subscription: Refactor code for creating subscription dicts.

This commit refactors code to create subscription dicts so
that we can efficiently compute can_remove_subscribers_group
setting when we add support to set the setting to anonymous
groups.

zerver/lib/subscription_info.py

@@ -17,7 +17,7 @@ from zerver.lib.stream_subscription import (
 )
 from zerver.lib.stream_traffic import get_average_weekly_stream_traffic, get_streams_traffic
 from zerver.lib.streams import get_web_public_streams_queryset, subscribed_to_stream
-from zerver.lib.timestamp import datetime_to_timestamp, timestamp_to_datetime
+from zerver.lib.timestamp import datetime_to_timestamp
 from zerver.lib.types import (
     APIStreamDict,
     NeverSubscribedStreamDict,
@@ -112,55 +112,69 @@ def get_web_public_subs(realm: Realm) -> SubscriptionInfo:
 def build_unsubscribed_sub_from_stream_dict(
     user: UserProfile, sub_dict: RawSubscriptionDict, stream_dict: APIStreamDict
 ) -> SubscriptionStreamDict:
-    # This function is only called from `apply_event` code.
+    subscription_stream_dict = build_stream_dict_for_sub(user, sub_dict, stream_dict)
-    raw_stream_dict = RawStreamDict(
-        can_remove_subscribers_group_id=stream_dict["can_remove_subscribers_group"],
-        creator_id=stream_dict["creator_id"],
-        date_created=timestamp_to_datetime(stream_dict["date_created"]),
-        deactivated=stream_dict["is_archived"],
-        description=stream_dict["description"],
-        first_message_id=stream_dict["first_message_id"],
-        history_public_to_subscribers=stream_dict["history_public_to_subscribers"],
-        invite_only=stream_dict["invite_only"],
-        is_web_public=stream_dict["is_web_public"],
-        message_retention_days=stream_dict["message_retention_days"],
-        name=stream_dict["name"],
-        rendered_description=stream_dict["rendered_description"],
-        id=stream_dict["stream_id"],
-        stream_post_policy=stream_dict["stream_post_policy"],
-    )
-
-    # We pass recent_traffic as None and avoid extra database query since we
-    # already have the traffic data from stream_dict sent with creation event.
-    subscription_stream_dict = build_stream_dict_for_sub(
-        user, sub_dict, raw_stream_dict, recent_traffic=None
-    )
-    subscription_stream_dict["stream_weekly_traffic"] = stream_dict["stream_weekly_traffic"]
 
