Fix overlap calc for consecutive subevents

src/pretix/control/forms/subevents.py

@@ -28,7 +28,7 @@ from django.forms import formset_factory
 from django.forms.utils import ErrorDict
 from django.urls import reverse
 from django.utils.functional import cached_property
-from django.utils.translation import gettext_lazy as _
+from django.utils.translation import gettext_lazy as _, pgettext_lazy
 from i18nfield.forms import I18nInlineFormSet
 
 from pretix.base.forms import I18nModelForm
@@ -102,6 +102,16 @@ class SubEventBulkForm(SubEventForm):
         required=False,
         limit_choices=('date_from', 'date_to'),
     )
+    skip_if_overlap = forms.BooleanField(
+        label=pgettext_lazy('subevent', 'Skip dates that overlap with any existing date'),
+        help_text=pgettext_lazy(
+            'subevent',
+            'This can be useful if all your dates happen in the same location and no repeated dates should '
+            'be created in conflict with existing special events. This respects even inactive dates and works best if '
+            'all dates have both a start and end time.'
+        ),
+        required=False,
+    )
 
     def __init__(self, *args, **kwargs):
         self.event = kwargs['event']

src/pretix/control/templates/pretixcontrol/subevents/bulk.html

@@ -379,6 +379,8 @@
                         <i class="fa fa-calendar"></i> {% trans "Add many time slots" %}</button>
                 </p>
             </div>
+            <hr />
+            {% bootstrap_field form.skip_if_overlap layout="control" horizontal_label_class='sr-only' horizontal_field_class='col-md-12' %}
         </fieldset>
         <fieldset>
             <legend>{% trans "General information" %}</legend>

src/pretix/control/views/subevents.py

@@ -917,6 +917,35 @@ class SubEventBulkCreate(SubEventEditorMixin, EventPermissionRequiredMixin, Asyn
             if len(subevents) > 100_000:
                 raise ValidationError(_('Please do not create more than 100.000 dates at once.'))
 
+        if form.cleaned_data.get("skip_if_overlap") and subevents:
+            def overlaps(a_from, a_to, b_from, b_to):
+                if a_from == b_from:
+                    return True
+                if a_from > b_from:
+                    # a starts after b
+                    # check if it starts before b ends
+                    return b_to and a_from < b_to
+                # a starts before b
+                # check if it ends before b starts
+                return a_to and a_to > b_from
+
+            date_min = min(se.date_from for se in subevents)
+            date_max = max(se.date_to or se.date_from for se in subevents)
+            dates_existing = list(self.request.event.subevents.annotate(
+                date_fromto=Coalesce('date_to', 'date_from'),
+            ).filter(
+                date_from__lte=date_max,
+                date_fromto__gte=date_min,
+            ).values('date_from', 'date_to'))
+            subevents = [
+                se for se in subevents if not any(
+                    overlaps(se.date_from, se.date_to, other['date_from'], other['date_to'])
+                    for other in dates_existing
+                )
+            ]
+            if not subevents:
+                raise ValidationError(_('All dates would be skipped because they conflict with existing dates.'))
+
         for i, se in enumerate(subevents):
             se.save(clear_cache=False)
             if i % 100 == 0: