var requests = new Array();

function ajax(url, callback, retrytime, rclass, obsolescent)
{
	newHttpRequest(getFolder()+url, callback, retrytime, rclass, obsolescent);
}

function newHttpRequest(url, callback, retrytime,rclass,obsolescent)
{
	if(rclass)
	{
		for(var n=0; n<requests.length; n++) if( ( requests[n].rclass == rclass && !obsolescent ) || ( requests[n].rclass == rclass && requests[n].url==url ) ) return;
		
		for(n=0; n<requests.length; n++)
		{
			if(requests[n].rclass == rclass && requests[n].obsolescent == true)
			{
				requests[n].Obsolete();
			}
		}
	}
	
	requests[requests.length] = new httpRequest(url, callback, retrytime,rclass,obsolescent);
	if(requests.length==1) requests[0].sendHttpRequest();
}

function getTime()
{
	var date = new Date();
	return date.getTime();
}

function httpRequest(url, callback, retrytime,rclass,obsolescent)
{
	var req;
	var state = 0;
	var time = getTime();
	var obsolete = false;
	this.rclass = rclass;
	this.obsolescent = obsolescent;
	this.url = url;
	
	this.sendHttpRequest = function()
	{
		_sendHttpRequest();
	}
	
	this.Obsolete = function()
	{
		obsolete = true;
	}
	
	function _sendHttpRequest()
	{
		state = 0;
		if(window.XMLHttpRequest)
		{
			req = new XMLHttpRequest();
			req.onreadystatechange = httpRequestCallback;
			req.open("GET", url, true);
			req.send(null);
		}
		else if(window.ActiveXObject)
		{
			req = new ActiveXObject("Microsoft.XMLHTTP");
			req.onreadystatechange = httpRequestCallback;
			req.open("GET", url, true);
			req.send();
		}
	}

	function httpRequestCallback()
	{		
		if (req.readyState == 4)
		{
			var ok = true;
			try { req.status }
			catch(err) { ok = false; }
			if (ok && req.status && req.status == 200)
			{
				requests.splice(0,1);
				if(!obsolete && callback) callback(req.responseText);
				while(requests.length>0 && requests[0].obsolete==true) requests.splice(0,1);
				if(requests.length>0) requests[0].sendHttpRequest();
			}
			else ok = false;
			
			if(!ok)
			{
				var date = new Date();
				if((!retrytime || retrytime==0 || date.getTime()<time+retrytime*1000) && !obsolete) _sendHttpRequest(); 
				else
				{
					requests.splice(0,1);
					while(requests.length>0 && requests[0].obsolete==true) requests.splice(0,1);
					if(requests.length>0) requests[0].sendHttpRequest();
				}
			}
		}
	}	
}

function getFolder()
{
	        return "http://www.simong.org/";
}