typedef NavigationGuardCallback = Future<bool> Function();

class NavigationGuard {
  static NavigationGuardCallback? _callback;

  static void register(NavigationGuardCallback callback) {
    _callback = callback;
  }

  static void unregister(NavigationGuardCallback callback) {
    if (_callback == callback) {
      _callback = null;
    }
  }

  static Future<void> attemptNavigation(
    Future<void> Function() performNavigation,
  ) async {
    if (_promptActive) return;
    final cb = _callback;
    if (cb == null) {
      await performNavigation();
      return;
    }
    _promptActive = true;
    bool allow = false;
    try {
      allow = await cb();
    } catch (_) {
      allow = false;
    } finally {
      _promptActive = false;
    }
    if (allow) {
      await performNavigation();
    }
  }

  static bool _promptActive = false;
}