let grid = [];
let snake = [];
let alive = true;
let snakeDirection = 0;
let AItype = "random";
let gridSize = 20;
let gridColumns = 10;
let gridRows = 10;
let eatenApples = 0;
let _textSize = 32;
let appleAmount = 1;
let gameSpeed = 10;
let buttonAddColoums = null;
let buttonAddRows = null;
let buttonUpgradeAI = null;
let buttonAddMoreApples = null;
let buttonSpeedUpgrade = null;
let SpeedUpgradePrice = 5;
let AddMoreApplesPrice = 1;
let AddColoumsPrice = 1;
let AddRowsPrice = 1;
let UpgradeAIPrice = 1;

function setup() {
	buttonAddColoums = createButton("Add coloums");
	buttonAddRows = createButton("Add rows");
	buttonUpgradeAI = createButton("Upgrade AI");
	buttonAddMoreApples = createButton("Add more apples");
	buttonSpeedUpgrade = createButton("Increase speed");
	createCanvas(windowWidth, windowHeight);
	background(255, 255, 255);
	for (let i = 0; i < gridColumns; i++) {
		grid[i] = [];
		for (let j = 0; j < gridRows; j++) {
			grid[i][j] = 0;
		}
	}
	buttonAddColoums.mousePressed(buttonAddColoumsPressed);
	buttonAddRows.mousePressed(buttonAddRowsPressed);
	buttonUpgradeAI.mousePressed(buttonUpgradeAIPressed);
	buttonAddMoreApples.mousePressed(buttonAddMoreApplesPressed);
	buttonSpeedUpgrade.mousePressed(buttonSpeedUpgradePressed);
	frameRate(gameSpeed);
	summonSnake();
	summonApple();
	drawGrid();
}

function buttonSpeedUpgradePressed(){

	if (eatenApples < SpeedUpgradePrice) {
		return;
	}

	eatenApples -= SpeedUpgradePrice;

	gameSpeed += 2;

	frameRate(gameSpeed);

	SpeedUpgradePrice += 5;
}

function buttonAddColoumsPressed(){
	if (eatenApples < AddColoumsPrice) {
		return;
	}
	eatenApples -= AddColoumsPrice;
	gridColumns++;
	grid.push([]);
	for (let i = 0; i < gridRows; i++) {
		grid[grid.length - 1][i] = 0;
	}
}
function buttonAddRowsPressed(){
	if (eatenApples < AddRowsPrice) {
		return;
	}
	eatenApples -= AddRowsPrice;
	gridRows++;
	for (let i = 0; i < gridColumns; i++) {
		grid[i].push(0);
	}
}
function buttonUpgradeAIPressed(){
	if (eatenApples < UpgradeAIPrice) {
		return;
	}
	eatenApples -= UpgradeAIPrice;
	AItype = "smart";
}

function buttonAddMoreApplesPressed(){
	if (eatenApples < AddMoreApplesPrice) {
		return;
	}
	eatenApples -= AddMoreApplesPrice;
	summonApple();
	appleAmount++;
}

function summonApple(){
	if (appleAmount >= gridColumns * gridRows) {
		for (let i = 0; i < grid.length; i++) {
			for (let j = 0; j < grid[0].length; j++) {
				if (grid[i][j] == 2) {
					grid[i][j] = 0;
				}
			}
		}
		return;
	}
	let x = grid.length - floor(random(1, grid.length +1));
	let y = grid[0].length - floor(random(1, grid[0].length +1));
	if(grid[x][y] == 2 || grid[x][y] == 1){
		summonApple();//best practice coding right here
		return;
	}
	grid[x][y] = 1;
}



function dontMoveBackwards(lastSnakeX, lastSnakeY, currentSnakeX, currentSnakeY, direction){
	if (direction == 0) {
		return lastSnakeX < currentSnakeX;
	}else if (direction == 1) {
		return lastSnakeY < currentSnakeY;
	}else if (direction == 2) {
		return lastSnakeX > currentSnakeX;
	}else if (direction == 3) {
		return lastSnakeY > currentSnakeY;
	}
}

function restartGame(){

	for (let i = 0; i < grid.length; i++) {
		for (let j = 0; j < grid[0].length; j++) {

			if (grid[i][j] == 2 || grid[i][j] == 1) {
				grid[i][j] = 0;
			}
		}
	}

	snake = [];

	summonSnake();

