library/apps/frontend/src/service-worker.js

/**
 * @copyright 2026 NHCarrigan
 * @license Naomi's Public License
 * @author Hikari
 */

const CACHE_VERSION = 'library-v1';
const STATIC_CACHE = `${CACHE_VERSION}-static`;
const DYNAMIC_CACHE = `${CACHE_VERSION}-dynamic`;
const IMAGE_CACHE = `${CACHE_VERSION}-images`;

// Static assets to cache on install
const STATIC_ASSETS = [
  '/offline.html'
];

// Install event - cache static assets
self.addEventListener('install', (event) => {
  console.log('[Service Worker] Installing...');
  event.waitUntil(
    caches.open(STATIC_CACHE).then((cache) => {
      console.log('[Service Worker] Caching static assets');
      return cache.addAll(STATIC_ASSETS).catch((err) => {
        console.error('[Service Worker] Failed to cache static assets:', err);
        // Don't fail installation if caching fails
        return Promise.resolve();
      });
    }).then(() => {
      return self.skipWaiting();
    })
  );
});

// Activate event - clean up old caches
self.addEventListener('activate', (event) => {
  console.log('[Service Worker] Activating...');
  event.waitUntil(
    caches.keys().then((cacheNames) => {
      return Promise.all(
        cacheNames
          .filter((cacheName) => {
            return cacheName.startsWith('library-') && cacheName !== STATIC_CACHE && cacheName !== DYNAMIC_CACHE && cacheName !== IMAGE_CACHE;
          })
          .map((cacheName) => {
            console.log('[Service Worker] Deleting old cache:', cacheName);
            return caches.delete(cacheName);
          })
      );
    }).then(() => {
      return self.clients.claim();
    })
  );
});

// Fetch event - implement caching strategies
self.addEventListener('fetch', (event) => {
  const { request } = event;
  const url = new URL(request.url);

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

  // Skip Chrome extensions and other protocols
  if (!url.protocol.startsWith('http')) {
    return;
  }

  // API requests - Network first, cache fallback
  if (url.pathname.startsWith('/api/')) {
    event.respondWith(
      fetch(request)
        .then((response) => {
          // Clone the response before caching
          const responseClone = response.clone();
          caches.open(DYNAMIC_CACHE).then((cache) => {
            cache.put(request, responseClone);
          });
          return response;
        })
        .catch(() => {
          return caches.match(request).then((cachedResponse) => {
            if (cachedResponse) {
              return cachedResponse;
            }
            // Return offline page for failed API requests
            return caches.match('/offline.html');
          });
        })
    );
    return;
  }

  // Images - Cache first, network fallback
  if (request.destination === 'image' || url.pathname.match(/\.(jpg|jpeg|png|gif|webp|svg)$/)) {
    event.respondWith(
      caches.match(request).then((cachedResponse) => {
        if (cachedResponse) {
          return cachedResponse;
        }
        return fetch(request).then((response) => {
          const responseClone = response.clone();
          caches.open(IMAGE_CACHE).then((cache) => {
            cache.put(request, responseClone);
          });
          return response;
        });
      })
    );
    return;
  }

  // Static assets - Cache first, network fallback
  if (url.pathname.match(/\.(js|css|woff|woff2|ttf|eot)$/)) {
    event.respondWith(
      caches.match(request).then((cachedResponse) => {
        if (cachedResponse) {
          return cachedResponse;
        }
        return fetch(request).then((response) => {
          const responseClone = response.clone();
          caches.open(STATIC_CACHE).then((cache) => {
            cache.put(request, responseClone);
          });
          return response;
        });
      })
    );
    return;
  }

  // HTML pages - Network first, cache fallback
  event.respondWith(
    fetch(request)
      .then((response) => {
        // Only cache successful responses
        if (response.ok) {
          const responseClone = response.clone();
          caches.open(DYNAMIC_CACHE).then((cache) => {
            cache.put(request, responseClone);
          });
        }
        return response;
      })
      .catch(() => {
        return caches.match(request).then((cachedResponse) => {
          if (cachedResponse) {
            return cachedResponse;
          }
          // Return offline page as fallback
          return caches.match('/offline.html');
        });
      })
  );
});

// Message event - handle cache clearing requests
self.addEventListener('message', (event) => {
  if (event.data && event.data.type === 'SKIP_WAITING') {
    self.skipWaiting();
  }
  if (event.data && event.data.type === 'CLEAR_CACHE') {
    event.waitUntil(
      caches.keys().then((cacheNames) => {
        return Promise.all(
          cacheNames.map((cacheName) => caches.delete(cacheName))
        );
      })
    );
  }
});