const CACHE = 'stackchain-dashboard-shell-v5';
const OUTAGE_STATUSES = new Set([500, 502, 503, 504]);
const BASE = new URL('./', self.location.href).pathname;
const SHELL = [
  BASE,
  BASE + 'manifest.webmanifest',
  BASE + 'static/icons/stackchain-192.png',
  BASE + 'static/icons/stackchain-512.png',
  BASE + 'static/markdown.js',
  BASE + 'static/commands.js',
  BASE + 'static/search-preview.js',
  BASE + 'static/widgets.js',
  BASE + 'static/drafts.js',
  BASE + 'static/issue-outbox.js',
  BASE + 'static/offline-work.js',
  BASE + 'static/my-work.js',
  BASE + 'static/pick-work.js',
  BASE + 'static/conversation.js',
  BASE + 'static/issue-sheet.js',
  BASE + 'static/create-issue-sheet.js',
  BASE + 'static/pull-sheet.js',
  BASE + 'static/review-sheet.js',
  BASE + 'static/work-route.js',
  BASE + 'static/context-poller.js',
];

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

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

self.addEventListener('fetch', event => {
  const request = event.request;
  if (request.method !== 'GET' || request.url.includes('/api/')) return;
  const url = new URL(request.url);
  if (url.origin !== self.location.origin || !url.pathname.startsWith(BASE)) return;
  if (request.mode === 'navigate') {
    event.respondWith(
      fetch(request).then(async response => {
        const cache = await caches.open(CACHE);
        if (response.ok) {
          await cache.put(BASE, response.clone());
        } else if (OUTAGE_STATUSES.has(response.status)) {
          const cached = await cache.match(BASE);
          if (cached) return cached;
        }
        return response;
      }).catch(async () => {
        const cache = await caches.open(CACHE);
        return cache.match(BASE);
      })
    );
    return;
  }
  if (url.origin === self.location.origin && SHELL.includes(url.pathname)) {
    event.respondWith(caches.match(request).then(cached => cached || fetch(request)));
  }
});