Improvements around the waiting list (#2219)

* Waiting list: Support for seated events, pre-fill customer email address

* Allow people to remove themselves

* Update src/pretix/base/settings.py

Co-authored-by: Richard Schreiber <schreiber@rami.io>

* Update src/pretix/control/views/waitinglist.py

Co-authored-by: Richard Schreiber <schreiber@rami.io>

* Update src/pretix/control/views/waitinglist.py

Co-authored-by: Richard Schreiber <schreiber@rami.io>

* Update src/pretix/control/views/waitinglist.py

Co-authored-by: Richard Schreiber <schreiber@rami.io>

* Update src/pretix/presale/views/waiting.py

Co-authored-by: Richard Schreiber <schreiber@rami.io>

* Resolve a review note

* Review notes

* Fix linter issues

* Fix import

Co-authored-by: Richard Schreiber <schreiber@rami.io>

src/pretix/presale/forms/waitinglist.py

@@ -20,6 +20,7 @@
 # <https://www.gnu.org/licenses/>.
 #
 from django import forms
+from django.core.exceptions import ObjectDoesNotExist, ValidationError
 from django.utils.translation import gettext_lazy as _
 from phonenumber_field.formfields import PhoneNumberField
 from phonenumbers.data import _COUNTRY_CODE_TO_REGION_CODE
@@ -28,7 +29,8 @@ from pretix.base.forms.questions import (
     NamePartsFormField, WrappedPhoneNumberPrefixWidget, guess_country,
 )
 from pretix.base.i18n import get_babel_locale, language
-from pretix.base.models import WaitingListEntry
+from pretix.base.models import Quota, WaitingListEntry
+from pretix.presale.views.event import get_grouped_items
 
 
 class WaitingListForm(forms.ModelForm):
@@ -40,8 +42,35 @@ class WaitingListForm(forms.ModelForm):
 
     def __init__(self, *args, **kwargs):
         self.event = kwargs.pop('event')
+        self.channel = kwargs.pop('channel')
         super().__init__(*args, **kwargs)
 
+        choices = [
+            ('', '')
+        ]
+        items, display_add_to_cart = get_grouped_items(
+            self.event, self.instance.subevent, require_seat=None
+        )
+        for i in items:
+            if not i.allow_waitinglist:
+                continue
+
+            if i.has_variations:
+                for v in i.available_variations:
+                    if v.cached_availability[0] == Quota.AVAILABILITY_OK:
+                        continue
+                    choices.append((f'{i.pk}-{v.pk}', f'{i.name} – {v.value}'))
+
+            else:
+                if i.cached_availability[0] == Quota.AVAILABILITY_OK:
+                    continue
+                choices.append((f'{i.pk}', f'{i.name}'))
+
+        self.fields['itemvar'] = forms.ChoiceField(
+            label=_('Product'),
+            choices=choices,
+        )
+
         event = self.event
 
         if event.settings.waiting_list_names_asked:
@@ -73,3 +102,23 @@ class WaitingListForm(forms.ModelForm):
                 )
         else:
             del self.fields['phone']
+
+    def clean(self):
+        try:
+            iv = self.data.get('itemvar', '')
+            if '-' in iv:
+                itemid, varid = iv.split('-')
+            else:
+                itemid, varid = iv, None
+
+            self.instance.item = self.instance.event.items.get(pk=itemid)
+            if varid:
+                self.instance.variation = self.instance.item.variations.get(pk=varid)
+            else:
+                self.instance.variation = None
+
+        except ObjectDoesNotExist:
+            raise ValidationError(_("Invalid product selected."))
+
+        data = super().clean()
+        return data