// Minimal service worker: caches the app shell so the cockpit launches fast and
// survives brief network blips. Live data (the bridge WebSocket, /api, and map
// tiles) is never cached — only same-origin GET app assets.
const CACHE = 'g1000-shell-v2';

self.addEventListener('install', () => 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 url = new URL(e.request.url);
  // Only same-origin GET app shell; skip the API and let the WS pass through.
  if (e.request.method !== 'GET' || url.origin !== location.origin) return;
  if (url.pathname.startsWith('/api') || url.pathname === '/ws') return;

  // The HTML entry is NETWORK-FIRST: a reload always gets the latest build (and
  // thus the latest hashed assets). Falls back to cache only when offline.
  const isDoc = e.request.mode === 'navigate' || url.pathname === '/' || url.pathname.endsWith('.html');
  if (isDoc) {
    e.respondWith(
      fetch(e.request)
        .then((res) => { caches.open(CACHE).then((c) => c.put(e.request, res.clone())); return res; })
        .catch(() => caches.match(e.request).then((c) => c || caches.match('/')))
    );
    return;
  }

  // Hashed assets are immutable → stale-while-revalidate (fast + self-healing).
  e.respondWith(
    caches.open(CACHE).then(async (cache) => {
      const cached = await cache.match(e.request);
      const network = fetch(e.request)
        .then((res) => { if (res && res.ok) cache.put(e.request, res.clone()); return res; })
        .catch(() => cached);
      return cached || network;
    })
  );
});