(function (root) {

    // Store setTimeout reference so promise-polyfill will be unaffected by
    // other code modifying setTimeout (like sinon.useFakeTimers())
    var setTimeoutFunc = setTimeout;

    function noop() {
    }

    // Polyfill for Function.prototype.bind
    function bind(fn, thisArg) {
        return function () {
            fn.apply(thisArg, arguments);
        };
    }

    function Promise(fn) {
        if (typeof this !== 'object') throw new TypeError('Promises must be constructed via new');
        if (typeof fn !== 'function') throw new TypeError('not a function');
        this._state = 0;
        this._handled = false;
        this._value = undefined;
        this._deferreds = [];

        doResolve(fn, this);
    }

    function handle(self, deferred) {
        while (self._state === 3) {
            self = self._value;
        }
        if (self._state === 0) {
            self._deferreds.push(deferred);
            return;
        }
        self._handled = true;
        Promise._immediateFn(function () {
            var cb = self._state === 1 ? deferred.onFulfilled : deferred.onRejected;
            if (cb === null) {
                (self._state === 1 ? resolve : reject)(deferred.promise, self._value);
                return;
            }
            var ret;
            try {
                ret = cb(self._value);
            } catch (e) {
                reject(deferred.promise, e);
                return;
            }
            resolve(deferred.promise, ret);
        });
    }

    function resolve(self, newValue) {
        try {
            // Promise Resolution Procedure: https://github.com/promises-aplus/promises-spec#the-promise-resolution-procedure
            if (newValue === self) throw new TypeError('A promise cannot be resolved with itself.');
            if (newValue && (typeof newValue === 'object' || typeof newValue === 'function')) {
                var then = newValue.then;
                if (newValue instanceof Promise) {
                    self._state = 3;
                    self._value = newValue;
                    finale(self);
                    return;
                } else if (typeof then === 'function') {
                    doResolve(bind(then, newValue), self);
                    return;
                }
            }
            self._state = 1;
            self._value = newValue;
            finale(self);
        } catch (e) {
            reject(self, e);
        }
    }

    function reject(self, newValue) {
        self._state = 2;
        self._value = newValue;
        finale(self);
    }

    function finale(self) {
        if (self._state === 2 && self._deferreds.length === 0) {
            Promise._immediateFn(function () {
                if (!self._handled) {
                    Promise._unhandledRejectionFn(self._value);
                }
            });
        }

        for (var i = 0, len = self._deferreds.length; i < len; i++) {
            handle(self, self._deferreds[i]);
        }
        self._deferreds = null;
    }

    function Handler(onFulfilled, onRejected, promise) {
        this.onFulfilled = typeof onFulfilled === 'function' ? onFulfilled : null;
        this.onRejected = typeof onRejected === 'function' ? onRejected : null;
        this.promise = promise;
    }

    /**
     * Take a potentially misbehaving resolver function and make sure
     * onFulfilled and onRejected are only called once.
     *
     * Makes no guarantees about asynchrony.
     */
    function doResolve(fn, self) {
        var done = false;
        try {
            fn(function (value) {
                if (done) return;
                done = true;
                resolve(self, value);
            }, function (reason) {
                if (done) return;
                done = true;
                reject(self, reason);
            });
        } catch (ex) {
            if (done) return;
            done = true;
            reject(self, ex);
        }
    }

    Promise.prototype['catch'] = function (onRejected) {
        return this.then(null, onRejected);
    };

    Promise.prototype.then = function (onFulfilled, onRejected) {
        var prom = new (this.constructor)(noop);

        handle(this, new Handler(onFulfilled, onRejected, prom));
        return prom;
    };

    Promise.all = function (arr) {
        var args = Array.prototype.slice.call(arr);

        return new Promise(function (resolve, reject) {
            if (args.length === 0) return resolve([]);
            var remaining = args.length;

            function res(i, val) {
                try {
                    if (val && (typeof val === 'object' || typeof val === 'function')) {
                        var then = val.then;
                        if (typeof then === 'function') {
                            then.call(val, function (val) {
                                res(i, val);
                            }, reject);
                            return;
                        }
                    }
                    args[i] = val;
                    if (--remaining === 0) {
                        resolve(args);
                    }
                } catch (ex) {
                    reject(ex);
                }
            }

            for (var i = 0; i < args.length; i++) {
                res(i, args[i]);
            }
        });
    };

    Promise.resolve = function (value) {
        if (value && typeof value === 'object' && value.constructor === Promise) {
            return value;
        }

        return new Promise(function (resolve) {
            resolve(value);
        });
    };

    Promise.reject = function (value) {
        return new Promise(function (resolve, reject) {
            reject(value);
        });
    };

    Promise.race = function (values) {
        return new Promise(function (resolve, reject) {
            for (var i = 0, len = values.length; i < len; i++) {
                values[i].then(resolve, reject);
            }
        });
    };

    // Use polyfill for setImmediate for performance gains
    Promise._immediateFn = (typeof setImmediate === 'function' && function (fn) {
            setImmediate(fn);
        }) ||
        function (fn) {
            setTimeoutFunc(fn, 0);
        };

    Promise._unhandledRejectionFn = function _unhandledRejectionFn(err) {
        if (typeof console !== 'undefined' && console) {
            console.warn('Possible Unhandled Promise Rejection:', err); // eslint-disable-line no-console
        }
    };

    /**
     * Set the immediate function to execute callbacks
     * @param fn {function} Function to execute
     * @deprecated
     */
    Promise._setImmediateFn = function _setImmediateFn(fn) {
        Promise._immediateFn = fn;
    };

    /**
     * Change the function to execute on unhandled rejection
     * @param {function} fn Function to execute on unhandled rejection
     * @deprecated
     */
    Promise._setUnhandledRejectionFn = function _setUnhandledRejectionFn(fn) {
        Promise._unhandledRejectionFn = fn;
    };

    if (typeof module !== 'undefined' && module.exports) {
        module.exports = Promise;
    } else if (!root.Promise) {
        root.Promise = Promise;
    }

})(this);