const CACHE_VERSION = '2026-07-17-v1';
const CACHE_PREFIX = 'bis-blog-';
const CORE_CACHE = `${CACHE_PREFIX}core-${CACHE_VERSION}`;
const PAGE_CACHE = `${CACHE_PREFIX}pages-${CACHE_VERSION}`;
const ASSET_CACHE = `${CACHE_PREFIX}assets-${CACHE_VERSION}`;
const IMAGE_CACHE = `${CACHE_PREFIX}images-${CACHE_VERSION}`;

const CORE_ASSETS = [
  '/',
  '/offline.html',
  '/manifest.webmanifest',
  '/images/Bi.ico',
  '/images/pwa-192x192.png',
  '/images/pwa-512x512.png',
  '/images/pwa-maskable-512x512.png',
  '/images/apple-touch-icon.png',
];

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

self.addEventListener('activate', (event) => {
  event.waitUntil((async () => {
    const cacheNames = await caches.keys();
    await Promise.all(
      cacheNames
        .filter((name) => name.startsWith(CACHE_PREFIX) && ![CORE_CACHE, PAGE_CACHE, ASSET_CACHE, IMAGE_CACHE].includes(name))
        .map((name) => caches.delete(name))
    );
    await self.clients.claim();
    const clients = await self.clients.matchAll({ type: 'window' });
    clients.forEach((client) => client.postMessage({ type: 'OFFLINE_READY' }));
  })());
});

self.addEventListener('message', (event) => {
  if (event.data?.type === 'SKIP_WAITING') self.skipWaiting();
});

async function trimCache(cacheName, maxEntries) {
  const cache = await caches.open(cacheName);
  const keys = await cache.keys();
  if (keys.length > maxEntries) {
    await Promise.all(keys.slice(0, keys.length - maxEntries).map((key) => cache.delete(key)));
  }
}

async function networkFirst(request) {
  try {
    const response = await fetch(request);
    if (response.ok) {
      const cache = await caches.open(PAGE_CACHE);
      await cache.put(request, response.clone());
      void trimCache(PAGE_CACHE, 40);
    }
    return response;
  } catch {
    return (await caches.match(request)) || (await caches.match('/offline.html'));
  }
}

async function cacheFirst(request, cacheName, maxEntries) {
  const cached = await caches.match(request);
  if (cached) return cached;

  const response = await fetch(request);
  if (response.ok || response.type === 'opaque') {
    const cache = await caches.open(cacheName);
    await cache.put(request, response.clone());
    void trimCache(cacheName, maxEntries);
  }
  return response;
}

async function staleWhileRevalidate(request) {
  const cache = await caches.open(ASSET_CACHE);
  const cached = await cache.match(request);
  const network = fetch(request).then((response) => {
    if (response.ok) cache.put(request, response.clone());
    return response;
  }).catch(() => cached);
  return cached || network;
}

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

  const url = new URL(request.url);
  if (request.mode === 'navigate') {
    event.respondWith(networkFirst(request));
    return;
  }

  if (request.destination === 'image') {
    event.respondWith(cacheFirst(request, IMAGE_CACHE, 100));
    return;
  }

  if (
    url.origin === self.location.origin &&
    ['style', 'script', 'font', 'worker'].includes(request.destination)
  ) {
    event.respondWith(staleWhileRevalidate(request));
  }
});