/*!

** Unobtrusive Ajax support library for jQuery

** Copyright (C) Microsoft Corporation. All rights reserved.

*/

/*jslint white: true, browser: true, onevar: true, undef: true, nomen: true, eqeqeq: true, plusplus: true, bitwise: true, regexp: true, newcap: true, immed: true, strict: false */

/*global window: false, jQuery: false */

/*

data-ajax=true //开启绑定

data-ajax-mode//更新的形式 BEFORE插入到对象之前 AFTER插入到对象之后 为空就是覆盖

data-ajax-update//更新的对象

data-ajax-confirm//设置一个确定取消弹出框的文字，没有则不设置

data-ajax-loading//显示loading的对象

data-ajax-loading-duration//持续时间 默认是0

data-ajax-method//提交方式

data-ajax-url//提交url

data-ajax-begin//ajax前触发的函数或者一段程序

data-ajax-complete//完成后，此时还没有加载返回的数据，请求成功或失败时均调用

data-ajax-success//成功，加载完成的数据

data-ajax-failure//失败

*/

(function ($) {

    var data_click = "unobtrusiveAjaxClick",

        data_validation = "unobtrusiveValidation";

    //第二核心，判断是否函数，不是则构造一个匿名函数

    function getFunction(code, argNames) {

        var fn = window, parts = (code || "").split(".");

        while (fn && parts.length) {

            fn = fn[parts.shift()];

        }//查找函数名有时候是命名空间比如xxx.xxx

        if (typeof (fn) === "function") {

            return fn;

        }

        argNames.push(code);

        //如果不是函数对象则自己构造一个并返回，吊！

        return Function.constructor.apply(null, argNames);

    }

    function isMethodProxySafe(method) {

        return method === "GET" || method === "POST";

    }

    //可以添加各种提交方式，应该是为Web Api做的补充

    function asyncOnBeforeSend(xhr, method) {

        if (!isMethodProxySafe(method)) {

            xhr.setRequestHeader("X-HTTP-Method-Override", method);

        }

        //注：X-HTTP-Method-Override是一个非标准的HTTP报头。

        //这是为不能发送某些HTTP请求类型（如PUT或DELETE）的客户端而设计的

    }

    //完成后的

    function asyncOnSuccess(element, data, contentType) {

        var mode;

        if (contentType.indexOf("application/x-javascript") !== -1) {  // jQuery already executes JavaScript for us

            return;

        }

        mode = (element.getAttribute("data-ajax-mode") || "").toUpperCase();

        $(element.getAttribute("data-ajax-update")).each(function (i, update) {

            var top;

            switch (mode) {

            case "BEFORE":

                top = update.firstChild;

                $("<div />").html(data).contents().each(function () {

                    update.insertBefore(this, top);

                });

                break;

            case "AFTER":

                $("<div />").html(data).contents().each(function () {

                    update.appendChild(this);

                });

                break;

            default:

                $(update).html(data);

                break;

            }

        });

    }

    //主要函数

    //绑定的对象和参数

    function asyncRequest(element, options) {

        var confirm, loading, method, duration;

        confirm = element.getAttribute("data-ajax-confirm");

        if (confirm && !window.confirm(confirm)) {

            return;

        }

        loading = $(element.getAttribute("data-ajax-loading"));//

        duration = element.getAttribute("data-ajax-loading-duration") || 0;//默认是0

        $.extend(options, {

            type: element.getAttribute("data-ajax-method") || undefined,

            url: element.getAttribute("data-ajax-url") || undefined,

            beforeSend: function (xhr) {//ajax前触发，此处的xhr将在下面用apply传递出去

                var result;

                asyncOnBeforeSend(xhr, method);//判断是否添加特种的提交方式

                result = getFunction(element.getAttribute("data-ajax-begin"), ["xhr"]).apply(this, arguments);//argument：替换函数对象的其中一个属性对象，存储参数。这里是将原先的参数传递出去，吊！

                if (result !== false) {

                    loading.show(duration);

                }

                return result;

            },

            complete: function () {

                loading.hide(duration);

                getFunction(element.getAttribute("data-ajax-complete"), ["xhr", "status"]).apply(this, arguments);

            },

            success: function (data, status, xhr) {

                asyncOnSuccess(element, data, xhr.getResponseHeader("Content-Type") || "text/html");

                getFunction(element.getAttribute("data-ajax-success"), ["data", "status", "xhr"]).apply(this, arguments);

            },

            error: getFunction(element.getAttribute("data-ajax-failure"), ["xhr", "status", "error"])

        });

        options.data.push({ name: "X-Requested-With", value: "XMLHttpRequest" });

        method = options.type.toUpperCase();//大写

        if (!isMethodProxySafe(method)) {

            options.type = "POST";

            options.data.push({ name: "X-HTTP-Method-Override", value: method });

        }

        //最后都是调用jquery的ajax

        $.ajax(options);

    }

    function validate(form) {

        //可以取消验证

        var validationInfo = $(form).data(data_validation);

        return !validationInfo || !validationInfo.validate || validationInfo.validate();

    }

    $(document).on("click", "a[data-ajax=true]", function (evt) {

        evt.preventDefault();

        asyncRequest(this, {

            url: this.href,

            type: "GET",

            data: []

        });

    });

    $(document).on("click", "form[data-ajax=true] input[type=image]", function (evt) {//这个不常用

        var name = evt.target.name,

            $target = $(evt.target),

            form = $target.parents("form")[0],

            offset = $target.offset();

        $(form).data(data_click, [

            { name: name + ".x", value: Math.round(evt.pageX - offset.left) },

            { name: name + ".y", value: Math.round(evt.pageY - offset.top) }

        ]);

        setTimeout(function () {

            $(form).removeData(data_click);

        }, 0);

    });

    $(document).on("click", "form[data-ajax=true] :submit", function (evt) {

        var name = evt.target.name,

            form = $(evt.target).parents("form")[0];

        $(form).data(data_click, name ? [{ name: name, value: evt.target.value }] : []);

        setTimeout(function () {

            $(form).removeData(data_click);

        }, 0);

    });

    $(document).on("submit", "form[data-ajax=true]", function (evt) {

        var clickInfo = $(this).data(data_click) || [];

        evt.preventDefault();

        if (!validate(this)) {

            return;

        }

        asyncRequest(this, {

            url: this.action,

            type: this.method || "GET",

            data: clickInfo.concat($(this).serializeArray())//写得好，序列化表单并拼接，以后的ajax都可以这样，方便啊

        });

    });

}(jQuery));