client & server: added error handling for lobby connection issues

components/client_interface.gd

@@ -123,3 +123,7 @@ func _on_web_client_tcp_connection_status_changed(new_status: WebClientTCP.Conne
 			lobby_code_input.editable = false
 			chat_message_input.editable = true
 			send_chat_message_button.disabled = false
+
+
+func _on_web_client_tcp_received_connection_message(message: String) -> void:
+	_write_line(message)

components/web_client_tcp.gd

@@ -29,6 +29,7 @@ signal disconnected_from_lobby()
 signal client_joined_lobby(client_name: String, currently_connected_client_names: Array[String])
 signal client_left_lobby(client_name: String, currently_connected_client_names: Array[String])
 
+signal received_connection_message(message: String)
 signal received_chat_message(client_name: String, message: String)
 
 signal connection_status_changed(new_status: ConnectionStatus)
@@ -94,11 +95,8 @@ func _handle_response(response: String) -> void:
 				_client_id = data["client_id"]
 				connected_to_lobby.emit.call_deferred(_lobby_id)
 				connection_status_changed.emit.call_deferred(ConnectionStatus.JOINED)
-		"join_lobby":
+		"join_lobby_response":
-			if data["status"] == "ok":
+			_handle_join(data)
-				_client_id = data["client_id"]
-				connected_to_lobby.emit.call_deferred(_lobby_id)
-				connection_status_changed.emit.call_deferred(ConnectionStatus.JOINED)
 		"client_joined_lobby":
 			_currently_connected_client_names.assign(data["connected_client_names"])
 			client_joined_lobby.emit.call_deferred(data["new_client_name"], _currently_connected_client_names)
@@ -115,6 +113,19 @@ func _handle_response(response: String) -> void:
 		"receive_chat_message":
 			received_chat_message.emit.call_deferred(data["client_name"], data["message"])
 
+func _handle_join(data) -> void:
+	match data["status"]:
+		"lobby_not_found":
+			received_connection_message.emit.call_deferred("Could not join; lobby does not exist")
+			connection_status_changed.emit.call_deferred(ConnectionStatus.LOBBYLESS)
+		"lobby_full":
+			received_connection_message.emit.call_deferred("Could not join; lobby is full")
+			connection_status_changed.emit.call_deferred(ConnectionStatus.LOBBYLESS)
+		"ok":
+			_client_id = data["client_id"]
+			connected_to_lobby.emit.call_deferred(_lobby_id)
+			connection_status_changed.emit.call_deferred(ConnectionStatus.JOINED)
+
 func  _exit_tree() -> void:
 	disconnect_from_server()
 
@@ -138,6 +149,7 @@ func join_lobby(lobby_id: String, client_name: String) -> void:
 	_client_name = client_name
 	
 	_send_message(TCPMessages.join_lobby(_lobby_id, client_name))
+	connection_status_changed.emit.call_deferred(ConnectionStatus.ATTEMPTING_JOIN)
 
 func leave_lobby() -> void:
 	_send_message(TCPMessages.leave_lobby(_lobby_id, _client_id))

game.tscn

@@ -153,6 +153,7 @@ text = "Start Game!"
 [connection signal="disconnected_from_lobby" from="WebClientTCP" to="HBoxContainer/ClientInterface" method="_on_web_client_tcp_disconnected_from_lobby"]
 [connection signal="disconnected_from_server" from="WebClientTCP" to="HBoxContainer/ClientInterface" method="_on_web_client_tcp_disconnected_from_server"]
 [connection signal="received_chat_message" from="WebClientTCP" to="HBoxContainer/ClientInterface" method="_on_web_client_tcp_received_chat_message"]
+[connection signal="received_connection_message" from="WebClientTCP" to="HBoxContainer/ClientInterface" method="_on_web_client_tcp_received_connection_message"]
 [connection signal="pressed" from="HBoxContainer/ClientInterface/MarginContainer/VBoxContainer/ServerInputs/ConnectButton" to="HBoxContainer/ClientInterface" method="_on_connect_button_pressed"]
 [connection signal="pressed" from="HBoxContainer/ClientInterface/MarginContainer/VBoxContainer/ServerInputs/CreateLobbyButton" to="HBoxContainer/ClientInterface" method="_on_create_lobby_button_pressed"]
 [connection signal="pressed" from="HBoxContainer/ClientInterface/MarginContainer/VBoxContainer/ServerInputs/CreateLobbyButton" to="HBoxContainer/GameUI" method="_on_create_lobby_button_pressed"]

server_tcp.py

@@ -6,6 +6,8 @@ import ssl
 import asyncio
 from websockets.asyncio.server import serve
 
