sw.js

const CACHE_NAME = 'tradeconvert-v1';
const STATIC_ASSETS = [
  '/',
  '/css/main.css',
  '/js/converters.js',
  '/assets/favicon.png',
  '/assets/og-image.jpg',
  'https://fonts.googleapis.com/css2?family=Playfair+Display:wght@400;600;700;900&family=Source+Serif+4:ital,opsz,wght@0,8..60,300;0,8..60,400;0,8..60,600;1,8..60,400&family=JetBrains+Mono:wght@400;500;600&display=swap'
];

// Install event: Cache critical static assets
self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) => {
      console.log('Opened cache');
      return cache.addAll(STATIC_ASSETS);
    })
  );
  self.skipWaiting();
});

// Activate event: Clean up old caches
self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((cacheNames) => {
      return Promise.all(
        cacheNames.map((cacheName) => {
          if (cacheName !== CACHE_NAME) {
            console.log('Deleting old cache:', cacheName);
            return caches.delete(cacheName);
          }
        })
      );
    })
  );
  self.clients.claim();
});

// Fetch event: Network-first for HTML pages (Stale-while-revalidate), Cache-first for static assets
self.addEventListener('fetch', (event) => {
  const requestUrl = new URL(event.request.url);

  // For static assets (CSS, JS, Images, Fonts), try cache first, then network
  if (requestUrl.pathname.match(/\.(css|js|png|jpg|jpeg|svg|woff2?|ttf)$/) || requestUrl.hostname.includes('fonts.googleapis.com')) {
    event.respondWith(
      caches.match(event.request).then((response) => {
        if (response) {
          return response; // Return from cache
        }
        return fetch(event.request).then((networkResponse) => {
          // Cache the new resource
          if (networkResponse && networkResponse.status === 200 && networkResponse.type === 'basic') {
            const responseToCache = networkResponse.clone();
            caches.open(CACHE_NAME).then((cache) => {
              cache.put(event.request, responseToCache);
            });
          }
          return networkResponse;
        });
      })
    );
  } else {
    // For HTML pages and API calls, use Stale-while-revalidate or Network-first
    event.respondWith(
      caches.match(event.request).then((cachedResponse) => {
        const fetchPromise = fetch(event.request).then((networkResponse) => {
          if (networkResponse && networkResponse.status === 200) {
            const responseToCache = networkResponse.clone();
            caches.open(CACHE_NAME).then((cache) => {
              cache.put(event.request, responseToCache);
            });
          }
          return networkResponse;
        }).catch(() => {
          // If network fails and no cache exists, just let it fail or return offline page
        });

        // Return cached immediately if present, but update in background
        return cachedResponse || fetchPromise;
      })
    );
  }
});