server {
    listen 4000 default_server;
    listen [::]:4000 default_server;

    server_name _;
    root /tmp;

    client_max_body_size 100m;
    client_body_temp_path /tmp/nginx/body;
    fastcgi_temp_path /tmp/nginx/fastcgi;
    proxy_temp_path /tmp/nginx/proxy;
    scgi_temp_path /tmp/nginx/scgi;
    uwsgi_temp_path /tmp/nginx/uwsgi;

    # Security headers
    add_header X-Frame-Options SAMEORIGIN;
    add_header X-Content-Type-Options nosniff;
    add_header X-XSS-Protection "1; mode=block";
    add_header Referrer-Policy strict-origin-when-cross-origin;

    # Logging
    access_log /dev/stdout;
    error_log /dev/stderr;

    # Gzip compression
    gzip on;
    gzip_vary on;
    gzip_min_length 1024;
    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/atom+xml
        image/svg+xml;

    # Proxy to Keila application
    location / {
        proxy_pass http://127.0.0.1:4001;
        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;
        proxy_set_header X-Forwarded-Host $host;
        proxy_set_header X-Forwarded-Port $server_port;
        proxy_cache_bypass $http_upgrade;
        proxy_redirect off;
        
        # Timeout settings
        proxy_connect_timeout 60s;
        proxy_send_timeout 60s;
        proxy_read_timeout 60s;
    }

    # Health check endpoint
    location /healthz {
        proxy_pass http://127.0.0.1:4001/healthz;
        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;
        access_log off;
    }

    # Static files caching
    location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2|ttf|eot)$ {
        proxy_pass http://127.0.0.1:4001;
        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;
        
        expires 1y;
        add_header Cache-Control "public, immutable";
    }
}