const CACHE_NAME = 'credittracker-v33';
const ASSETS = [
  './index.html',
  './manifest.json',
  './icon.svg',
  './icon-maskable.svg'
];

// Install: pre-cache all app shell files
self.addEventListener('install', event => {
  event.waitUntil(
    caches.open(CACHE_NAME).then(cache => cache.addAll(ASSETS))
  );
  self.skipWaiting();
});

// Activate: clean up old caches
self.addEventListener('activate', event => {
  event.waitUntil(
    caches.keys().then(keys =>
      Promise.all(keys.filter(k => k !== CACHE_NAME).map(k => caches.delete(k)))
    )
  );
  self.clients.claim();
});

// Fetch: cache-first for app files, network-first for everything else
self.addEventListener('fetch', event => {
  // Only handle same-origin GET requests
  if (event.request.method !== 'GET') return;

  event.respondWith(
    caches.match(event.request).then(cached => {
      if (cached) return cached;
      return fetch(event.request).then(response => {
        // Cache successful responses for app assets
        if (response.ok) {
          const clone = response.clone();
          caches.open(CACHE_NAME).then(cache => cache.put(event.request, clone));
        }
        return response;
      });
    }).catch(() => {
      // Offline fallback: return the app shell
      return caches.match('./index.html');
    })
  );
});