var isIE = (document.all) ? true : false;

var $ = function (id) {
	return "string" == typeof id ? document.getElementById(id) : id;
};

if(!isIE){
	HTMLElement.prototype.__defineGetter__("currentStyle", function () {
		return this.ownerDocument.defaultView.getComputedStyle(this, null);
	});
}

var Class = {
  create: function() {
	return function() {
	  this.initialize.apply(this, arguments);
	}
  }
}

Object.extend = function(destination, source) {
	for (var property in source) {
		destination[property] = source[property];
	}
	return destination;
}


var FadeStruct = function(options){
	this.run = false;//是否渐变
	this.start = 0;//开始值
	this.end = 0;//结束值
	this.target = 0;//目标值
	Object.extend(this, options || {});
}

var Fade = Class.create();
Fade.prototype = {
  initialize: function(obj, options) {
	
	var obj = $(obj);
	obj.style.overflow = "hidden";
	this._obj = obj;
	
	this._timer = null;//定时器
	this._finish = true;//是否执行完成
	this._fun = function(){};//渐变程序
	this._x = this._y = 0;//变换点位置
	
	//设置获取透明度程序
	this._setOpacity = isIE ? function(opacity){ obj.style.filter = "alpha(opacity:" + opacity + ")"; } : function(opacity){ obj.style.opacity = opacity / 100; };
	this._getOpacity = isIE ? function(){ return parseInt(obj.filters["alpha"].opacity); } : function(opacity){ return 100 * parseFloat(obj.currentStyle.opacity); };
	
	//获取边框宽度程序
	this._xBorder = function(){ return (parseInt(obj.currentStyle.borderLeftWidth) + parseInt(obj.currentStyle.borderRightWidth)); }
	this._yBorder = function(){ return (parseInt(obj.currentStyle.borderTopWidth) + parseInt(obj.currentStyle.borderBottomWidth)); }
	
	this.SetOptions(options);
	
	this.Mode = this.options.Mode;
	this.Time = Math.abs(this.options.Time);
	this.onFinish = this.options.onFinish;
	
	//先设置特殊默认值
	this.Opacity = new FadeStruct({ end: 100 });
	this.Top = new FadeStruct({ start: this._obj.offsetTop, end: this._obj.offsetTop });
	this.Left = new FadeStruct({ start: this._obj.offsetLeft, end: this._obj.offsetLeft });
	this.Height = new FadeStruct({ end: this._obj.offsetHeight - this._yBorder() });
	this.Width = new FadeStruct({ end: this._obj.offsetWidth - this._xBorder() });
	
	//再设置用户默认值
	Object.extend(this.Opacity, this.options.Opacity);
	Object.extend(this.Top, this.options.Top);
	Object.extend(this.Left, this.options.Left);
	Object.extend(this.Height, this.options.Height);
	Object.extend(this.Width, this.options.Width);
	
	//变换位置参数
	this.Height.pos = Number(this.options.Height.pos);
	this.Width.pos = Number(this.options.Width.pos);
	
