/* 

Simple AJAX handler (ver 0.2)
Copyright (C) 2007-2008 Hamid Zarrabi-Zadeh
Licensed under GPL
//---------------------- User Interface -----------------------


	request (destURL, arguments, callBackFunc);
	formRequest (destURL, formID, callBackFunc);


//----------------------- Sample Usage ------------------------
	

1)	var ajax = new AJAX();
	ajax.request('search.php', {name: 'ali', id: 12}, showResults);

2)	var ajax = new AJAX({ method: 'post', xml: true, timeout: 60 });
	ajax.formRequest('query.php', 'myForm', analyzeResponse);

*/

//------------------------- AJAX Class -------------------------


function AJAX(args)
{
	// args: {method, timeout, xml}
	args = args || {}; 
	this.method = (args.method == 'get') ? 'get' : 'post';
	this.requestTimeout = args.timeout || 30;  // in seconds
	this.xmlResponse = (args.xml == true);  

	this.callBackFunction = null;
	this.httpRequest = this.createHttpRequest();
	if (!this.httpRequest)
		alert('cannot create httpReauest object...');
}


//------------------------- initializers -------------------------


// create an XMLHttpRequest object
AJAX.prototype.createHttpRequest = function() 
{
	if (window.XMLHttpRequest) // Mozilla, Safari,... 
		return new XMLHttpRequest();
	try { // IE 
		return new ActiveXObject("Msxml2.XMLHTTP");
	} catch (e) {
		try {
			return new ActiveXObject("Microsoft.XMLHTTP");
		} catch (e) {}
	}
	return null;
}


//------------------------- AJAX Requests -------------------------


// handle changes in the httpRequest status
AJAX.prototype.handler = function() 
{
	var response = null;
	if (this.httpRequest.readyState == 4) 
	{
		if (this.httpRequest.status == 200) 
		{
			if (this.xmlResponse)
				response = this.httpRequest.responseXML;
			else
				response = this.httpRequest.responseText;
		} 
		if (this.callBackFunction != null)
			this.callBackFunction.call(this, response);
	}
}


// make a request 
AJAX.prototype.request = function(destURL, params, procFunc) 
{
	if (!this.httpRequest)
		return;
	var args = this.hashToStr(params);
	this.callBackFunction = procFunc;
	this.httpRequest.onreadystatechange = this.handler.bind(this);
	this.httpRequest.open(this.method, destURL, true);
	this.httpRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	this.httpRequest.setRequestHeader("Content-length", args.length);
	this.httpRequest.setRequestHeader("Connection", "close");
    if (this.httpRequest.timeout) 
		this.httpRequest.timeout = this.requestTimeout;
    if (this.httpRequest.overrideMimeType) 
		this.httpRequest.overrideMimeType(this.xmlResponse ? 'text/xml' : 'text/html');
	this.httpRequest.send(args);
}


// make a form request
AJAX.prototype.formRequest = function(destURL, formID, procFunc) 
{
	var args = this.getFormData(formID);
	this.request(destURL, args, procFunc);
}


//------------------------- Misc -------------------------


// return form contents as a hash table
AJAX.prototype.getFormData = function(formID) 
{
	var theForm = document.getElementById(formID);
	var str = '';
	for (var e=0 ; e < theForm.elements.length ; e++) 
	{
		var name = theForm.elements[e].name;
		if (!name) continue;
		args[name] = encodeURIComponent(theForm.elements[e].value);
	}
	return args;
} 



// convert a hash table to a string
AJAX.prototype.hashToStr = function(table) 
{
	var args = [];
	for (var name in table)
		args.push(name+ '='+ table[name]);
	return args.join('&');
}


// Prototype bind funciton
Function.prototype.bind = function(obj) 
{
	var method = this,
	temp = function() {	return method.apply(obj, arguments); };
	return temp;
}