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

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

var CurrentStyle = function(element) {
    return element.currentStyle || document.defaultView.getComputedStyle(element, null);
}

var Bind = function(object, fun) {
    var args = Array.prototype.slice.call(arguments).slice(2);
    return function() {
        return fun.apply(object, args.concat(Array.prototype.slice.call(arguments)));
    }
}

/*Tween算子,用来设置图片切换的效果。
可能的值：Tween.Linear, Tween.Quad.easeIn, Tween.Quad.easeOut, Tween.Quad.easeInOut, Tween.Cubic.easeIn, Tween.Cubic.easeOut, 
        Tween.Cubic.easeInOut, Tween.Quart.easeIn, Tween.Quart.easeOut, Tween.Quart.easeInOut, Tween.Quint.easeIn, Tween.Quint.easeOut, 
        Tween.Quint.easeInOut, Tween.Sine.easeIn, Tween.Sine.easeOut, Tween.Sine.easeInOut, Tween.Expo.easeIn, Tween.Expo.easeOut, 
        Tween.Expo.easeInOut, Tween.Circ.easeIn, Tween.Circ.easeOut, Tween.Circ.easeInOut, Tween.Elastic.easeIn, Tween.Elastic.easeOut, 
        Tween.Elastic.easeInOut, Tween.Back.easeIn, Tween.Back.easeOut, Tween.Back.easeInOut, Tween.Bounce.easeIn, Tween.Bounce.easeOut, 
        Tween.Bounce.easeInOut*/
var Tween = {
    Linear: function(t, b, c, d) { return c * t / d + b; },
    Quad: {
        easeIn: function(t, b, c, d) {
            return c * (t /= d) * t + b;
        },
        easeOut: function(t, b, c, d) {
            return -c * (t /= d) * (t - 2) + b;
        },
        easeInOut: function(t, b, c, d) {
            if ((t /= d / 2) < 1) return c / 2 * t * t + b;
            return -c / 2 * ((--t) * (t - 2) - 1) + b;
        }
    },
    Cubic: {
        easeIn: function(t, b, c, d) {
            return c * (t /= d) * t * t + b;
        },
        easeOut: function(t, b, c, d) {
            return c * ((t = t / d - 1) * t * t + 1) + b;
        },
        easeInOut: function(t, b, c, d) {
            if ((t /= d / 2) < 1) return c / 2 * t * t * t + b;
            return c / 2 * ((t -= 2) * t * t + 2) + b;
        }
    },
    Quart: {
        easeIn: function(t, b, c, d) {
            return c * (t /= d) * t * t * t + b;
        },
        easeOut: function(t, b, c, d) {
            return -c * ((t = t / d - 1) * t * t * t - 1) + b;
        },
        easeInOut: function(t, b, c, d) {
            if ((t /= d / 2) < 1) return c / 2 * t * t * t * t + b;
            return -c / 2 * ((t -= 2) * t * t * t - 2) + b;
        }
    },
    Quint: {
        easeIn: function(t, b, c, d) {
            return c * (t /= d) * t * t * t * t + b;
        },
        easeOut: function(t, b, c, d) {
            return c * ((t = t / d - 1) * t * t * t * t + 1) + b;
        },
        easeInOut: function(t, b, c, d) {
            if ((t /= d / 2) < 1) return c / 2 * t * t * t * t * t + b;
            return c / 2 * ((t -= 2) * t * t * t * t + 2) + b;
        }
    },
    Sine: {
        easeIn: function(t, b, c, d) {
            return -c * Math.cos(t / d * (Math.PI / 2)) + c + b;
        },
        easeOut: function(t, b, c, d) {
            return c * Math.sin(t / d * (Math.PI / 2)) + b;
        },
        easeInOut: function(t, b, c, d) {
            return -c / 2 * (Math.cos(Math.PI * t / d) - 1) + b;
        }
    },
    Expo: {
        easeIn: function(t, b, c, d) {
            return (t == 0) ? b : c * Math.pow(2, 10 * (t / d - 1)) + b;
        },
        easeOut: function(t, b, c, d) {
            return (t == d) ? b + c : c * (-Math.pow(2, -10 * t / d) + 1) + b;
        },
        easeInOut: function(t, b, c, d) {
            if (t == 0) return b;
            if (t == d) return b + c;
            if ((t /= d / 2) < 1) return c / 2 * Math.pow(2, 10 * (t - 1)) + b;
            return c / 2 * (-Math.pow(2, -10 * --t) + 2) + b;
        }
    },
    Circ: {
        easeIn: function(t, b, c, d) {
            return -c * (Math.sqrt(1 - (t /= d) * t) - 1) + b;
        },
        easeOut: function(t, b, c, d) {
            return c * Math.sqrt(1 - (t = t / d - 1) * t) + b;
        },
        easeInOut: function(t, b, c, d) {
            if ((t /= d / 2) < 1) return -c / 2 * (Math.sqrt(1 - t * t) - 1) + b;
            return c / 2 * (Math.sqrt(1 - (t -= 2) * t) + 1) + b;
        }
    },
    Elastic: {
        easeIn: function(t, b, c, d, a, p) {
            if (t == 0) return b; if ((t /= d) == 1) return b + c; if (!p) p = d * .3;
            if (!a || a < Math.abs(c)) { a = c; var s = p / 4; }
            else var s = p / (2 * Math.PI) * Math.asin(c / a);
            return -(a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;
        },
        easeOut: function(t, b, c, d, a, p) {
            if (t == 0) return b; if ((t /= d) == 1) return b + c; if (!p) p = d * .3;
            if (!a || a < Math.abs(c)) { a = c; var s = p / 4; }
            else var s = p / (2 * Math.PI) * Math.asin(c / a);
            return (a * Math.pow(2, -10 * t) * Math.sin((t * d - s) * (2 * Math.PI) / p) + c + b);
        },
        easeInOut: function(t, b, c, d, a, p) {
            if (t == 0) return b; if ((t /= d / 2) == 2) return b + c; if (!p) p = d * (.3 * 1.5);
            if (!a || a < Math.abs(c)) { a = c; var s = p / 4; }
            else var s = p / (2 * Math.PI) * Math.asin(c / a);
            if (t < 1) return -.5 * (a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;
            return a * Math.pow(2, -10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p) * .5 + c + b;
        }
    },
    Back: {
        easeIn: function(t, b, c, d, s) {
            if (s == undefined) s = 1.70158;
            return c * (t /= d) * t * ((s + 1) * t - s) + b;
        },
        easeOut: function(t, b, c, d, s) {
            if (s == undefined) s = 1.70158;
            return c * ((t = t / d - 1) * t * ((s + 1) * t + s) + 1) + b;
        },
        easeInOut: function(t, b, c, d, s) {
            if (s == undefined) s = 1.70158;
            if ((t /= d / 2) < 1) return c / 2 * (t * t * (((s *= (1.525)) + 1) * t - s)) + b;
            return c / 2 * ((t -= 2) * t * (((s *= (1.525)) + 1) * t + s) + 2) + b;
        }
    },
    Bounce: {
        easeIn: function(t, b, c, d) {
            return c - Tween.Bounce.easeOut(d - t, 0, c, d) + b;
        },
        easeOut: function(t, b, c, d) {
            if ((t /= d) < (1 / 2.75)) {
                return c * (7.5625 * t * t) + b;
            } else if (t < (2 / 2.75)) {
                return c * (7.5625 * (t -= (1.5 / 2.75)) * t + .75) + b;
            } else if (t < (2.5 / 2.75)) {
                return c * (7.5625 * (t -= (2.25 / 2.75)) * t + .9375) + b;
            } else {
                return c * (7.5625 * (t -= (2.625 / 2.75)) * t + .984375) + b;
            }
        },
        easeInOut: function(t, b, c, d) {
            if (t < d / 2) return Tween.Bounce.easeIn(t * 2, 0, c, d) * .5 + b;
            else return Tween.Bounce.easeOut(t * 2 - d, 0, c, d) * .5 + c * .5 + b;
        }
    }
}