     return subscription_stream_dict
 
 
+def build_stream_api_dict(
+    raw_stream_dict: RawStreamDict, recent_traffic: dict[int, int] | None
+) -> APIStreamDict:
+    # Add a few computed fields not directly from the data models.
+    if recent_traffic is not None:
+        stream_weekly_traffic = get_average_weekly_stream_traffic(
+            raw_stream_dict["id"], raw_stream_dict["date_created"], recent_traffic
+        )
+    else:
+        stream_weekly_traffic = None
+
+    # Backwards-compatibility for clients that haven't been
+    # updated for the is_announcement_only -> stream_post_policy
+    # migration.
+    is_announcement_only = raw_stream_dict["stream_post_policy"] == Stream.STREAM_POST_POLICY_ADMINS
+
+    return APIStreamDict(
+        is_archived=raw_stream_dict["deactivated"],
+        can_remove_subscribers_group=raw_stream_dict["can_remove_subscribers_group_id"],
+        creator_id=raw_stream_dict["creator_id"],
+        date_created=datetime_to_timestamp(raw_stream_dict["date_created"]),
+        description=raw_stream_dict["description"],
+        first_message_id=raw_stream_dict["first_message_id"],
+        history_public_to_subscribers=raw_stream_dict["history_public_to_subscribers"],
+        invite_only=raw_stream_dict["invite_only"],
+        is_web_public=raw_stream_dict["is_web_public"],
+        message_retention_days=raw_stream_dict["message_retention_days"],
+        name=raw_stream_dict["name"],
+        rendered_description=raw_stream_dict["rendered_description"],
+        stream_id=raw_stream_dict["id"],
+        stream_post_policy=raw_stream_dict["stream_post_policy"],
+        stream_weekly_traffic=stream_weekly_traffic,
+        is_announcement_only=is_announcement_only,
+    )
+
+
 def build_stream_dict_for_sub(
     user: UserProfile,
     sub_dict: RawSubscriptionDict,
-    raw_stream_dict: RawStreamDict,
+    stream_dict: APIStreamDict,
-    recent_traffic: dict[int, int] | None,
 ) -> SubscriptionStreamDict:
     # Handle Stream.API_FIELDS
-    is_archived = raw_stream_dict["deactivated"]
+    is_archived = stream_dict["is_archived"]
-    can_remove_subscribers_group_id = raw_stream_dict["can_remove_subscribers_group_id"]
+    can_remove_subscribers_group = stream_dict["can_remove_subscribers_group"]
-    creator_id = raw_stream_dict["creator_id"]
+    creator_id = stream_dict["creator_id"]
-    date_created = datetime_to_timestamp(raw_stream_dict["date_created"])
+    date_created = stream_dict["date_created"]
-    description = raw_stream_dict["description"]
+    description = stream_dict["description"]
-    first_message_id = raw_stream_dict["first_message_id"]
+    first_message_id = stream_dict["first_message_id"]
-    history_public_to_subscribers = raw_stream_dict["history_public_to_subscribers"]
+    history_public_to_subscribers = stream_dict["history_public_to_subscribers"]
-    invite_only = raw_stream_dict["invite_only"]
+    invite_only = stream_dict["invite_only"]
-    is_web_public = raw_stream_dict["is_web_public"]
+    is_web_public = stream_dict["is_web_public"]
-    message_retention_days = raw_stream_dict["message_retention_days"]
+    message_retention_days = stream_dict["message_retention_days"]
-    name = raw_stream_dict["name"]
+    name = stream_dict["name"]
-    rendered_description = raw_stream_dict["rendered_description"]
+    rendered_description = stream_dict["rendered_description"]
-    stream_id = raw_stream_dict["id"]
+    stream_id = stream_dict["stream_id"]
-    stream_post_policy = raw_stream_dict["stream_post_policy"]
+    stream_post_policy = stream_dict["stream_post_policy"]
+    stream_weekly_traffic = stream_dict["stream_weekly_traffic"]
+    is_announcement_only = stream_dict["is_announcement_only"]
 
     # Handle Subscription.API_FIELDS.
     color = sub_dict["color"]
@@ -176,24 +190,11 @@ def build_stream_dict_for_sub(
     # updated for the in_home_view => is_muted API migration.
     in_home_view = not is_muted
 
-    # Backwards-compatibility for clients that haven't been
-    # updated for the is_announcement_only -> stream_post_policy
-    # migration.
-    is_announcement_only = raw_stream_dict["stream_post_policy"] == Stream.STREAM_POST_POLICY_ADMINS
-
-    # Add a few computed fields not directly from the data models.
-    if recent_traffic is not None:
-        stream_weekly_traffic = get_average_weekly_stream_traffic(
-            raw_stream_dict["id"], raw_stream_dict["date_created"], recent_traffic
-        )
-    else:
-        stream_weekly_traffic = None
-
     # Our caller may add a subscribers field.
     return SubscriptionStreamDict(
         is_archived=is_archived,
         audible_notifications=audible_notifications,
-        can_remove_subscribers_group=can_remove_subscribers_group_id,
+        can_remove_subscribers_group=can_remove_subscribers_group,
         color=color,
         creator_id=creator_id,
         date_created=date_created,
@@ -504,11 +505,11 @@ def gather_subscriptions_helper(
         stream_id = get_stream_id(sub_dict)
         sub_unsub_stream_ids.add(stream_id)
         raw_stream_dict = all_streams_map[stream_id]
+        stream_api_dict = build_stream_api_dict(raw_stream_dict, recent_traffic)
         stream_dict = build_stream_dict_for_sub(
             user=user_profile,
             sub_dict=sub_dict,
-            raw_stream_dict=raw_stream_dict,
+            stream_dict=stream_api_dict,
-            recent_traffic=recent_traffic,
         )
 
         # is_active is represented in this structure by which list we include it in.