server:Implement the START_GAME event handler in the engine

This commit adds the START_GAME event handler in the engine.The event
handler can be found in event folder.This event handler starts the game
and distributes the cards among players

fixes #148

backend/src/types.ts

@@ -55,6 +55,7 @@ export enum GameEventTypes {
     LEAVE_GAME = 'LEAVE_GAME',
     ANNOUNCE_UNO = 'ANNOUNCE_UNO',
     STATE_SYNC = 'STATE_SYNC',
+    START_GAME = 'START_GAME',
 }
 export type GameEvent =
     | {
@@ -92,6 +93,11 @@ export type GameEvent =
               currentTurn: number;
               lastThrownCard: string;
           };
+      }
+    | {
+          type: GameEventTypes.START_GAME;
+          playerId: string;
+          data?: null;
       };
 
 export enum ChatEventTypes {

backend/src/uno-game-engine/events/startGame.ts

@@ -0,0 +1,17 @@
+import assert from 'assert';
+import { GameEngine } from '../engine';
+import { EventResult, GameEvent } from '../../types';
+
+export function startGame(game: GameEngine, event: GameEvent): EventResult {
+    assert(event.type === 'START_GAME', 'Invalid event type');
+    if (event.playerId === game.players[0].id) {
+        game.status = 'STARTED';
+        game.allotCards();
+        return { type: 'SUCCESS', message: 'Game started successfully' };
+    } else {
+        return {
+            type: 'ERROR',
+            message: 'Only the Host can start the game',
+        };
+    }
+}

backend/src/uno-game-engine/gameEvents.ts

@@ -6,6 +6,7 @@ import { announceUNO } from './events/announceUno';
 import { drawCard } from './events/drawCard';
 import { joinGame } from './events/joinGame';
 import { leaveGame } from './events/leaveGame';
+import { startGame } from './events/startGame';
 import { throwCard } from './events/throwCard';
 
 type GameEventHandler = (game: GameEngine, event: GameEvent) => EventResult;
@@ -32,3 +33,4 @@ registerEventHandler(GameEventTypes.LEAVE_GAME, leaveGame);
 registerEventHandler(GameEventTypes.DRAW_CARD, drawCard);
 registerEventHandler(GameEventTypes.THROW_CARD, throwCard);
 registerEventHandler(GameEventTypes.ANNOUNCE_UNO, announceUNO);
+registerEventHandler(GameEventTypes.START_GAME, startGame);