/* raycer service worker
 * - app shell: network-first (so deploys propagate immediately), cache fallback for offline
 * - /api/*: network-only (data lives in Dexie)
 * - cross-origin (Dexie CDN): cache-first (immutable vendor assets)
 */

const VERSION = 'raycer-v2';
const SHELL_CACHE = `${VERSION}-shell`;

const PRECACHE = [
  '/',
  '/index.html',
  '/manifest.webmanifest',
  '/css/styles.css',
  '/js/app.js',
  '/js/api.js',
  '/js/db.js',
  '/js/theme.js',
  '/js/stats.js',
  '/js/calendar.js',
  '/icons/favicon.svg',
  '/icons/icon-192.png',
  '/icons/icon-512.png',
];

self.addEventListener('install', (event) => {
  event.waitUntil(
    (async () => {
      const cache = await caches.open(SHELL_CACHE);
      await cache.addAll(PRECACHE);
      self.skipWaiting();
    })()
  );
});

self.addEventListener('activate', (event) => {
  event.waitUntil(
    (async () => {
      const keys = await caches.keys();
      await Promise.all(
        keys
          .filter((k) => k !== SHELL_CACHE)
          .map((k) => caches.delete(k))
      );
      await self.clients.claim();
    })()
  );
});

self.addEventListener('fetch', (event) => {
  const req = event.request;
  if (req.method !== 'GET') return;

  const url = new URL(req.url);

  // API: network-only, never cache
  if (url.pathname.startsWith('/api/')) {
    event.respondWith(
      fetch(req).catch(
        () => new Response(JSON.stringify({ offline: true }), {
          status: 503,
          headers: { 'content-type': 'application/json' },
        })
      )
    );
    return;
  }

  // Same-origin (app shell + assets): network-first, cache fallback for offline
  if (url.origin === self.location.origin) {
    event.respondWith(
      (async () => {
        try {
          const fresh = await fetch(req);
          if (fresh.ok) {
            const cache = await caches.open(SHELL_CACHE);
            cache.put(req, fresh.clone()).catch(() => {});
          }
          return fresh;
        } catch {
          const cached = await caches.match(req);
          if (cached) return cached;
          if (req.mode === 'navigate') {
            const shell = await caches.match('/index.html');
            if (shell) return shell;
          }
          return new Response('offline', { status: 503 });
        }
      })()
    );
    return;
  }

  // Cross-origin (e.g. Dexie CDN): cache-first (immutable vendor assets)
  event.respondWith(
    (async () => {
      const cached = await caches.match(req);
      if (cached) return cached;
      try {
        const fresh = await fetch(req);
        if (fresh.ok) {
          const cache = await caches.open(SHELL_CACHE);
          cache.put(req, fresh.clone()).catch(() => {});
        }
        return fresh;
      } catch {
        return new Response('offline', { status: 503 });
      }
    })()
  );
});