// Veza Platform Service Worker
// v1.0.9 W4 Day 16 — strategy spec (per docs/ROADMAP_V1.0_LAUNCH.md) :
//   - Static assets  : StaleWhileRevalidate
//   - HLS segments   : CacheFirst, max-age 7d, max 50 entries
//   - API GET        : NetworkFirst, timeout 3s
//
// We intentionally stay on hand-rolled fetch handlers rather than
// migrating to Workbox : the existing implementation already carries
// push notifications + background sync + notificationclick, and the
// strategies the roadmap asks for are 60 lines below. Workbox would
// bring an additional 200+ KB of runtime + a build-step dependency
// for a feature set we already cover.

const CACHE_VERSION = '__BUILD_VERSION__';
const CACHE_NAME = `veza-platform-${CACHE_VERSION}`;
const STATIC_CACHE_NAME = `veza-static-${CACHE_VERSION}`;
const DYNAMIC_CACHE_NAME = `veza-dynamic-${CACHE_VERSION}`;

// Day 16 strategy constants — tunable here, NOT inline in the helpers.
const HLS_CACHE_MAX_ENTRIES = 50;
const HLS_CACHE_MAX_AGE_MS = 7 * 24 * 60 * 60 * 1000; // 7d
const NETWORK_FIRST_TIMEOUT_MS = 3000; // 3s — beyond this, serve cached

// Files to cache on install
const STATIC_ASSETS = [
  '/',
  '/dashboard',
  '/chat',
  '/library',
  '/profile',
  '/settings',
  '/manifest.json',
  '/icons/icon-192x192.png',
  '/icons/icon-512x512.png'
];

// API endpoints to cache with network-first strategy
const API_CACHE_PATTERNS = [
  /^https?:\/\/.*\/api\/v1\/user\/profile$/,
  /^https?:\/\/.*\/api\/v1\/library\/files$/,
  /^https?:\/\/.*\/api\/v1\/dashboard\/stats$/
];

// Install event - v0.801: skip waiting, no aggressive cache clear on install
self.addEventListener('install', (event) => {
  event.waitUntil(self.skipWaiting());
});

// Activate event - clean old version caches, claim
self.addEventListener('activate', (event) => {
  event.waitUntil(
    caches.keys().then((cacheNames) => {
      return Promise.all(
        cacheNames
          .filter((name) => !name.includes(CACHE_VERSION))
          .map((name) => caches.delete(name))
      );
    }).then(() => self.clients.claim())
  );
});

// Fetch event - handle requests with appropriate caching strategy
self.addEventListener('fetch', (event) => {
  const { request } = event;
  const url = new URL(request.url);

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

  // Skip WebSocket connections
  if (request.headers.get('upgrade') === 'websocket') {
    return;
  }

  // v0.801: JS/CSS chunks always from network - never cache
  if (url.pathname.includes('/sw.js') || 
      url.pathname.includes('/assets/') ||
      /\.(js|css|mjs)(\?.*)?$/.test(url.pathname)) {
    return;
  }

  // Skip external requests (except API)
  if (!url.origin.includes(self.location.origin) && !isApiRequest(request.url)) {
    return;
  }

  event.respondWith(
    handleRequest(request)
  );
});

// Handle different types of requests with appropriate strategies
async function handleRequest(request) {
  try {
    // Strategy 0: Cache First for audio files (offline playback)
    if (isAudioRequest(request.url)) {
      return await cacheAudio(request);
    }

    // Strategy 1: Cache First for static assets
    if (isStaticAsset(request.url)) {
      return await cacheFirst(request, STATIC_CACHE_NAME);
    }

    // Strategy 2: Network First for API requests
    if (isApiRequest(request.url)) {
      return await networkFirst(request, DYNAMIC_CACHE_NAME);
    }
    
    // Strategy 3: Stale While Revalidate for pages
    if (isPageRequest(request.url)) {
      return await staleWhileRevalidate(request, DYNAMIC_CACHE_NAME);
    }
    
