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 oScroll = this, oScroller = $(idScroller), oScrollMid = $(idScrollMid);
    
    this.SetOptions(options);
    this.Scroller = oScroller;    
    this.Speed = this.options.Speed;
    this.timer = null;
    this.Pause = 0;
    
    //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));
    
    //方向设置
    switch (this.options.Side.toLowerCase()) {
        case "right" :
            if(this.widthList <= this.widthScroller) return;
            this.Scroll = this.ScrollLeftRight;
            this.side = -1;
            break;
        case "left" :
            if(this.widthList <= this.widthScroller) return;
            this.Scroll = this.ScrollLeftRight;
            this.side = 1;
            break;
        case "down" :
            if(this.heightList <= this.heightScroller) return;
            this.Scroll = this.ScrollUpDown;
            this.side = -1;
            break;
        case "up" :
        default :
            if(this.heightList <= this.heightScroller) return;
            this.Scroll = this.ScrollUpDown;
            this.side = 1;
    }
    
    addEventHandler(oScroller, "mouseover", function() { oScroll.Stop(); });
    addEventHandler(oScroller, "mouseout", function() { oScroll.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:        20,//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
      PauseStep:    0//停顿时间(PauseHeight或PauseWidth大于0该参数才有效)
    };
    Object.extend(this.options, options || {});
  },  
  //上下滚动
  ScrollUpDown: function() {
    this.Scroller.scrollTop = this.GetScroll(this.Scroller.scrollTop, this.heightScroller, this.heightList, this.options.PauseHeight);
    
    var oScroll = this;
    this.timer = window.setTimeout(function(){ oScroll.Scroll(); }, this.Speed);
  },
  //左右滚动
  ScrollLeftRight: function() {
    //document.getElementById("test").innerHTML+=iStep+",";
    //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);
    
    var oScroll = this;
    this.timer = window.setTimeout(function(){ oScroll.Scroll(); }, this.Speed);
  },
  //获取设置滚动数据
  GetScroll: function(iScroll, iScroller, iList, iPause) {
    var oScroll = this, 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;
        } else {
            this.Pause += iStep;
        }
    }
    
    return (iScroll + iStep);
  },
  //开始
  Start: function() {
    this.Scroll();
  },
  //停止
  Stop: function() {
    clearTimeout(this.timer);
  }
};

window.onload = function(){
    new Scroller("idScroller", "idScrollMid",{ Side:"up", PauseHeight:25 });
   new Scroller("idScroller1", "idScrollMid1",{ Side:"up", PauseWidth:250, Speed:10 });
}