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

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;
}

function addEventHandler(oTarget, sEventType, fnHandler) {
    if (oTarget.addEventListener) {
        oTarget.addEventListener(sEventType, fnHandler, false);
    } else if (oTarget.attachEvent) {
        oTarget.attachEvent("on" + sEventType, fnHandler);
    } else {
        oTarget["on" + sEventType] = fnHandler;
    }
};


var Scroller = Class.create();
Scroller.prototype = {
    initialize: function(idScroller, idScrollMid, options) {
        var oThis = this, oScroller = $(idScroller), oScrollMid = $(idScrollMid);

        this.SetOptions(options);
        this.Side = this.options.Side || ["up"]; //方向
        this.scroller = oScroller;            //对象
        this.speed = this.options.Speed;    //速度
        this.timer = null;                    //时间
        this.pauseHeight = 0;                //定高
        this.pauseWidth = 0;                //定宽
        this.pause = 0;                        //定高(宽)
        this.side = 0;                        //参数

        //用于上下滚动
        this.heightScroller = parseInt(oScroller.style.height) || oScroller.offsetHeight;
        this.heightList = oScrollMid.offsetHeight;

        //用于左右滚动
        this.widthScroller = parseInt(oScroller.style.width) || oScroller.offsetWidth;
        this.widthList = oScrollMid.offsetWidth;

        //js取不到css设置的height和width

        oScroller.style.overflow = "hidden";
        oScrollMid.appendChild(oScrollMid.cloneNode(true));
        oScrollMid.appendChild(oScrollMid.cloneNode(true));

        addEventHandler(oScroller, "mouseover", function() { oThis.Stop(); });
        addEventHandler(oScroller, "mouseout", function() { oThis.Start(); });

        this.Start();
    },
    //设置默认属性
    SetOptions: function(options) {
        this.options = {//默认值
            Step: 1, //每次变化的px量
            Speed: 10, //速度(越大越慢)
            Side: ["up"], //滚动方向:"up"是上，"down"是下，"left"是左，"right"是右
            PauseHeight: 0, //隔多高停一次
            PauseWidth: 0, //隔多宽停一次
            //当上下和左右一起使用时必须设置PauseHeight和PauseWidth来设置转向位置
            PauseStep: 5000//停顿时间(PauseHeight或PauseWidth大于0该参数才有效)
        };
        Object.extend(this.options, options || {});
    },
    //转向
    Turn: function() {
        //通过设置方向数组的排列来转向
        this.Side.push(this.Side.shift().toLowerCase());
    },
    //上下滚动
    ScrollUpDown: function() {
        this.pause = this.pauseHeight;
        this.scroller.scrollTop = this.GetScroll(this.scroller.scrollTop, this.heightScroller, this.heightList, this.options.PauseHeight);
        this.pauseHeight = this.pause;

        var oThis = this;
        this.timer = window.setTimeout(function() { oThis.Start(); }, this.speed);
    },
    //左右滚动
    ScrollLeftRight: function() {
        this.pause = this.pauseWidth;
        //注意:scrollLeft超过1400会自动变回1400 注意长度
        this.scroller.scrollLeft = this.GetScroll(this.scroller.scrollLeft, this.widthScroller, this.widthList, this.options.PauseWidth);
        this.pauseWidth = this.pause;

        var oThis = this;
        this.timer = window.setTimeout(function() { oThis.Start(); }, this.speed);
    },
    //获取设置滚动数据
    GetScroll: function(iScroll, iScroller, iList, iPause) {
        var iStep = this.options.Step * this.side;

        if (this.side > 0) {
            if (iScroll >= (iList * 2 - iScroller)) { iScroll -= iList; }
        } else {
            if (iScroll <= 0) { iScroll += iList; }
        }

        this.speed = this.options.Speed;
        if (iPause > 0) {
            if (Math.abs(this.pause) >= iPause) {
                this.speed = this.options.PauseStep; this.pause = iStep = 0; this.Turn();
            } else {
                this.pause += iStep;
            }
        }

        return (iScroll + iStep);
    },
    //开始
    Start: function() {
        //方向设置
        switch (this.Side[0].toLowerCase()) {
            case "right":
                if (this.widthList < this.widthScroller) return;
                this.side = -1;
                this.ScrollLeftRight();
                break;
            case "left":
                if (this.widthList < this.widthScroller) return;
                this.side = 1;
                this.ScrollLeftRight();
                break;
            case "down":
                if (this.heightList < this.heightScroller) return;
                this.side = -1;
                this.ScrollUpDown();
                break;
            case "up":
            default:
                if (this.heightList < this.heightScroller) return;
                this.side = 1;
                this.ScrollUpDown();
        }
    },
    //停止
    Stop: function() {
        clearTimeout(this.timer);
    }
};

window.onload = function() {
    new Scroller("idScroller", "idScrollMid", { Side: ["up", "up"], PauseHeight: 175, PauseWidth: 150 });
}