(function (global) {
    //const cacheKey = global.cacheKey;
    const isOffline = 'onLine' in navigator && navigator.onLine === false;
    const hasServiceWorkerSupport = 'serviceWorker' in navigator;
    if (isOffline) {
        console.log('offline mode');
    }
    if (!hasServiceWorkerSupport) {
        console.log('service worker is not supported');
    }
    if (hasServiceWorkerSupport && !isOffline) {
        window.addEventListener('load', function () {
            const serviceWorkerPath = '/runtime-service-worker.js?v=3';
            navigator.serviceWorker
                .register(serviceWorkerPath, { scope: './' })
                .then(
                    function (registration) {
                        // Registration was successful
                        console.log(
                            'ServiceWorker registration successful with scope: ',
                            registration.scope
                        );
                    },
                    function (err) {
                        // registration failed :(
                        console.log('ServiceWorker registration failed: ', err);
                    }
                )
                .catch(function (err) {
                    console.log(err);
                });
        });

        // helper function to refresh the page
        var refreshPage = (function () {
            var refreshing;
            return function () {
                if (refreshing) return;
                // prevent multiple refreshes
                var refreshkey = 'refreshed' + location.href;
                var prevRefresh = localStorage.getItem(refreshkey);
                if (prevRefresh) {
                    localStorage.removeItem(refreshkey);
                    if (Date.now() - prevRefresh < 30000) {
                        return; // dont go into a refresh loop
                    }
                }
                refreshing = true;
                localStorage.setItem(refreshkey, Date.now());
                console.log('refereshing page');
                window.location.reload();
            };
        })();

        function messageServiceWorker(data) {
            return new Promise(function (resolve, reject) {
                if (navigator.serviceWorker.controller) {
                    var worker = navigator.serviceWorker.controller;
                    var messageChannel = new MessageChannel();
                    messageChannel.port1.onmessage = replyHandler;
                    worker.postMessage(data, [messageChannel.port2]);
                    function replyHandler(event) {
                        resolve(event.data);
                    }
                } else {
                    resolve();
                }
            });
        }
    }
})(window);