// A name for our cache, change this every time you update the app shell
const CACHE_NAME = 'timetracker-v2';

// The files that make up the "app shell"
const urlsToCache = [
  '/',
  '/index.html',
  'https://cdn.tailwindcss.com',
  'https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&display=swap'
];

// 1. Installation: Open the cache and add the app shell files.
self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME)
      .then((cache) => {
        console.log('Opened cache and added app shell');
        return cache.addAll(urlsToCache);
      })
  );
});

// 2. Activation: Clean up old caches. (NEW)
// This event fires after install and when the new service worker takes control.
self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((cacheNames) => {
      return Promise.all(
        cacheNames.map((cacheName) => {
          // If a cache is not the current one, delete it.
          if (cacheName !== CACHE_NAME) {
            console.log('Deleting old cache:', cacheName);
            return caches.delete(cacheName);
          }
        })
      );
    })
  );
});

// 3. Fetch: Serve from cache, fallback to network, and cache new requests. (IMPROVED)
self.addEventListener('fetch', (event) => {
  // We only want to cache GET requests
  if (event.request.method !== 'GET') {
    return;
  }
  
  event.respondWith(
    caches.match(event.request)
      .then((cachedResponse) => {
        // If the response is in the cache, return it.
        if (cachedResponse) {
          return cachedResponse;
        }

        // If not in cache, go to the network.
        return fetch(event.request).then((networkResponse) => {
          // If the network request is successful, cache it for next time.
          if (networkResponse && networkResponse.status === 200) {
            const responseToCache = networkResponse.clone(); // Clone the response
            caches.open(CACHE_NAME)
              .then((cache) => {
                cache.put(event.request, responseToCache);
              });
          }
          return networkResponse;
        });
      })
  );
});