function resolve_promise_value(promise,value) {//PromiseA+的完成
    var then;
    /*
        ret false 申明没有实行promise._resolve里的函数
        ret true 申明实行了promise._resolve里的函数
        ret error 申明实行promise._resolve里的函数过程当中涌现毛病
    */
    var ret = false;
    
    /*
        resolve(promise)和实行resolve状况时的回调函数后返回的效果都须要实行resolve(promise,value)
    */
    if (value === promise) {//传进来的对象不能即是当前的Promise对象
        promise.reject(new TypeError('TypeError'));
    } else if (value && value instanceof Promise){//回调返回的值或许resolve的值是Promise对象时须要守候该Promise对象的状况变动
        value.then(promise.resolve.bind(promise),promise.reject.bind(promise));
    } else if (type(value) === 'Object' || type(value) === 'Function') {
        try {
            then = value.then;
        } catch(getThenErr) {
            promise.reject(thenErr);
        }
        if (type(then) === 'Function') {
            try {
                then.call(value,promise.resolve.bind(promise),promise.reject.bind(promise));
            } catch(callThenErr) {
                if (promise.state === 'pending') {
                    promise.reject(callThenErr);
                } 
            }
        } else {
            ret = true;
            var fn;
            promise.setState('fulfilled');//设置当前Promise状况的状况和值
            promise.value = value;
            var error;
            while (fn = promise._resolve.shift()) {//实行resolve回调行列里的函数
                try {
                    if (typeof fn == 'function') {
                        var result = fn(value);
                        promise.value = result;
                    } 
                } catch (err) {
                    ret || (ret = err);//纪录第一个实行失足的函数的非常信息
                }
            }
        }
    }  else {
        ret = true;
        var fn;
        promise.setState('fulfilled');//设置当前Promise状况的状况和值
        promise.value = value;
        var error;
        while (fn = promise._resolve.shift()) {//实行resolve回调行列里的函数
            try {
                if (typeof fn == 'function') {
                    var result = fn(value);
                    promise.value = result;
                } 
            } catch (err) {
                (ret instanceof Error) || (ret = err);
            }
        }
    }

    if (promise.next) {
        if (ret === true) {
            resolve_promise_value(promise.next,promise.value);
        }
        else if (ret instanceof Error){
            promise.next.reject(ret);    
        }
    }
    
}

function type(arg) {//推断对象范例函数
    return  Object.prototype.toString.call(arg).match(/ (\w+)/)[1];
}

function Promise(fn,value,state) {
    if (!(this instanceof Promise)) {//防备不必new挪用Promise函数
        return new Promise(fn);
    }
    this._resolve = [];//Promise对象的fulfilled时实行的回调行列
    this._reject = [];//Promise对象的rejected时实行的回调行列
    this.next = null;//实行下一个Promise对象
    this.value = value || null;//当前Promise对象的值
    this.state = state || 'pending';//当前Promise对象的状况
    this.id = Promise.idFactory();
    /*
        new 的时刻假如有函数，就实行该函数，把resolve和reject函数作为参数传进去，而且绑定对应的Promise对象
    */
    try {
      fn && fn(this.resolve.bind(this),this.reject.bind(this));
    } catch (e) {
      this.reject(e);
    }
}

Promise.prototype = {
    equal: function(promise) {//依据id推断两个Promise对象是不是相称
        return promise && (type(promise.then) === 'Function') && (this.id === promise.id);
    },
    resolve: function(value) {
        if(this.state !== 'pending'){
            return;
        }
        setTimeout((function() {
            resolve_promise_value(this,value)
        }).bind(this),0);
        