    // Default: Network only
    return await fetch(request);
    
  } catch (error) {
    console.error('[SW] Request failed:', error);
    
    // Return offline page for navigation requests
    if (isPageRequest(request.url)) {
      return await getOfflinePage();
    }
    
    // Return cached version if available
    const cachedResponse = await caches.match(request);
    if (cachedResponse) {
      return cachedResponse;
    }
    
    // Return generic offline response
    return new Response('Offline', { 
      status: 503, 
      statusText: 'Service Unavailable' 
    });
  }
}

// Cache First strategy
async function cacheFirst(request, cacheName) {
  const cachedResponse = await caches.match(request);
  
  if (cachedResponse) {
    return cachedResponse;
  }
  
  const networkResponse = await fetch(request);
  
  if (networkResponse.ok) {
    const cache = await caches.open(cacheName);
    cache.put(request, networkResponse.clone());
  }
  
  return networkResponse;
}

// Network First strategy with 3s timeout (Day 16).
// Race the network request against a fixed timeout. If the network
// hasn't replied within NETWORK_FIRST_TIMEOUT_MS, fall back to the
// cached version IF one exists — otherwise let the request continue
// (no point timing out into a hard error).
async function networkFirst(request, cacheName) {
  const cache = await caches.open(cacheName);
  const cachedPromise = cache.match(request);

  const networkPromise = fetch(request).then((networkResponse) => {
    if (networkResponse.ok) {
      // Best-effort cache write ; clone first to avoid the
      // "Response body is already used" trap.
      cache.put(request, networkResponse.clone()).catch(() => {});
    }
    return networkResponse;
  });

  // If the network is slow, return the cached response after the
  // timeout. The network request keeps running in the background and
  // updates the cache for the next visit.
  const timed = new Promise((resolve) => {
    setTimeout(async () => {
      const cached = await cachedPromise;
      if (cached) {
        console.log('[SW] networkFirst: 3s timeout hit, serving cached');
        resolve(cached);
      }
      // No cached response — let the network race continue.
    }, NETWORK_FIRST_TIMEOUT_MS);
  });

  try {
    return await Promise.race([networkPromise, timed.then((v) => v || networkPromise)]);
  } catch (error) {
    const cached = await cachedPromise;
    if (cached) {
      console.log('[SW] networkFirst: network failed, serving cached');
      return cached;
    }
    throw error;
  }
}

// Stale While Revalidate strategy
// CORRECTION DURABLE: Clone la réponse IMMÉDIATEMENT pour éviter "Response body is already used"
async function staleWhileRevalidate(request, cacheName) {
  const cachedResponse = await caches.match(request);
  
  const networkResponsePromise = fetch(request)
    .then((networkResponse) => {
      if (networkResponse.ok) {
        // ✅ Cloner IMMÉDIATEMENT la réponse avant toute autre opération
        const responseToCache = networkResponse.clone();
        
        // Mettre en cache de manière asynchrone (sans bloquer)
        caches.open(cacheName).then((cache) => {
          cache.put(request, responseToCache).catch((err) => {
            console.warn('[SW] Failed to cache response:', err);
          });
        });
      }
      return networkResponse;
    })
    .catch(() => null);
  
  return cachedResponse || await networkResponsePromise;
}

// Get offline page
async function getOfflinePage() {
  const cache = await caches.open(STATIC_CACHE_NAME);
  const offlineResponse = await cache.match('/');
  
