const SIZE = 4;
const NEW_VALUES = [2, 4];
const TILE_SIZE = 100;
const GRID_PADDING = 10;
const { createCanvas } = require('canvas');

class Game2048 {
  constructor() {
    this.board = Array.from({ length: SIZE }, () => Array(SIZE).fill(0));
    this.addNewTile();
    this.addNewTile();
  }

  addNewTile() {
    const emptyCells = [];
    for (let r = 0; r < SIZE; r++) {
      for (let c = 0; c < SIZE; c++) {
        if (this.board[r][c] === 0) {
          emptyCells.push([r, c]);
        }
      }
    }
    if (emptyCells.length > 0) {
      const [row, col] = emptyCells[Math.floor(Math.random() * emptyCells.length)];
      this.board[row][col] = NEW_VALUES[Math.floor(Math.random() * NEW_VALUES.length)];
    }
  }

  moveLeft() {
    let moved = false;
    for (let row = 0; row < SIZE; row++) {
      let newRow = this.board[row].filter(val => val !== 0);
      for (let col = 0; col < newRow.length - 1; col++) {
        if (newRow[col] === newRow[col + 1]) {
          newRow[col] *= 2;
          newRow.splice(col + 1, 1);
          moved = true;
        }
      }
      while (newRow.length < SIZE) {
        newRow.push(0);
      }
      if (this.board[row].toString() !== newRow.toString()) {
        moved = true;
        this.board[row] = newRow;
      }
    }
    return moved;
  }

  rotateBoard() {
    const newBoard = Array.from({ length: SIZE }, () => Array(SIZE).fill(0));
    for (let row = 0; row < SIZE; row++) {
      for (let col = 0; col < SIZE; col++) {
        newBoard[col][SIZE - row - 1] = this.board[row][col];
      }
    }
    this.board = newBoard;
  }

  move(direction) {
    let moved = false;
    for (let i = 0; i < direction; i++) {
      this.rotateBoard();
    }
    moved = this.moveLeft();
    for (let i = direction; i < 4; i++) {
      this.rotateBoard();
    }
    if (moved) {
      this.addNewTile();
    }
    return moved;
  }

  isGameOver() {
    for (let row = 0; row < SIZE; row++) {
      for (let col = 0; col < SIZE; col++) {
        if (this.board[row][col] === 0) return false;
        if (col < SIZE - 1 && this.board[row][col] === this.board[row][col + 1]) return false;
        if (row < SIZE - 1 && this.board[row][col] === this.board[row + 1][col]) return false;
      }
    }
    return true;
  }

  drawBoard() {
    const canvas = createCanvas(SIZE * (TILE_SIZE + GRID_PADDING) + GRID_PADDING, SIZE * (TILE_SIZE + GRID_PADDING) + GRID_PADDING);
    const ctx = canvas.getContext('2d');

    ctx.fillStyle = '#bbada0';
    ctx.fillRect(0, 0, canvas.width, canvas.height);

    for (let row = 0; row < SIZE; row++) {
      for (let col = 0; col < SIZE; col++) {
        const value = this.board[row][col];
        const x = col * (TILE_SIZE + GRID_PADDING) + GRID_PADDING;
        const y = row * (TILE_SIZE + GRID_PADDING) + GRID_PADDING;
        ctx.fillStyle = value ? '#eee4da' : '#cdc1b4';
        ctx.fillRect(x, y, TILE_SIZE, TILE_SIZE);
        if (value) {
          ctx.font = 'bold 40px Arial';
          ctx.fillStyle = '#776e65';
          ctx.textAlign = 'center';
          ctx.textBaseline = 'middle';
          ctx.fillText(value, x + TILE_SIZE / 2, y + TILE_SIZE / 2);
        }
      }
    }

    return canvas.toBuffer();
  }
}

module.exports = Game2048;