//容器对象,滑动对象,切换数量
var SlideTrans = function(container, slider, count, options) {
    this._slider = $(slider);
    this._container = $(container); //容器对象
    this._timer = null; //定时器
    this._count = Math.abs(count); //切换数量
    this._target = 0; //目标值
    this._t = this._b = this._c = 0; //tween参数

    this.Index = 0; //当前索引

    this.SetOptions(options);

    this.Auto = !!this.options.Auto;
    this.Duration = Math.abs(this.options.Duration);
    this.Time = Math.abs(this.options.Time);
    this.Pause = Math.abs(this.options.Pause);
    this.Tween = this.options.Tween;
    this.onStart = this.options.onStart;
    this.onFinish = this.options.onFinish;

    var bVertical = !!this.options.Vertical;
    this._css = bVertical ? "top" : "left"; //方向

    //样式设置
    var p = CurrentStyle(this._container).position;
    p == "relative" || p == "absolute" || (this._container.style.position = "relative");
    this._container.style.overflow = "hidden";
    this._slider.style.position = "absolute";

    this.Change = this.options.Change ? this.options.Change :
		this._slider[bVertical ? "offsetHeight" : "offsetWidth"] / this._count;
};
SlideTrans.prototype = {
    //设置默认属性
    SetOptions: function(options) {
        this.options = {//默认值
            Vertical: true, //是否垂直方向（方向不能改）
            Auto: true, //是否自动
            Change: 0, //改变量
            Duration: 50, //滑动持续时间
            Time: 10, //滑动延时
            Pause: 2000, //停顿时间(Auto为true时有效)
            onStart: function() { }, //开始转换时执行
            onFinish: function() { }, //完成转换时执行
            Tween: Tween.Quart.easeOut//tween算子
        };
        Extend(this.options, options || {});
    },
    //开始切换
    Run: function(index) {
        //修正index
        index == undefined && (index = this.Index);
        index < 0 && (index = this._count - 1) || index >= this._count && (index = 0);
        //设置参数
        this._target = -Math.abs(this.Change) * (this.Index = index);
        this._t = 0;
        this._b = parseInt(CurrentStyle(this._slider)[this.options.Vertical ? "top" : "left"]);
        this._c = this._target - this._b;

        this.onStart();
        this.Move();
    },
    //移动
    Move: function() {
        clearTimeout(this._timer);
        //未到达目标继续移动否则进行下一次滑动
        if (this._c && this._t < this.Duration) {
            this.MoveTo(Math.round(this.Tween(this._t++, this._b, this._c, this.Duration)));
            this._timer = setTimeout(Bind(this, this.Move), this.Time);
        } else {
            this.MoveTo(this._target);
            this.Auto && (this._timer = setTimeout(Bind(this, this.Next), this.Pause));
        }
    },
    //移动到
    MoveTo: function(i) {
        this._slider.style[this._css] = i + "px";
    },
    //下一个
    Next: function() {
        this.Run(++this.Index);
    },
    //上一个
    Previous: function() {
        this.Run(--this.Index);
    },
    //停止
    Stop: function() {
        clearTimeout(this._timer); this.MoveTo(this._target);
    }
};

function myRandom(iStart, iLast) {
    var iLength = iLast - iStart + 1;
    return Math.floor(Math.random() * iLength + iStart);
}