内容分发与 CDN：静态加速、边缘缓存与缓存失效

// Vite 构建产物示意
dist/assets/
    ├── index-DX3f2ka9.js    // 内容哈希
    ├── vendor-9f1c4b7d.js
    └── main-8a2e1f0c.css

# CDN 或源站 Nginx 配置：哈希资源长期缓存
location ~* \.(js|css|svg)$ {
    expires 1y;
    add_header Cache-Control "public, max-age=31536000, immutable";
}
location ~* \.html$ {
    expires -1;  # HTML 永不缓存，确保引用最新资源
    add_header Cache-Control "no-cache";
}

HTTP/1.1 200 OK
Content-Type: application/json
Cache-Control: private, max-age=0, must-revalidate

// Cloudflare Worker：基于 URL 的缓存策略路由
addEventListener('fetch', (event) => {
  event.respondWith(handle(event.request));
});

async function handle(request) {
  const url = new URL(request.url);
  let cacheTtl = 0;

  // 静态资源：永久缓存
  if (/\.(js|css|svg|webp|avif)$/.test(url.pathname)) {
    cacheTtl = 31536000;
  }
  // 公共时间线：短 TTL 缓存
  else if (url.pathname.startsWith('/api/public/timeline')) {
    cacheTtl = 30;
  }
  // 个性化 API：不缓存
  else if (url.pathname.startsWith('/api/')) {
    cacheTtl = 0;
  }

  const response = await fetch(request); // 回源
  if (cacheTtl > 0 && response.status === 200) {
    const headers = new Headers(response.headers);
    headers.set('Cache-Control', `public, s-maxage=${cacheTtl}`);
    return new Response(response.body, { status: 200, headers });
  }
  return response;
}

# Nginx 缓存键：只保留影响内容的参数
proxy_cache_key "$scheme$host$uri?image_view=$arg_image_view&w=$arg_w";
proxy_cache_key "$scheme$host$uri"  # 忽略 utm / t 等无关参数

// Cloudflare Worker 动态聚合：合并多个接口请求
async function handleTimeline(request) {
  const token = request.headers.get('Authorization');
  if (!token) return new Response('Unauthorized', { status: 401 });

  // 在边缘并行请求多个内部服务，合并响应
  const [posts, profile, notifications] = await Promise.all([
    fetch('https://api.internal/timeline', { headers: { Authorization: token } }),
    fetch('https://api.internal/me', { headers: { Authorization: token } }),
    fetch('https://api.internal/notifications/count', { headers: { Authorization: token } }),
  ]);

  const [postData, profileData, notifData] = await Promise.all([
    posts.json(), profile.json(), notifData.json(),
  ]);

  return Response.json({
    posts: postData,
    profile: profileData,
    unreadNotifications: notifData.count,
  });
}

// Go 侧配合：源站主动清除 CDN 缓存（Purge API）
func (s *CacheService) PurgeURL(ctx context.Context, url string) error {
	// 调用 CDN 提供商的 purge 接口
	req, _ := http.NewRequestWithContext(ctx, "POST",
		s.cdnBase+"/v1/purge", strings.NewReader(`{"urls":["`+url+`"]}`))
	req.Header.Set("Authorization", "Bearer "+s.cdnToken)
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	return resp.Body.Close()
}

# 启用 Brotli 压缩（优先于 gzip）
brotli on;
brotli_comp_level 5;
brotli_types text/plain text/css application/json application/javascript image/svg+xml;

# 仅在客户端声明支持时启用
add_header "Accept-Encoding" "gzip, deflate, br, zstd";

// 通过 Cache-Tag 实现「一个用户的内容整体失效」
// 源站响应时打上标签
const headers = new Headers();
headers.set('Cache-Tag', `user:${userId}`);
// 更新用户资料后，按标签批量失效
await cdn.purgeByTag(`user:${userId}`);

# Nginx CDN：忽略无意义的查询参数
proxy_cache_key "$uri?image_view";