/**
 * [上下滚动]
 * @author: wsl(shuiling.wang@yoho.cn)
 * @date: 2016/12/13
 */

// 类创建函数
var Class = {
    create: function() {
        return function() {
            this.initialize.apply(this, arguments);
        };
    }
};

var Scroller = Class.create();

function $(element) {
    var i, length, elements;

    if (arguments.length > 1) {
        for (i = 0, length = arguments.length, elements = []; i < length; i++) {
            elements.push($(arguments[i]));
        }
        return elements;
    }
    if (typeof element === 'string') {
        return document.getElementById(element);
    } else {
        return element;
    }
}

// 对象属性方法扩展
Function.prototype.bind = function(object) { // eslint-disable-line
    var method = this;

    return function() {
        method.apply(object, arguments);
    };
};

Scroller.prototype = {

    // 第一个参数定义要滚动的区域,第二个参数定义每次滚动的高度
    initialize: function(element, height, delay) {
        this.element = $(element);
        this.element.innerHTML += this.element.innerHTML;
        this.height = height;
        this.delay = delay * 1000;
        this.maxHeight = this.element.scrollHeight / 2;
        this.counter = 0;
        this.scroll();
        this.timer = '';
        this.element.onmouseover = this.stop.bind(this);
        this.element.onmouseout = function() {
            this.timer = setTimeout(this.scroll.bind(this), 1000);
        }.bind(this);
    },
    scroll: function() {
        if (this.element.scrollTop < this.maxHeight) {
            this.element.scrollTop ++;
            this.counter ++;
        } else {
            this.element.scrollTop = 0;
            this.counter = 0;
        }

        if (this.counter < this.height) {
            this.timer = setTimeout(this.scroll.bind(this), 10);
        } else {
            this.counter = 0;
            this.timer = setTimeout(this.scroll.bind(this), this.delay);
        }
    },
    stop: function() {
        clearTimeout(this.timer);
    }
};

module.exports = Scroller;