Alien.prototype = Object.create(Phaser.Sprite.prototype);
Alien.constructor = Alien;

function Alien(spaceship) {
	this.spaceship = spaceship;

	this.isActivated = false;
	this.speed = Alien.DEFAULT_SPEED_DOT_PER_SEC;
	this.angleFromSpaceship = 0;
	this.angleFromAlien = 0;

	Phaser.Sprite.call(this, game, 0, 0, 'alien_normal');
	this.anchor.set(0.5);

	game.add.existing(this);
	this.moveRandomPosition();

	// this.setActive(true);
}




Alien.prototype.moveRandomPosition = function() {
	this.angleFromAlien = game.rnd.integerInRange(0, 360);
	// console.log(this.angleFromAlien);

	var radians = this.angleFromAlien * Math.PI / 180;

	var radious = Alien.START_RADIOUS_PX * ( ( (100 + game.rnd.integerInRange(0, Alien.START_RANDOM_RADIOUS_PERCENT) ) / 100) );
	var posX = Math.sin(radians) * radious;
	var posY = Math.cos(radians) * radious;

	this.x = game.world.centerX + posX;
	this.y = game.world.centerY + posY;
	// this.x = this.spaceship.x + posX;
	// this.y = this.spaceship.y + posY;


	var alienAngle = this.getAngle(this.spaceship.x, this.spaceship.y, this.x, this.y);
	this.angle = this.getSpriteAngle(alienAngle);

	this.angleFromAlien = alienAngle;

	// this.angle = this.getSpriteAngle(this.angleFromAlien);
}

Alien.prototype.update = function() {
	if(!this.isActivated)
		return;

	var deltaTime = game.time.elapsed / 1000;

	var radians = this.angleFromAlien * Math.PI / 180;
	var moveX = Math.sin(radians) * this.speed * deltaTime;
	var moveY = Math.cos(radians) * this.speed * deltaTime;

	this.x -= moveX;
	this.y -= moveY;

	var distanceX = this.x - game.world.centerX;
	var distanceY = this.y - game.world.centerY;
	var distanceFromCenter = Math.sqrt(Math.abs(distanceX * distanceX) + Math.abs(distanceY * distanceY));
	if(distanceFromCenter > Alien.START_RADIOUS_PX)
		this.moveRandomPosition();
}


Alien.prototype.stop = function() {
	this.setActive(false);
}

Alien.prototype.setActive = function(isActivated) {
	this.isActivated = isActivated;
}

Alien.prototype.getSpriteAngle = function (angle){
	return 360 - angle;
}

Alien.prototype.getAngle = function (x1, y1, x2, y2){
	var dx = x2 - x1;
	var dy = y2 - y1;


	var rad= Math.atan2(dx, dy);
	var degree = (rad * 180) / Math.PI ;
	if(degree < 0)
		degree += 360;

	return degree;
}

Alien.prototype.goRandomPosition = function() {
	// set random position
	var SPAWN_BOX_LEFT		= 80;
	var SPAWN_BOX_WIDTH		= game.world.width - 160;
	var SPAWN_BOX_TOP		= 280;
	var SPAWN_BOX_HEIGHT	= game.world.height - 400;

	this.x = SPAWN_BOX_LEFT + Math.random() * SPAWN_BOX_WIDTH;
	this.y = SPAWN_BOX_TOP + Math.random() * SPAWN_BOX_HEIGHT;

	// if(isDebugMode()) {
	// 	this.game.add.graphics()
	// 		.beginFill(0xffffff, 0.1)
	// 		.drawRect(SPAWN_BOX_LEFT, SPAWN_BOX_TOP, SPAWN_BOX_WIDTH, SPAWN_BOX_HEIGHT);
	// }

}



Alien.DEFAULT_SPEED_DOT_PER_SEC		= 100;

Alien.START_RADIOUS_PX				= 600;
Alien.START_RANDOM_RADIOUS_PERCENT	= 40;