const CACHE_NAME = 'whisky-vault-v4'; // Increment version for "Ironclad" strategy

// CONFIG: Core pages and assets to pre-cache immediately on install
const CORE_PAGES = [
    '/',              // Dashboard / Home
    '/tasting/new',   // Critical: Add Tasting Screen
    '/scan',          // Critical: Scan Screen
];

const STATIC_ASSETS = [
    '/manifest.json',
    '/icon-192.png',
    '/icon-512.png',
    '/favicon.ico',
];

self.addEventListener('install', (event) => {
    event.waitUntil(
        caches.open(CACHE_NAME).then((cache) => {
            console.log('⚡ PWA: Pre-caching core pages and assets...');
            // Combine items to cache
            return cache.addAll([...CORE_PAGES, ...STATIC_ASSETS]);
        })
    );
    self.skipWaiting();
});

self.addEventListener('activate', (event) => {
    event.waitUntil(
        caches.keys().then((cacheNames) => {
            return Promise.all(
                cacheNames.map((cacheName) => {
                    if (cacheName !== CACHE_NAME) {
                        return caches.delete(cacheName);
                    }
                })
            );
        })
    );
    self.clients.claim();
});

// Helper for Network-First with Timeout
function fetchWithTimeout(request, timeoutMs = 3000) {
    return new Promise((resolve, reject) => {
        const timeoutId = setTimeout(() => {
            reject(new Error('Network timeout'));
        }, timeoutMs);

        fetch(request).then(
            (response) => {
                clearTimeout(timeoutId);
                resolve(response);
            },
            (err) => {
                clearTimeout(timeoutId);
                reject(err);
            }
        );
    });
}

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

    // CRITICAL: Always bypass cache for auth, api, and supabase requests
    const isAuthRequest = url.pathname.includes('/auth/') ||
        url.pathname.includes('/v1/auth/') ||
        url.pathname.includes('/v1/token');
    const isApiRequest = url.pathname.includes('/api/');
    const isSupabaseRequest = url.hostname.includes('supabase.co');

    if (isAuthRequest || isApiRequest || isSupabaseRequest) {
        return;
    }

    // 1. NEXT.JS DATA (RSC): Stale-While-Revalidate with empty JSON fallback
    if (url.pathname.startsWith('/_next/data/')) {
        event.respondWith(
            fetchWithTimeout(event.request, 2000)
                .catch(async () => {
                    const cachedResponse = await caches.match(event.request);
                    if (cachedResponse) return cachedResponse;

                    // Fallback to empty JSON to prevent "Application Error" screens
                    return new Response(JSON.stringify({}), {
                        headers: { 'Content-Type': 'application/json' }
                    });
                })
        );
        return;
    }

    // 2. ASSETS & APP SHELL: Stale-While-Revalidate
    const isAsset = event.request.destination === 'style' ||
        event.request.destination === 'script' ||
        event.request.destination === 'worker' ||
        event.request.destination === 'font' ||
        event.request.destination === 'image' ||
        url.pathname.startsWith('/_next/static');

    if (isAsset) {
        event.respondWith(
            caches.match(event.request).then((cachedResponse) => {
                const fetchPromise = fetch(event.request).then((networkResponse) => {
                    if (networkResponse && networkResponse.status === 200) {
                        const responseClone = networkResponse.clone();
                        caches.open(CACHE_NAME).then((cache) => {
                            cache.put(event.request, responseClone);
                        });
                    }
                    return networkResponse;
                });
                return cachedResponse || fetchPromise;
            })
        );
        return;
    }

    // 3. NAVIGATION: Ironclad Navigation Fallback
    if (event.request.mode === 'navigate') {
        event.respondWith(
            fetchWithTimeout(event.request, 3000)
                .catch(async () => {
                    console.log('[SW] Navigation network failure, attempting cache fallback');
                    const cachedResponse = await caches.match(event.request);
                    if (cachedResponse) return cachedResponse;

                    // CRITICAL FALLBACK: Load the Root App Shell ('/')
                    // This allows Next.js to bootstrap and handle the routing client-side
                    console.warn('⚠️ PWA: Route not in cache, fallback to Root App Shell');
                    return caches.match('/');
                })
        );
        return;
    }
});