zerver: Add endpoints and events for reminders.

There are similar to what exists for scheduled messages expect
the PATCH requests which will be added later when the
functionality is implemented.

zerver/lib/scheduled_messages.py

@@ -3,6 +3,7 @@ from django.utils.translation import gettext as _
 from zerver.lib.exceptions import ResourceNotFoundError
 from zerver.models import ScheduledMessage, UserProfile
 from zerver.models.scheduled_jobs import (
+    APIReminderDirectMessageDict,
     APIScheduledDirectMessageDict,
     APIScheduledStreamMessageDict,
 )
@@ -12,7 +13,9 @@ def access_scheduled_message(
     user_profile: UserProfile, scheduled_message_id: int
 ) -> ScheduledMessage:
     try:
-        return ScheduledMessage.objects.get(id=scheduled_message_id, sender=user_profile)
+        return ScheduledMessage.objects.get(
+            id=scheduled_message_id, sender=user_profile, delivery_type=ScheduledMessage.SEND_LATER
+        )
     except ScheduledMessage.DoesNotExist:
         raise ResourceNotFoundError(_("Scheduled message does not exist"))
 
@@ -32,3 +35,20 @@ def get_undelivered_scheduled_messages(
         scheduled_message.to_dict() for scheduled_message in scheduled_messages
     ]
     return scheduled_message_dicts
+
+
+def get_undelivered_reminders(
+    user_profile: UserProfile,
+) -> list[APIReminderDirectMessageDict]:
+    reminders = ScheduledMessage.objects.filter(
+        realm_id=user_profile.realm_id,
+        sender=user_profile,
+        # Notably, we don't require failed=False, since we will want
+        # to display those to users.
+        delivered=False,
+        delivery_type=ScheduledMessage.REMIND,
+    ).order_by("scheduled_timestamp")
+    reminder_dicts: list[APIReminderDirectMessageDict] = [
+        reminder.to_reminder_dict() for reminder in reminders
+    ]
+    return reminder_dicts