events {
    worker_connections 2048;
    use epoll;
    multi_accept on;
}

http {
    upstream backend {
        least_conn;
        server app1:3001 max_fails=3 fail_timeout=30s;
        server app2:3002 max_fails=3 fail_timeout=30s;
        server app3:3003 max_fails=3 fail_timeout=30s;
    }

    # 缓存配置
    proxy_cache_path /var/cache/nginx levels=1:2 keys_zone=app_cache:10m max_size=1g inactive=60m use_temp_path=off;

    # 限流配置
    limit_req_zone $binary_remote_addr zone=general:10m rate=100r/s;
    limit_conn_zone $binary_remote_addr zone=addr:10m;

    server {
        listen 80;
        server_name _;

        # 健康检查端点
        location /health {
            access_log off;
            return 200 "healthy\n";
            add_header Content-Type text/plain;
        }

        # 静态资源缓存
        location /_next/static/ {
            proxy_pass http://backend;
            proxy_cache app_cache;
            proxy_cache_valid 200 365d;
            proxy_cache_use_stale error timeout updating;
            add_header X-Cache-Status $upstream_cache_status;
            expires 365d;
            add_header Cache-Control "public, immutable";
        }

        # 图片资源缓存
        location ~* \.(jpg|jpeg|png|gif|webp|avif|svg|ico)$ {
            proxy_pass http://backend;
            proxy_cache app_cache;
            proxy_cache_valid 200 365d;
            proxy_cache_use_stale error timeout updating;
            add_header X-Cache-Status $upstream_cache_status;
            expires 365d;
            add_header Cache-Control "public, immutable";
        }

        # API 路由
        location /api/ {
            proxy_pass http://backend;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection 'upgrade';
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            
            # API 缓存
            proxy_cache app_cache;
            proxy_cache_valid 200 5m;
            proxy_cache_methods GET HEAD;
            proxy_cache_bypass $http_pragma $http_authorization;
            
            # 连接超时
            proxy_connect_timeout 60s;
            proxy_send_timeout 60s;
            proxy_read_timeout 60s;
        }

        # 主应用路由
        location / {
            limit_req zone=general burst=200 nodelay;
            limit_conn addr 10;
            
            proxy_pass http://backend;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection 'upgrade';
            proxy_set_header Host $host;
            proxy_set_header X-Real-IP $remote_addr;
            proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
            proxy_set_header X-Forwarded-Proto $scheme;
            
            # 缓冲配置
            proxy_buffering on;
            proxy_buffer_size 4k;
            proxy_buffers 8 4k;
            proxy_busy_buffers_size 8k;
            
            # 连接超时
            proxy_connect_timeout 60s;
            proxy_send_timeout 60s;
            proxy_read_timeout 60s;
        }

        # Gzip 压缩
        gzip on;
        gzip_vary on;
        gzip_proxied any;
        gzip_comp_level 6;
        gzip_types text/plain text/css text/xml text/javascript application/json application/javascript application/xml+rss application/rss+xml font/truetype font/opentype application/vnd.ms-fontobject image/svg+xml;
    }
}