import AbstractView from './AbstractView.js'

export default class extends AbstractView {
	constructor(params) {
		super(params, 'Game');
		this.game = null;
	}

	async getHtml() {
		return `
			<h1>Game</h1>
			<button id='startGameButton'>Start Game</button>
			<button id='stopGameButton'>Stop Game</button>
		`;
	}

	async postInit() {
		document.getElementById('startGameButton').onclick = this.startGame.bind(this);
		document.getElementById('stopGameButton').onclick = this.stopGame.bind(this);
	}

	startGame() {
		if (this.game == null) {
			document.getElementById('startGameButton').innerHTML = 'Reset Game';
			this.game = new Game;
		}
		else {
			document.getElementById('app').removeChild(this.game.canvas);
			this.game.cleanup();
			this.game = new Game;
		}
	}

	stopGame() {
		if (!this.game)
			return;
		document.getElementById('app').removeChild(this.game.canvas);
		this.game.cleanup();
		this.game = null;
		document.getElementById('startGameButton').innerHTML = 'Start Game';
	}
}

class Game {
	constructor() {
		//Global variables
		this.globVars = {
			CANVASHEIGHT: 270,
			CANVASWIDTH: 480,
			PADDLEHEIGHT: 70,
			PADDLEWIDTH: 10,
			PADDLEMARGIN: 5,
			PADDLESPEED: 3,
			BALLRADIUS: 5,
			BALLSPEED: 2,
			MAXBOUNCEANGLE: 10 * (Math.PI / 12)
		};

		this.canvas = document.createElement('canvas');
		this.canvas.id = 'gameCanvas';
		this.canvas.width = this.globVars.CANVASWIDTH;
		this.canvas.height = this.globVars.CANVASHEIGHT;
		this.canvas.style.border = '1px solid #d3d3d3';
		this.canvas.style.backgroundColor = '#f1f1f1';
		this.context = this.canvas.getContext('2d');
		document.getElementById('app').appendChild(this.canvas);

		this.paddles = [
			new Paddle(this.context,
				this.globVars.PADDLEMARGIN,
				this.globVars
			),
			new Paddle(this.context,
				this.globVars.CANVASWIDTH - this.globVars.PADDLEMARGIN - this.globVars.PADDLEWIDTH,
				this.globVars
			)
		];
		this.ball = new Ball(this.context, this.globVars);

		this.interval = setInterval(this.updateGame.bind(this), 10);

		this.keys = [];
		this.keyUpHandler = this.keyUpHandler.bind(this);
		this.keyDownHandler = this.keyDownHandler.bind(this);
		document.addEventListener('keydown', this.keyDownHandler);
		document.addEventListener('keyup', this.keyUpHandler);
	}

	cleanup() {
		clearInterval(this.interval);
		document.removeEventListener('keydown', this.keyDownHandler);
		document.removeEventListener('keyup', this.keyUpHandler);
	}

	clear() {
		this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
	}

	updateGame() {

		if (this.keys.includes('Escape'))
			this.cleanup();

		//Paddle movement
		if (this.keys.includes('s') &&
			this.paddles[0].y + this.globVars.PADDLEHEIGHT < this.globVars.CANVASHEIGHT - this.globVars.PADDLEMARGIN)
				this.paddles[0].y += this.globVars.PADDLESPEED;
		if (this.keys.includes('w') &&
			this.paddles[0].y > 0 + this.globVars.PADDLEMARGIN)
				this.paddles[0].y -= this.globVars.PADDLESPEED;

		if (this.keys.includes('ArrowDown') &&
			this.paddles[1].y + this.globVars.PADDLEHEIGHT < this.globVars.CANVASHEIGHT - this.globVars.PADDLEMARGIN)
				this.paddles[1].y += this.globVars.PADDLESPEED;
		if (this.keys.includes('ArrowUp') &&
			this.paddles[1].y > 0 + this.globVars.PADDLEMARGIN)
				this.paddles[1].y -= this.globVars.PADDLESPEED;

		//Ball collisions
		if (this.detectCollision(this.paddles[0], this.ball))
			this.calculateBallVelocity(this.paddles[0].getCenter().y, this.ball);
		else if (this.detectCollision(this.paddles[1], this.ball))
			this.calculateBallVelocity(this.paddles[1].getCenter().y, this.ball, -1);

		if (this.ball.y - this.ball.radius <= 0)
			this.ball.vy *= -1;
		else if (this.ball.y + this.ball.radius >= this.canvas.height)
			this.ball.vy *= -1;
		this.ball.x += this.ball.vx;
		this.ball.y += this.ball.vy;

		this.clear();
		this.paddles[0].update();
		this.paddles[1].update();
		this.ball.update();
	}

	detectCollision(paddle, ball) {
		let paddleCenter = paddle.getCenter();
		let dx = Math.abs(ball.x - paddleCenter.x);
		let dy = Math.abs(ball.y - paddleCenter.y);
		if (dx <= ball.radius + paddle.width / 2 &&
			dy <= ball.radius + paddle.height / 2)
				return true;
		return false;
	}

	calculateBallVelocity(paddleCenterY, ball, side = 1) {
		let relativeIntersectY = paddleCenterY - ball.y;
		let normRelIntersectY = relativeIntersectY / this.globVars.PADDLEHEIGHT / 2;
		let bounceAngle = normRelIntersectY * this.globVars.MAXBOUNCEANGLE;

		ball.vx = this.globVars.BALLSPEED * side * Math.cos(bounceAngle);
		ball.vy = this.globVars.BALLSPEED * -Math.sin(bounceAngle);
	}

	keyUpHandler(ev) {
		const idx = this.keys.indexOf(ev.key);
		if (idx != -1)
			this.keys.splice(idx, 1);
	}

	keyDownHandler(ev) {
		if (!this.keys.includes(ev.key))
			this.keys.push(ev.key);
	}
}

class Paddle {
	constructor(context, paddleSide, globVars) {
		this.width = globVars.PADDLEWIDTH;
		this.height = globVars.PADDLEHEIGHT;
		this.x = paddleSide;
		this.y = globVars.CANVASHEIGHT / 2 - this.height / 2;
		this.ctx = context;
		this.update();
	}

	update() {
		this.ctx.fillStyle = 'black';
		this.ctx.fillRect(this.x, this.y, this.width, this.height);
	}

	getCenter() {
		return {
			x: this.x + this.width / 2,
			y: this.y + this.height / 2
		};
	}
}

class Ball {
	constructor(context, globVars) {
		this.radius = globVars.BALLRADIUS;
		this.x = globVars.CANVASWIDTH / 2;
		this.y = globVars.CANVASHEIGHT / 2;
		this.vx = -globVars.BALLSPEED;
		this.vy = 0;
		this.ctx = context;
		this.update();
	}

	update() {
		this.ctx.fillStyle = 'black';
		this.ctx.beginPath();
		this.ctx.arc(this.x, this.y, this.radius, 0, 2 * Math.PI);
		this.ctx.fill();
	}
}