// JavaScript Document
var focusContsID = "focus_conts";
var focusBtnsID = "focus_btns";
var focusPicID = "focus_big_pic";
var focusTxtID = "focus_link_txt"; 
var curren = "curren";
var normal = "normal";
var Length = 0; 
var autoPlay = true;
var interval = 3500;

 //删除一个独立的dom节点
function remove(elem){
	if(elem != null){
		elem.parentNode.removeChild(elem);
	}
}
//查找相关元素的后一个兄弟元素
function next(elem){
	do{elem = elem.nextSibling;}while(elem && elem.nodeType != 1);
	return elem;
}
//查找元素第一个子元素
function first(elem){
	elem = elem.firstChild;
	return (elem && elem.nodeType!=1)?next(elem):elem;
}
//查找相关元素的前一个兄弟元素	
function prev(elem){
	do{ elem = elem.previousSibling;	}while(elem && elem.nodeType != 1);
	return elem;
}
//查找元素最后一个子元素
function last (elem){
	elem = elem.lastChild;
	return (elem && elem.nodeType!=1)?prev(elem):elem;
} 
//为另一个元素追加一个子元素
function append(parent,elem){
	if(elem != null){
		parent.appendChild(elem);
	}
}
//在一个元素之前插入元素
function before(parent,before,elem){
	if(elem != null){
		parent.insertBefore(elem,before);
	}
}
 
function changeCont(index){
	if(index<0 || !index) index= 0;
	var child_node,clone_node;
	var focus_node = document.getElementById(focusContsID).getElementsByTagName('a')[index];   
	
	var focusPic = document.getElementById(focusPicID);
	child_node = first(focusPic);
	if(child_node){ remove(child_node);} 
	var focusTxt = document.getElementById(focusTxtID);
	child_node = first(focusTxt);
	if(child_node){ remove(child_node);}   
	
	clone_node = focus_node.cloneNode(true);
	child_node = first(clone_node);
	remove (child_node);
	append(focusTxt,clone_node);
	 
	clone_node = focus_node.cloneNode(true);
	child_node = last(clone_node);
	remove (child_node);
	append(focusPic,clone_node);
 
	var focusBtns = document.getElementById(focusBtnsID).getElementsByTagName('li'); 
	for(var i=0; i<Length; i++) {
		focusBtns[i].className = "normal";  
	}
	focusBtns[index].className = "curren"; 
	 
}
function init() {
	if(!document.getElementById(focusContsID)) return false;
	if(!document.getElementById(focusBtnsID)) return false;
	if(!document.getElementById(focusPicID)) return false;
	if(!document.getElementById(focusTxtID)) return false;
	var focusBtns = document.getElementById(focusBtnsID).getElementsByTagName('li'); 
	
	Length = focusBtns.length;
	changeCont(); 
	setInterval('autoiFocus()',interval);
	
	document.getElementById(focusPicID).onmouseout = function(){ autoPlay = true;};
	document.getElementById(focusPicID).onmouseover = function(){ autoPlay = false;};  
	for (var i=0;i<Length;i++){ 
		focusBtns[i].tabindex=i;
		focusBtns[i].onmouseover = function(){ 
			changeCont(this.tabindex); 
			autoPlay = false;
		}
		focusBtns[i].onmouseout = function(){  
			autoPlay = true;
		}
	}  
} 
function autoiFocus() { 
	if(!autoPlay) return false;
	var focusBtns = document.getElementById(focusBtnsID).getElementsByTagName('li'); 
	var nowIndex = -1;
	for(var i=0; i<Length; i++) {
		if (focusBtns[i].className == curren )  nowIndex = i;
	}
	var nextIndex = (nowIndex + 1)%Length;
	changeCont(nextIndex); 
}