ref: fix types for mentions serializer (#83424)

-1 mixins!

<!-- Describe your PR here. -->

Author: asottile-sentry

Diff for: pyproject.toml

@@ -163,7 +163,6 @@ module = [
     "sentry.api.serializers.models.project",
     "sentry.api.serializers.models.role",
     "sentry.api.serializers.models.rule",
-    "sentry.api.serializers.rest_framework.mentions",
     "sentry.auth.helper",
     "sentry.auth.provider",
     "sentry.auth.system",
@@ -340,6 +339,7 @@ module = [
     "sentry.api.helpers.group_index.update",
     "sentry.api.helpers.source_map_helper",
     "sentry.api.serializers.models.organization_member.*",
+    "sentry.api.serializers.rest_framework.group_notes",
     "sentry.audit_log.services.*",
     "sentry.auth.services.*",
     "sentry.auth.view",

Diff for: src/sentry/api/serializers/rest_framework/__init__.py

@@ -5,7 +5,6 @@
 from .group_notes import *  # noqa: F401,F403
 from .json import *  # noqa: F401,F403
 from .list import *  # noqa: F401,F403
-from .mentions import *  # noqa: F401,F403
 from .origin import *  # noqa: F401,F403
 from .project import *  # noqa: F401,F403
 from .project_key import *  # noqa: F401,F403

Diff for: src/sentry/api/serializers/rest_framework/group_notes.py

@@ -1,11 +1,64 @@
+from __future__ import annotations
+
+from typing import TypedDict
+
 from rest_framework import serializers
 from rest_framework.serializers import ListField
 
 from sentry.api.fields.actor import ActorField
-from sentry.api.serializers.rest_framework.mentions import MentionsMixin
+from sentry.models.organizationmember import OrganizationMember
+from sentry.models.team import Team
+from sentry.types.actor import Actor
+
+
+class _SeparatedActors(TypedDict):
+    users: list[Actor]
+    teams: list[Actor]
+
+
+def separate_actors(actors: list[Actor]) -> _SeparatedActors:
+    users = [actor for actor in actors if actor.is_user]
+    teams = [actor for actor in actors if actor.is_team]
+
+    return {"users": users, "teams": teams}
 
 
-class NoteSerializer(serializers.Serializer, MentionsMixin):
+class NoteSerializer(serializers.Serializer[None]):
     text = serializers.CharField()
     mentions = ListField(child=ActorField(), required=False)
     external_id = serializers.CharField(allow_null=True, required=False)
+
+    def validate_mentions(self, mentions: list[Actor]) -> list[Actor]:
+        if mentions and "projects" in self.context:
+
+            separated_actors = separate_actors(mentions)
+            # Validate that all mentioned users exist and are on the project.
+            users = separated_actors["users"]
+
+            mentioned_user_ids = {user.id for user in users}
+
+            projects = self.context["projects"]
+            user_ids = list(
+                OrganizationMember.objects.filter(
+                    teams__projectteam__project__in=[p.id for p in projects],
+                    user_id__in=mentioned_user_ids,
+                ).values_list("user_id", flat=True)
+            )
+
+            if len(mentioned_user_ids) > len(user_ids):
+                raise serializers.ValidationError("Cannot mention a non team member")
+
+            # Validate that all mentioned teams exist and are on the project.
+            teams = separated_actors["teams"]
+            mentioned_team_ids = {team.id for team in teams}
+            if (
+                len(mentioned_team_ids)
+                > Team.objects.filter(
+                    id__in=mentioned_team_ids, projectteam__project__in=projects
+                ).count()
+            ):
+                raise serializers.ValidationError(
+                    "Mentioned team not found or not associated with project"
+                )
+
+        return mentions