sw.js

/**
 * Flow Service Worker
 * Network-first for HTML, cache-first for assets
 */

const CACHE_NAME = 'flow-v5';

const STATIC_ASSETS = [
  '/flow/',
  '/flow/index.html',
  '/flow/time.html',
  '/flow/offline.html',
  '/flow/styles.css',
  '/flow/app.js',
  '/flow/manifest.json',
  '/flow/icon-192.png',
  '/flow/icon-512.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 up 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: Network-first for HTML, cache-first for assets
self.addEventListener('fetch', (event) => {
  if (event.request.method !== 'GET') return;
  if (!event.request.url.startsWith(self.location.origin)) return;

  const isHTML = event.request.mode === 'navigate' || 
                 event.request.destination === 'document' ||
                 event.request.url.endsWith('.html');

  if (isHTML) {
    // Network-first for HTML pages
    event.respondWith(
      fetch(event.request)
        .then(networkResponse => {
          if (networkResponse && networkResponse.status === 200) {
            const cacheCopy = networkResponse.clone();
            caches.open(CACHE_NAME).then(cache => {
              cache.put(event.request, cacheCopy);
            });
          }
          return networkResponse;
        })
        .catch(() => {
          return caches.match(event.request)
            .then(cached => cached || caches.match('/flow/offline.html'));
        })
    );
  } else {
    // Cache-first for assets
    event.respondWith(
      caches.match(event.request).then(cachedResponse => {
        const fetchPromise = fetch(event.request)
          .then(networkResponse => {
            if (networkResponse && networkResponse.status === 200) {
              const cacheCopy = networkResponse.clone();
              caches.open(CACHE_NAME).then(cache => {
                cache.put(event.request, cacheCopy);
              });
            }
            return networkResponse;
          })
          .catch(() => cachedResponse);

        return cachedResponse || fetchPromise;
      })
    );
  }
});

// Handle messages from clients
self.addEventListener('message', (event) => {
  if (event.data === 'skipWaiting') {
    self.skipWaiting();
  }
});