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)
      || (ROOT === '/' && key === 'timmy-shell-v4')
    ).map(key => caches.delete(key))))
    .then(() => self.clients.claim()),
));
self.addEventListener('fetch', event => {
  if (event.request.method !== 'GET') return;
  const pathname = new URL(event.request.url).pathname;
  if (!pathname.startsWith(ROOT)) return;
  if (pathname.startsWith(appPath('api/'))) {
    event.respondWith(fetch(event.request));
    return;
  }
  event.respondWith(
    fetch(event.request)
      .then(response => {
        if (!/\bno-store\b/i.test(response.headers.get('cache-control') || '')) {
          const copy = response.clone();
          caches.open(CACHE).then(cache => cache.put(event.request, copy));
        }
        return response;
      })
      .catch(() => caches.open(CACHE).then(async cache =>
        (await cache.match(event.request)) || cache.match(appPath('index.html'))
      )),
  );
});
