// Service worker cache strategy for player pages, assets, media, and playlists.

const CACHE_VERSION = 'v38';
const PAGE_CACHE = `pulse-signage-player-pages-${CACHE_VERSION}`;
const ASSET_CACHE = `pulse-signage-player-assets-${CACHE_VERSION}`;
const MEDIA_CACHE = `pulse-signage-player-media-${CACHE_VERSION}`;
const PLAYLIST_CACHE = `pulse-signage-player-playlists-${CACHE_VERSION}`;

function normalizeRequest(request) {
  const url = new URL(request.url);
  return new Request(`${url.origin}${url.pathname}`, {
    method: 'GET',
    headers: request.headers,
    mode: 'same-origin',
    credentials: 'same-origin'
  });
}

function shouldBypassCache(request) {
  if (!request) {
    return false;
  }

  if (request.cache === 'reload' || request.cache === 'no-store') {
    return true;
  }

  const cacheControl = String(request.headers.get('cache-control') || '').toLowerCase();
  const pragma = String(request.headers.get('pragma') || '').toLowerCase();
  return cacheControl.includes('no-cache') || cacheControl.includes('max-age=0') || pragma.includes('no-cache');
}

async function cacheResponse(cacheName, request, response, cacheKeyRequest) {
  if (!response || !response.ok) {
    return;
  }
  const cache = await caches.open(cacheName);
  await cache.put(cacheKeyRequest || request, response.clone());
}

async function networkFirst(request, cacheName, cacheKeyRequest) {
  try {
    const response = await fetch(request);
    if (response && response.ok) {
      await cacheResponse(cacheName, request, response, cacheKeyRequest);
      return response;
    }
    if (response && response.status === 304) {
      const cached = await caches.match(cacheKeyRequest || request);
      if (cached) {
        return cached;
      }
    }
    const cached = await caches.match(cacheKeyRequest || request);
    if (cached) {
      return cached;
    }
    return response;
  } catch (_error) {
    const cached = await caches.match(cacheKeyRequest || request);
    if (cached) {
      return cached;
    }
    return new Response('', { status: 504, statusText: 'Offline' });
  }
}

async function cacheFirst(request, cacheName) {
  const cached = await caches.match(request);
  if (cached) {
    return cached;
  }
  const response = await fetch(request);
  if (response && response.ok) {
    await cacheResponse(cacheName, request, response);
  }
  return response;
}

async function staleWhileRevalidate(request, cacheName) {
  const cached = await caches.match(request);
  const networkPromise = fetch(request).then(async function (response) {
    if (response && response.ok) {
      await cacheResponse(cacheName, request, response);
    }
    return response;
  }).catch(function () {
    return null;
  });

  if (cached) {
    networkPromise.catch(function () {
      return null;
    });
    return cached;
  }

  const networkResponse = await networkPromise;
  if (networkResponse) {
    return networkResponse;
  }

  return new Response('', { status: 504, statusText: 'Offline' });
}

async function networkOnly(request) {
  return fetch(request);
}

self.addEventListener('install', function (event) {
  self.skipWaiting();
  event.waitUntil(Promise.resolve());
});

self.addEventListener('activate', function (event) {
  event.waitUntil((async function () {
    const expected = [PAGE_CACHE, ASSET_CACHE, MEDIA_CACHE, PLAYLIST_CACHE];
    const keys = await caches.keys();
    await Promise.all(keys.filter(function (key) {
      return expected.indexOf(key) === -1;
    }).map(function (key) {
      return caches.delete(key);
    }));
    await self.clients.claim();
  })());
});

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

  const url = new URL(request.url);
  if (url.origin !== self.location.origin) {
    return;
  }

  if (url.pathname === '/sw.js') {
    return;
  }

  if (shouldBypassCache(request)) {
    event.respondWith(networkOnly(request));
    return;
  }

  if (url.pathname.startsWith('/assets/')) {
    event.respondWith(cacheFirst(request, ASSET_CACHE));
    return;
  }

  if (url.pathname.startsWith('/media/')) {
    event.respondWith(networkOnly(request));
    return;
  }

  if (request.mode === 'navigate' || url.pathname === '/' || url.pathname === '/onboard' || /^\/screen\/[^/]+$/.test(url.pathname)) {
    event.respondWith(networkFirst(request, PAGE_CACHE, normalizeRequest(request)));
    return;
  }

  if (url.pathname.startsWith('/api/screens/') && url.pathname.endsWith('/playlist')) {
    event.respondWith(networkFirst(request, PLAYLIST_CACHE, normalizeRequest(request)));
  }
});