/*
 * 跨域执行的ajax
 * @url: request url
 * @callback: callback function
 * @errorhandle: error handle function
 * @timer: request interval
 * @retrial: error request times(value=-1:infinity)
 * var playAjax = new AJAX_OBJ(url, onSuccessHandler,onErrorHandler,2, 1000);
	   playAjax.getRequestData();playAjax.postRequestData("");
	   onSuccessHandler(data)
	   onErrorHandler(data)
 */


var objPool = [];

function AJAX_OBJ(url, callback, errorhandle, timer, retrial) {
    this.xmlHttp = null;
    this.num = 0;
    this.url = url;
    this.urlParameters = "";
    this.callback = callback;
    this.errorhandle = errorhandle;

    this.timer = timer || 5000;
    this.timeout = -1;
    this.retrial = retrial || 1;

    this.childnodes = null;
}

/*创建 XMLHttpRequest 对象，IE 浏览器使用 ActiveXObject，而其他的浏览器使用名为 XMLHttpRequest 的 JavaScript 内建对象。*/
AJAX_OBJ.prototype.createXMLHttpRequest = function() {
    var xmlh = null;
    if (window.ActiveXObject) {
        xmlh = new ActiveXObject("Microsoft.XMLHttp");
    } else if (window.XMLHttpRequest) {
        xmlh = new XMLHttpRequest();
    }
    return xmlh;
}

/*获取一个XMLHttpRequest 对象*/
AJAX_OBJ.prototype.getInstance = function() {
    for (var i = 0; i < objPool.length; i++) {
        if (objPool[i].readyState == 0 || objPool[i].readyState == 4) { // 返回已有的readyState属性值为0或者4的XMLHttpRequest对象，readyState=0，请求未初始化（在调用 open() 之前）；readyState=4，请求已完成（可以访问服务器响应并使用它）
            return objPool[i];
        }
    }
    objPool[objPool.length] = this.createXMLHttpRequest(); //如果已有的XMLHttpRequest对象都属于非空闲状态，则创建返回一个新的XMLHttpRequest对象
    return objPool[objPool.length - 1];
}

/*GET请求数据*/
AJAX_OBJ.prototype.getRequestData = function(heads) {
    this.xmlHttp = this.getInstance(); //获取一个XMLHttpRequest 对象
    var request_url = this.url + this.urlParameters; //服务器端脚本的 URL

    // alert(request_url);
    var self = this;
    if (request_url.indexOf("?") > -1) {
        request_url = request_url + "&random=" + Math.random(); //如果XMLHttpRequest提交的URL与历史一样则使用缓存，地址后面加上随机数可以避免使用缓存，取到最新的数据
    } else {
        request_url = request_url + "?random=" + Math.random();
    }

    this.xmlHttp.onreadystatechange = function() { //每当 readyState 改变时，onreadystatechange 函数就会被执行。
        self.stateChanged();
    };

    this.xmlHttp.open("GET", request_url, true); //向服务器发送一个请求

    if (heads == "chaoxing") {
        this.setRequestHeader(heads); //设置请求头
    } else {
        this.setDefaultRequestHeader(heads); //设置请求头
    }


    this.xmlHttp.send(null);
    //显示加载
    //showLoading();
}

/*POST请求数据*/
AJAX_OBJ.prototype.postRequestData = function(param, heads) {
    this.xmlHttp = this.getInstance(); //获取一个XMLHttpRequest 对象
    var request_url = this.url + this.urlParameters; //服务器端脚本的 URL
    //alert(request_url);
    var self = this;
    if (request_url.indexOf("?") > -1) {
        request_url = request_url + "&random=" + Math.random(); //如果XMLHttpRequest提交的URL与历史一样则使用缓存，地址后面加上随机数可以避免使用缓存，取到最新的数据
    } else {
        request_url = request_url + "?random=" + Math.random();
    }

    this.xmlHttp.onreadystatechange = function() { //每当 readyState 改变时，onreadystatechange 函数就会被执行。
        self.stateChanged();
    };

    this.xmlHttp.open("POST", request_url, true); //向服务器发送一个请求
    this.setDefaultRequestHeader(heads); //设置请求头

    if (param == null || param === undefined || param == "") {
        this.xmlHttp.send(null);
    } else {
        this.xmlHttp.send(param);
    }
    //显示加载
    //showLoading();
}

