protected function filter(array $data): array
    {
        $result = [];
        foreach ($data as $key => $value) {
            if ($value['inactive']) {
                continue;
            }

            $result[$key] = $value;
            if (isset($value['children'])) {
                $result[$key]['children'] = $this->filter($value['children']);
            }
        }

        return $result;
    }