Refactors logic for chat user list and scroll

- Refactors server side code to use instance variable instead of
background thread to generate a list of connected users
- Send this user list anytime any change is made to the list. It can
be: join, update username, disconnect
- In js, render the entire user list everytime it is received.
- Scroll to the bottom of the chat, everytime the current user
sends a message
- Else, if already at the bottom of the chat, scroll to the bottom
after appending incoming status or chat message. But if the user
is scrolled up in the chat window, then do not scroll to the bottom
- When refreshed or close tab is clicked, default browser warning is
shown.
- On receiving disconnect, the browser removes user from room.
- If refreshed, it is shown as if the user left and joined again.

1 files changed, 52 insertions, 48 deletions

diff --git a/onionshare/web/chat_mode.py b/onionshare/web/chat_mode.py
index 05014a22..ed946a14 100644
--- a/onionshare/web/chat_mode.py
+++ b/onionshare/web/chat_mode.py
@@ -1,4 +1,12 @@
-from flask import Request, request, render_template, make_response, flash, redirect, session
+from flask import (
+    Request,
+    request,
+    render_template,
+    make_response,
+    flash,
+    redirect,
+    session,
+)
 from werkzeug.utils import secure_filename
 from flask_socketio import emit, join_room, leave_room
 
@@ -14,8 +22,8 @@ class ChatModeWeb:
 
         self.web = web
 
-        self.can_upload = True
-        self.uploads_in_progress = []
+        # This tracks users in the room
+        self.connected_users = []
 
         # This tracks the history id
         self.cur_history_id = 0
@@ -31,11 +39,14 @@ class ChatModeWeb:
         def index():
             history_id = self.cur_history_id
             self.cur_history_id += 1
-            session["name"] = self.common.build_username()
+            session["name"] = (
+                session.get("name")
+                if session.get("name")
+                else self.common.build_username()
+            )
             session["room"] = self.web.settings.default_settings["chat"]["room"]
             self.web.add_request(
-                request.path,
-                {"id": history_id, "status_code": 200},
+                request.path, {"id": history_id, "status_code": 200},
             )
 
             self.web.add_request(self.web.REQUEST_LOAD, request.path)
@@ -43,7 +54,7 @@ class ChatModeWeb:
                 render_template(
                     "chat.html",
                     static_url_path=self.web.static_url_path,
-                    username=session.get("name")
+                    username=session.get("name"),
                 )
             )
             return self.web.add_security_headers(r)
@@ -52,16 +63,16 @@ class ChatModeWeb:
         def joined(message):
             """Sent by clients when they enter a room.
             A status message is broadcast to all people in the room."""
-            session["worker"] = UserListWorker(self.web.socketio)
-            session["thread"] = self.web.socketio.start_background_task(
-                session["worker"].background_thread, session["name"]
-            )
+            self.connected_users.append(session.get("name"))
             join_room(session.get("room"))
             emit(
                 "status",
-                {"msg": session.get("name") + " has entered the room.",
-                "user": session.get("name")},
-                room=session.get("room")
+                {
+                    "msg": "{} has joined.".format(session.get("name")),
+                    "connected_users": self.connected_users,
+                    "user": session.get("name"),
+                },
+                room=session.get("room"),
             )
 
         @self.web.socketio.on("text", namespace="/chat")
@@ -70,8 +81,8 @@ class ChatModeWeb:
             The message is sent to all people in the room."""
             emit(
                 "message",
-                {"msg": session.get("name") + ": " + message["msg"]},
-                room=session.get("room")
+                {"msg": "{}: {}".format(session.get("name"), message["msg"])},
+                room=session.get("room"),
             )
 
         @self.web.socketio.on("update_username", namespace="/chat")
@@ -80,40 +91,33 @@ class ChatModeWeb:
             The message is sent to all people in the room."""
             current_name = session.get("name")
             session["name"] = message["username"]
-            session["worker"].stop_thread()
-            session["worker"] = UserListWorker(self.web.socketio)
-            session['thread'] = self.web.socketio.start_background_task(
-                session["worker"].background_thread, session['name']
-            )
+            self.connected_users[
+                self.connected_users.index(current_name)
+            ] = session.get("name")
             emit(
                 "status",
-                {"msg": current_name + " has updated their username to: " + session.get("name"),
-                "old_name": current_name,
-                "new_name": session.get("name")
+                {
+                    "msg": "{} has updated their username to: {}".format(
+                        current_name, session.get("name")
+                    ),
+                    "connected_users": self.connected_users,
+                    "old_name": current_name,
+                    "new_name": session.get("name"),
                 },
-                room=session.get("room")
+                room=session.get("room"),
             )
 
-
-
-class UserListWorker(object):
-
-    def __init__(self, socketio):
-        """
-        assign socketio object to emit
-        """
-        self.socketio = socketio
-        self.switch = True
-
-    def background_thread(self, name):
-        count = 0
-        while self.switch:
-            self.socketio.sleep(5)
-            count += 1
-            self.socketio.emit('update_list',
-                {'name': name, 'count': count},
-                namespace="/chat",
-                broadcast=True)
-
-    def stop_thread(self):
-        self.switch = False
+        @self.web.socketio.on("disconnect", namespace="/chat")
+        def disconnect():
+            """Sent by clients when they disconnect from a room.
+            A status message is broadcast to all people in the room."""
+            self.connected_users.remove(session.get("name"))
+            leave_room(session.get("room"))
+            emit(
+                "status",
+                {
+                    "msg": "{} has left the room.".format(session.get("name")),
+                    "connected_users": self.connected_users,
+                },
+                room=session.get("room"),
+            )