/* 自定义请求头信息，heads对象，key-value形式 */
AJAX_OBJ.prototype.setDefaultRequestHeader = function(heads) {
        this.xmlHttp.setRequestHeader("Content-type", "application/json;charset=utf-8");
        this.xmlHttp.setRequestHeader("Accept", "application/json;charset=UTF-8");
        this.xmlHttp.setRequestHeader("normal_login_token", cookieHandler.get("normal_login_token"));
        //   this.xmlHttp.setRequestHeader("prodCode","fxcloud2.0");
        heads = heads || {};
        for (var key in heads) {
            this.xmlHttp.setRequestHeader(key, heads[key]);
        }
    }
    /*超星图书请求头信息，head对象，key-value形式 */
AJAX_OBJ.prototype.setRequestHeader = function(heads) {
        this.xmlHttp.setRequestHeader("Content-type", "application/json;charset=utf-8");
        this.xmlHttp.setRequestHeader("Accept", "application/json;charset=UTF-8");
        //this.xmlHttp.setRequestHeader("Content-length",param.length);
        heads = heads || {};
        for (var key in heads) {
            this.xmlHttp.setRequestHeader(key, heads[key]);
        }
    }
    /*每当 readyState 改变时,执行此方法*/
AJAX_OBJ.prototype.stateChanged = function() {
    if (this.xmlHttp.readyState == 4) { //请求已完成
        if (this.xmlHttp.status == 200) { //请求成功时，调用回到函数callback,将请求到的对象作为函数参数
            //隐藏加载
            //hiddenLoading();
            if (this.xmlHttp.getResponseHeader("normal_login_token") == null) {
                // console.log('--------------token 未过期-------------')
            } else {
                var token = this.xmlHttp.getResponseHeader("normal_login_token");
                cookieHandler.set("normal_login_token", token); //保存最新token
                // 解析token 设置isli
                verifyToken(token);
            }
            this.callback(this.xmlHttp);
        } else { //error handling 请求失败时，再次请求
            //alert("请求失败");
            this.num++;
            //隐藏加载
            //hiddenLoading();
            this.errorhandle(this.xmlHttp.status);
            if (this.retrial != -1 && this.num < this.retrial) {
                clearTimeout(this.timeout);
                //this.timeout = setTimeout(function(){self.requestData();}, this.timer);
            } else if (this.retrial == -1) { //
                var self = this;
                clearTimeout(this.timeout);
                //this.timeout = setTimeout(function(){self.requestData();}, this.timer);
            }
        }
    }
}

/*向请求地址增加参数*/
AJAX_OBJ.prototype.addParameter = function(params) {
    if (params.length > 0) {
        this.urlParameters = "";
        for (var i = 0; i < params.length; i++) {
            var curr_param = params[i];
            if (i == 0) this.urlParameters += "?" + curr_param.name + "=" + curr_param.value;
            else this.urlParameters += "&" + curr_param.name + "=" + curr_param.value;
        }
    }
}

/*获取返回来的xml数据的某个节点*/
AJAX_OBJ.prototype.getNodes = function(param, index) {
    if (typeof(this.xmlHttp.responseXML) != "undefined") {
        if (typeof(param) != "undefined" && typeof(index) != "undefined") {
            this.childnodes = this.xmlHttp.responseXML.getElementsByTagName(param)[index].childNodes;
            return this.childnodes;
        } else if (typeof(param) != "undefined") {
            this.childnodes = this.xmlHttp.responseXML.getElementsByTagName(param);
            return this.childnodes;
        } else {
            return null;
        }
    } else {
        return null;
    }
}