var t;
var delay = 4 * 1000;
var delay_click = 10 * 1000;

function set_class(id,className){
	document.getElementById(id).className = className;

	var index = parseInt(className.substr(className.length-1,1));
	setBannerVisibility(index);

	clearTimeout(t);

	t = setTimeout('swapBanners()', delay);
}

function set_class_click(id,className){
	document.getElementById(id).className = className;

	var index = parseInt(className.substr(className.length-1,1));
	setBannerVisibility(index);

	clearTimeout(t);
}

function stop_rotation(){
	clearTimeout(t);
}

function resume_rotation(){
	t = setTimeout('swapBanners()', delay);
}

function swapBanners(){
  var active = $('#main');

  var old_class = active.attr("class")
  var index = parseInt(old_class.substr(old_class.length-1,1));


  if(index == 4){
	  index = 1;
  }else{
	  index = index + 1;
  }

  var new_class = old_class.substr(0,old_class.length - 1) + index;

  setBannerVisibility(index);

  //alert('old class= '+old_class + ' new idx = '+ index+' new class= ' + new_class);

  set_class('main',new_class);
}

//hack for IE
function setBannerVisibility(index){

  var banner;
  for(var i = 1; i<=4; i++){
	  banner = $('#banner'+i);
	  if(i == index){
		  banner.attr({style: "display:block"});
	  }
	  else{
		  banner.attr({style: "display:none"});
	  }
  }
}

$(document).ready(function(){
  t = setTimeout('swapBanners()', delay);
});