// posimai-sc SW — same-origin の静的資産のみキャッシュ（CDN は対象外）
const CACHE = 'posimai-sc-v8';
const STATIC = [
  '/',
  '/index.html',
  '/manifest.json',
  '/logo.png',
  '/js/app.js',
  '/js/data/drills.js',
  '/js/data/categories.js'
];

self.addEventListener('install', e => {
  e.waitUntil(
    Promise.all([
      caches.open(CACHE).then(c =>
        c.addAll(
          STATIC.filter(u => {
            try {
              new URL(u, self.location.origin);
              return true;
            } catch {
              return false;
            }
          })
        )
      ),
      self.skipWaiting()
    ])
  );
});

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

self.addEventListener('fetch', e => {
  if (e.request.method !== 'GET') return;
  if (!e.request.url.startsWith(self.location.origin)) return;

  e.respondWith(
    caches.open(CACHE).then(cache =>
      cache.match(e.request).then(cached => {
        const network = fetch(e.request)
          .then(res => {
            // type:'basic' = same-origin only; CORS レスポンスはキャッシュしない
            if (res.ok && res.type === 'basic') {
              cache.put(e.request, res.clone()).catch(err => {
                console.warn('[sc-sw] cache.put failed (quota?):', err);
              });
            }
            return res;
          })
          .catch(() => cached || new Response('Offline', { status: 503, statusText: 'Service Unavailable' }));
        return cached || network;
      })
    )
  );
});