chore: refactoring the implementation of singleton pattern for socketManager as explained in week 21.2

Author: Aadesh Kulkarni

apps/ws/src/Game.ts

@@ -6,7 +6,7 @@ import {
 } from './messages';
 import { db } from './db';
 import { randomUUID } from 'crypto';
-import { SocketManager, User } from './SocketManager';
+import { socketManager, User } from './SocketManager';
 
 type GAME_STATUS = 'IN_PROGRESS' | 'COMPLETED' | 'ABANDONED' | 'TIME_UP';
 type GAME_RESULT = "WHITE_WINS" | "BLACK_WINS" | "DRAW";
@@ -125,7 +125,7 @@ export class Game {
       return;
     }
 
-    SocketManager.getInstance().broadcast(
+    socketManager.broadcast(
       this.gameId,
       JSON.stringify({
         type: INIT_GAME,
@@ -257,7 +257,7 @@ export class Game {
 
     this.lastMoveTime = moveTimestamp;
 
-    SocketManager.getInstance().broadcast(
+    socketManager.broadcast(
       this.gameId,
       JSON.stringify({
         type: MOVE,
@@ -333,7 +333,7 @@ export class Game {
       }
     });
 
-    SocketManager.getInstance().broadcast(
+    socketManager.broadcast(
       this.gameId,
       JSON.stringify({
         type: GAME_ENDED,

apps/ws/src/GameManager.ts

@@ -14,7 +14,7 @@ import {
 } from './messages';
 import { Game, isPromoting } from './Game';
 import { db } from './db';
-import { SocketManager, User } from './SocketManager';
+import { socketManager, User } from './SocketManager';
 import { Square } from 'chess.js';
 import { GameStatus } from '@prisma/client';
 
@@ -41,7 +41,7 @@ export class GameManager {
       return;
     }
     this.users = this.users.filter((user) => user.socket !== socket);
-    SocketManager.getInstance().removeUser(user);
+    socketManager.removeUser(user);
   }
 
   removeGame(gameId: string) {
@@ -59,7 +59,7 @@ export class GameManager {
             return;
           }
           if (user.userId === game.player1UserId) {
-            SocketManager.getInstance().broadcast(
+            socketManager.broadcast(
               game.gameId,
               JSON.stringify({
                 type: GAME_ALERT,
@@ -70,15 +70,15 @@ export class GameManager {
             );
             return;
           }
-          SocketManager.getInstance().addUser(user, game.gameId);
+          socketManager.addUser(user, game.gameId);
           await game?.updateSecondPlayer(user.userId);
           this.pendingGameId = null;
         } else {
           const game = new Game(user.userId, null);
           this.games.push(game);
           this.pendingGameId = game.gameId;
-          SocketManager.getInstance().addUser(user, game.gameId);
-          SocketManager.getInstance().broadcast(
+          socketManager.addUser(user, game.gameId);
+          socketManager.broadcast(
             game.gameId,
             JSON.stringify({
               type: GAME_ADDED,
@@ -182,7 +182,7 @@ export class GameManager {
           }),
         );
 
-        SocketManager.getInstance().addUser(user, gameId);
+        socketManager.addUser(user, gameId);
       }
     });
   }

apps/ws/src/SocketManager.ts

@@ -13,7 +13,7 @@ export class User {
   }
 }
 
-export class SocketManager {
+class SocketManager {
   private static instance: SocketManager;
   private interestedSockets: Map<string, User[]>;
   private userRoomMappping: Map<string, string>;
@@ -24,12 +24,12 @@ export class SocketManager {
   }
 
   static getInstance() {
-    if (this.instance) {
-      return this.instance;
+    if (SocketManager.instance) {
+      return SocketManager.instance;
     }
 
-    this.instance = new SocketManager();
-    return this.instance;
+    SocketManager.instance = new SocketManager();
+    return SocketManager.instance;
   }
 
   addUser(user: User, roomId: string) {
@@ -72,3 +72,5 @@ export class SocketManager {
     this.userRoomMappping.delete(user.userId);
   }
 }
+
+export const socketManager = SocketManager.getInstance()