server {
    listen 80;

    root /usr/share/nginx/html;
    index index.html;

    # Single-page application fallback
    location / {
        try_files $uri $uri/ /index.html;
    }

    # Proxy REST API to the backend service
    location /api/ {
        proxy_pass http://backend:3001;
        proxy_http_version 1.1;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }

    # Proxy socket.io with WebSocket upgrade support
    location /socket.io/ {
        proxy_pass http://backend:3001;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_set_header Host $host;
    }
}