const CACHE = 'premier-gunner-v6';
const SHELL = [
  '/', '/index.html', '/login.html',
  '/css/styles.css',
  '/js/app.js', '/js/api.js', '/js/dashboard.js',
  '/vendor/chart.umd.min.js',
  '/manifest.webmanifest',
  '/icons/logo.svg', '/icons/favicon.svg',
  '/icons/icon-192.png', '/icons/icon-512.png',
];

self.addEventListener('install', (e) => {
  // Pre-cache the new shell, but do NOT skipWaiting automatically — we wait
  // until the page tells us to (via the "Refresh" banner) so the update is
  // controlled and the user is never interrupted mid-action.
  e.waitUntil(caches.open(CACHE).then((c) => c.addAll(SHELL)));
});

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())
  );
});

// The page posts this when the user taps "Refresh" on the update banner.
self.addEventListener('message', (e) => {
  if (e.data && e.data.type === 'SKIP_WAITING') self.skipWaiting();
});

self.addEventListener('fetch', (e) => {
  const url = new URL(e.request.url);
  if (e.request.method !== 'GET') return;
  // Never cache the API — always go to network so data stays fresh and auth works.
  if (url.pathname.startsWith('/api/')) return;

  e.respondWith(
    caches.match(e.request).then((cached) => {
      const network = fetch(e.request).then((res) => {
        if (res.ok && url.origin === location.origin) {
          const copy = res.clone();
          caches.open(CACHE).then((c) => c.put(e.request, copy));
        }
        return res;
      }).catch(() => cached);
      return cached || network;
    })
  );
});