import { useEffect } from 'react';

const SCRIPT_ELEMENT_ID = 'umami-analytics-script';

/**
 * Injects the self-hosted Umami tracking script (see
 * aidlc-docs/features/react-frontend/operations/monitoring/umami-setup.md) when both
 * VITE_UMAMI_SCRIPT_URL and VITE_UMAMI_WEBSITE_ID are configured at build time.
 *
 * Silently does nothing if either variable is missing (e.g. local development, or a
 * build for which the Umami instance/website has not been set up yet) — safe default,
 * no crash on missing config, mirroring the existing Sentry DSN pattern.
 *
 * Skipped during local development (`pnpm dev`) by default so local testing does not
 * pollute production/test visitor analytics.
 */
export function UmamiAnalytics() {
  useEffect(() => {
    const scriptUrl = import.meta.env.VITE_UMAMI_SCRIPT_URL;
    const websiteId = import.meta.env.VITE_UMAMI_WEBSITE_ID;

    if (import.meta.env.DEV || !scriptUrl || !websiteId) {
      return;
    }

    if (document.getElementById(SCRIPT_ELEMENT_ID)) {
      return;
    }

    const script = document.createElement('script');
    script.id = SCRIPT_ELEMENT_ID;
    script.src = scriptUrl;
    script.defer = true;
    script.setAttribute('data-website-id', websiteId);
    document.head.appendChild(script);

    return () => {
      document.getElementById(SCRIPT_ELEMENT_ID)?.remove();
    };
  }, []);

  return null;
}