events {
    worker_connections 1024;
}

http {
    upstream chat_agent {
        server chat-agent:5000;
    }

    # Rate limiting
    limit_req_zone $binary_remote_addr zone=api:10m rate=10r/s;
    limit_req_zone $binary_remote_addr zone=websocket:10m rate=5r/s;

    server {
        listen 80;
        server_name localhost;

        # Security headers
        add_header X-Frame-Options DENY;
        add_header X-Content-Type-Options nosniff;
        add_header X-XSS-Protection "1; mode=block";
        add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;

        # Gzip compression
        gzip on;
        gzip_vary on;
        gzip_min_length 1024;
        gzip_types text/plain text/css application/json application/javascript text/xml application/xml application/xml+rss text/javascript;

        # Static files
        location /static/ {
            alias /app/static/;
            expires 1y;
            add_header Cache-Control "public, immutable";
        }

        # WebSocket connections
        location /socket.io/ {
            limit_req zone=websocket burst=10 nodelay;
            
            proxy_pass http://chat_agent;
            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;
            
            # WebSocket timeout settings
            proxy_read_timeout 86400;
            proxy_send_timeout 86400;
        }

        # API endpoints
        location /api/ {
            limit_req zone=api burst=20 nodelay;
            
            proxy_pass http://chat_agent;
            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;
        }

        # Health check endpoint
        location /health {
            proxy_pass http://chat_agent;
            access_log off;
        }

        # Main application
        location / {
            proxy_pass http://chat_agent;
            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;
        }
    }

    # HTTPS configuration (uncomment and configure for production)
    # server {
    #     listen 443 ssl http2;
    #     server_name your-domain.com;
    #
    #     ssl_certificate /etc/nginx/ssl/cert.pem;
    #     ssl_certificate_key /etc/nginx/ssl/key.pem;
    #     ssl_protocols TLSv1.2 TLSv1.3;
    #     ssl_ciphers ECDHE-RSA-AES256-GCM-SHA512:DHE-RSA-AES256-GCM-SHA512:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384;
    #     ssl_prefer_server_ciphers off;
    #
    #     # Include the same location blocks as above
    # }
}