var fgm = {
	$: function(id) {
		return typeof id === "object" ? id : document.getElementById(id);
	},
	$$: function(tagName, oParent) {
		return (oParent || document).getElementsByTagName(tagName);
	},
	$$$: function(className, element, tagName) {
		var i = 0, aClass = [], reClass = new RegExp("(^|\\s)" + className + "(\\s|$)"), aElement = fgm.$$(tagName || "*", element || document);
		for (i = 0; i < aElement.length; i++) reClass.test(aElement[i].className) && aClass.push(aElement[i]);
		return aClass;
	},
	index: function(element) {
		var aChildren = element.parentNode.children, i;
		for(i = 0; i < aChildren.length; i++) if(aChildren[i] === element) return i;
		return -1;
	},
	on: function(element, type, handler) {
		return element.addEventListener ? element.addEventListener(type, handler, !1) : element.attachEvent("on" + type, handler);	
	},
	bind: function(object, handler) {
		return function() {
			return handler.apply(object, arguments);
		};	
	}
};
function Tab(id) {
	this.obj = fgm.$(id);
	this.oTab = fgm.$$$("tab", this.obj)[0];
	this.aTab = fgm.$$("li", this.oTab);
	this.oSwitch = fgm.$$$("switchBtn", this.oTab)[0];
	this.oPrev = fgm.$$("a", this.oSwitch)[0];
	this.oNext = fgm.$$("a", this.oSwitch)[1];
	this.aItems = fgm.$$$("items", this.obj);
	this.iNow = 0;		
	fgm.on(this.oSwitch, "click", fgm.bind(this, this.fnClick));
	fgm.on(this.oTab, "click", fgm.bind(this, this.fnMouseOver));
}
Tab.prototype = {
	fnMouseOver: function(ev) {
		var oEv = ev || event,
		oTarget = oEv.target || oEv.srcElement;
		oTarget.tagName.toUpperCase() === "LI" && (this.iNow = fgm.index(oTarget));
		this.fnSwitch();
	},
	fnClick: function(ev) {
		var oEv = ev || event,
		oTarget = oEv.target || oEv.srcElement,
		i;
		switch(fgm.index(oTarget)) {
			case 0:
				if(oTarget.className == "prev") {
					this.aTab[this.iNow].style.display = "block";
					this.iNow--;	
				};
				break;
			case 1:
				if(oTarget.className == "next") {					
					for(i = 0; i < this.iNow; i++) this.aTab[i].style.display = "none";
					this.iNow++;	
				};
				break;
		};
		this.aTab[this.iNow].style.display = "block";		
		this.fnSwitch();	
	},
	fnSwitch: function() {
		for(var i = 0; i < this.aTab.length; i++) (this.aTab[i].className = "", this.aItems[i].style.display = "none");	
		this.aTab[this.iNow].className = "current";
		this.aItems[this.iNow].style.display = "block";
		this.oPrev.className = this.iNow == 0 ? "prevNot" : "prev";
		this.oNext.className = this.iNow == this.aTab.length - 1 ? "nextNot" : "next";
	}
};
//应用
fgm.on(window, "load", function() {
	var aItem = fgm.$$$("item"),
	i = 0;
	for(; i < aItem.length; i++) new Tab(aItem[i]);
});