// Adds an eventlistner to object
function addEvent(object, type, func) {
	if(object.addEventListener)
		object.addEventListener(type, func, false);
	else if (object.attachEvent)
		object.attachEvent("on" + type, func);
}

// Removes an eventlistner from object
function removeEvent(object, type, func) {
	if(object.removeEventListener)
		object.removeEventListener(type, func, false);
	else if (object.detachEvent)
		object.detachEvent("on" + type, func);
}

// Class for requesting updates periodically using ajax
function StatusUpdate(_url, _frequency) {
	var request;
	var timer;
	var url = _url;
	var frequency = _frequency * 1000;
	var me = this;
	var callbacks = new Object();
	var updates = new Object();

	this.start = function() {
		if((!window.XMLHttpRequest && !window.ActiveXObject) || frequency == 0) return false;

		timer = setTimeout(me.doUpdate, frequency);
	}

	this.stop = function() {
		clearTimeout(timer);

		request = null;
	}

	this.onUpdate = function(id, func) {
		callbacks[id] = func;
	}

	this.doUpdate = function() {
		if(request && request.readyState < 4) return;
		if(window.XMLHttpRequest) request = new XMLHttpRequest();
		if(window.ActiveXObject) request = new ActiveXObject("Microsoft.XMLHTTP");
		request.open("GET", url, true);
		request.onreadystatechange = function() {
			if(request.readyState < 4 || request.status != 200) return;
			var activeCallbacks = new Array();
			var regex = /\{(\w+)::([^\}]*)\}/g;

			while(result = regex.exec(request.responseText)) {
				var key = result[1];
				var value = result[2];
				if(defined(updates[key]) && updates[key] == value) continue;
				updates[key] = value;
				if(defined(callbacks[key])) activeCallbacks.push(callbacks[key]);
				setElementContent(key, value);
			}
			for(var i = 0; i < activeCallbacks.length; i++) { (activeCallbacks[i])(updates); }
			timer = setTimeout(me.doUpdate, frequency);
		}
		request.send("");
	}

	this.forceUpdate = function() {
		this.stop();
		this.doUpdate();
	}
}