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

var isIE6 = isIE && ([/MSIE (\d)\.0/i.exec(navigator.userAgent)][0][1] == 6);

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

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


var Extend = function(destination, source)
{
    for (var property in source)
    {
        destination[property] = source[property];
    }
}

var Bind = function(object, fun)
{
    return function()
    {
        return fun.apply(object, arguments);
    }
}

var Each = function(list, fun)
{
    for (var i = 0, len = list.length; i < len; i++) { fun(list[i], i); }
};

var Contains = function(a, b)
{
    return a.contains ? a != b && a.contains(b) : !!(a.compareDocumentPosition(b) & 16);
}


var OverLay = Class.create();
OverLay.prototype = {
    initialize: function(options)
    {

        this.SetOptions(options);

        this.Lay = $BX(this.options.Lay) || document.body.insertBefore(document.createElement("div"), document.body.childNodes[0]);

        this.Color = this.options.Color;
        this.Opacity = parseInt(this.options.Opacity);
        this.zIndex = parseInt(this.options.zIndex);

        with (this.Lay.style) { display = "none"; zIndex = this.zIndex; left = top = 0; position = "fixed"; width = height = "100%"; }

        if (isIE6)
        {
            this.Lay.style.position = "absolute";
            //ie6设置覆盖层大小程序
            this._resize = Bind(this, function()
            {
                this.Lay.style.width = Math.max(document.documentElement.scrollWidth, document.documentElement.clientWidth) + "px";
                this.Lay.style.height = Math.max(document.documentElement.scrollHeight, document.documentElement.clientHeight) + "px";
            });
            //遮盖select
            this.Lay.innerHTML = '<iframe style="position:absolute;top:0;left:0;width:100%;height:100%;filter:alpha(opacity=0);"></iframe>'
        }
    },
    //设置默认属性
    SetOptions: function(options)
    {
        this.options = {//默认值
            Lay: null, //覆盖层对象
            Color: "#CCC", //背景色
            Opacity: 50, //透明度(0-100)
            zIndex: 1000//层叠顺序
        };
        Extend(this.options, options || {});
    },
    //显示
    Show: function()
    {
        //兼容ie6
        if (isIE6) { this._resize(); window.attachEvent("onresize", this._resize); }
        //设置样式
        with (this.Lay.style)
        {
            //设置透明度
            isIE ? filter = "alpha(opacity:" + this.Opacity + ")" : opacity = this.Opacity / 100;
            backgroundColor = this.Color; display = "block";
        }
    },
    //关闭
    Close: function()
    {
        this.Lay.style.display = "none";
        if (isIE6) { window.detachEvent("onresize", this._resize); }
    }
};



var LightBox = Class.create();
LightBox.prototype = {
    initialize: function(box, options)
    {

        this.Box = $BX(box); //显示层

        this.OverLay = new OverLay(options); //覆盖层

        this.SetOptions(options);

        this.Fixed = !!this.options.Fixed;
        this.Over = !!this.options.Over;
        this.Center = !!this.options.Center;
        this.onShow = this.options.onShow;

        this.Box.style.zIndex = this.OverLay.zIndex + 1;
        this.Box.style.display = "none";

        //兼容ie6用的属性
        if (isIE6)
        {
            this._top = this._left = 0; this._select = [];
            this._fixed = Bind(this, function() { this.Center ? this.SetCenter() : this.SetFixed(); });
        }
    },
    //设置默认属性
    SetOptions: function(options)
    {
        this.options = {//默认值
            Over: true, //是否显示覆盖层
            Fixed: false, //是否固定定位
            Center: true, //是否居中
            onShow: function() { } //显示时执行
        };
        Extend(this.options, options || {});
    },
    //兼容ie6的固定定位程序
    SetFixed: function()
    {
        this.Box.style.top = document.documentElement.scrollTop - this._top + this.Box.offsetTop + "px";
        this.Box.style.left = document.documentElement.scrollLeft - this._left + this.Box.offsetLeft + "px";

        this._top = document.documentElement.scrollTop; this._left = document.documentElement.scrollLeft;
    },
    //兼容ie6的居中定位程序
    SetCenter: function()
    {
        this.Box.style.marginTop = document.documentElement.scrollTop - this.Box.offsetHeight / 2 + "px";
        this.Box.style.marginLeft = document.documentElement.scrollLeft - this.Box.offsetWidth / 2 + "px";
    },
    //显示
    Show: function(options)
    {
        //固定定位
        this.Box.style.position = this.Fixed && !isIE6 ? "fixed" : "absolute";

        //覆盖层
        this.Over && this.OverLay.Show();

        this.Box.style.display = "block";

        //居中
        if (this.Center)
        {
            this.Box.style.top = this.Box.style.left = "50%";
            //设置margin
            if (this.Fixed)
            {
                this.Box.style.marginTop = -this.Box.offsetHeight / 2 + "px";
                this.Box.style.marginLeft = -this.Box.offsetWidth / 2 + "px";
            } else
            {
                this.SetCenter();
            }
        }

        //兼容ie6
        if (isIE6)
        {
            if (!this.Over)
            {
                //没有覆盖层ie6需要把不在Box上的select隐藏
                this._select.length = 0;
                Each(document.getElementsByTagName("select"), Bind(this, function(o)
                {
                    if (!Contains(this.Box, o)) { o.style.visibility = "hidden"; this._select.push(o); }
                }))
            }
            //设置显示位置
            this.Center ? this.SetCenter() : this.Fixed && this.SetFixed();
            //设置定位
            this.Fixed && window.attachEvent("onscroll", this._fixed);
        }

        this.onShow();
    },
    //关闭
    Close: function()
    {
        this.Box.style.display = "none";
        this.OverLay.Close();
        if (isIE6)
        {
            window.detachEvent("onscroll", this._fixed);
            Each(this._select, function(o) { o.style.visibility = "visible"; });
        }
    }
};