/*! Native Promise Only
    v0.7.6-a (c) Kyle Simpson
    MIT License: http://getify.mit-license.org
*/

(function UMD(name,context,definition){
	// special form of UMD for polyfilling across evironments
	context[name] = context[name] || definition();
	if (typeof module != "undefined" && module.exports) { module.exports = context[name]; }
	else if (typeof define == "function" && define.amd) { define(function $AMD$(){ return context[name]; }); }
})("Promise",typeof global != "undefined" ? global : this,function DEF(){
	/*jshint validthis:true */
	"use strict";

	var builtInProp,          // 对象属性定义函数
		cycle, 		  // 标识是否已发起异步执行请求 
		scheduling_queue, // 异步执行请求队列
		ToString = Object.prototype.toString, // 类型判断
		// 延迟执行函数
		timer = (typeof setImmediate != "undefined") ?
			function timer(fn) { return setImmediate(fn); } :
			setTimeout
	;

	// damnit, IE8.
	try {
		Object.defineProperty({},"x",{});
		builtInProp = function builtInProp(obj,name,val,config) {
			return Object.defineProperty(obj,name,{
				value: val,
				writable: true,
				configurable: config !== false
			});
		};
	}
	catch (err) {
		builtInProp = function builtInProp(obj,name,val) {
			obj[name] = val;
			return obj;
		};
	}

	// Note: using a queue instead of array for efficiency
	// 异步请求队列
	scheduling_queue = (function Queue() {
		var first // 指向队首元素
		  , last  // 指向队尾元素
		  , item;

		function Item(fn,self) {
			this.fn = fn;
			this.self = self;
			this.next = void 0;
		}

		return {
			// 元素入队
			add: function add(fn,self) {
				item = new Item(fn,self);
				if (last) {
					last.next = item;
				}
				else {
					first = item;
				}
				last = item;
				item = void 0;
			},
			// 清空队列 
			drain: function drain() {
				var f = first;
				first = last = cycle = void 0;

				// 从队首元素开始遍历所有队列元素
				while (f) {
					f.fn.call(f.self);
					f = f.next;
				}
			}
		};
	})();

	// 安排执行状态变化事件的处理函数
	function schedule(fn,self) {
		scheduling_queue.add(fn,self);
		// 防止重复发起异步执行请求
		if (!cycle) {
			cycle = timer(scheduling_queue.drain);
		}
	}

	// promise duck typing
	// 检查是否为thenable对象
	function isThenable(o) {
		var _then, o_type = typeof o;

		if (o != null &&
			(
				o_type == "object" || o_type == "function"
			)
		) {
			_then = o.then;
		}
		return typeof _then == "function" ? _then : false;
	}

	function notify() {
		for (var i=0; i<this.chain.length; i++) {
			notifyIsolated(
				this,
				(this.state === 1) ? this.chain[i].success : this.chain[i].failure,
				this.chain[i]
			);
		}
		this.chain.length = 0;
	}

	// NOTE: This is a separate function to isolate
	// the `try..catch` so that other code can be
	// optimized better
	function notifyIsolated(self,cb,chain) {
		var ret, _then;
		try {
			if (cb === false) {
				chain.reject(self.msg);
			}
			else {
				if (cb === true) {
					ret = self.msg;
				}
				else {
					ret = cb.call(void 0,self.msg);
				}

				if (ret === chain.promise) {
					chain.reject(TypeError("Promise-chain cycle"));
				}
				else if (_then = isThenable(ret)) {
					_then.call(ret,chain.resolve,chain.reject);
				}
				else {
					chain.resolve(ret);
				}
			}
		}
		catch (err) {
			chain.reject(err);
		}
	}

	function resolve(msg) {
		var _then, def_wrapper, self = this;

		// already triggered?
		if (self.triggered) { return; }

		self.triggered = true;

		// unwrap
		if (self.def) {
			self = self.def;
		}

		try {
			if (_then = isThenable(msg)) {
				def_wrapper = new MakeDefWrapper(self);
				_then.call(msg,
					function $resolve$(){ resolve.apply(def_wrapper,arguments); },
					function $reject$(){ reject.apply(def_wrapper,arguments); }
				);
			}
			else {
				self.msg = msg;
				self.state = 1;
				if (self.chain.length > 0) {
					schedule(notify,self);
				}
			}
		}
		catch (err) {
			reject.call(def_wrapper || (new MakeDefWrapper(self)),err);
		}
	}

	function reject(msg) {
		var self = this;

		// already triggered?
		if (self.triggered) { return; }

		self.triggered = true;

