events {
    worker_connections 1024;
}

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    upstream streamlit {
        server localhost:8501;
    }

    server {
        listen 7860;
        server_name localhost;

        # Restricted CORS configuration for elevatics.cloud
        add_header Access-Control-Allow-Origin "https://elevatics.cloud" always;
        add_header Access-Control-Allow-Methods "GET, POST, OPTIONS" always;
        add_header Access-Control-Allow-Headers "DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range,Authorization" always;
        add_header X-Frame-Options "ALLOW-FROM https://elevatics.cloud" always;
        add_header Content-Security-Policy "frame-ancestors https://elevatics.cloud" always;
        
        # Handle OPTIONS method
        if ($request_method = "OPTIONS") {
            add_header Access-Control-Allow-Origin "https://elevatics.cloud" always;
            add_header Access-Control-Allow-Methods "GET, POST, OPTIONS" always;
            add_header Access-Control-Allow-Headers "DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range,Authorization" always;
            add_header Access-Control-Max-Age 1728000;
            add_header Content-Type text/plain;
            add_header Content-Length 0;
            return 204;
        }

        location / {
            proxy_pass http://streamlit;
            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_redirect off;
            proxy_http_version 1.1;
            proxy_set_header Upgrade $http_upgrade;
            proxy_set_header Connection "upgrade";
            
            # Additional security headers for iframe
            add_header X-Frame-Options "ALLOW-FROM https://elevatics.cloud" always;
            add_header Content-Security-Policy "frame-ancestors https://elevatics.cloud" always;
        }
    }
}