typedef RouteNavigator = void Function(String target, {bool replace});

const Set<String> _allowedRoutes = {
  '/settings',
  '/todo',
  '/calendar/dayweek',
  '/messages/invites',
};

const List<String> _allowedRoutePrefixes = [
  '/calendar/events/',
];

class RouteNavigationTool {
  RouteNavigationTool._();

  static final RouteNavigationTool instance = RouteNavigationTool._();

  RouteNavigator? _navigator;

  void bindNavigator(RouteNavigator navigator) {
    _navigator = navigator;
  }

  void clearNavigator() {
    _navigator = null;
  }

  Map<String, dynamic> execute(Map<String, dynamic> args) {
    final target = args['target'];
    if (target is! String || target.isEmpty) {
      return {
        'ok': false,
        'error': 'target is required',
      };
    }
    if (!_isAllowedTarget(target)) {
      return {
        'ok': false,
        'target': target,
        'error': 'target is not allowed',
      };
    }
    final replace = args['replace'] == true;
    final navigator = _navigator;
    if (navigator == null) {
      return {
        'ok': false,
        'target': target,
        'replace': replace,
        'error': 'navigator not bound',
      };
    }
    navigator(target, replace: replace);
    return {
      'ok': true,
      'target': target,
      'replace': replace,
      'applied': true,
    };
  }

  bool _isAllowedTarget(String target) {
    if (!target.startsWith('/')) {
      return false;
    }
    final normalized = target.split('?').first;
    if (_allowedRoutes.contains(normalized)) {
      return true;
    }
    for (final prefix in _allowedRoutePrefixes) {
      if (normalized.startsWith(prefix)) {
        return true;
      }
    }
    return false;
  }
}