/*
 * Author: Alan Wei
 * Email: Alan.Wei@live.com
 * 
 * Create: 2016-02-02 18:20:15
 * Update: 2016-02-02 18:20:20
*/

(function () {
    if (!window.aUtils) window.aUtils = function () { };

    aUtils.EventBase = function () {

        //内部变量, 存储事件
        var eventStore = {
            exampleEventName: [{
                id: "用于监听标识, 主要用于注销事件.",
                callback: function () { /*回调*/ },
                current: {}, /*回调执行时的当前对象*/
                one: false /*是否是一次性监听*/
            }]
        };

        /**
         * 获取事件
         * @returns {} 
         */
        this.getEventStore = function () {
            return eventStore;
        };

        /**
         * 触发事件 (剩余的参数将会被依次传递到回调函数里)
         * @param {string} eventNames 事件名称(以空格分隔多个事件)
         * @param {object} current 回调函数中的this
         * @returns {this} 
         */
        this.emit = function (eventNames, current) {
            if (!eventNames || typeof (eventNames) !== "string") { return this; }

            var names = eventNames.split(" ");
            for (var index = 0; index < names.length; index++) {
                var eventName = names[index];

                var events = eventStore[eventName];
                if (!events || events.length <= 0) {
                    continue;
                }
                for (var i = 0; i < events.length; i++) {
                    var evt = events[i];
                    var callabck = evt.callback || function () { };
                    var args = Array.prototype.slice.call(arguments, 2, arguments.length);
                    /*
                 * 优先使用订阅事件时传递的this
                 * 如果注册时事件传递了current, 则回调函数的当前对象为注册时传递的current
                 * */
                    try {
                        callabck.apply(evt.current || current || this, args);
                    } catch (ex) {
                    }
                    if (evt.one) {
                        events.splice(i, 1);
                    }
                }
            }

            return this;
        };


        /**
         * 订阅事件
         * @param {string} eventNames 事件名称
         * @param {function} callback 事件触发时的回调
         * @param {string} eventId 事件标识
         * @param {object} current 回调函数中的this
         * @param {bool} isOne 是否是一次订阅
         * @returns {this} 
         */
        this.on = function (eventNames, callback, eventId, current, isOne) {
            if (!eventNames || typeof (eventNames) !== "string") { return this; }

            var names = eventNames.split(" ");
            for (var index = 0; index < names.length; index++) {
                var eventName = names[index];

                if (eventStore[eventName] === undefined) {
                    eventStore[eventName] = [];
                }
                var events = eventStore[eventName];
                if (eventId) {
                    /* 如果传递了 eventId, 通过赋值的方式注册事件, 这意味着在事件的注册表里, 同一个事件标识只能出现一次. */
                    for (var i = 0; i < events.length; i++) {
                        if (events[i]["id"] === eventId) {
                            events[i] = {
                                id: eventId,
                                callback: callback,
                                current: current,
                                one: !!isOne
                            };
                            continue;
                        }
                    }

                }
                events.push({
                    id: eventId || Date.now(),
                    callback: callback,
                    current: current,
                    one: !!isOne
                });
            }



            return this;
        };

        /**
         * 订阅发布即焚(一次性事件)事件
         * @param {string} eventNames 事件名称
         * @param {function} callback 事件订阅回调
         * @param {string} eventId 事件标识
         * @param {object} current 回掉函数中的this
         * @returns {this} 
         */
        this.one = function (eventNames, callback, eventId, current) {
            this.on(eventNames, callback, eventId, current, true);
        };


        /**
         * 取消订阅
         * @param {string} eventName 事件名称
         * @param {string} eventId 事件标识(on注册事件时传递的唯一值)
         * @returns {this} 
         */
        this.off = function (eventName, eventId) {
            var events = eventStore[eventName];
            if (!events || events.length <= 0) { return this; }

            if (arguments.length === 1) {
                /*如果没有传递eventId, 表示注销所有事件.*/
                eventStore[eventName] = [];
                return this;
            }

            for (var i = 0; i < events.length; i++) {
                var evt = events[i];
                if (evt["id"] === eventId) {
                    events.splice(i, 1);
                }
            }
            return this;
        };

        /**
         * 事件是否已经存在
         * @param {string} eventName 事件名称
         * @param {string} eventId 事件标识
         * @returns {bool}  是否存在
         */
        this.isExist = function (eventName, eventId) {
            var events = eventStore[eventName] || [];
            for (var i = 0; i < events.length; i++) {
                var found = events[i]["id"] === eventId;
                if (found) {
                    return true;
                }
            }
            return false;
        };



        /**
         * examples
         * @returns {} 
         */
        this.example = function () {
            this.on("exempleEvent", function (firstName, lastName) {
                console.log("this1", this);
                console.log("Hello " + firstName + " " + lastName);
            }, "greet1");

            this.on("exempleEvent", function (firstName, lastName) {
                console.log("this2", this);
                console.log("Hello " + firstName + " " + lastName);
            }, "greet2");

            this.on("exempleEvent", function (firstName, lastName) {
                console.log("this2-2", this);
                console.log("Hello " + firstName + " " + lastName);
            }, "greet2");

            this.on("exempleEvent", function (firstName, lastName) {
                console.log("this random", this);
                console.log("Hello " + firstName + " " + lastName);
            }, undefined, { random: true });

            this.one("exempleEvent", function (firstName, lastName) {
                console.log("thisOne", this);
                console.log("Hello " + firstName + " " + lastName);
            }, "greetone");

            this.emit("exampleEvent").emit("exampleEvent");
            return this;
        };
    };


    /**
     * 继承 aUtils.EventBase
     * @param {function} fn 继承 aUtils.EventBase
     * @returns {this} 
     */
    aUtils.EventBase.implement = function (fn) {
        fn.prototype = new aUtils.EventBase();
        fn.prototype.constructor = fn;
        return this;
    };

})();