const CACHE_NAME = 'timetracker-v3'; // Update this if you change anything!

// Cache only local assets here. Avoid opaque external resources in addAll().
const urlsToCache = [
  '/',
  '/index.html',
  '/manifest.json'
  // Add local JS/CSS files here if you have them, e.g., '/main.js', '/styles.css'
];

// Install: Cache core files
self.addEventListener('install', (event) => {
  console.log('[SW] Install event');

  event.waitUntil(
    caches.open(CACHE_NAME)
      .then(cache => {
        console.log('[SW] Caching app shell:', urlsToCache);
        return cache.addAll(urlsToCache);
      })
      .catch(err => {
        console.error('[SW] Install cache error:', err);
      })
  );
});

// Activate: Clean up old caches
self.addEventListener('activate', (event) => {
  console.log('[SW] Activate event');

  event.waitUntil(
    caches.keys().then(cacheNames => {
      return Promise.all(
        cacheNames.map(name => {
          if (name !== CACHE_NAME) {
            console.log('[SW] Deleting old cache:', name);
            return caches.delete(name);
          }
        })
      );
    })
  );
});

// Fetch: Cache-first strategy with dynamic caching
self.addEventListener('fetch', (event) => {
  if (event.request.method !== 'GET') return;

  console.log('[SW] Fetch request:', event.request.url);

  event.respondWith(
    caches.match(event.request)
      .then(cachedResponse => {
        if (cachedResponse) {
          console.log('[SW] Serving from cache:', event.request.url);
          return cachedResponse;
        }

        return fetch(event.request)
          .then(networkResponse => {
            if (
              networkResponse &&
              networkResponse.status === 200 &&
              networkResponse.type !== 'opaque'
            ) {
              const responseToCache = networkResponse.clone();
              caches.open(CACHE_NAME).then(cache => {
                console.log('[SW] Dynamically caching:', event.request.url);
                cache.put(event.request, responseToCache);
              });
            }
            return networkResponse;
          })
          .catch(err => {
            console.error('[SW] Network request failed:', event.request.url, err);
            // Optionally, return a fallback page or image here
          });
      })
  );
});