domain'] = forms.ChoiceField(
+                label=_('Domain'),
+                help_text=_('You can add more domains in your organizer account.'),
+                choices=[('', _('Same as organizer account') + (f" ({domain})" if domain else ""))] + [
+                    (d.domainname, d.domainname) for d in self.instance.organizer.domains.filter(mode=KnownDomain.MODE_ORG_ALT_DOMAIN)
+                ],
+                initial=current_domain_assignment.domain_id if current_domain_assignment else "",
                 required=False,
-                help_text=_('You need to configure the custom domain in the webserver beforehand.')
             )
         self.fields['limit_sales_channels'].queryset = self.event.organizer.sales_channels.all()
         self.fields['limit_sales_channels'].widget = SalesChannelCheckboxSelectMultiple(self.event, attrs={
             'data-inverse-dependency': '<[name$=all_sales_channels]',
         }, choices=self.fields['limit_sales_channels'].widget.choices)
 
-    def clean_domain(self):
-        d = self.cleaned_data['domain']
-        if d:
-            if d == urlparse(settings.SITE_URL).hostname:
-                raise ValidationError(
-                    _('You cannot choose the base domain of this installation.')
-                )
-            if KnownDomain.objects.filter(domainname=d).exclude(event=self.instance.pk).exists():
-                raise ValidationError(
-                    _('This domain is already in use for a different event or organizer.')
-                )
-        return d
-
     def save(self, commit=True):
         instance = super().save(commit)
 
-        if self.domain:
-            current_domain = instance.domains.first()
-            if self.cleaned_data['domain']:
-                if current_domain and current_domain.domainname != self.cleaned_data['domain']:
-                    current_domain.delete()
-                    KnownDomain.objects.create(
-                        organizer=instance.organizer, event=instance, domainname=self.cleaned_data['domain']
-                    )
-                elif not current_domain:
-                    KnownDomain.objects.create(
-                        organizer=instance.organizer, event=instance, domainname=self.cleaned_data['domain']
-                    )
-            elif current_domain:
-                current_domain.delete()
+        try:
+            current_domain_assignment = instance.alternative_domain_assignment
+        except AlternativeDomainAssignment.DoesNotExist:
+            current_domain_assignment = None
+        if self.cleaned_data['domain'] and not hasattr(instance, 'domain'):
+            domain = self.instance.organizer.domains.get(mode=KnownDomain.MODE_ORG_ALT_DOMAIN, domainname=self.cleaned_data["domain"])
+            AlternativeDomainAssignment.objects.update_or_create(
+                event=instance,
+                defaults={
+                    "domain": domain,
+                }
+            )
+            instance.cache.clear()
+        elif current_domain_assignment:
+            current_domain_assignment.delete()
             instance.cache.clear()
 
         return instance