import { useEffect } from 'react';
import { useNavigate } from 'react-router-dom';

/**
 * Forwards OS-level deep-link opens into the React Router navigation stack.
 *
 * Uses the global window.Capacitor object to avoid a hard npm dependency on
 * @capacitor/app (which is installed on the native build machine but not in
 * the web/CI build environment).
 *
 * When the OS launches the app via a URL (Amber NIP-55 callback, custom scheme,
 * or universal link), Capacitor fires an `appUrlOpen` event. This component
 * listens for it and navigates to the correct in-app route.
 *
 * Amber deep-link example:
 *   org.skatespots.app://amber-callback?event=<data>
 *   → navigates to /amber-callback?event=<data>
 */

// Type for the global Capacitor object injected by the native runtime
interface CapacitorGlobal {
  isNativePlatform?: () => boolean;
  Plugins?: {
    App?: {
      addListener: (
        event: string,
        handler: (data: { url: string }) => void
      ) => Promise<{ remove: () => void }>;
    };
  };
}

export function DeepLinkHandler() {
  const navigate = useNavigate();

  useEffect(() => {
    const cap = (window as unknown as { Capacitor?: CapacitorGlobal }).Capacitor;
    if (!cap?.isNativePlatform?.()) return;

    const AppPlugin = cap?.Plugins?.App;
    if (!AppPlugin) return;

    let removeListener: (() => void) | undefined;

    AppPlugin.addListener('appUrlOpen', (event) => {
      try {
        const url = new URL(event.url);
        // Pre-capture Amber callback event param into sessionStorage so
        // AmberCallbackPage can find it after React Router renders the route.
        const eventParam = url.searchParams.get('event');
        if (eventParam) {
          try {
            sessionStorage.setItem('amber_callback_event', eventParam);
            sessionStorage.setItem('amber_callback_url', event.url);
            sessionStorage.setItem('amber_callback_timestamp', Date.now().toString());
          } catch { /* ignore storage errors */ }
        }
        // Extract path + query + fragment from the deep link URL
        const path = url.pathname + url.search + url.hash;
        if (path && path !== '/') {
          navigate(path, { replace: true });
        }
      } catch {
        // Invalid URL — ignore
      }
    }).then((listener) => {
      removeListener = () => listener.remove();
    }).catch(() => {
      // Plugin not available — ignore
    });

    return () => {
      removeListener?.();
    };
  }, [navigate]);

  return null;
}