	for (let i = 0; i < appleAmount; i++) {
		summonApple();
	}

	alive = true;
}

function runSnake(){
	let x = snake[0][0];
	let y = snake[0][1];
	for (let i = snake.length - 1; i > 0; i--) {
		snake[i][0] = snake[i - 1][0];
		snake[i][1] = snake[i - 1][1];
	}
	snakeAI();
	let lastSnakeX = snake[1][0]
	let lastSnakeY = snake[1][1];
	if (dontMoveBackwards(lastSnakeX, lastSnakeY, x, y, snakeDirection)) {
		snakeDirection = (snakeDirection + 2) % 4;
	}
	if (snakeDirection == 0) {
		snake[0][0] += 1;
	}else if (snakeDirection == 1) {
		snake[0][1] += 1;
	}else if (snakeDirection == 2) {
		snake[0][0] -= 1;
	}else if (snakeDirection == 3) {
		snake[0][1] -= 1;
	}
	if (snake[0][1] >= grid[0].length || snake[0][1] < 0 || snake[0][0] >= grid.length || snake[0][0] < 0) {
		alive = false;
		return;
	}
	if (grid[snake[0][0]][snake[0][1]] == 2) {
		alive = false;
		return;
	}
	if (grid[snake[0][0]][snake[0][1]] == 1) {
		snake.push([snake[snake.length - 1][0], snake[snake.length - 1][1]]);
		summonApple();
		eatenApples++;
	}
	drawSnakeOnGrid();
}

function summonSnake(){
	let x = grid.length - floor(random(1, grid.length));
	let y = grid[0].length - floor(random(1, grid[0].length));
	snake.push([x, y]);
	snake.push([x - 1, y]);
	snake.push([x - 2, y]);
	drawSnakeOnGrid();
}

function drawSnakeOnGrid(){
	for (let i = 0; i < grid.length; i++) {
		for (let j = 0; j < grid[0].length; j++) {
			if (grid[i][j] == 2) {
				grid[i][j] = 0;
			}
		}
	}

	for (let i = 0; i < snake.length; i++) {

		let x = snake[i][0];
		let y = snake[i][1];

		// prevent crash
		if (
			x < 0 ||
			y < 0 ||
			x >= grid.length ||
			y >= grid[0].length
		){
			alive = false;
			return;
		}

		grid[x][y] = 2;
	}
}

function drawGrid() {
	for (let i = 0; i < grid.length; i++) {
		for (let j = 0; j < grid[0].length; j++) {
			if (grid[i][j] == 1) {
				fill(255, 0, 0);
			}else if (grid[i][j] == 2) {
				fill(0, 255, 0);
			}else {
				fill(255, 255, 255);
			}
			rect(i * gridSize, j * gridSize, gridSize, gridSize);
		}
	}
}

function draw() {

	if (alive == false){
		restartGame();
	}

	background(255);

	runSnake();
	drawGrid();

	fill(0, 0, 0);
	textSize(_textSize);

	text("₴ " + eatenApples, gridColumns * gridSize + gridSize + _textSize*3, _textSize * 1);

	text("Apples: " + appleAmount, gridColumns * gridSize + gridSize, _textSize * 2);

	buttonAddMoreApples.html("Add more apples ₴ " + AddMoreApplesPrice);
	buttonAddMoreApples.position(gridColumns * gridSize + gridSize + _textSize*6, _textSize * 1.5);

	text("AI: " + AItype, gridColumns * gridSize + gridSize, _textSize * 3);

	buttonUpgradeAI.html("Upgrade AI ₴ " + UpgradeAIPrice);
	buttonUpgradeAI.position(gridColumns * gridSize + gridSize + _textSize*6, _textSize * 2.5);

	text("Coloums: " + gridColumns, gridColumns * gridSize + gridSize, _textSize * 4);

	buttonAddColoums.html("Add coloums ₴ " + AddColoumsPrice);
	buttonAddColoums.position(gridColumns * gridSize + gridSize + _textSize*6, _textSize * 3.5);

	text("Rows: " + gridRows, gridColumns * gridSize + gridSize, _textSize * 5);

	buttonAddRows.html("Add rows ₴ " + AddRowsPrice);
	buttonAddRows.position(gridColumns * gridSize + gridSize + _textSize*6, _textSize * 4.5);

	text("Speed: " + gameSpeed, gridColumns * gridSize + gridSize, _textSize * 6);

	buttonSpeedUpgrade.html("Increase speed ₴ " + SpeedUpgradePrice);
	buttonSpeedUpgrade.position(gridColumns * gridSize + gridSize + _textSize*6, _textSize * 5.5);
}

function mousePressed() {

}

function snakeAI(){
	switch (AItype) {
		case "random":
			snakeAIrandom();
			break;
	}
}

function snakeAIrandom() {
	snakeDirection = floor(random(0, 4));
}

function snakeAIrandomNowallHit(){
	snakeDirection = floor(random(0, 4));
}