/* Mineflappy offline cache.
   Cache-first for the app shell, with a background refresh so a new
   deploy is picked up on the next visit. */
const CACHE = 'mineflappy-v1';
const ASSETS = [
  './',
  './index.html',
  './manifest.webmanifest',
  './icon-192.png',
  './icon-512.png',
  './apple-touch-icon.png',
  './favicon-32.png'
];

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

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

self.addEventListener('fetch', e => {
  const req = e.request;
  if (req.method !== 'GET' || new URL(req.url).origin !== location.origin) return;

  e.respondWith(
    caches.match(req).then(hit => {
      const network = fetch(req).then(res => {
        if (res && res.status === 200 && res.type === 'basic') {
          const copy = res.clone();
          caches.open(CACHE).then(c => c.put(req, copy));
        }
        return res;
      }).catch(() => hit || caches.match('./index.html'));
      return hit || network;
    })
  );
});