const CACHE_NAME = 'workout-planner-v1';

// Assets to pre-cache for offline shell
const PRECACHE_URLS = [
  '/icons/favicon.svg',
  '/icons/icon-192x192.png',
  '/manifest.json',
];

// Install: pre-cache critical assets
self.addEventListener('install', (event) => {
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) => cache.addAll(PRECACHE_URLS))
  );
  self.skipWaiting();
});

// Activate: clean old caches
self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((keys) =>
      Promise.all(
        keys
          .filter((key) => key !== CACHE_NAME)
          .map((key) => caches.delete(key))
      )
    )
  );
  self.clients.claim();
});

// Fetch: network-first for API/pages, cache-first for static assets
self.addEventListener('fetch', (event) => {
  const { request } = event;
  const url = new URL(request.url);

  // Skip non-GET requests
  if (request.method !== 'GET') return;

  // Skip API routes — always go to network
  if (url.pathname.startsWith('/api/')) return;

  // Static assets (icons, fonts, images): cache-first
  if (
    url.pathname.startsWith('/icons/') ||
    url.pathname.startsWith('/_next/static/') ||
    url.pathname.endsWith('.svg') ||
    url.pathname.endsWith('.png') ||
    url.pathname.endsWith('.woff2')
  ) {
    event.respondWith(
      caches.match(request).then((cached) => {
        if (cached) return cached;
        return fetch(request).then((response) => {
          if (response.ok) {
            const clone = response.clone();
            caches.open(CACHE_NAME).then((cache) => cache.put(request, clone));
          }
          return response;
        });
      })
    );
    return;
  }

  // Pages: network-first with offline fallback
  event.respondWith(
    fetch(request)
      .then((response) => {
        if (response.ok) {
          const clone = response.clone();
          caches.open(CACHE_NAME).then((cache) => cache.put(request, clone));
        }
        return response;
      })
      .catch(() => caches.match(request))
  );
});