const CACHE_NAME = 'coppertone-cache-v4';

const urlsToCache = [
  '/',
  '/index.html',
  '/favicon.ico',
];

self.addEventListener('install', (event) => {
  // Skip waiting to activate immediately
  self.skipWaiting();
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) => {
      // Only cache what exists, ignore failures
      return Promise.allSettled(urlsToCache.map(url => cache.add(url)));
    })
  );
});

self.addEventListener('fetch', (event) => {
  // Skip non-GET requests and chrome-extension URLs
  if (event.request.method !== 'GET' || event.request.url.startsWith('chrome-extension://')) {
    return;
  }

  // Skip API requests - let them go directly to network
  if (event.request.url.includes('/api/')) {
    return;
  }

  // Network-first strategy for JS/CSS assets (hashed filenames change on rebuild)
  if (event.request.url.includes('/assets/')) {
    event.respondWith(
      fetch(event.request)
        .then((response) => {
          // Clone and cache successful responses
          if (response.ok) {
            const responseClone = response.clone();
            caches.open(CACHE_NAME).then((cache) => cache.put(event.request, responseClone));
          }
          return response;
        })
        .catch(() => {
          return caches.match(event.request).then((cachedResponse) => {
            // Always return a valid Response - never undefined
            return cachedResponse || new Response('Asset not available offline', {
              status: 503,
              statusText: 'Service Unavailable',
              headers: { 'Content-Type': 'text/plain' }
            });
          });
        })
    );
    return;
  }

  // Cache-first for static assets
  event.respondWith(
    caches.match(event.request).then((response) => {
      if (response) return response;
      return fetch(event.request)
        .then((networkResponse) => {
          // Cache successful responses for static content
          if (networkResponse.ok && !event.request.url.includes('/api/')) {
            const responseClone = networkResponse.clone();
            caches.open(CACHE_NAME).then((cache) => cache.put(event.request, responseClone));
          }
          return networkResponse;
        })
        .catch(() => {
          // Return a fallback for navigation requests
          if (event.request.mode === 'navigate') {
            return caches.match('/index.html').then((cachedIndex) => {
              return cachedIndex || new Response('Page not available offline', {
                status: 503,
                statusText: 'Service Unavailable',
                headers: { 'Content-Type': 'text/html' }
              });
            });
          }
          return new Response('Network error', {
            status: 503,
            statusText: 'Service Unavailable',
            headers: { 'Content-Type': 'text/plain' }
          });
        });
    })
  );
});

self.addEventListener('activate', (event) => {
  // Claim clients immediately
  event.waitUntil(
    Promise.all([
      self.clients.claim(),
      // Clear old caches
      caches.keys().then((cacheNames) =>
        Promise.all(
          cacheNames.map((cacheName) => {
            if (cacheName !== CACHE_NAME) {
              return caches.delete(cacheName);
            }
            return undefined;
          })
        )
      )
    ])
  );
});