	//设置成默认状态
	this.Show = !this.options.Show;
	this.Step = 1;
	this.Start();
	//重新设置Step
	this.Step = Math.abs(this.options.Step);
  },
  //设置默认属性
  SetOptions: function(options) {
	this.options = {//默认值
		Step:		3,//变化率
		Time:		1,//变化间隔
		Opacity:	{},//透明渐变参数
		Height:		{},//高度渐变参数
		Width:		{},//宽度渐变参数
		Top:		{},//Top渐变参数
		Left:		{},//Left渐变参数
		Mode:		"both",//渐变顺序
		Show:		false,//是否默认打开状态
		onFinish:	function(){}//完成时执行
	};
	Object.extend(this.options, options || {});
  },		
  //触发
  Start: function() {
	clearTimeout(this._timer);
	//取反表示要设置的状态
	this.Show = !this.Show;
	//为避免透明度为null值，需要先设置一次透明度
	if(this.Opacity.run){ this._setOpacity(this.Show ? this.Opacity.start : this.Opacity.end); }
	//根据状态设置目标值
	if(this.Show){
		this.Opacity.target = this.Opacity.end;
		this.Top.target = this.Top.end;
		this.Left.target = this.Left.end;
		this.Height.target = this.Height.end;
		this.Width.target = this.Width.end;
	} else{
		this.Opacity.target = this.Opacity.start;
		this.Top.target = this.Top.start;
		this.Left.target = this.Left.start;
		this.Height.target = this.Height.start;
		this.Width.target = this.Width.start;
	}
	//设置渐变程序
	switch (this.Mode.toLowerCase()) {
		case "width" :
			this._fun = function(){
				this.SetWidth() && this.SetHeight();
				//由于分了两步，下面的步长变成两倍
				this.Step = 2*this.Step;
				this.SetOpacity(); this.SetTop(); this.SetLeft();
				this.Step = this.Step/2;
			}
			break;
		case "height" :
			this._fun = function(){
				this.SetHeight() && this.SetWidth();
				//由于分了两步，下面的步长变成两倍
				this.Step = 2*this.Step;
				this.SetOpacity(); this.SetTop(); this.SetLeft();
				this.Step = this.Step/2;
			}
			break;
		case "both" :
		default :
			this._fun = function(){ this.SetHeight(); this.SetWidth(); this.SetOpacity(); this.SetTop(); this.SetLeft();}
	}
	//获取变换点位置
	//由于设置变换点后与top和left变换有冲突只能执行其一
	if(this.Height.pos){ this._y = this._obj.offsetTop + this._obj.offsetHeight * this.Height.pos; this.Top.run = false; }
	if(this.Width.pos){ this._x = this._obj.offsetLeft + this._obj.offsetWidth * this.Width.pos; this.Left.run = false; }
	
	this.Run();
  },
  //执行
  Run: function() {
	clearTimeout(this._timer);
	this._finish = true;
	//执行渐变
	this._fun();
	//$("aa").innerHTML+=","
	//未完成继续执行
	if (this._finish) { this.onFinish(); }
	else { var oThis = this; this._timer = setTimeout(function(){ oThis.Run(); }, this.Time); }
  },
  //设置高度渐变
  SetHeight: function() {
	var iGet = this.Get(this.Height, this._obj.offsetHeight - this._yBorder());
	if(isNaN(iGet)) return true;
	
	//如果有变换点设置
	if(this.Height.pos){ this._obj.style.top = this._y - this._obj.offsetHeight * this.Height.pos + "px"; }
	this._obj.style.height = iGet + "px";
	return false;
  },
  //设置宽度渐变
  SetWidth: function() {
	var iGet = this.Get(this.Width, this._obj.offsetWidth - this._xBorder());
	if(isNaN(iGet)) return true;
	
	if(this.Width.pos){ this._obj.style.left = this._x - this._obj.offsetWidth * this.Width.pos + "px"; }
	this._obj.style.width = iGet + "px";
	return false;
  },
  //设置top渐变
  SetTop: function() {
	var iGet = this.Get(this.Top, this._obj.offsetTop);
	if(isNaN(iGet)) return true;
	
	this._obj.style.top = iGet + "px";
	return false;
  },
  //设置left渐变
  SetLeft: function() {
	var iGet = this.Get(this.Left, this._obj.offsetLeft);
	if(isNaN(iGet)) return true;
	
	this._obj.style.left = iGet + "px";
	return false;
  },
  //设置透明渐变
  SetOpacity: function() {
	var iGet = this.Get(this.Opacity, this._getOpacity());
	if(isNaN(iGet)) return true;
	
	this._setOpacity(iGet);
	return false;
  },
  //获取设置值
  Get: function(o, now){
	if(o.run){
		var iStep = (o.target - now) / this.Step;
		if(iStep){		
			this._finish = false;
			if(Math.abs(iStep) < 1){ iStep = iStep > 0 ? 1 : -1; }
			return now + iStep;
		}
	}
  }
};