sw.js

const CACHE_NAME = 'pomodoro-v9';
const ASSETS = [
  './',
  './index.html',
  './style.css',
  './app.js',
  './sync.js',
  './icon.svg',
  './manifest.json'
];

self.addEventListener('install', e => {
  e.waitUntil(caches.open(CACHE_NAME).then(c => c.addAll(ASSETS)));
  self.skipWaiting();
});

self.addEventListener('activate', e => {
  e.waitUntil(
    caches.keys().then(keys =>
      Promise.all(keys.filter(k => k !== CACHE_NAME).map(k => caches.delete(k)))
    )
  );
  self.clients.claim();
});

self.addEventListener('message', e => {
  if (e.data && e.data.type === 'notification') {
    self.registration.showNotification(e.data.title, {
      body: e.data.body,
      icon: 'icon.svg'
    });
  }
});

self.addEventListener('notificationclick', e => {
  e.notification.close();
  e.waitUntil(
    self.clients.matchAll({ type: 'window', includeUncontrolled: true }).then(clients => {
      if (clients.length) {
        return clients[0].focus();
      }
      return self.clients.openWindow('./');
    })
  );
});

self.addEventListener('fetch', e => {
  if (e.request.method !== 'GET') return;
  if (!e.request.url.startsWith(self.location.origin)) return;
  e.respondWith(
    fetch(e.request)
      .then(r => {
        const clone = r.clone();
        caches.open(CACHE_NAME).then(c => c.put(e.request, clone));
        return r;
      })
      .catch(() => caches.match(e.request))
  );
});