/*****
	 * deliverables:
	 * snake game ends when
	 * 1 snake touches itself
	 * 2 snake touches outside border
	 * when the game ends, the gameplay should stop and the user should be notified that the game is over
	 * the snake should grow one length when it eats the apple
	 * the new apple should appear randomly on the screen after the previous one has been eaten
	 * the snake should be controlled by the arrow keys on the keyboard
	 * the game will show a score of how many apples have been eaten
	 */
	var gameCanvas = document.getElementById("myCanvas");
	let ctx = myCanvas.getContext("2d");
	//apple size
	var appleWidth = 10;
	var appleHeight = 10;

	

	const DIRECTION = {
	    NORTH: 'NORTH',
	    SOUTH: 'SOUTH',
	    EAST: 'EAST',
	    WEST: 'WEST'
	};

	var snake;
	var snakeDirection;
	var score;
	var appleLocation;
	var gameOver;

	var dx = 10;
	var dy = 10;
	
	var lives = 3;



	ctx.fillRect(0, 0, myCanvas.width, myCanvas.height);
	ctx.strokeRect(0, 0, myCanvas.width, myCanvas.height);

	document.addEventListener("keydown", keyDownHandler, false);
	document.addEventListener('mousedown', handleMouseClick);

	function startGame() {
		snake = [{
	        x: 150,
	        y: 150
	    },
	    {
	        x: 140,
	        y: 150
	    },
	    {
	        x: 130,
	        y: 150
	    },
	    {
	        x: 120,
	        y: 150
	    },
	    {
	        x: 110,
	        y: 150
	    },
	    {
	        x: 100,
	        y: 150
	    },
	    {
	        x: 90,
	        y: 150
	    },
	    {
	        x: 80,
	        y: 150
	    },
	    {
	        x: 70,
	        y: 60
	    },
	    {
	        x: 50,
	        y: 150
	    }
	];
	
	snakeDirection = DIRECTION.EAST;
	appleLocation = {
	    x: 250,
		y: 150	
	};
	score = 0;

	gameInterval = setInterval(Draw, 100);
}

	function Draw() {
		ctx.clearRect(0, 0, myCanvas.width, myCanvas.height);

	    drawApple();
	    moveSnake();
	    drawSnake();
	    collision();
	    eatApple();
		drawScore();
	}

	function keyDownHandler(e) {
	    if (e.key == "Right" || e.key == "ArrowRight") {
	        snakeDirection = DIRECTION.EAST;
	    } else if (e.key == "Left" || e.key == "ArrowLeft") {
	        snakeDirection = DIRECTION.WEST;
	    } else if (e.key == "Up" || e.key == "ArrowUp") {
	        snakeDirection = DIRECTION.NORTH;
	    } else if (e.key == "Down" || e.key == "ArrowDown") {
	        snakeDirection = DIRECTION.SOUTH;
	    }
	}

	function drawApple() {
	    ctx.fillStyle = 'red';
	    ctx.strokestyle = 'darkred';
	    ctx.fillRect(appleLocation.x, appleLocation.y, appleWidth, appleHeight);
	    ctx.strokeRect(appleLocation.x, appleLocation.y, appleWidth, appleHeight)
	}

	function drawSnake() {
	    snake.forEach(drawSnakePart)
	}

	function drawSnakePart(snake) {
	    ctx.fillStyle = 'lightgreen';
	    ctx.strokestyle = 'darkgreen';
	    ctx.fillRect(snake.x, snake.y, 10, 10);
	    ctx.strokeRect(snake.x, snake.y, 10, 10);
	}

	function moveSnake() {
	    //create copy of snake
	    var snakeCopy = [];

	    //loop through snake 
	    for (var i = 0; i < snake.length; i++) {
	        //for each iteration, add snake body to snake copy
	        snakeCopy.push({
	            x: snake[i].x,
	            y: snake[i].y
	        });
	    }
	    for (var i = 0; i < snake.length; i++) {

	        if (i === 0) {
	            if (snakeDirection === DIRECTION.EAST) {
	                snake[i].x += dx;
	            }
	            if (snakeDirection === DIRECTION.WEST) {
	                snake[i].x -= dx;
	            }
	            if (snakeDirection === DIRECTION.NORTH) {
	                snake[i].y -= dy;
	            }
	            if (snakeDirection === DIRECTION.SOUTH) {
	                snake[i].y += dy;
	            }
	        } else {
	            snake[i].x = snakeCopy[i - 1].x;
	            snake[i].y = snakeCopy[i - 1].y;
	        }
	    }
	}

	function collision() {
	    var headX = snake[0].x;
	    var headY = snake[0].y;

	    if (headX >= myCanvas.width || headY >= myCanvas.height || headY <= myCanvas.height - 610 || headX <= myCanvas.width - 610) {
			ctx.fillText("GAME OVER. You hit the wall. Poor snaky.", 120, 300);
			stopGame(gameInterval);//stop the game
			gameOver = true;
	    } else {
	        snakeBodyCollision();
	    }
			
	
	}

	function snakeBodyCollision() {
	    for (var i = 1; i < snake.length; i++)
	        if (snake[0].x == snake[i].x && snake[0].y == snake[i].y) {
	            ctx.fillText("Oh, boy. You just bit yourself. GAME OVER.", 120, 300);
	            stopGame(gameInterval);//stop the game
			gameOver = true;
	        }
	}

	function eatApple() {
	    if (snake[0].x == appleLocation.x && snake[0].y == appleLocation.y) {

	        appleLocation.x = Math.floor(Math.random() * 50) * 10;
			appleLocation.y = Math.floor(Math.random() * 50) * 10;
			
			var snakeTail = snake[snake.length - 1];

	        snake.push({
	            x: snakeTail.x,
	            y: snakeTail.y
	        });
	        score++;
	    }
	}

	function drawScore() {
	    ctx.font = "16px Arial";
	    ctx.fillstyle = "#0095DD";
	    ctx.fillText("Score: " + score, 8, 20);
	}

	function handleMouseClick(evt) {
		if (gameOver) {
			startGame();
			
			
			//document.location.reload();
			
		}   
	}  

	function stopGame(interval) {
		clearInterval(gameInterval); // Needed for Chrome to end game
	}
		
	var gameInterval;

	startGame();