(function(window)
{
	function Aliens(image, point)
	{
		this.image			= image;
		this.offsetPosition	= point;
		this.position		= point.clone();
		this.initialize();
	}
	Aliens.prototype = new Container();
		Aliens.prototype.image			= null;
		Aliens.prototype.spriteSheet	= null;
		Aliens.prototype.bitmapSequence	= null;
		Aliens.prototype.boundry		= null;				// Rectangle "within the Aliens can move"
		Aliens.prototype.position		= new Point(0,0);	// Point respresenting the x and y postion of this (the Aliens). Used as offset when moving/position each Alien
		Aliens.prototype.offsetPosition	= new Point(0,0);	// Point respresenting the x and y postion of this (the Aliens). Used to reset the position when resetting the game
		Aliens.prototype.width			= 0;				// The width of this (the aliens). Updated on every tick
		Aliens.prototype.height			= 0;				// The height of this (the aliens). Updated on every tick
		Aliens.prototype.speed			= 2;				// The speed of which the aliens move (x and y increments)
		Aliens.prototype.enabled		= false;
		Aliens.prototype.alienWidth		= 0;
		Aliens.prototype.alienHeight	= 0;
		Aliens.prototype.aliens			= [];	// Array to hold each Alien instance
		Aliens.prototype.direction		= null;	// Identifies the current direction the aliens move
		Aliens.prototype.totalAliens	= 0;	// Total amount of aliens (left)
		// Signals
		Aliens.prototype.alienKilled	= new signals.Signal();
		Aliens.prototype.allKilled		= new signals.Signal();
		Aliens.prototype.reachedBottom	= new signals.Signal();
		Aliens.prototype.shotFired		= new signals.Signal();
		// Const
		Aliens.DIR_LEFT		= 'Aliens.DIR_LEFT';
		Aliens.DIR_RIGHT	= 'Aliens.DIR_RIGHT';
		Aliens.DIR_NONE		= 'Aliens.DIR_NONE';
		// Constructor:
		Aliens.prototype.Container_initialize = Aliens.prototype.initialize;	// Unique to avoid overiding base class
		/**
		* INIT METHODS
		*/
		Aliens.prototype.initialize = function()
		{
			this.Container_initialize();
			this.alienWidth		= this.image.width/2;
			this.alienHeight	= this.image.height/2;
			this.spriteSheet	= new SpriteSheet(this.image,this.alienWidth,this.alienHeight,{blackClosed:[0,1,'blackOpen'],blackOpen:[1,2,'blackClosed'],greenClosed:[2,3,'greenOpen'],greenOpen:[3,4,'greenClosed'] });
			this.bitmapSequence	= new BitmapSequence(this.spriteSheet);
			this.setup();
		}
		Aliens.prototype.setup = function()
		{
			this.x			= this.offsetPosition.x;
			this.y			= this.offsetPosition.y;
			this.position.x	= this.offsetPosition.x;
			this.position.y	= this.offsetPosition.y;
			this.width		= 0;
			this.enabled	= false;
			this.boundry	= new Rectangle(0, 0, Registry.get('STAGE_WIDTH'), Registry.get('STAGE_HEIGHT') - 40 - this.offsetPosition.y);
			this.direction	= Aliens.DIR_RIGHT;
			this.aliens		= [];
			this.createAliens(4);
			this.createAliens(0);
			this.createAliens(4);
		}
		Aliens.prototype.createAliens = function(type)
		{
			switch(type)
			{
				case 4:
					var _coords		= [{x:0,y:0},{x:0,y:1},{x:0,y:2},{x:1,y:2},{x:2,y:0},{x:2,y:1},{x:2,y:2},{x:2,y:3},{x:2,y:4}];
					var _sequence	= 'blackClosed';
					var _color		= '#000';
					break;
				case 0:
					var _coords		= [{x:0,y:0},{x:0,y:1},{x:0,y:2},{x:0,y:3},{x:0,y:4},{x:1,y:0},{x:1,y:4},{x:2,y:0},{x:2,y:1},{x:2,y:2},{x:2,y:3},{x:2,y:4}];
					var _sequence	= 'greenClosed';
					var _color		= '#4d852b';
					break;
				default: // For TEST only
					var _coords		= [{x:0,y:0},{x:1,y:0}];
					var _sequence	= 'blackClosed';
					var _color		= '#000';
					break;
			}
			var _this		= this;
			var _offsetX	= this.width == 0 ? this.x : this.x + this.width + 25;
			for(var i=0; i<_coords.length; ++i)
			{
				this.bitmapSequence	= this.bitmapSequence.clone(); // Rather than creating a brand new instance each time, and setting every property, we can just clone the current one
				var alien	= new Alien(this.bitmapSequence, this.spriteSheet, this.alienWidth, this.alienHeight, _sequence, _color);
				alien.x		= _coords[i].x * (this.alienWidth+4) + _offsetX;
				alien.y		= _coords[i].y * (this.alienHeight+4) + this.y;
				alien.shotFired.add(function(point) { _this.onAlienShooting(point); });
				this.addChild(alien);
				this.aliens.push(alien);
			}
			this.totalAliens	= this.aliens.length;
			this.updateWidthAndHeight();
		}
		Aliens.prototype.onAlienShooting = function(point)
		{
			point.x	+= this.x;
			point.y	+= this.y;
			this.shotFired.dispatch(point); // Would be easier w/ Signal bubbling :/
		}
		/**
		* HITTEST METHODS
		*/
		Aliens.prototype.checkForHit = function(bullit)
		{
			for(var i=0; i<this.totalAliens; ++i)
			{
				var alien	= this.aliens[i];
				if(bullit && alien.inHitArea(new Point(bullit.x, bullit.y)) === true)
				{
					this.destroyAlien(alien);
					// Update the width dn height used in movement calculations
					this.updateWidthAndHeight();
					// Dispatch Signals
					this.alienKilled.dispatch(new Point(this.x + alien.x + alien.width/2, this.y + alien.y), alien.color, bullit);
					if(this.totalAliens == 0) this.allKilled.dispatch();
					break;
				}
			}
		}
		/**
		* RENDERING METHODS
		*/
		Aliens.prototype.enable = function()
		{
			for(var i=0; i<this.totalAliens; ++i) this.aliens[i].enable();
			this.enabled	= true;
		}
		Aliens.prototype.update = function()
		{
			if(this.enabled === false) return false;
			if(this.y + this.height >= this.boundry.height)
			{
				this.reachedBottom.dispatch();
				return false;
			}
			if(this.direction == Aliens.DIR_RIGHT)	this.updatePositionMovingRight();
			if(this.direction == Aliens.DIR_LEFT)	this.updatePositionMovingLeft();
			this.x	= this.position.x;
			this.y	= this.position.y;
		}
		Aliens.prototype.updatePositionMovingRight = function()
		{
			if(this.x + this.speed + this.width - this.boundry.x >= this.boundry.width)
			{
				this.position.x	= this.boundry.width - this.width;
				this.position.y	= this.position.y + this.alienHeight;
				this.direction	= Aliens.DIR_LEFT;
			}
			else
			{
				this.position.x	= this.x + this.speed;
			}
		}
		Aliens.prototype.updatePositionMovingLeft = function()
		{
			if(this.x - this.speed <= this.boundry.x)
			{
				this.position.x	= this.boundry.x;
				this.position.y	= this.position.y + this.alienHeight;
				this.direction	= Aliens.DIR_RIGHT;
			}
			else
			{
				this.position.x	= this.x - this.speed;
			}
		}
		// Since width and height are not recognised properties on a Container, we update them manually on each tick
		// The width/height is used to calculate when when aliens are close to the edges of their boundry (allowed movement)
		Aliens.prototype.updateWidthAndHeight = function()
		{
			var _min	= new Point(Registry.get('STAGE_WIDTH'), Registry.get('STAGE_HEIGHT'));
			var _max	= new Point(0,0);
			for(var i=0; i<this.totalAliens; ++i)
			{
				var alien	= this.aliens[i];
				_min.x		= Math.min(_min.x, alien.x);
				_min.y		= Math.min(_min.y, alien.y);
				_max.x		= Math.max(_max.x, alien.x + alien.width);
				_max.y		= Math.max(_max.y, alien.y + alien.height);
			}
			this.width		= _max.x - _min.x;
			this.height		= _max.y - _min.y;
			this.boundry.x	= 0 - _min.x;
		}
		/**
		* DESTROY METHODS
		*/
		Aliens.prototype.disable = function()
		{
			//this.alienKilled.removeAll(); // Don't remove the alienKilled Signal, 'cause the spaceship might have fired bullit that are still active...
			this.allKilled.removeAll();
			this.reachedBottom.removeAll();
			this.shotFired.removeAll();
			this.direction	= Aliens.DIR_NONE;
			for(var i=0; i<this.totalAliens; ++i)
			{
				if(this.aliens[i]) this.aliens[i].disable();
			}
		}
		Aliens.prototype.destroyAlien = function(alien)
		{
			this.aliens.splice(this.aliens.indexOf(alien), 1);
			this.totalAliens	= this.aliens.length;
			alien.disable();
			this.removeChild(alien);
		}
		Aliens.prototype.destroyAliens = function()
		{
			for(var i=0; i<this.aliens.length; ++i)
			{
				if(this.aliens[i])
				{
					this.aliens[i].disable();
					this.aliens[i].parent.removeChild(this.aliens[i]);
				}
			}
		}
		Aliens.prototype.reset = function()
		{
			this.alienKilled.removeAll();
			this.destroyAliens();
			this.setup();
		}
	window.Aliens = Aliens;
}(window));