implement ai opponent, random strategy

src/front/game/ai/solver.ts

@@ -0,0 +1,22 @@
+import { BoardPosition } from '../board/abstract-board';
+import { Board } from '../board/board';
+import { GamePiece } from '../piece/interface';
+
+export class AiSolver {
+    constructor(private board: Board) {}
+
+    solveNextTurn(_piece: GamePiece): { x: BoardPosition; y: BoardPosition } {
+        // eslint-disable-next-line no-constant-condition
+        while (true) {
+            const randomX: BoardPosition = Math.floor(
+                Math.random() * 4,
+            ) as never;
+            const randomY: BoardPosition = Math.floor(
+                Math.random() * 4,
+            ) as never;
+            if (this.board.canStack(randomX, randomY)) {
+                return { x: randomX, y: randomY };
+            }
+        }
+    }
+}

src/front/game/index.ts

@@ -11,6 +11,7 @@ import { GamePiece } from './piece/interface';
 import { WinChecker } from './win';
 import { showMessageBar } from './message-bar';
 import { Vector } from '../engine/math/vector';
+import { AiSolver } from './ai/solver';
 
 type Player = 'player1' | 'player2';
 
@@ -23,6 +24,7 @@ export class Game {
     private pointer: Pointer;
     private boardPosition: { x: BoardPosition; y: BoardPosition } = null;
     private winChecker: WinChecker;
+    private ai: AiSolver;
 
     constructor(private engine: Engine) {}
 
@@ -40,6 +42,7 @@ export class Game {
         this.orbitIo.setTarget(this.board.getCenter());
         this.pointer.onClick(() => this.onClick());
         this.winChecker = new WinChecker(this.board);
+        this.ai = new AiSolver(this.board);
     }
 
     tick(_deltaTime: number) {
@@ -112,11 +115,24 @@ export class Game {
 
         if (this.currentPlayer === 'player1') {
             this.currentPlayer = 'player2';
+            this.playAsAi();
         } else {
             this.currentPlayer = 'player1';
         }
     }
 
+    private playAsAi(): void {
+        const position = this.ai.solveNextTurn(
+            new Nought({ x: 0, y: 0, z: 0 }),
+        );
+        const piece = this.buildCurrentPlayerPiece({
+            ...position,
+            z: this.board.getStackHeight(position),
+        });
+        this.board.stack(position, piece);
+        this.advanceTurn();
+    }
+
     private reset() {
         this.currentPlayer = 'player1';