var numberOfImages = 12;
var timer;
var imgBaseDir = "/common/images";
include('/common/js/snow.js');

window.onload=function(){

	//initsnow();
	$('hpimage').src = imgBaseDir + "/header/"+getNewImage();
	timer = new PeriodicalExecuter(changeImage,10);	
	//showFirefoxWarning();
}

function changeImage(){

	timer.stop();
	var picId = 'hpimage';
	var oldSrc = $(picId).src;
	var src= imgBaseDir + "/header/"+getNewImage();
	while (isSameImage(oldSrc,src)){
		src= imgBaseDir + "/header/"+getNewImage();
	}
	var img = new Image();
	img.name=picId
	img.onload=function(img){
		var img=this;
		var id = "hpimage";
		var hide =  new Effect.Fade(id, {duration: 1.0, from:1.0, to:0.01, queue: { scope: id, position: 'front' }, afterFinish: function(effect) {
			$(id).src=effect.img.src;
			$(id).name=effect.img.name;
			new Effect.Appear(id, { duration: 1.0, from:0.01, to:1.0, queue: { scope: id, position: 'front' }});
			timer = new PeriodicalExecuter(changeImage,10);
		}});
		hide.img=img;
	};
	img.src=src;
}

function getNewImage(){

	var num = Math.floor(Math.random()*numberOfImages)+1;
	return "header"+num+".gif";
}

function isSameImage(oldSrc,newSrc){
	return getImageName(oldSrc)==getImageName(newSrc);
}

function getImageName(src){
	var lastSlash = src.lastIndexOf("/");
	return src.substring(lastSlash,src.length);
}

function include(filename) {
	var head = document.getElementsByTagName('head')[0];
	
	script = document.createElement('script');
	script.src = filename;
	script.type = 'text/javascript';
	
	head.appendChild(script)
}

function showFirefoxWarning() {
	if (navigator.userAgent.indexOf("Firefox")!=-1) {

		var warning=getCookie("CMES-FIREFOX-WARNING")
		if (warning.length==0) {
			document.cookie="CMES-FIREFOX-WARNING=true"
			insertMessage(); 
			Element.show('messageInfo');
			Element.show('messageBackground');
		}

	}
}

function closeFirefoxWarning() {
	Element.hide('messageInfo');
	Element.hide('messageBackground');
}

function insertMessage() {

	var code = "<div id='messageBackground' style='display:none'></div>";
	code += "<div id='messageInfo' style='display:none'>"
	code += "<h2>Important Notice</h2>";
	code += "<p>We have received reports of problems accessing some of the pages on our website using Mozilla Firefox. The symptom is a page that appears to be loading but never does. This problem appears to be caused by a known caching bug in Firefox. More information about this can be found on the <a href='https://bugzilla.mozilla.org/show_bug.cgi?id=571521' target='_blank'>Mozilla support pages</a></p>";
	code += "<p>If you experience problems accessing our website please use another browser such as Microsoft Internet Explorer or <a href='http://www.google.com/chrome' target='_blank'>Google Chrome</a></p>";
	code += "<p>The Coventry Model Engineering Society wish to apologise for this inconvenience</p>";
	code += "<p><input type='button' value='Continue...' onClick='closeFirefoxWarning()' /></p>";
	code += "</div>";


	new Insertion.Bottom('mainContentTable', code);

}

function getCookie(Name) {
  var search = Name + "="
  var returnvalue = "";
  if (document.cookie.length > 0) {
    offset = document.cookie.indexOf(search)
    // if cookie exists
    if (offset != -1) { 
      offset += search.length
      // set index of beginning of value
      end = document.cookie.indexOf(";", offset);
      // set index of end of cookie value
      if (end == -1) end = document.cookie.length;
      returnvalue=unescape(document.cookie.substring(offset, end))
      }
   }
  return returnvalue;
}