gameEvent: Implement Throw Card Event

Adds the throw card event handler.

Fixes #44

Signed-off-by: Sagnik Mandal <[email protected]>

ARCHITECTURE.md

@@ -26,11 +26,17 @@ format of the message is:
 
 ```json
 {
-	"type": "DRAW_CARD",
-	"player": "player1",
+	"type": "THROW_CARD",
+	"playerId": "1",
 	"data": {
-		"cardID": "red-5"
+		"card": {
+			"color": "red",
+			"value": "5",
+			"type": "number",
+			"id": "card-number-red-5"
+		}
 	}
+
 }
 ```
 Other possible values for `type` are `THROW_CARD`, `ANNOUNCE_UNO`, etc.

backend/eventRecipients.ts

@@ -36,4 +36,4 @@ export function scheduleSend(clientId: ClientId, event: AppEvent) {
 // eslint-disable-next-line @typescript-eslint/no-unused-vars
 export function doSendEvent(clientId: ClientId, event: AppEvent) {
     //todo: Send all the events in the queue to the client, only if the response object is available.
-}
+}

backend/src/types.d.ts

@@ -1,9 +1,9 @@
 // We declare those types which are used throughout the application here.
 // For types that are used only in one file, we can declare them in that file itself.
 
-type CardType = 'number' | 'special' | 'wild';
+type CardType = 'number' | 'special';
 
-type CardColor = 'red' | 'blue' | 'green' | 'yellow';
+type CardColor = 'red' | 'blue' | 'green' | 'yellow' | 'wild';
 
 type SpecialCardNames = 'skip' | 'reverse' | 'draw2' | 'draw4' | 'colchange';
 type CardNumbers = '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9';
@@ -46,5 +46,5 @@ type GameEvent =
       };
 
 // Represent all the events that can be sent to the client
-type AppEvent = GameEvent
+type AppEvent = GameEvent;
 //todo: Add more events

backend/uno-game-engine/engine.ts

@@ -47,11 +47,19 @@ export class GameEngine {
         this.currentPlayerIndex =
             (this.currentPlayerIndex + this.direction) % this.players.length;
     }
-    drawCardFromDeck(player: Player) {
+    drawCardFromDeck(player: Player, numCards = 1) {
         //todo: Handle the case when the deck is empty and we have to move the thrown cards back to the deck
-        this.players
-            .find((p: Player) => p.id === player.id)
-            .cards.push(this.cardDeck.pop());
+        // this.players
+        //     .find((p: Player) => p.id === player.id)
+        //     .cards.push(this.cardDeck.pop());
+        const currentPlayer = this.players.find((p) => p.id === player.id);
+        if (!currentPlayer) {
+            throw new Error('Player not found');
+        }
+
+        for (let i = 0; i < numCards; i++) {
+            currentPlayer.cards.push(this.cardDeck.pop());
+        }
     }
     dispatchEvent(event: GameEvent) {
         // handle different types of events based on event.type

backend/uno-game-engine/events/throwCard.ts

@@ -0,0 +1,84 @@
+import { registerEventHandler } from '../gameEvents';
+import { GameEngine } from '../engine';
+
+function findPlayer(game: GameEngine, playerId: string) {
+    return game.players.find((p) => p.id === playerId);
+}
+
+function findCard(player, cardId: string) {
+    return player.cards.find((c) => c.id === cardId);
+}
+
+export function throwCard(game: GameEngine, event: GameEvent): EventResult {
+    const { currentPlayerIndex, players } = game;
+    const currentPlayer = players[currentPlayerIndex];
+
+    // check if the player is the current player
+    if (currentPlayer.id !== event.playerId) {
+        return { type: 'ERROR', message: 'It is not your turn' };
+    }
+
+    // check if the card is present in the player's hand
+    const player = findPlayer(game, event.playerId);
+    if (!player) {
+        return { type: 'ERROR', message: 'Player not found' };
+    }
+    const card = findCard(player, event.data.card.id);
+    if (!card) {
+        return { type: 'ERROR', message: 'Card not found' };
+    }
+
+    // check if the card can be thrown
+    if (game.lastThrownCard && !canThrowCard(game.lastThrownCard, card)) {
+        return { type: 'ERROR', message: 'Cannot throw this card' };
+    }
+
+    player.cards = player.cards.filter((c) => c.id !== card.id);
+
+    game.thrownCards.push(card);
+    game.lastThrownCard = card;
+
+    game.nextPlayer();
+
+    // handle special cards
+    if (card.type === 'special') {
+        handleSpecialCard(game, card);
+    }
+
+    return { type: 'SUCCESS', message: 'Card thrown successfully' };
+}
+
+function canThrowCard(lastThrownCard: UNOCard, card: UNOCard): boolean {
+    return (
+        lastThrownCard.color === card.color ||
+        lastThrownCard.value === card.value ||
+        card.color === 'wild'
+    );
+}
+
+function handleSpecialCard(game: GameEngine, card: UNOCard) {
+    switch (card.value) {
+        case 'skip':
+            game.nextPlayer();
+            break;
+        case 'reverse':
+            game.direction *= -1;
+            break;
+        case 'draw2':
+            {
+                const nextPlayer = game.players[game.currentPlayerIndex];
+                game.drawCardFromDeck(nextPlayer, 2);
+            }
+            break;
+        case 'draw4':
+            {
+                const currentPlayer = game.players[game.currentPlayerIndex];
+                game.drawCardFromDeck(currentPlayer, 4);
+            }
+            break;
+        default:
+            break;
+    }
+}
+
+registerEventHandler('THROW_CARD', throwCard);