// Spendlight service worker. Makes the home-screen app open instantly and
// show its shell offline. It never touches /api: household data is always
// fetched fresh and never stored here.

const SHELL = 'spendlight-shell';
const ASSETS = 'spendlight-assets';
const MAX_ASSETS = 80;

self.addEventListener('install', () => self.skipWaiting());

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

self.addEventListener('fetch', (event) => {
  const request = event.request;
  const url = new URL(request.url);
  if (request.method !== 'GET' || url.origin !== self.location.origin || url.pathname.startsWith('/api/')) return;

  // Pages: always try the network first so a new version shows up at once.
  if (request.mode === 'navigate') {
    event.respondWith(
      fetch(request)
        .then((response) => {
          if (response.ok) {
            const copy = response.clone();
            caches.open(SHELL).then((cache) => cache.put('/', copy));
          }
          return response;
        })
        .catch(() => caches.match('/').then((cached) => cached || Response.error())),
    );
    return;
  }

  // Versioned files never change, so a cached copy is always right.
  if (url.pathname.startsWith('/assets/')) {
    event.respondWith(
      caches.open(ASSETS).then(async (cache) => {
        const cached = await cache.match(request);
        if (cached) return cached;
        const response = await fetch(request);
        if (response.ok) {
          await cache.put(request, response.clone());
          const keys = await cache.keys();
          if (keys.length > MAX_ASSETS) await Promise.all(keys.slice(0, keys.length - MAX_ASSETS).map((k) => cache.delete(k)));
        }
        return response;
      }),
    );
  }
});