//sparkl javascript library
//February 2008
//original code Neil J Anderson
//rubbish about: http://neilanderson.freehostia.com/
//version 0.1

//ajax module

/*
DOCUMENTATION

  doesn't require sparkl so may declare the namespace
	
  nja - 2008-02-06

*/

/*
TO DO / REVISION HISTORY
 
  * timer for timing out requests
	* queue for queueing requests
	* it should probably have its own DOM insertion to show that a request is being used.


*/


//AJAX MODULE
//xmlhttprequest


/*
 MODULE

  * sparkl.ajax

 PROPERTIES

  * timeout -- when to cancel a request defaults to 1000 - 1 second
 
 PRIVATE METHODS
 
  * _request -- the method used to get a request
  * parse -- parse an object to paired string

 CLASS xhr
 
  xhr PUBLIC METHODS
 
   * get -- a new get request 
   * post -- a new post request

*/

//namespace
var sparkl = sparkl || {};

sparkl.ajax = {};//xmlhttprequest

//PRIVATE METHODS

//factory to store the request to use
sparkl.ajax._request = (function(){
  var factories = [
	  function(){return new XMLHttpRequest();},
		function(){return new ActiveXObject('Msxml2.XMLHTTP');},
		function(){return new ActiveXObject('Microsoft.XMLHTTP');}
	];
	for(var i=0; i<factories.length; i++){
	  try{
		  var factory = factories[i];
			var request = factory();
			if(request != null){
			  return _request = factory;
			};
		}
		catch(e){
		};
	};	
})();

//parse an object passed as args
sparkl.ajax._parse = function(args){
  var keys = [];
	for(i in args){
	  var k = i + '=' + args[i];
		keys.push(k);
	};
  return keys.join('&');
};

//XHR CLASS

//basic class
sparkl.ajax.xhr = function(url){
  this.url = url;
};

//CLASS METHODS

//a get request
sparkl.ajax.xhr.prototype.get = function(callback, args){
  var _r = sparkl.ajax._request();
	if(typeof args == 'object'){
	  args = sparkl.ajax.parse(args);
	};
	var page = this.url + '?' + args;
	_r.onreadystatechange = function(){
	  if(_r.readyState == 4 && _r.status == 200){
		  callback(_r.responseText);
		};
	};
  _r.open('GET', page);
	_r.send(null);
};

//a post request
sparkl.ajax.xhr.prototype.post = function(callback, args){
	if(typeof args == 'object'){
	  args = sparkl.ajax.parse(args);
	};
  var _r = sparkl.ajax._request();
	_r.onreadystatechange = function(){
	  if(_r.readyState == 4 && _r.status == 200){
		  callback(_r.responseText);
		};
	};
  _r.open('POST', this.url);
  _r.setRequestHeader('Content-Type',
	   'application/x-www-form-urlencoded'
		 );
	_r.send(args);
};