const CACHE_NAME = "version-1";
const urlsToCache = ['index.html', 'offline.html'];

const self = this;

//Install SW
self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME)
      .then((cache) => {
        console.log('Opened cache');

        return cache.addAll(urlsToCache);
      })
  )
});

//Listen for requests
self.addEventListener('fetch', (event) => {
  event.respondWith(
    caches.match(event.request)
      .then(() => {
        return fetch(event.request)
          .catch(() => caches.match('offline.html'));
      })
  );
});
//Activate the SW
self.addEventListener('activate', (event) => {
  const cacheWhiteList = [];
  cacheWhiteList.push(CACHE_NAME);

  event.waitUntil(
    caches.keys().then((cacheNames) => Promise.all(
      cacheNames.map((cacheName) => {
        if (!cacheWhiteList.includes(cacheName)) {
          return caches.delete(cacheName);
        }
      })
    ))
  )
});