/*! loadCSS rel=preload polyfill. [c]2017 Filament Group, Inc. MIT License */
(function(w) {
    'use strict';
    // rel=preload support test
    if (!w.loadCSS) {
        w.loadCSS = function() {};
    }
    // define on the loadCSS obj
    var rp = (loadCSS.relpreload = {});
    // rel=preload feature support test
    // runs once and returns a function for compat purposes
    rp.support = (function() {
        var ret;
        try {
            ret = w.document.createElement('link').relList.supports('preload');
        } catch (e) {
            ret = false;
        }
        return function() {
            return ret;
        };
    })();

    // if preload isn't supported, get an asynchronous load by using a non-matching media attribute
    // then change that media back to its intended value on load
    rp.bindMediaToggle = function(link) {
        // remember existing media attr for ultimate state, or default to 'all'
        var finalMedia = link.media || 'all';

        function enableStylesheet() {
            // unbind listeners
            if (link.addEventListener) {
                link.removeEventListener('load', enableStylesheet);
            } else if (link.attachEvent) {
                link.detachEvent('onload', enableStylesheet);
            }
            link.setAttribute('onload', null);
            link.media = finalMedia;
        }

        // bind load handlers to enable media
        if (link.addEventListener) {
            link.addEventListener('load', enableStylesheet);
        } else if (link.attachEvent) {
            link.attachEvent('onload', enableStylesheet);
        }

        // Set rel and non-applicable media type to start an async request
        // note: timeout allows this to happen async to let rendering continue in IE
        setTimeout(function() {
            link.rel = 'stylesheet';
            link.media = 'only x';
        });
        // also enable media after 3 seconds,
        // which will catch very old browsers (android 2.x, old firefox) that don't support onload on link
        setTimeout(enableStylesheet, 3000);
    };

    // loop through link elements in DOM
    rp.poly = function() {
        // double check this to prevent external calls from running
        if (rp.support()) {
            return;
        }
        var links = w.document.getElementsByTagName('link');
        for (var i = 0; i < links.length; i++) {
            var link = links[i];
            // qualify links to those with rel=preload and as=style attrs
            if (
                link.rel === 'preload' &&
                link.getAttribute('as') === 'style' &&
                !link.getAttribute('data-loadcss')
            ) {
                // prevent rerunning on link
                link.setAttribute('data-loadcss', true);
                // bind listeners to toggle media back
                rp.bindMediaToggle(link);
            }
        }
    };

    // if unsupported, run the polyfill
    if (!rp.support()) {
        // run once at least
        rp.poly();

        // rerun poly on an interval until onload
        var run = w.setInterval(rp.poly, 500);
        if (w.addEventListener) {
            w.addEventListener('load', function() {
                rp.poly();
                w.clearInterval(run);
            });
        } else if (w.attachEvent) {
            w.attachEvent('onload', function() {
                rp.poly();
                w.clearInterval(run);
            });
        }
    }

    // commonjs
    if (typeof exports !== 'undefined') {
        exports.loadCSS = loadCSS;
    } else {
        w.loadCSS = loadCSS;
    }
})(typeof global !== 'undefined' ? global : this);