direct_messages: Add support for DMs to use DM group if exists.

This commit adds support for 1:1 DMs to be represented using
`DirectMessageGroup` object, if there already exists a
`DirectMessageGroup` for that pair of users. If no such group
exists, we fall back to the legacy code.

This is done as a part of migrating 1:1 DMs to be represented
using `DirectMessageGroup`.

Part of #25713

zerver/lib/recipient_users.py

@@ -5,6 +5,7 @@ from django.utils.translation import gettext as _
 
 from zerver.models import DirectMessageGroup, Recipient, UserProfile
 from zerver.models.recipients import (
+    check_direct_message_group_exists,
     get_direct_message_group_hash,
     get_or_create_direct_message_group,
 )
@@ -34,12 +35,18 @@ def get_recipient_from_user_profiles(
         if forwarder_user_profile.id not in recipient_profiles_map:
             raise ValidationError(_("User not authorized for this query"))
 
-    # If the direct message is just between the sender and
-    # another person, force it to be a personal internally
-    if len(recipient_profiles_map) == 2 and sender.id in recipient_profiles_map:
+    # Make sure the sender is included in the recipient
+    # profiles map.
+    recipient_profiles_map[sender.id] = sender
+
+    # If the direct message is just between the sender and another
+    # person or a self DM, and there is no corresponding direct
+    # message group, force it to be a personal internally.
+    if len(recipient_profiles_map) <= 2 and not check_direct_message_group_exists(
+        list(recipient_profiles_map)
+    ):
         del recipient_profiles_map[sender.id]
 
-    assert recipient_profiles_map
     if len(recipient_profiles_map) == 1:
         [user_profile] = recipient_profiles_map.values()
         return Recipient(
@@ -48,8 +55,6 @@ def get_recipient_from_user_profiles(
             type_id=user_profile.id,
         )
 
-    # Otherwise, we need a direct message group. Make sure the sender
-    # is included in the group direct messages
     recipient_profiles_map[sender.id] = sender
 
     user_ids = list(recipient_profiles_map)

zerver/models/recipients.py

@@ -149,6 +149,15 @@ class DirectMessageGroup(models.Model):
         db_table = "zerver_huddle"
 
 
+def check_direct_message_group_exists(id_list: list[int]) -> bool:
+    direct_message_group_hash = get_direct_message_group_hash(id_list)
+    direct_message_group_exists = DirectMessageGroup.objects.filter(
+        huddle_hash=direct_message_group_hash
+    ).exists()
+
+    return direct_message_group_exists
+
+
 def get_direct_message_group_hash(id_list: list[int]) -> str:
     id_list = sorted(set(id_list))
     hash_key = ",".join(str(x) for x in id_list)

zerver/tests/test_email_mirror.py

@@ -1025,7 +1025,7 @@ class TestMissedMessageEmailMessages(ZulipTestCase):
         incoming_valid_message["To"] = mm_address
         incoming_valid_message["Reply-to"] = self.example_email("othello")
 
-        with self.assert_database_query_count(16):
+        with self.assert_database_query_count(17):
             process_message(incoming_valid_message)
 
         # confirm that Hamlet got the message

zerver/tests/test_example.py

@@ -362,7 +362,7 @@ class TestQueryCounts(ZulipTestCase):
         hamlet = self.example_user("hamlet")
         cordelia = self.example_user("cordelia")
 
-        with self.assert_database_query_count(15):
+        with self.assert_database_query_count(16):
             self.send_personal_message(
                 from_user=hamlet,
                 to_user=cordelia,

zerver/tests/test_message_send.py

@@ -2463,7 +2463,7 @@ class PersonalMessageSendTest(ZulipTestCase):
 
         # Have the administrator send a message, and verify that allows the user to reply.
         self.send_personal_message(admin, user_profile)
-        with self.assert_database_query_count(16):
+        with self.assert_database_query_count(17):
             self.send_personal_message(user_profile, admin)
 
         # Tests that user cannot initiate direct message thread in groups.
@@ -2526,7 +2526,7 @@ class PersonalMessageSendTest(ZulipTestCase):
             acting_user=None,
         )
         # Tests if the user is allowed to send to administrators.
-        with self.assert_database_query_count(16):
+        with self.assert_database_query_count(17):
             self.send_personal_message(user_profile, admin)
         self.send_personal_message(admin, user_profile)
         # Tests if we can send messages to self irrespective of the value of the setting.
@@ -2586,6 +2586,28 @@ class PersonalMessageSendTest(ZulipTestCase):
             "Direct messages are disabled in this organization.",
         )
 
+    def test_direct_message_represented_as_direct_message_group(self) -> None:
+        hamlet = self.example_user("hamlet")
+        iago = self.example_user("iago")
+        user_ids = [iago.id, hamlet.id]
+
+        # A direct message between two users with no corresponding direct message
+        # group is forced to be personal internally
+        message_id = self.send_personal_message(iago, hamlet)
+        message = Message.objects.filter(id=message_id).first()
+
+        assert message is not None
+        self.assertEqual(message.recipient.type, Recipient.PERSONAL)
+
+        # A direct message between two users with a direct message group existing,
+        # becomes a group direct message.
+        get_or_create_direct_message_group(user_ids)
+        message_id = self.send_personal_message(iago, hamlet, "test")
+        message = Message.objects.filter(id=message_id).first()
+
+        assert message is not None
+        self.assertEqual(message.recipient.type, Recipient.DIRECT_MESSAGE_GROUP)
+
     def test_non_ascii_personal(self) -> None:
         """
         Sending a direct message containing non-ASCII characters succeeds.

zerver/tests/test_signup.py

@@ -1053,7 +1053,7 @@ class LoginTest(ZulipTestCase):
         # to sending messages, such as getting the welcome bot, looking up
         # the alert words for a realm, etc.
         with (
-            self.assert_database_query_count(94),
+            self.assert_database_query_count(95),
             self.assert_memcached_count(14),
             self.captureOnCommitCallbacks(execute=True),
         ):

zerver/tests/test_subs.py

@@ -6058,7 +6058,7 @@ class GetSubscribersTest(ZulipTestCase):
             polonius.id,
         ]
 
-        with self.assert_database_query_count(43):
+        with self.assert_database_query_count(46):
             self.common_subscribe_to_streams(
                 self.user_profile,
                 streams,

zerver/tests/test_users.py

@@ -1018,7 +1018,7 @@ class QueryCountTest(ZulipTestCase):
         prereg_user = PreregistrationUser.objects.get(email="fred@zulip.com")
 
         with (
-            self.assert_database_query_count(84),
+            self.assert_database_query_count(86),
             self.assert_memcached_count(19),
             self.capture_send_event_calls(expected_num_events=10) as events,
         ):