		// unwrap
		if (self.def) {
			self = self.def;
		}

		self.msg = msg;
		self.state = 2;
		if (self.chain.length > 0) {
			schedule(notify,self);
		}
	}

	function iteratePromises(Constructor,arr,resolver,rejecter) {
		for (var idx=0; idx<arr.length; idx++) {
			(function IIFE(idx){
				Constructor.resolve(arr[idx])
				.then(
					function $resolver$(msg){
						resolver(idx,msg);
					},
					rejecter
				);
			})(idx);
		}
	}

	// 下一个Promise节点的内部状态数据结构体
	function MakeDefWrapper(self) {
		this.def = self; // Promise链中前一个Promise节点的内部状态对象
		this.triggered = false; // 标识当前的Promise是否被触发
	}

	// Promise内部状态数据结构体
	function MakeDef(self) {
		this.promise = self;
		this.state = 0; // Promise状态, 0:pending, 1:fulfilled, 2:rejected
		this.triggered = false; // 标识当前的Promise是否被触发
		this.chain = []; //
		this.msg = void 0; // 
	}

	function Promise(executor) {
		if (typeof executor != "function") {
			throw TypeError("Not a function");
		}

		if (this.__NPO__ !== 0) {
			throw TypeError("Not a promise");
		}

		// instance shadowing the inherited "brand"
		// to signal an already "initialized" promise
		this.__NPO__ = 1;

		// 内部结构体
		var def = new MakeDef(this);

		this["then"] = function then(success,failure) {
			var o = {
				success: typeof success == "function" ? success : true,
				failure: typeof failure == "function" ? failure : false
			};
			// Note: `then(..)` itself can be borrowed to be used against
			// a different promise constructor for making the chained promise,
			// by substituting a different `this` binding.
			o.promise = new this.constructor(function extractChain(resolve,reject) {
				if (typeof resolve != "function" || typeof reject != "function") {
					throw TypeError("Not a function");
				}

				o.resolve = resolve;
				o.reject = reject;
			});
			// Promise链, 一个Promise实例下可有多个Promise子实例
			def.chain.push(o);

			if (def.state !== 0) {
				schedule(notify,def);
			}

			return o.promise;
		};
		this["catch"] = function $catch$(failure) {
			return this.then(void 0,failure);
		};

		try {
			// 调用工厂方法
			executor.call(
				void 0,
				function publicResolve(msg){
					resolve.call(def,msg);
				},
				function publicReject(msg) {
					reject.call(def,msg);
				}
			);
		}
		catch (err) {
			reject.call(def,err);
		}
	}

	var PromisePrototype = builtInProp({},"constructor",Promise,
		/*configurable=*/false
	);

	builtInProp(
		Promise,"prototype",PromisePrototype,
		/*configurable=*/false
	);

	// built-in "brand" to signal an "uninitialized" promise
	builtInProp(PromisePrototype,"__NPO__",0,
		/*configurable=*/false
	);

	builtInProp(Promise,"resolve",function Promise$resolve(msg) {
		var Constructor = this;

		// spec mandated checks
		// note: best "isPromise" check that's practical for now
		if (msg && typeof msg == "object" && msg.__NPO__ === 1) {
			return msg;
		}

		return new Constructor(function executor(resolve,reject){
			if (typeof resolve != "function" || typeof reject != "function") {
				throw TypeError("Not a function");
			}

			resolve(msg);
		});
	});

	builtInProp(Promise,"reject",function Promise$reject(msg) {
		return new this(function executor(resolve,reject){
			if (typeof resolve != "function" || typeof reject != "function") {
				throw TypeError("Not a function");
			}

			reject(msg);
		});
	});

	builtInProp(Promise,"all",function Promise$all(arr) {
		var Constructor = this;

		// spec mandated checks
		if (ToString.call(arr) != "[object Array]") {
			return Constructor.reject(TypeError("Not an array"));
		}
		if (arr.length === 0) {
			return Constructor.resolve([]);
		}

		return new Constructor(function executor(resolve,reject){
			if (typeof resolve != "function" || typeof reject != "function") {
				throw TypeError("Not a function");
			}

			var len = arr.length, msgs = Array(len), count = 0;

			iteratePromises(Constructor,arr,function resolver(idx,msg) {
				msgs[idx] = msg;
				if (++count === len) {
					resolve(msgs);
				}
			},reject);
		});
	});

	builtInProp(Promise,"race",function Promise$race(arr) {
		var Constructor = this;

		// spec mandated checks
		if (ToString.call(arr) != "[object Array]") {
			return Constructor.reject(TypeError("Not an array"));
		}

		return new Constructor(function executor(resolve,reject){
			if (typeof resolve != "function" || typeof reject != "function") {
				throw TypeError("Not a function");
			}

			iteratePromises(Constructor,arr,function resolver(idx,msg){
				resolve(msg);
			},reject);
		});
	});

	return Promise;
});
