model: Use the sort_unread_topics method to sort unread topics.

This commit introduces the sort_unread_topics function to sort
according to stream names instead of stream id. This also replaces
the use of bisect and is removed.

zulipterminal/model.py

@@ -2,7 +2,6 @@
 Defines the `Model`, fetching and storing data retrieved from the Zulip server
 """
 
-import bisect
 import itertools
 import json
 import time
@@ -65,6 +64,7 @@
     StreamData,
     TidiedUserInfo,
     UserStatus,
+    sort_unread_topics,
     asynch,
     canonicalize_color,
     classify_unread_counts,
@@ -911,7 +911,10 @@ def next_unread_topic_from_message_id(
                 self.stream_id_from_name(self.narrow[0][1]),
                 self.narrow[1][1],
             )
-        unread_topics = sorted(self.unread_counts["unread_topics"].keys())
+        unread_topics = sort_unread_topics(
+            self.unread_counts["unread_topics"],
+            self.pinned_streams + self.unpinned_streams,
+        )
         next_topic = False
         stream_start: Optional[Tuple[int, str]] = None
         if current_topic is None:
@@ -921,7 +924,10 @@ def next_unread_topic_from_message_id(
             # current_topic is not in unread_topics, and the next unmuted topic
             # is to be returned. This does not modify the original unread topics
             # data, and is just used to compute the next unmuted topic to be returned.
-            bisect.insort(unread_topics, current_topic)
+            unread_topics = sort_unread_topics(
+                {**self.unread_counts["unread_topics"], current_topic: 0},
+                self.pinned_streams + self.unpinned_streams,
+            )
         # loop over unread_topics list twice for the case that last_unread_topic was
         # the last valid unread_topic in unread_topics list.
         for unread_topic in unread_topics * 2: