sw.js

/* ============================================
   OFFLOAD — Service Worker
   Cache-first strategy for offline PWA support
   ============================================ */

const CACHE_NAME = 'offload-v1';
const STATIC_ASSETS = [
  './',
  './index.html',
  './css/style.css',
  './js/app.js',
  './js/data-store.js',
  './js/audio-engine.js',
  './js/ceremony-renderer.js',
  './js/sentiment-analyzer.js',
  './manifest.json',
  './icon-192.png',
  './icon-512.png',
  './apple-touch-icon.png',
  './favicon-32x32.png',
  './maskable-icon-512.png',
  './og-image.png',
  './lyf-badge.png',
  './moon-new-moon.png',
  './moon-waxing-crescent.png',
  './moon-first-quarter.png',
  './moon-waxing-gibbous.png',
  './moon-full-moon.png',
  './moon-waning-gibbous.png',
  './moon-last-quarter.png',
  './moon-waning-crescent.png'
];

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

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

// Fetch: Cache-first strategy
self.addEventListener('fetch', (event) => {
  const { request } = event;

  // Skip non-GET requests
  if (request.method !== 'GET') {
    return;
  }

  // Skip cross-origin requests
  if (!request.url.startsWith(self.location.origin)) {
    return;
  }

  event.respondWith(
    caches.match(request).then((cachedResponse) => {
      if (cachedResponse) {
        // Return cached response and refresh in background
        fetch(request)
          .then((networkResponse) => {
            if (networkResponse && networkResponse.ok) {
              caches.open(CACHE_NAME).then((cache) => {
                cache.put(request, networkResponse.clone());
              });
            }
          })
          .catch(() => {
            // Network failed, cached response is fine
          });
        return cachedResponse;
      }

      // Not in cache, fetch from network
      return fetch(request)
        .then((networkResponse) => {
          if (!networkResponse || !networkResponse.ok) {
            return networkResponse;
          }

          // Cache the new response
          const responseToCache = networkResponse.clone();
          caches.open(CACHE_NAME).then((cache) => {
            cache.put(request, responseToCache);
          });

          return networkResponse;
        })
        .catch(() => {
          // Network failed, no cache available
          return new Response('Offline — content not available', {
            status: 503,
            statusText: 'Service Unavailable',
            headers: { 'Content-Type': 'text/plain' }
          });
        });
    })
  );
});

// Background sync for offline writes
self.addEventListener('sync', (event) => {
  if (event.tag === 'offload-sync') {
    event.waitUntil(Promise.resolve());
  }
});