// Service Worker for 宇之然内容创作平台
const CACHE_NAME = 'yuzhiran-v3';
const CACHE_URLS = [
  '/index.html',
  '/offline.html',
  '/manifest.json'
];

// 安装事件：预缓存核心资源
self.addEventListener('install', (event) => {
  console.log('[SW] Installing...');
  event.waitUntil(
    caches.open(CACHE_NAME).then((cache) => {
      console.log('[SW] Pre-caching core assets');
      return cache.addAll(CACHE_URLS.map(url => {
        return new Promise((resolve, reject) => {
          fetch(url).then(response => {
            if (response.ok) {
              resolve(url);
            } else {
              reject(new Error(`Failed to fetch ${url}: ${response.status}`));
            }
          }).catch(() => { resolve(url); });
        });
      }));
    }).catch(err => { console.error('[SW] Install failed:', err); })
  );
  self.skipWaiting();
});

// 激活事件：清理旧缓存
self.addEventListener('activate', (event) => {
  console.log('[SW] Activating...');
  event.waitUntil(
    caches.keys().then((cacheNames) => {
      return Promise.all(
        cacheNames.map((cache) => {
          if (cache !== CACHE_NAME) {
            console.log('[SW] Deleting old cache:', cache);
            return caches.delete(cache);
          }
        })
      );
    })
  );
  self.clients.claim();
});

// 网络请求拦截
self.addEventListener('fetch', (event) => {
  const { request } = event;
  const url = new URL(request.url);

  // 只处理同源请求
  if (url.origin !== location.origin) { return; }

  // API 请求：Network Only
  if (url.pathname.startsWith('/api/')) {
    event.respondWith(fetch(request));
    return;
  }

  // HTML 文档：Network First（确保 landing page 始终加载最新版）
  if (url.pathname === '/' || url.pathname.endsWith('.html')) {
    event.respondWith(
      fetch(request)
        .then(response => {
          if (response.ok) {
            const clone = response.clone();
            caches.open(CACHE_NAME).then(cache => cache.put(request, clone));
          }
          return response;
        })
        .catch(() => {
          return caches.match(request).then(cached => {
            return cached || caches.match('/offline.html');
          });
        })
    );
    return;
  }

  // 其他静态资源：Cache First
  event.respondWith(
    caches.match(request).then((cached) => {
      if (cached) {
        fetch(request).then(response => {
          if (response.ok) {
            caches.open(CACHE_NAME).then(cache => cache.put(request, response));
          }
        });
        return cached;
      }
      return fetch(request).then(response => {
        if (response.ok && response.status === 200) {
          const clone = response.clone();
          caches.open(CACHE_NAME).then(cache => cache.put(request, clone));
        }
        return response;
      }).catch(() => {
        if (request.destination === 'document') {
          return caches.match('/offline.html');
        }
      });
    })
  );
});

// 后台同步
self.addEventListener('sync', (event) => {
  if (event.tag === 'sync-logs') { event.waitUntil(syncLogs()); }
});

async function syncLogs() {
  console.log('[SW] Syncing logs...');
}