(function () {

    'use strict';

    /**
     * wraps a promise in a timeout, allowing the promise to reject if not resolve with a specific period of time
     * @param {integer} ms - milliseconds to wait before rejecting promise if not resolved
     * @param {Promise} promise to monitor
     * @example
     *  promiseTimeout(1000, fetch('https://courseof.life/johndoherty.json'))
     *      .then(function(cvData){
     *          alert(cvData);
     *      })
     *      .catch(function(){
     *          alert('request either failed or timed-out');
     *      });
     * @returns {Promise} resolves as normal if not timed-out, otherwise rejects
     */
    function promiseTimeout(ms, promise) {

        return new Promise(function (resolve, reject) {

            // create a timeout to reject promise if not resolved
            var timer = requestTimeout(function () {
                reject(new Error('Promise Timed Out'));
            }, ms);

            promise.then(function (res) {
                clearRequestTimeout(timer);
                resolve(res);
            })
            .catch(function (err) {
                clearRequestTimeout(timer);
                reject(err);
            });
        });
    }

    /* #region helpers */

    var requestAnimFrame = window.requestAnimationFrame ||
            window.webkitRequestAnimationFrame ||
            window.mozRequestAnimationFrame ||
            window.oRequestAnimationFrame ||
            window.msRequestAnimationFrame || function(callback) {
                window.setTimeout(callback, 1000 / 60);
            };

    /**
     * Behaves the same as setTimeout except uses requestAnimationFrame() where possible for better performance
     * @param {function} fn The callback function
     * @param {int} delay The delay in milliseconds
     * @returns {object} handle to the timeout object
     */
    function requestTimeout(fn, delay) {

        if (!window.requestAnimationFrame && !window.webkitRequestAnimationFrame &&
            !(window.mozRequestAnimationFrame && window.mozCancelRequestAnimationFrame) && // Firefox 5 ships without cancel support
            !window.oRequestAnimationFrame && !window.msRequestAnimationFrame) return window.setTimeout(fn, delay);

        var start = new Date().getTime();
        var handle = {};

        var loop = function() {
            var current = new Date().getTime();
            var delta = current - start;

            if (delta >= delay) {
                fn.call();
            }
            else {
                handle.value = requestAnimFrame(loop);
            }
        };

        handle.value = requestAnimFrame(loop);

        return handle;
    }

    /**
     * Behaves the same as clearTimeout except uses cancelRequestAnimationFrame() where possible for better performance
     * @param {object} handle The callback function
     * @returns {void}
     */
    function clearRequestTimeout(handle) {
        if (handle) {
            window.cancelAnimationFrame ? window.cancelAnimationFrame(handle.value) :
            window.webkitCancelAnimationFrame ? window.webkitCancelAnimationFrame(handle.value) :
            window.webkitCancelRequestAnimationFrame ? window.webkitCancelRequestAnimationFrame(handle.value) : /* Support for legacy API */
            window.mozCancelRequestAnimationFrame ? window.mozCancelRequestAnimationFrame(handle.value) :
            window.oCancelRequestAnimationFrame	? window.oCancelRequestAnimationFrame(handle.value) :
            window.msCancelRequestAnimationFrame ? window.msCancelRequestAnimationFrame(handle.value) :
            clearTimeout(handle);
        }
    }

    /* #endregion */

    if (typeof window === 'undefined') {
        module.exports = promiseTimeout;
    }
    else {
        window.promiseTimeout = promiseTimeout;
    }

})();