/* The contents of this file are protected by copyright law.
 * All rights are retained.
 * A non-exclusive license is hereby granted to use the file
 * in connection with the website http://www.covariable.com/
 * Copyright 2006 Woodley Packard and Steven Stanek
 */


/* Uses a junk variable to make certain that GETs are unique. That is, after a change is made
 * a get request may return a different value from a call before the modification was made. You do
 * not want the browser to return an old cached version of the get after the modification.
 */
 var junk=Math.floor(Math.random()*100000000);

function xmlh()
{
	try {
		return new XMLHttpRequest();
	} catch(e) {
		var XMLHTTP_IDS = ['MSXML2.XMLHTTP.5.0', 'MSXML2.XMLHTTP.4.0', 'MSXML2.XMLHTTP.3.0', 'MSXML2.XMLHTTP', 'Microsoft.XMLHTTP'];
		for(var i in XMLHTTP_IDS) {
			try { return new ActiveXObject(XMLHTTP_IDS[i]); }
			catch(e) {}
		}
		alert("unable to create xmlhttprequest");
		return null;
	}
}

function urlencode(string)
{
	string = string.replace(new RegExp("%", "g"), "%25");
	string = string.replace(new RegExp("#", "g"), "%23");
	string = string.replace(new RegExp("\\+", "g"), "%2B");
	string = string.replace(new RegExp("&", "g"), "%26");
	string = string.replace(new RegExp("=", "g"), "%3D");
	string = string.replace(new RegExp("/", "g"), "%2F");
	string = string.replace(new RegExp(" ", "g"), "+");
	return string;
}

function urldecode(string)
{
	string = string.replace(new RegExp("\\+", "g"), " ");
	string = string.replace(new RegExp("%23", "g"), "#");
	string = string.replace(new RegExp("%2B", "g"), "+");
	string = string.replace(new RegExp("%26", "g"), "&");
	string = string.replace(new RegExp("%3D", "g"), "=");
	string = string.replace(new RegExp("%2F", "g"), "/");
	string = string.replace(new RegExp("%25", "g"), "%");
	string = string.replace(new RegExp("%20", "g"), " ");
	return string;
}

var dontbothermeagain = 0;
function ajaxPost(target, type, data)
{
	var req = xmlh();
	req.open('POST', target, false);
	req.setRequestHeader("Content-type", type);
	req.send(data);
	if(req.status == 200)
	{
		if(req.responseText == "200 Session Expired")
		{
			if(!dontbothermeagain)alert("Your session has expired.  Please log in again.");
			dontbothermeagain=1;
			throw("session expired");
		}
		return req.responseText;
	}
	else alert(req.status + ": " + req.statusText);
	return null;
}

function ajaxGet(target)
{
	var req = xmlh();
	if(target.search("\\?") != -1)
		req.open('GET', target+"&junk="+junk, false);
	else
		req.open('GET', target+"?junk="+junk, false);
	req.send("");
	if(req.status == 200)
	{
		if(req.responseText == "200 Session Expired\n" || req.responseText == "200 Session Expired")
		{
			if(!dontbothermeagain)alert("Your session has expired.  Please log in again.");
			dontbothermeagain=1;
			throw("session expired");
		}
		return req.responseText;
	}
	else alert(target + "\n" + req.status + ": " + req.statusText);
	return null;
}