// JavaScript Document

var ajaxRequest = null; // The XMLHTTPREQUEST object

function initialiseAjax()
{
	if (ajaxRequest!=null)
	{
		//Close the request as a new request has just been started
		ajaxRequest.abort();
		ajaxRequest = null;
		return initialiseAjax();
	}
	if(window.XMLHttpRequest && !(window.ActiveXObject))
	{
    	try
		{
			ajaxRequest = new XMLHttpRequest();
        }
		catch(e)
		{
			ajaxRequest = null;
        }
    // branch for IE/Windows ActiveX version
    }
	else if(window.ActiveXObject)
	{
       	try
		{
        	ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
      	}
		catch(e)
		{
        	try
			{
          		ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
        	}
			catch(e)
			{
          		ajaxRequest = null;
        	}
		}
    }
	return true;
}

function convertArguments(args)
{
	var args_txt = "";
	for (var key in args)
	{
		if (args_txt!="")
		{
			args_txt += "&";
		}
		args_txt += encodeURIComponent(key) + "=" + encodeURIComponent(args[key]);
	}
	return args_txt;
}

/**
 * Helper for creating a simple ajax query, which takes in a callback
 */
function simpleAjaxQuery(url, args, callback, async)
{
	if (async == null)
	{
		async = true;	
	}
	if (!initialiseAjax())
	{
		return false;
	}

	if (ajaxRequest!=null)
	{
		if (async)
		{
			ajaxRequest.open('POST', url, async);
			ajaxRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
			ajaxRequest.onreadystatechange = callback;
			ajaxRequest.send(convertArguments(args));
		}
		else
		{
			ajaxRequest.open('POST', url, async);
			ajaxRequest.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
			//ajaxRequest.onreadystatechange = callback;
			ajaxRequest.send(convertArguments(args));
			callback(ajaxRequest);
		}
	}
	else
	{
		alert ("Failed to init");	
	}
	return true;
}

/**
 * Helper for creating an ajax query that executes any resulting data on the clients side
 */
function simpleAjaxQueryExec(url, args)
{
	simpleAjaxQuery(url, args,
		function()
		{
			if (ajaxRequest.readyState==4)
			{
				try
				{
					if (ajaxRequest.status == 200)
					{
						//Data received
						var response = ajaxRequest.responseText;
						ajaxRequest = null;
						eval(response);
					}
					else
					{
						ajaxRequest = null;
					}
				}
				catch (e)
				{
					ajaxRequest = null;
				}
			}				
		}
	);
}