model/api_types: Create method in model to handle stream unsubscription.

This commit adds a function named "_unsubscribe_from_streams" to
model.py. This function updates subscription data by removing
unsubscribed streams from class variables - pinned_streams,
unpinned_streams, muted_streams, and visual_notified_streams.

Co-authored-by: Abhirup Pal <abhiruppalmethodist@gmail.com>
Co-authored-by: Vishwesh Pillai <vishwesh103@gmail.com>

Author: theViz343

zulipterminal/api_types.py

@@ -411,6 +411,11 @@ class RealmUserEvent(TypedDict):
 # (also -peer_add and -peer_remove; FIXME: -add & -remove are not yet supported)
 
 
+class RemovedSubscription(TypedDict):
+    stream_id: int
+    name: str
+
+
 # Update of personal properties
 class SubscriptionUpdateEvent(SubscriptionSettingChange):
     type: Literal["subscription"]

zulipterminal/model.py

@@ -43,6 +43,7 @@
     PrivateMessageUpdateRequest,
     RealmEmojiData,
     RealmUser,
+    RemovedSubscription,
     StreamComposition,
     StreamMessageUpdateRequest,
     Subscription,
@@ -1205,6 +1206,28 @@ def make_reduced_stream_data(stream: Subscription) -> StreamData:
             new_visual_notified_streams
         )
 
+    def _unsubscribe_from_streams(
+        self, subscriptions: List[RemovedSubscription]
+    ) -> None:
+        for subscription in subscriptions:
+            stream_id = subscription["stream_id"]
+            self.pinned_streams[:] = [
+                stream
+                for stream in self.pinned_streams
+                if stream.get("id") != stream_id
+            ]
+            self.unpinned_streams[:] = [
+                stream
+                for stream in self.unpinned_streams
+                if stream.get("id") != stream_id
+            ]
+            if stream_id in self.muted_streams:
+                self.muted_streams.remove(stream_id)
+            if stream_id in self.visual_notified_streams:
+                self.visual_notified_streams.remove(stream_id)
+            if stream_id in self.stream_dict:
+                del self.stream_dict[stream_id]
+
     def _group_info_from_realm_user_groups(
         self, groups: List[Dict[str, Any]]
     ) -> List[str]: