// Loader
var XML_LOADING = 1;
var XML_LOADED = 2;
var XML_INTERACTIVE = 3;
var XML_COMPLETE = 4;

function Loader()
{
	this.xmlhttp = null;
	this.handlers = null;
	this.xmlDoc = null;
	
	// fromFile should be in main.js
	this.fromFile = config.fromFile;

	if (!this.fromFile)
	{
		if (window.XMLHttpRequest)
		{
			this.xmlhttp = new XMLHttpRequest();
		}
		else if (window.ActiveXObject)
		{
			try
			{
				this.xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
			}
			catch(e)
			{
				this.xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
			}
		}
		else
		{
			alert("error creating xmlhttp");
		}
	}
	else
	{
		if (document.implementation && document.implementation.createDocument)
		{
			this.xmlDoc = document.implementation.createDocument("", "", null);
		}
		else if (window.ActiveXObject)
		{
			this.xmlDoc = new ActiveXObject("Microsoft.XMLDOM");
		}
		else
		{
			alert("error creating xmlDoc");
		}
	}
	
	this.handlers = new Array(5);
}

Loader.prototype.getXML = function()
{
	if (!this.fromFile)
	{
		if (this.xmlhttp.responseXML)
		{
			return this.xmlhttp.responseXML;
		}
		else
		{
			return null;
		}
	}
	else
	{
		if (this.xmlDoc)
		{
			return this.xmlDoc;
		}
		else
		{
			return null;
		}
	}
}

Loader.prototype.load = function (URL, async)
{
	try
	{
		if (!this.fromFile)
		{
			this.xmlhttp.open("GET", URL, async);

			if (async)
			{
				var ref = this;
				this.xmlhttp.onreadystatechange = function()
				{
					ref.callHandler(ref);
				};
				this.xmlhttp.send(null);
			}
			else
			{
				this.xmlhttp.send(null);
				return this.xmlhttp.responseXML;
			}
		}
		else
		{
			// todo: load for firefox NOK
			this.xmlDoc.load(URL);

			// simulate async
			if (async)
			{
				this.callHandler(this);
			}
			else
			{
				return this.xmlDoc;
			}
		}
	}
	catch(ex)
	{
		//alert(ex);
		alert("Can not load " + URL);
		this.xmlhttp.abort();
	}
}

Loader.prototype.callHandler = function (self)
{
	
	if (!this.fromFile)
	{
		if (self.handlers[self.xmlhttp.readyState])
		{
			if (self.xmlhttp.readyState == XML_COMPLETE)
			{
				self.handlers[self.xmlhttp.readyState](self.xmlhttp.responseXML);
			}
			else
			{
				self.handlers[self.xmlhttp.readyState]();
			}
		}
	}
	else
	{
		self.handlers[4]();
	}
}

Loader.prototype.setHandler = function (state, pointer)
{
	if (this.handlers != null)
	{
		this.handlers[state] = pointer;
	}
}

Loader.prototype.clearHandlers = function ()
{
	if (this.handlers != null)
	{
		for (var i=0; i < this.handlers.length; i++)
		{
			this.handlers[i] = null;
		}
	}
}