sw.js

const CACHE = 'b64pro-v0.4.2';
const ASSETS = [
  './', './index.html', './manifest.json', './icon.svg', './icon-maskable.svg',
  './vendor/fflate-0.8.3.js', './vendor/qrcode-generator-1.4.4.js',
  './screenshots/desktop-wide.png', './screenshots/mobile-narrow.png',
];
const assetUrls = new Set(ASSETS.map(asset => new URL(asset, self.location.href).href));

self.addEventListener('install', event => {
  event.waitUntil(caches.open(CACHE).then(cache => cache.addAll(ASSETS)).then(() => self.skipWaiting()));
});

self.addEventListener('activate', event => {
  event.waitUntil(caches.keys().then(keys => Promise.all(
    keys.filter(key => key.startsWith('b64pro-v') && key !== CACHE).map(key => caches.delete(key))
  )).then(() => self.clients.claim()));
});

self.addEventListener('fetch', event => {
  const url = new URL(event.request.url);
  const entry = new URL('./index.html', self.location.href);
  if (url.origin !== entry.origin) return;
  if (event.request.method === 'POST' && url.pathname === entry.pathname && url.searchParams.has('share')) {
    event.respondWith((async () => {
      const form = await event.request.formData();
      const file = form.get('file');
      if (file && typeof file !== 'string') {
        const cache = await caches.open('b64pro-share');
        await cache.put(new URL('./shared-file', self.location.href), new Response(file, {
          headers: { 'X-Filename': encodeURIComponent(file.name), 'Content-Type': file.type || 'application/octet-stream' }
        }));
        entry.searchParams.set('share', 'file');
      } else {
        const value = form.get('data') || form.get('url') || form.get('title') || '';
        entry.searchParams.set('data', String(value));
        entry.searchParams.set('mode', 'text');
      }
      return Response.redirect(entry.href, 303);
    })());
    return;
  }
  if (event.request.method !== 'GET') return;
  // Query strings can contain user input. Never cache those URLs.
  const plain = new URL(url);
  plain.search = '';
  if (!assetUrls.has(plain.href)) return;
  event.respondWith(caches.open(CACHE).then(async cache => {
    const cached = await cache.match(plain.href);
    if (cached) return cached;
    const response = await fetch(plain.href);
    if (response.ok) await cache.put(plain.href, response.clone());
    return response;
  }));
});

self.addEventListener('message', event => {
  if (event.data === 'skipWaiting') self.skipWaiting();
});