const ROOT = new URL(self.registration.scope).pathname;
const appPath = path => `${ROOT}${String(path).replace(/^\/+/, '')}`;
const CACHE_NAMESPACE = `timmy-shell:${ROOT}:`;
const CACHE = `${CACHE_NAMESPACE}v5`;
const ASSETS = [
  '',
  'index.html',
  'styles.css',
  'app.js',
  'src/domain.js',
  'src/analysis.js',
  'manifest.webmanifest',
  'assets/timmy.svg',
  'assets/icon-192.svg',
  'assets/icon-512.svg',
].map(appPath);

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(CACHE_NAMESPACE) && key !== CACHE).map(key => caches.delete(key))))
    .then(() => self.clients.claim()),
));
self.addEventListener('fetch', event => {
  if (event.request.method !== 'GET' || !new URL(event.request.url).pathname.startsWith(ROOT)) return;
  event.respondWith(
    fetch(event.request)
      .then(response => {
        const copy = response.clone();
        caches.open(CACHE).then(cache => cache.put(event.request, copy));
        return response;
      })
      .catch(() => caches.match(event.request).then(hit => hit || caches.match(appPath('index.html')))),
  );
});