/**
 * KundenKarte PWA Service Worker
 * Offline-First für Schaltschrank-Dokumentation
 */

const CACHE_NAME = 'kundenkarte-pwa-v12.4';
const OFFLINE_CACHE = 'kundenkarte-offline-v12.4';

// Statische Assets die immer gecached werden (ohne Query-String)
const STATIC_ASSETS = [
	'pwa.php',
	'img/pwa-icon-192.png',
	'img/pwa-icon-512.png',
	'../../../includes/jquery/js/jquery.min.js'
];

// Assets mit Versions-Query-String - NICHT cachen, immer vom Netzwerk laden
const VERSIONED_ASSETS = ['pwa.css', 'pwa.js'];

// Install - Cache statische Assets
self.addEventListener('install', event => {
	console.log('[SW] Installing...');
	event.waitUntil(
		caches.open(CACHE_NAME).then(cache => {
			console.log('[SW] Caching static assets');
			return cache.addAll(STATIC_ASSETS);
		})
	);
	self.skipWaiting();
});

// Activate - Alte Caches löschen
self.addEventListener('activate', event => {
	console.log('[SW] Activating...');
	event.waitUntil(
		caches.keys().then(keys => {
			return Promise.all(
				keys.filter(key => key !== CACHE_NAME && key !== OFFLINE_CACHE)
					.map(key => {
						console.log('[SW] Deleting old cache:', key);
						return caches.delete(key);
					})
			);
		})
	);
	self.clients.claim();
});

// Fetch Strategy
self.addEventListener('fetch', event => {
	const url = new URL(event.request.url);

	// PWA Auth Endpoints - immer Netzwerk
	if (url.pathname.includes('pwa_auth.php')) {
		event.respondWith(fetch(event.request));
		return;
	}

	// Versionierte Assets (CSS/JS mit ?v=X) - IMMER Netzwerk, kein Cache
	// Damit neue Versionen sofort geladen werden
	if (url.search && VERSIONED_ASSETS.some(a => url.pathname.includes(a))) {
		event.respondWith(
			fetch(event.request).catch(() => caches.match(event.request))
		);
		return;
	}

	// AJAX Requests - Netzwerk mit Offline-Fallback
	if (url.pathname.includes('/ajax/')) {
		event.respondWith(
			fetch(event.request)
				.then(response => {
					// Cache erfolgreiche GET-Requests für Offline
					if (event.request.method === 'GET' && response.ok) {
						const clone = response.clone();
						caches.open(OFFLINE_CACHE).then(cache => {
							cache.put(event.request, clone);
						});
					}
					return response;
				})
				.catch(() => {
					// Offline - versuche aus Cache
					return caches.match(event.request).then(cached => {
						if (cached) {
							return cached;
						}
						// Kein Cache - Offline-Fehler
						return new Response(JSON.stringify({
							success: false,
							offline: true,
							error: 'Offline - Keine Verbindung'
						}), {
							headers: { 'Content-Type': 'application/json' }
						});
					});
				})
		);
		return;
	}

	// PHP Seiten - Network First
	if (url.pathname.endsWith('.php')) {
		event.respondWith(
			fetch(event.request)
				.then(response => {
					// Cache für Offline
					const clone = response.clone();
					caches.open(CACHE_NAME).then(cache => {
						cache.put(event.request, clone);
					});
					return response;
				})
				.catch(() => caches.match(event.request))
		);
		return;
	}

	// Statische Assets (JS, CSS, Bilder) - Stale-While-Revalidate
	// Liefert sofort aus Cache, holt parallel frische Version für nächsten Aufruf
	event.respondWith(
		caches.open(CACHE_NAME).then(cache => {
			return cache.match(event.request).then(cached => {
				const fetchPromise = fetch(event.request).then(response => {
					if (response.ok) {
						cache.put(event.request, response.clone());
					}
					return response;
				}).catch(() => cached);

				return cached || fetchPromise;
			});
		})
	);
});

// Background Sync für Offline-Änderungen
self.addEventListener('sync', event => {
	if (event.tag === 'sync-changes') {
		console.log('[SW] Syncing offline changes...');
		event.waitUntil(syncOfflineChanges());
	}
});

// Offline-Änderungen synchronisieren
async function syncOfflineChanges() {
	// Wird von pwa.js gesteuert - sendet Message wenn sync fertig
	const clients = await self.clients.matchAll();
	clients.forEach(client => {
		client.postMessage({ type: 'SYNC_REQUESTED' });
	});
}

// Messages von der App
self.addEventListener('message', event => {
	if (event.data && event.data.type === 'SKIP_WAITING') {
		self.skipWaiting();
	}
});