sw.js

// Service worker: caches the app shell for offline use and updates cache on fetch.
const CACHE_PREFIX = 'read-txt-';
const CACHE_NAME = 'read-txt-v6';
// Pre-cache the core app shell for offline use.
self.addEventListener('install', (event) => {
    event.waitUntil(
        caches.open(CACHE_NAME).then((cache) => {
            return cache.addAll([
                './',
                './index.html',
                './style.css',
                './js/app.js',
                './js/ui.js',
                './js/storage.js',
                './js/speech.js',
                './manifest.webmanifest',
                './icons/android-chrome-192x192.png',
                './icons/android-chrome-512x512.png',
                './icons/apple-touch-icon.png',
                './icons/favicon-32x32.png',
                './icons/favicon-16x16.png',
                './icons/favicon.ico'
            ]);
        })
    );
    self.skipWaiting();
});

// Clear old caches when a new service worker activates.
self.addEventListener('activate', (event) => {
    event.waitUntil(
        caches.keys().then((keys) => {
            const keysToDelete = keys.filter((key) => key.startsWith(CACHE_PREFIX) && key !== CACHE_NAME);
            return Promise.all(keysToDelete.map((key) => caches.delete(key)));
        })
    );
    self.clients.claim();
});

// Network-first fetch with cache fallback.
self.addEventListener('fetch', (event) => {
    if (event.request.method !== 'GET') return;
    const url = new URL(event.request.url);
    if (url.protocol !== 'http:' && url.protocol !== 'https:') return;

    event.respondWith(
        fetch(event.request)
            .then((networkResponse) => {
                if (!networkResponse.ok) {
                    return networkResponse;
                }
                const responseClone = networkResponse.clone();
                caches
                    .open(CACHE_NAME)
                    .then((cache) => cache.put(event.request, responseClone))
                    .catch((error) => {
                        console.error('Failed to update cache for request:', event.request.url, error);
                    });
                return networkResponse;
            })
            .catch(() => {
                return caches.match(event.request);
            })
    );
});