function $(id) { return document.getElementById(id); }

function addLoadEvent(func){
	var oldonload = window.onload;
	if (typeof window.onload != 'function') {
		window.onload = func;
	} else {
		window.onload = function(){
			oldonload();
			func();
		}
	}
}

function addBtn() {
	if(!$('ibanner')||!$('ibanner_pic')) return;
	var picList = $('ibanner_pic').getElementsByTagName('a');
	if(picList.length==0) return;
	var btnBox = document.createElement('div');
	btnBox.setAttribute('id','ibanner_btn');
	var SpanBox ='';
	for(var i=1; i<=picList.length; i++ ) {
		var spanList = '<span class="normal">'+i+'</span>';
		SpanBox += spanList;
	}
	btnBox.innerHTML = SpanBox;
	$('ibanner').appendChild(btnBox);
	$('ibanner_btn').getElementsByTagName('span')[0].className = 'current';
	for (var m=0; m<picList.length; m++){
		var attributeValue = 'picLi_'+m
		picList[m].setAttribute('id',attributeValue);
	}
}

function classNormal(){
	var btnList = $('ibanner_btn').getElementsByTagName('span');
	for (var i=0; i<btnList.length; i++){
		btnList[i].className='normal';
	}
}

function picNormal() {
	var picList = $('ibanner_pic').getElementsByTagName('a');
	for (var i=0; i<picList.length; i++){
		picList[i].filters?(picList[i].filters[0].opacity= '0'):(picList[i].style.opacity='0');
		picList[i].style.zIndex='0';
	}
}

var timer;
function downOpacity(prevNum, nextID, delay) {
	clearInterval(timer);
	var picList = $('ibanner_pic').getElementsByTagName('a');
	picList[nextID].filters?(picList[nextID].filters[0].opacity= '100'):(picList[nextID].style.opacity='1');
	picList[nextID].style.zIndex='1';
	picList[prevNum].filters?(picList[prevNum].filters[0].opacity= '100'):(picList[prevNum].style.opacity='1');
	picList[prevNum].style.zIndex='2';
	var elem= document.getElementById('picLi_'+prevNum);
	var o= 9;
	timer= setInterval(function(){
		elem.filters?(elem.filters[0].opacity= o* 10):(elem.style.opacity = o/10);
		o-= 1;
		if ( o< 0 ) clearInterval(timer);
	},delay);
}

function iBanner() {
	if(!$('ibanner')||!$('ibanner_pic')||!$('ibanner_btn')) return;
	var btnList = $('ibanner_btn').getElementsByTagName('span');
	var picList = $('ibanner_pic').getElementsByTagName('a');
	if (picList.length==1) return;
	for (var m=0; m<btnList.length; m++){
		btnList[m].onmouseover = function() {
			for(var n=0; n<btnList.length; n++) {
				if (btnList[n].className == 'current') {
					var prevNum = n;
				}
			}
			var nextNum = this.childNodes[0].nodeValue-1;
			if(nextNum!=prevNum) {
				classNormal();
				this.className='current';
				picNormal();
				downOpacity(prevNum, nextNum, 30);
			}
		}
	}	
}

function autoBanner() {
	if(!$('ibanner')||!$('ibanner_pic')||!$('ibanner_btn')) return;
	var autoKey= false;
	$('ibanner').onmouseover = function(){autoKey = true};
	$('ibanner').onmouseout = function(){autoKey = false};
	var btnList = $('ibanner_btn').getElementsByTagName('span');
	var picList = $('ibanner_pic').getElementsByTagName('a');
	if(picList.length==1) return;
	setInterval(function(){
		if(autoKey) return;
		for(var i=0; i<btnList.length; i++) {
			if (btnList[i].className == 'current') {
				var prevNum = i;
			}
		}
		if (prevNum==(picList.length-1) ){
			classNormal();
			btnList[0].className='current';
			picNormal();
			downOpacity(prevNum, 0, 30);
		}else {
			classNormal();
			btnList[prevNum+1].className='current';
			picNormal();
			downOpacity(prevNum, prevNum+1, 30);
		}
	},5000);
}

addLoadEvent(addBtn);
addLoadEvent(iBanner);
addLoadEvent(autoBanner);