Don't send notifications for changes in irrelevant time range

aleksis/apps/chronos/model_extensions.py

-from datetime import date
+import zoneinfo
+from datetime import date, timedelta
 from typing import Optional, Union
 from urllib.parse import urljoin
 
 from django.conf import settings
 from django.dispatch import receiver
 from django.urls import reverse
+from django.utils import timezone
 from django.utils.formats import date_format
 from django.utils.translation import gettext_lazy as _
 from django.utils.translation import ngettext
@@ -19,6 +21,7 @@ from aleksis.apps.chronos.models import (
     SupervisionSubstitution,
 )
 from aleksis.core.models import Announcement, Group, Notification, Person
+from aleksis.core.util.core_helpers import get_site_preferences
 
 from .managers import TimetableType
 from .models import Lesson, LessonPeriod, Subject
@@ -172,6 +175,21 @@ def send_notifications(sender: Revision, **kwargs):
         if change.deleted:
             continue
 
+        dt_start, dt_end = change.instance.time_range
+        dt_start = dt_start.replace(tzinfo=zoneinfo.ZoneInfo(settings.TIME_ZONE))
+        dt_end = dt_end.replace(tzinfo=zoneinfo.ZoneInfo(settings.TIME_ZONE))
+
+        send_time = get_site_preferences()["chronos__time_for_sending_notifications"]
+
+        start_range = timezone.now().replace(hour=send_time.hour, minute=send_time.minute)
+        if timezone.now().time() > send_time:
+            start_range = start_range - timedelta(days=1)
+        end_range = start_range + timedelta(days=1)
+
+        if dt_start <= end_range and dt_end >= start_range:
+            # Skip this because it's not in the current range for notifications
+            continue
+
         recipients = []
         if isinstance(change.instance, LessonSubstitution):
             recipients += change.instance.lesson_period.lesson.teachers.all()
@@ -333,11 +351,12 @@ def send_notifications(sender: Revision, **kwargs):
                 new=change.instance.teacher.full_name,
             )
 
-        day = (
-            change.instance.date if hasattr(change.instance, "date") else change.instance.date_start
-        )
         url = urljoin(
-            settings.BASE_URL, reverse("my_timetable_by_date", args=[day.year, day.month, day.day])
+            settings.BASE_URL,
+            reverse(
+                "my_timetable_by_date",
+                args=[dt_start.date().year, dt_start.date().month, dt_start.date().day],
+            ),
         )
 
         for recipient in recipients:

aleksis/apps/chronos/models.py

@@ -469,6 +469,12 @@ class LessonSubstitution(ExtensibleModel, TeacherPropertiesMixin, WeekRelatedMix
         week = CalendarWeek(week=self.week, year=self.year)
         return week[self.lesson_period.period.weekday]
 
+    @property
+    def time_range(self):
+        return timezone.datetime.combine(
+            self.date, self.lesson_period.period.time_start
+        ), timezone.datetime.combine(self.date, self.lesson_period.period.time_end)
+
     def get_teachers(self):
         return self.teachers
 
@@ -1024,6 +1030,16 @@ class SupervisionSubstitution(ExtensibleModel):
     def teachers(self):
         return [self.teacher]
 
+    @property
+    def time_range(self):
+        return timezone.datetime.combine(
+            self.date,
+            self.supervision.break_item.time_start or self.supervision.break_item.time_end,
+        ), timezone.datetime.combine(
+            self.date,
+            self.supervision.break_item.time_end or self.supervision.break_item.time_start,
+        )
+
     def __str__(self):
         return f"{self.supervision}, {date_format(self.date)}"
 
@@ -1136,6 +1152,12 @@ class Event(SchoolTermRelatedExtensibleModel, GroupPropertiesMixin, TeacherPrope
         """Get teachers relation."""
         return self.teachers
 
+    @property
+    def time_range(self):
+        return timezone.datetime.combine(
+            self.date_start, self.period_from.time_start
+        ), timezone.datetime.combine(self.date_end, self.period_to.time_end)
+
     class Meta:
         # Heads up: Link to period implies uniqueness per site
         ordering = ["date_start"]
@@ -1207,6 +1229,12 @@ class ExtraLesson(
         """Get subject."""
         return self.subject
 
+    @property
+    def time_range(self):
+        return timezone.datetime.combine(
+            self.date, self.period.time_start
+        ), timezone.datetime.combine(self.date, self.period.time_end)
+
     class Meta:
         # Heads up: Link to period implies uniqueness per site
         verbose_name = _("Extra lesson")

aleksis/apps/chronos/preferences.py

+from datetime import time
+
 from django.utils.translation import gettext_lazy as _
 
 from dynamic_preferences.preferences import Section
-from dynamic_preferences.types import BooleanPreference, IntegerPreference
+from dynamic_preferences.types import BooleanPreference, IntegerPreference, TimePreference
 
 from aleksis.core.registries import person_preferences_registry, site_preferences_registry
 
@@ -67,3 +69,12 @@ class AffectedGroupsUseParentGroups(BooleanPreference):
     verbose_name = _(
         "Show parent groups in header box in substitution views instead of original groups"
     )
+
+
+@site_preferences_registry.register
+class TimeForSendingNotifications(TimePreference):
+    section = chronos
+    name = "time_for_sending_notifications"
+    default = time(17, 00)
+    verbose_name = _("Time for sending notifications for the next day")
+    required = True