// sw.js — service worker (upgrade #7).
//
// Two strategies:
//  - app shell (html/css/js/hls.js/icons): cache-first → instant repeat loads, offline guide UI
//  - iptv-org JSON proxied via the relay (…/relay?url=…/*.json): stale-while-revalidate
//    → instant paint from cache, silent refresh in the background
//
// Live stream manifests + segments (the rest of /relay) and /probe, /metrics are
// NEVER cached — the relay marks them no-store and we bypass them here, so the SW
// is the sole freshness authority for metadata only.

const SHELL = 'orb-shell-v1';
const DATA = 'orb-data-v1';

const SHELL_ASSETS = [
  '/', '/index.html', '/styles.css',
  '/app.js', '/player.js', '/zapper.js', '/guide.js', '/ambient.js',
  '/lexicon.js', '/memory.js', '/health.js', '/epg-worker.js',
  '/lib/hls.min.js', '/lib/xmltv-parse.js',
  '/providers/source-provider.js', '/providers/mock.js', '/providers/iptv-org.js',
  '/manifest.webmanifest', '/icons/icon-192.png', '/icons/icon-512.png',
];

self.addEventListener('install', (e) => {
  e.waitUntil(caches.open(SHELL).then((c) => c.addAll(SHELL_ASSETS)).then(() => self.skipWaiting()));
});

self.addEventListener('activate', (e) => {
  e.waitUntil(
    caches.keys()
      .then((keys) => Promise.all(keys.filter((k) => ![SHELL, DATA].includes(k)).map((k) => caches.delete(k))))
      .then(() => self.clients.claim()),
  );
});

self.addEventListener('fetch', (e) => {
  const req = e.request;
  if (req.method !== 'GET') return;
  const url = new URL(req.url);
  if (url.origin !== self.location.origin) return; // same-origin only

  if (url.pathname === '/probe' || url.pathname === '/metrics') return;

  if (url.pathname === '/relay') {
    const upstream = url.searchParams.get('url') || '';
    // Only the JSON metadata is cacheable; stream manifests/segments are not.
    if (/\.json(\?|$)/i.test(upstream)) {
      e.respondWith(staleWhileRevalidate(req, DATA));
    }
    return; // streams/segments → straight to the relay, uncached
  }

  // App shell / static assets → cache-first.
  if (SHELL_ASSETS.includes(url.pathname)
      || url.pathname.startsWith('/icons/')
      || url.pathname.startsWith('/providers/')
      || url.pathname.startsWith('/lib/')) {
    e.respondWith(cacheFirst(req, SHELL));
  }
});

async function cacheFirst(req, cacheName) {
  const cache = await caches.open(cacheName);
  const hit = await cache.match(req);
  if (hit) return hit;
  try {
    const res = await fetch(req);
    if (res.ok) cache.put(req, res.clone());
    return res;
  } catch {
    if (req.mode === 'navigate') {
      const idx = await cache.match('/index.html');
      if (idx) return idx;
    }
    return new Response('offline', { status: 503, statusText: 'offline' });
  }
}

async function staleWhileRevalidate(req, cacheName) {
  const cache = await caches.open(cacheName);
  const hit = await cache.match(req);
  const network = fetch(req)
    .then((res) => { if (res.ok) cache.put(req, res.clone()); return res; })
    .catch(() => hit || new Response('offline', { status: 503 }));
  return hit || network;
}