/// <reference lib="webworker" />

// Claude Chat PWA — Service Worker
// Cache-First fuer statische Assets, Network-First fuer API-Calls

declare const self: ServiceWorkerGlobalScope;

const CACHE_NAME = 'claude-chat-v1';

// Statische Assets die gecacht werden sollen
const STATIC_ASSETS = [
  '/',
  '/favicon.png',
  '/manifest.json',
];

// ============ Install — Statische Assets vorladen ============

self.addEventListener('install', (event: ExtendableEvent) => {
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) => {
      return cache.addAll(STATIC_ASSETS);
    })
  );
  // Sofort aktivieren, nicht auf alte Tabs warten
  self.skipWaiting();
});

// ============ Activate — Alte Caches loeschen ============

self.addEventListener('activate', (event: ExtendableEvent) => {
  event.waitUntil(
    caches.keys().then((names) => {
      return Promise.all(
        names
          .filter((name) => name !== CACHE_NAME)
          .map((name) => caches.delete(name))
      );
    })
  );
  // Sofort alle Clients uebernehmen
  self.clients.claim();
});

// ============ Fetch — Caching-Strategie ============

self.addEventListener('fetch', (event: FetchEvent) => {
  const url = new URL(event.request.url);

  // WebSocket-Requests ignorieren
  if (url.protocol === 'ws:' || url.protocol === 'wss:') {
    return;
  }

  // API-Calls: Network-First mit Cache-Fallback
  if (url.pathname.startsWith('/api/')) {
    event.respondWith(networkFirst(event.request));
    return;
  }

  // Statische Assets: Cache-First mit Network-Fallback
  event.respondWith(cacheFirst(event.request));
});

/** Cache-First: Zuerst im Cache suchen, dann Netzwerk */
async function cacheFirst(request: Request): Promise<Response> {
  const cached = await caches.match(request);
  if (cached) return cached;

  try {
    const response = await fetch(request);
    // Erfolgreiche Responses cachen
    if (response.ok) {
      const cache = await caches.open(CACHE_NAME);
      cache.put(request, response.clone());
    }
    return response;
  } catch {
    // Offline-Fallback fuer HTML-Seiten
    if (request.headers.get('accept')?.includes('text/html')) {
      const cached = await caches.match('/');
      if (cached) return cached;
    }
    return new Response('Offline', { status: 503 });
  }
}

/** Network-First: Zuerst Netzwerk versuchen, dann Cache */
async function networkFirst(request: Request): Promise<Response> {
  try {
    const response = await fetch(request);
    // Erfolgreiche GET-Responses cachen
    if (response.ok && request.method === 'GET') {
      const cache = await caches.open(CACHE_NAME);
      cache.put(request, response.clone());
    }
    return response;
  } catch {
    const cached = await caches.match(request);
    if (cached) return cached;
    return new Response(JSON.stringify({ error: 'Offline' }), {
      status: 503,
      headers: { 'Content-Type': 'application/json' },
    });
  }
}

export {};