const RESOURCE_URL = 'https://static.cloudcachetci.com/qcloud/main/scripts/release/common/vendors/jquery-3.2.1.min.js';

async function fetchResource(event, request, cache) {
  // 缓存未命中：回源获取资源，并写入边缘函数独立缓存
  const response = await fetch(RESOURCE_URL);
  response.headers.set('Cache-Control', 's-maxage=10');
  event.waitUntil(cache.put(request, response.clone()));
  response.headers.append('x-edgefunctions-cache', 'miss');
  return response;
}

async function handleEvent(event) {
  const cache = caches.default;

  // 读、写、删使用同一个指定了 eo.cacheKey 的 Request 对象
  const request = new Request(RESOURCE_URL, {
    eo: { cacheKey: 'jquery-v1' },
  });

  try {
    let response = await cache.match(request);
    if (!response) {
      return fetchResource(event, request, cache);
    }
    response.headers.append('x-edgefunctions-cache', 'hit');
    return response;
  } catch (e) {
    // 缓存过期（504）或异常：删除后重新回源并写入
    try {
      await cache.delete(request);
    } catch {}
    return fetchResource(event, request, cache);
  }
}

addEventListener('fetch', (event) => {
  event.respondWith(handleEvent(event));
});