let canvas = document.getElementById('snake');
let context = canvas.getContext('2d');
let box = 32;
let snake = [];
snake[0] = {
  x: 8 * box,
  y: 8 * box,
};
let direction = 'right';
let food = {
  x: Math.floor(Math.random() * 15 + 1) * box,
  y: Math.floor(Math.random() * 15 + 1) * box,
};

const foodImg = new Image();
foodImg.src =
  'https://png.pngtree.com/png-vector/20220709/ourmid/pngtree-vector-clip-art-and-illustration-of-red-apple-png-image_5827049.png';

function drawScore() {
  context.fillStyle = '#fff';
  context.font = '2rem Arial';
  context.fillText(snake.length, 2 * box, 1.6 * box);
}

let score = 0; //contador de peças da cobrinha

function criarBG() {
  context.fillStyle = 'black';
  context.fillRect(0, 0, 16 * box, 16 * box);
}

function criarCobrinha() {
  for (i = 0; i < snake.length; i++) {
    context.fillStyle = '#FFF';
    context.fillRect(snake[i].x, snake[i].y, box, box);
  }
}

function drawFood() {
  context.drawImage(foodImg, food.x, food.y, box, box);
}

document.addEventListener('keydown', update);

function update(event) {
  if (event.keyCode == 37 && direction != 'right') direction = 'left';
  if (event.keyCode == 38 && direction != 'down') direction = 'up';
  if (event.keyCode == 39 && direction != 'left') direction = 'right';
  if (event.keyCode == 40 && direction != 'up') direction = 'down';
}

function iniciarJogo() {
  if (snake[0].x > 15 * box && direction == 'right') snake[0].x = 0;
  if (snake[0].x < 0 && direction == 'left') snake[0].x = 16 * box;
  if (snake[0].y > 15 * box && direction == 'down') snake[0].y = 0;
  if (snake[0].y < 0 && direction == 'up') snake[0].y = 16 * box;

  for (i = 1; i < snake.length; i++) {
    if (snake[0].x == snake[i].x && snake[0].y == snake[i].y) {
      clearInterval(jogo);
      alert('Game Over :(');
    }
  }

  criarBG();
  criarCobrinha();
  drawFood();
  drawScore();

  let snakeX = snake[0].x;
  let snakeY = snake[0].y;

  if (direction == 'right') snakeX += box;
  if (direction == 'left') snakeX -= box;
  if (direction == 'up') snakeY -= box;
  if (direction == 'down') snakeY += box;

  if (snakeX != food.x || snakeY != food.y) {
    snake.pop();
  } else {
    food.x = Math.floor(Math.random() * 15 + 1) * box;
    food.y = Math.floor(Math.random() * 15 + 1) * box;
    score++; //incrementa o contador quando a cobrinha ganha uma peça
  }

  let newHead = {
    x: snakeX,
    y: snakeY,
  };

  snake.unshift(newHead);
}

let jogo = setInterval(iniciarJogo, 100);