snapshot of https://github.com/zulip/zulip.git @ 48c69911c7dd4e03b20552eb3bd77ad8151c1357 (2026-09-15)

zerver/actions/reactions.py

@@ -0,0 +1,190 @@
+from typing import Literal
+
+from typing_extensions import TypedDict
+
+from zerver.actions.user_topics import do_set_user_topic_visibility_policy
+from zerver.lib.emoji import check_emoji_request, get_emoji_data
+from zerver.lib.exceptions import ReactionExistsError
+from zerver.lib.message import (
+    access_message_and_usermessage,
+    event_recipient_ids_for_action_on_messages,
+    set_visibility_policy_possible,
+    should_change_visibility_policy,
+    visibility_policy_for_participation,
+)
+from zerver.lib.message_cache import update_message_cache
+from zerver.lib.streams import access_stream_by_id
+from zerver.lib.user_message import create_historical_user_messages
+from zerver.models import Message, Reaction, UserProfile
+from zerver.tornado.django_api import send_event_on_commit
+
+
+class ReactionEvent(TypedDict):
+    type: Literal["reaction"]
+    op: Literal["add", "remove"]
+    user_id: int
+    message_id: int
+    emoji_name: str
+    emoji_code: str
+    reaction_type: str
+
+
+def notify_reaction_update(
+    user_profile: UserProfile,
+    message: Message,
+    reaction: Reaction,
+    op: Literal["add", "remove"],
+) -> None:
+    event: ReactionEvent = {
+        "type": "reaction",
+        "op": op,
+        "user_id": user_profile.id,
+        "message_id": message.id,
+        "emoji_name": reaction.emoji_name,
+        "emoji_code": reaction.emoji_code,
+        "reaction_type": reaction.reaction_type,
+    }
+
+    # Update the cached message since new reaction is added.
+    update_message_cache([message])
+
+    user_ids = event_recipient_ids_for_action_on_messages([message.id], message.is_channel_message)
+    send_event_on_commit(user_profile.realm, event, list(user_ids))
+
+
+def do_add_reaction(
+    user_profile: UserProfile,
+    message: Message,
+    emoji_name: str,
+    emoji_code: str,
+    reaction_type: str,
+) -> None:
+    """Should be called while holding a SELECT FOR UPDATE lock
+    (e.g. via access_message(..., lock_message=True)) on the
+    Message row, to prevent race conditions.
+    """
+
+    reaction = Reaction(
+        user_profile=user_profile,
+        message=message,
+        emoji_name=emoji_name,
+        emoji_code=emoji_code,
+        reaction_type=reaction_type,
+    )
+
+    reaction.save()
+
+    # Determine and set the visibility_policy depending on 'automatically_follow_topics_policy'
+    # and 'automatically_unmute_topics_in_muted_streams_policy'.
+    if set_visibility_policy_possible(
+        user_profile, message
+    ) and UserProfile.AUTOMATICALLY_CHANGE_VISIBILITY_POLICY_ON_PARTICIPATION in [
+        user_profile.automatically_follow_topics_policy,
+        user_profile.automatically_unmute_topics_in_muted_streams_policy,
+    ]:
+        stream_id = message.recipient.type_id
+        (stream, sub) = access_stream_by_id(user_profile, stream_id)
+        assert stream is not None
+        if sub:
+            new_visibility_policy = visibility_policy_for_participation(user_profile, sub.is_muted)
+            if new_visibility_policy and should_change_visibility_policy(
+                new_visibility_policy,
+                user_profile,
+                stream_id,
+                topic_name=message.topic_name(),
+            ):
+                do_set_user_topic_visibility_policy(
+                    user_profile=user_profile,
+                    stream=stream,
+                    topic_name=message.topic_name(),
+                    visibility_policy=new_visibility_policy,
+                )
+
+    notify_reaction_update(user_profile, message, reaction, "add")
+
+
+def check_add_reaction(
+    user_profile: UserProfile,
+    message_id: int,
+    emoji_name: str,
+    emoji_code: str | None,
+    reaction_type: str | None,
+) -> None:
+    message, user_message = access_message_and_usermessage(
+        user_profile, message_id, lock_message=True, is_modifying_message=True
+    )
+
+    if emoji_code is None or reaction_type is None:
+        emoji_data = get_emoji_data(message.realm_id, emoji_name)
+
+        if emoji_code is None:
+            # The emoji_code argument is only required for rare corner
+            # cases discussed in the long block comment below.  For simple
+            # API clients, we allow specifying just the name, and just
+            # look up the code using the current name->code mapping.
+            emoji_code = emoji_data.emoji_code
+
+        if reaction_type is None:
+            reaction_type = emoji_data.reaction_type
+
+    if Reaction.objects.filter(
+        user_profile=user_profile,
+        message=message,
+        emoji_code=emoji_code,
+        reaction_type=reaction_type,
+    ).exists():
+        raise ReactionExistsError
+
+    query = Reaction.objects.filter(
+        message=message, emoji_code=emoji_code, reaction_type=reaction_type
+    )
+    if query.exists():
+        # If another user has already reacted to this message with
+        # same emoji code, we treat the new reaction as a vote for the
+        # existing reaction.  So the emoji name used by that earlier
+        # reaction takes precedence over whatever was passed in this
+        # request.  This is necessary to avoid a message having 2
+        # "different" emoji reactions with the same emoji code (and
+        # thus same image) on the same message, which looks ugly.
+        #
+        # In this "voting for an existing reaction" case, we shouldn't
+        # check whether the emoji code and emoji name match, since
+        # it's possible that the (emoji_type, emoji_name, emoji_code)
+        # triple for this existing reaction may not pass validation
+        # now (e.g. because it is for a realm emoji that has been
+        # since deactivated).  We still want to allow users to add a
+        # vote any old reaction they see in the UI even if that is a
+        # deactivated custom emoji, so we just use the emoji name from
+        # the existing reaction with no further validation.
+        reaction = query.first()
+        assert reaction is not None
+        emoji_name = reaction.emoji_name
+    else:
+        # Otherwise, use the name provided in this request, but verify
+        # it is valid in the user's realm (e.g. not a deactivated
+        # realm emoji).
+        check_emoji_request(user_profile.realm, emoji_name, emoji_code, reaction_type)
+
+    if user_message is None:
+        # See called function for more context.
+        create_historical_user_messages(user_id=user_profile.id, message_ids=[message.id])
+
+    do_add_reaction(user_profile, message, emoji_name, emoji_code, reaction_type)
+
+
+def do_remove_reaction(
+    user_profile: UserProfile, message: Message, emoji_code: str, reaction_type: str
+) -> None:
+    """Should be called while holding a SELECT FOR UPDATE lock
+    (e.g. via access_message(..., lock_message=True)) on the
+    Message row, to prevent race conditions.
+    """
+    reaction = Reaction.objects.filter(
+        user_profile=user_profile,
+        message=message,
+        emoji_code=emoji_code,
+        reaction_type=reaction_type,
+    ).get()
+    reaction.delete()
+
+    notify_reaction_update(user_profile, message, reaction, "remove")