  if (offlineResponse) {
    return offlineResponse;
  }
  
  return new Response(`
    <!DOCTYPE html>
    <html>
      <head>
        <title>Veza - Hors ligne</title>
        <meta charset="utf-8">
        <meta name="viewport" content="width=device-width, initial-scale=1">
        <style>
          body { 
            font-family: system-ui, sans-serif; 
            text-align: center; 
            padding: 2rem; 
            background: #1a1a1a; 
            color: white;
          }
          .offline-container {
            max-width: 400px;
            margin: 0 auto;
            padding: 2rem;
            border-radius: 8px;
            background: #2a2a2a;
          }
          .offline-icon {
            font-size: 4rem;
            margin-bottom: 1rem;
          }
        </style>
      </head>
      <body>
        <div class="offline-container">
          <div class="offline-icon">📱</div>
          <h1>Veza - Mode Hors Ligne</h1>
          <p>Vous êtes actuellement hors ligne. Certaines fonctionnalités peuvent être limitées.</p>
          <button onclick="window.location.reload()">Réessayer</button>
        </div>
      </body>
    </html>
  `, {
    headers: { 'Content-Type': 'text/html' }
  });
}

// v0.12.5: Audio file caching for offline playback.
// v1.0.9 Day 16: enforce 50-entry cap + 7-day TTL per the roadmap spec.
const AUDIO_CACHE_NAME = `veza-audio-${CACHE_VERSION}`;

function isAudioRequest(url) {
  const path = new URL(url).pathname;
  return /\.(mp3|m4a|ogg|wav|flac|aac|opus|ts|m4s)(\?.*)?$/.test(path) ||
    path.includes('/audio/') ||
    path.includes('/hls/');
}

// CacheFirst with TTL + LRU. The HLS cache holds up to 50 segments ;
// each is valid for 7 days from the moment it was first cached. Older
// entries are pruned on every miss-then-fetch ; the cap is enforced
// FIFO (oldest-cached first to evict).
async function cacheAudio(request) {
  const cache = await caches.open(AUDIO_CACHE_NAME);
  const cached = await cache.match(request);

  // Hit — but check the age before serving. The cache stores the
  // response with its `date` header preserved ; we compute age client-side.
  if (cached) {
    if (!isCachedEntryStale(cached)) {
      return cached;
    }
    // Stale : fall through to refresh, but if the network is offline
    // we'll happily serve the stale entry below rather than fail.
    console.log('[SW] HLS cache: entry stale (>7d), refreshing');
  }

  try {
    const response = await fetch(request);
    if (response.ok) {
      // Clone ONCE then put — `Response.body` is single-use.
      const responseToCache = response.clone();
      await cache.put(request, responseToCache);
      // Best-effort eviction : never block the user on it.
      pruneAudioCache(cache).catch((err) =>
        console.warn('[SW] HLS cache prune failed:', err),
      );
    }
    return response;
  } catch (error) {
    // Network down — serve the stale entry if we have one ; this is
    // the offline-playback path the roadmap acceptance asks for.
    if (cached) {
      console.log('[SW] HLS cache: network failed, serving stale (offline)');
      return cached;
    }
    throw error;
  }
}

// isCachedEntryStale reads the response's `date` header and returns
// true if the entry is older than HLS_CACHE_MAX_AGE_MS. Returns false
// if the header is missing (newer entries always have one ; missing
// = legacy entry pre-Day 16, give it the benefit of the doubt).
function isCachedEntryStale(response) {
  const dateHeader = response.headers.get('date');
  if (!dateHeader) return false;
  const cachedAt = Date.parse(dateHeader);
  if (Number.isNaN(cachedAt)) return false;
  return Date.now() - cachedAt > HLS_CACHE_MAX_AGE_MS;
}

// pruneAudioCache enforces HLS_CACHE_MAX_ENTRIES. Cache `keys()`
// returns Requests in insertion order, so we evict from the head
// (FIFO ≈ LRU when access is the same as insertion order, which it
// is for content-addressed segments — they're never re-inserted).
async function pruneAudioCache(cache) {
  const keys = await cache.keys();
  if (keys.length <= HLS_CACHE_MAX_ENTRIES) return;
  const toEvict = keys.length - HLS_CACHE_MAX_ENTRIES;
  for (let i = 0; i < toEvict; i++) {
    // eslint-disable-next-line no-await-in-loop
    await cache.delete(keys[i]);
  }
}

