var banners;
var banner_count;
var show_seconds = 3000;

function rotateBanner() {
	banners = getElementsByClassName('main_banner');
	banner_count = banners.length;
	if (banner_count > 1) {
		nextBanner(1);
	}
}

function hideBanner(id) {
	new Effect.Fade('banner' + id);
}

function showBanner(id) {
	new Effect.Appear('banner' + id);
}

function nextBanner(id) {
	window.setTimeout('hideBanner(' + id + ')',show_seconds);
	id++;
	if (id > banner_count) {
		id = 1;
	}
	window.setTimeout('showBanner(' + id + ')',show_seconds);
	window.setTimeout('nextBanner(' + id + ')',show_seconds * 2);
}

function getElementsByClassName(className, tag, elm){
	var testClass = new RegExp("(^|\\\\s)" + className + "(\\\\s|$)");
	var tag = tag || "*";
	var elm = elm || document;
	var elements = (tag == "*" && elm.all)? elm.all : elm.getElementsByTagName(tag);
	var returnElements = [];
	var current;
	var length = elements.length;
	for(var i=0; i<length; i++){
		current = elements[i];
		if(testClass.test(current.className)){
			returnElements.push(current);
		}
	}
	return returnElements;
}