    },
    setState: function(state) {//设置Promise对象的状况
        this.state = state;
    },
    reject: function(value) {
        if (this.state === 'pending') {
            setTimeout((function() {
                this.setState('rejected');//设置Promise对象状况
                this.value = value;//纪录Promise对象对应的值
                var fn;
                var error;
                if (this._reject.length === 0) {
                    if (this.next) {
                        this.next.reject(value);
                    }
                    return;
                }
                while (fn = this._reject.shift()) {//实行reject回调函数
                    try {
                        if (typeof fn == 'function') {//关于回调函数行列，只需纪录末了一个函数的实行效果
                            var result = fn(value);
                            this.value = result;
                        } 
                    } catch (err) {//捕捉非常，保证回调行列里的函数每一个都被实行
                        error || (error = err);
                    }
                }
                if (this.next) {
                    if (error) {
                        this.next.reject(error);
                    } 
                    /*
                        实行完当前Promise对象的回调后，假如Promise链上有下一个Promise对象，继承实行，当前的Promise对象的值传进去
                        假如error为true则申明上面代码实行中有非常，把非常对象传给下一个Promise对象
                    */
                    else {
                        resolve_promise_value(this.next,result);
                    }
                }
            }).bind(this),0)
            
        }
    },
    then: function(resolve,reject) {//增添resolve和reject回调
        if (this.state != 'pending') {//假如当前Promise对象已resolve或reject则依据当前Promise对象状况异步实行传进来的resolve或reject函数
            this.state === 'fulfilled' ? (resolve = resolve || function() {}) : (reject = reject || function() {});
            setTimeout(this.state === 'fulfilled' ? resolve.bind(null,this.value) : reject.bind(null,this.value),0);
            return;
        }
        (type(resolve) === 'Function') && this._resolve.push(resolve);//纪录resolve回调
        (type(reject) === 'Function') && this._reject.push(reject);
        this.next = new Promise();//返回一个新的Promise对象
        return this.next;
    },
    catch: function(reject) {//then(undefined,callback)的语法糖
        return this.then(void 0,reject);
    }
}
Promise.all = function(promiseArr) {
    if (type(promiseArr) !== 'Array') {//参数须要Promise数组
        new Error('need a Array');
    }
    var count = 0;
    var result = [];//纪录每一个Promise的效果
    var ret = new Promise();//返回新的Promose对象
    for (var i = 0; i< promiseArr.length ;i++) {
        promiseArr[i].then((function(i) {//每一个Promise fulfilled后纪录效果而且推断是不是悉数Promise对象已fulfilled
            return function(value) {
                result[i] = value;
                count++;
                if (count === promiseArr.length) {//悉数Promise fulfilled的话就实行resovle
                    ret.resolve(result); 
                }
            }
        })(i),function(value) {
            if (ret.state === 'pending') {//有一个Promise对象reject而且ret照样pending状况的话就直接返回
                ret.reject(value);
            }    
        })
    }
    return ret;
}

Promise.race = function(promiseArr) {
    if (type(promiseArr) !== 'Array') {
        new Error('need a Array');
    }
    var ret = new Promise();
    for (var i = 0; i< promiseArr.length ;i++) {
        promiseArr[i].then(function(value) {
            if (ret.state === 'pending') {//有一个Promise对象resolve的话就返回，而且摒弃其他的Promise对象的效果
                ret.resolve(value);
            }
        },function(value) {
            if (ret.state === 'pending') {//有一个Promise对象reject的话就返回，而且摒弃其他的Promise对象的效果
                ret.reject(value);
            }    
        });
    }
    return ret;
}

Promise.resolve = function(arg) {
    if (arg && typeof arg.then === 'function') {//参数是Promise对象的话直接返回
        return arg;
    } else {//否则用参数组织一个Promise对象
        var result = new Promise(null,arg,'fulfilled');
        //result.resolve(arg);
        return result;
    }
}

Promise.reject = function(arg) {//同resolve
    if (arg && typeof arg.then === 'function') {
        return arg;
    } else {
        var result = new Promise(null,arg,'reject');
        //result.reject(arg);
        return result;
    }
}
Promise.idFactory = (function() {//id组织工场，id用于比较是不是是同一个Promise对象
    var _id = 0;
    return function() {
        return _id += 1;
    }
})();

module.exports = Promise;