+MAX_LOBBY_CLIENT_COUNT = 6
+
 # Generates a 6-character code from the letters A-Z
 def generate_code() -> str:
     result = ""
@@ -42,7 +44,15 @@ class LobbyManager:
         print(f"Created lobby {lobby_id}")
 
     # Joins a client to an existing lobby
-    async def join_lobby(self, lobby_id, client_id, client_name, websocket) -> None:
+    async def join_lobby(self, lobby_id, client_id, client_name, websocket) -> str:
+        if not self.lobby_id_exists(lobby_id):
+            # Cannot join; lobby does not exist
+            return "lobby_not_found"  
+
+        if self.get_lobby_player_count(lobby_id) >= MAX_LOBBY_CLIENT_COUNT:
+            # Lobby full! Cannot join
+            return "lobby_full"  
+        
         # Add client to lobby
         self.active_lobbies[lobby_id].connected_clients[client_id] = Client(
             client_id,
@@ -62,6 +72,8 @@ class LobbyManager:
             })
         )
 
+        return "ok"
+    
     # Removes a client from a lobby
     async def leave_lobby(self, lobby_id, client_id) -> None:
         try:
@@ -201,7 +213,9 @@ async def process_input(message: str, websocket) -> None:
             new_client_id,
         )
 
-        # Join requesting client to new lobby
+        # Join requesting client to new lobby.
+        # No error handling here, since lobby was just created, so it
+        # must exist and be empty
         await lobby_manager.join_lobby(
             new_lobby_id,
             new_client_id,
@@ -226,28 +240,51 @@ async def process_input(message: str, websocket) -> None:
     # Join client to existing lobby
     elif data_object["response"] == "join_lobby":
         lobby_id = data_object["lobby_id"]
-        new_client_id = lobby_manager.get_unique_client_id(lobby_id)
+        client_id = lobby_manager.get_unique_client_id(lobby_id)
+        client_name = data_object["client_name"]
 
         # Join client to lobby
-        await lobby_manager.join_lobby(
+        response = await lobby_manager.join_lobby(
             lobby_id,
-            new_client_id,
+            client_id,
-            data_object["client_name"],
+            client_name,
             websocket,
         )
 
-        # Send success confirmation
+        match response:
-        await lobby_manager.send_message(
+            case "lobby_not_found":
-            lobby_id,
+                await websocket.send(
-            new_client_id,
+                    json.dumps({
-            json.dumps({
+                        "response": "join_lobby_response",
-                "response": "join_lobby",
+                        "status": "lobby_not_found",
-                "status": "ok",
+                    })
-                "client_id": new_client_id,
+                )
-            }),
-        )
                 
-        print(f"Client {new_client_id} joined lobby {lobby_id}")
+                print(f"Client {client_name} could not connect; lobby {lobby_id} does not exist")
+            
+            case "lobby_full":
+                await websocket.send(
+                    json.dumps({
+                        "response": "join_lobby_response",
+                        "status": "lobby_full",
+                    })
+                )
+
+                print(f"Client {client_name} could not connect; lobby {lobby_id} is full")
+            
+            case "ok":
+                # Send success confirmation
+                await lobby_manager.send_message(
+                    lobby_id,
+                    client_id,
+                    json.dumps({
+                        "response": "join_lobby_response",
+                        "status": "ok",
+                        "client_id": client_id,
+                    }),
+                )
+
+                print(f"Client {client_id} joined lobby {lobby_id}")
 
     # Disconnect client from lobby
     elif data_object["response"] == "leave_lobby":