// Helper functions - only cache images, fonts, ico (never js/css)
function isStaticAsset(url) {
  const path = new URL(url).pathname;
  if (path.includes('/assets/')) return false;
  return /\.(png|jpg|jpeg|gif|svg|webp|woff|woff2|ttf|eot|ico)(\?.*)?$/.test(path);
}

function isApiRequest(url) {
  return url.includes('/api/') || API_CACHE_PATTERNS.some(pattern => pattern.test(url));
}

function isPageRequest(url) {
  const urlObj = new URL(url);
  return urlObj.pathname.match(/^\/[^.]*$/) && !isApiRequest(url);
}

// Message handling for communication with the main thread
self.addEventListener('message', (event) => {
  const { type } = event.data;
  
  switch (type) {
    case 'SKIP_WAITING':
      self.skipWaiting();
      break;
      
    case 'GET_VERSION':
      event.ports[0].postMessage({
        type: 'VERSION',
        payload: { version: CACHE_NAME }
      });
      break;
      
    case 'CLEAR_CACHE':
      caches.keys().then((cacheNames) => {
        return Promise.all(
          cacheNames.map((cacheName) => caches.delete(cacheName))
        );
      }).then(() => {
        event.ports[0].postMessage({
          type: 'CACHE_CLEARED',
          payload: { success: true }
        });
      });
      break;

    // v0.12.5: Cache a specific audio URL for offline playback
    case 'CACHE_AUDIO':
      if (event.data.url) {
        caches.open(AUDIO_CACHE_NAME).then(async (cache) => {
          try {
            await cache.add(event.data.url);
            event.ports[0]?.postMessage({ type: 'AUDIO_CACHED', payload: { success: true, url: event.data.url } });
          } catch (err) {
            event.ports[0]?.postMessage({ type: 'AUDIO_CACHED', payload: { success: false, error: err.message } });
          }
        });
      }
      break;

    default:
      console.log('[SW] Unknown message type:', type);
  }
});

// Background sync for offline actions
self.addEventListener('sync', (event) => {
  if (event.tag === 'background-sync') {
    event.waitUntil(doBackgroundSync());
  }
});

async function doBackgroundSync() {
  console.log('[SW] Performing background sync...');
  // Implement background sync logic here
  // For example: sync offline messages, upload queued files, etc.
}

// Push notifications
self.addEventListener('push', (event) => {
  if (!event.data) {
    return;
  }

  const data = event.data.json();
  const url = data.link || data.url || '/';
  const options = {
    body: data.body,
    icon: '/icons/icon-192x192.png',
    badge: '/icons/badge-72x72.png',
    vibrate: [100, 50, 100],
    data: {
      dateOfArrival: Date.now(),
      primaryKey: data.primaryKey || 1,
      url
    },
    actions: [
      {
        action: 'explore',
        title: 'Ouvrir',
        icon: '/icons/checkmark.png'
      },
      {
        action: 'close',
        title: 'Fermer',
        icon: '/icons/xmark.png'
      }
    ]
  };

  event.waitUntil(
    self.registration.showNotification(data.title, options)
  );
});

// Notification click handling
self.addEventListener('notificationclick', (event) => {
  event.notification.close();

  if (event.action === 'close') {
    return;
  }

  const urlToOpen = event.notification.data?.url || event.notification.data?.link || '/';

  event.waitUntil(
    self.clients.matchAll({ type: 'window' }).then((clientList) => {
      // Check if a window is already open
      for (const client of clientList) {
        if (client.url === urlToOpen && 'focus' in client) {
          return client.focus();
        }
      }
      
      // Open a new window
      if (self.clients.openWindow) {
        return self.clients.openWindow(urlToOpen);
      }
    })
  );
});

console.log('[SW] Veza Platform Service Worker loaded');