function array_length(arr) {
  var length = 0;
  for(val in arr) {
     if(!(val in Array.prototype))
        length++;
  }
  return length;
}

var playlist	= 0;
var interval;

function lib_bwcheck() {
    this.ver	= navigator.appVersion;
    this.agent	= navigator.userAgent;
    this.dom	= document.getElementById ? 1 : 0;
    this.opera5	= (navigator.userAgent.indexOf("Opera")>-1 && document.getElementById) ? 1 : 0;
    this.ie5	= (this.ver.indexOf("MSIE 5") > -1 && this.dom && !this.opera5) ? 1 : 0; 
    this.ie6	= (this.ver.indexOf("MSIE 6") > -1 && this.dom && !this.opera5) ? 1 : 0;
    this.ie4	= (document.all && !this.dom && !this.opera5) ? 1 : 0;
    this.ie		= this.ie4 || this.ie5 || this.ie6
    this.mac	= this.agent.indexOf("Mac") > -1
    this.ns6	= (this.dom && parseInt(this.ver) >= 5) ? 1 : 0; 
    this.ns4	= (document.layers && !this.dom) ? 1 : 0;
    this.bw		= (this.ie6 || this.ie5 || this.ie4 || this.ns4 || this.ns6 || this.opera5);
    return this
}
var bw = lib_bwcheck();

function layerSwitch(whichLayer,state) {
	if (document.getElementById) {
		// this is the way the standards work
		var style2 = document.getElementById(whichLayer).style;
		if (bw.ie5 == 1 || bw.ie6 == 1) {
			style2.visibility = (state == 1 ? "visible" : "hidden");
		} else
			style2.display = (state == 1 ? "block" : "");

	} else if (document.all) {
		// this is the way old msie versions work
		var style2 = document.all[whichLayer].style;
		style2.display = (state == 1 ? "block" : "");
	} else if (document.layers) {
		// this is the way nn4 works
		var style2 = document.layers[whichLayer].style;
		style2.display = (state == 1 ? "block" : "");
	}
}

function showImageToggle() {
	//promoimage en promoheadline moeten juiste waarde krijgen
	document.getElementById('promoimage').src			= webroot + 'images/promo/' + promoimage[promoid[active]];
	document.getElementById('promoimage').alt			= promotext[promoid[active]];
	document.getElementById('promoheadline').innerHTML	= promotext[promoid[active]];
	
	if (document.getElementById('newslink' + promoid[active])) {
		if (typeof document.getElementById('promoheadline').href != 'undefined') {
			document.getElementById('promoheadline').href	= document.getElementById('newslink' + promoid[active]).href;
			document.getElementById('playlink').href		= document.getElementById('newslink' + promoid[active]).href;
			document.getElementById('promolink').href		= document.getElementById('newslink' + promoid[active]).href;
		}
		document.getElementById('newslink' + promoid[1]).className		= active == 1 ? 'blacktext' : 'graytext';
		document.getElementById('newslink' + promoid[2]).className		= active == 2 ? 'blacktext' : 'graytext';
		document.getElementById('newslink' + promoid[3]).className		= active == 3 ? 'blacktext' : 'graytext';
	}
}

function startShowLoop() {
	if (active > 0)
		clearInterval(interval);
	active++;
	if (active > 3)
		active = 1;
		
	showImageToggle();
	
	interval = window.setInterval("startShowLoop()", 5 * 1000);
}

function pauseShowLoop(mouseid) {
	clearInterval(interval);
	active = mouseid;
	
	showImageToggle();
}

function resumeShowLoop() {
	interval = window.setInterval("startShowLoop()", 5 * 1000);
}

function clickBack() {
	active = active == 1 ? array_length(promoimage) : active - 1;
	pauseShowLoop(active);
}

function clickNext() {
	active = active >= array_length(promoimage) ? 1 : active + 1;
	pauseShowLoop(active);
}

function init() {
	for(i in promoimage) {
		menubutton1_over = newImage(webroot + 'images/promo/' + promoimage[i]);
	}
	if (active == 0)
		startShowLoop();
	else
		interval = window.setInterval("startShowLoop()", 5 * 1000);
}