admin/settings/classes/nav-menu-options.class.php
<?php if ( ! defined( 'ABSPATH' ) ) { die; } // Cannot access directly.
/**
 *
 * Nav Menu Options Class
 *
 * @since 1.0.0
 * @version 1.0.0
 *
 */
if ( ! class_exists( 'ULF_Nav_Menu_Options' ) ) {
  class ULF_Nav_Menu_Options extends ULF_Abstract{

    // constans
    public $unique     = '';
    public $abstract   = 'menu';
    public $sections   = array();
    public $pre_fields = array();
    public $args       = array(
      'data_type'      => 'serialize',
      'class'          => '',
      'defaults'       => array(),
    );

    // run menu construct
    public function __construct( $key, $params ) {

      $this->unique     = $key;
      $this->args       = apply_filters( "ulf_{$this->unique}_args", wp_parse_args( $params['args'], $this->args ), $this );
      $this->sections   = apply_filters( "ulf_{$this->unique}_sections", $params['sections'], $this );
      $this->pre_fields = $this->pre_fields( $this->sections );

      add_action( 'wp_nav_menu_item_custom_fields', array( $this, 'wp_nav_menu_item_custom_fields' ), 10, 4 );
      add_action( 'wp_update_nav_menu_item', array( $this, 'wp_update_nav_menu_item' ), 10, 3 );

      add_filter( 'wp_edit_nav_menu_walker', array( $this, 'wp_edit_nav_menu_walker' ), 10, 2 );

    }

    // instance
    public static function instance( $key, $params ) {
      return new self( $key, $params );
    }

    public function wp_edit_nav_menu_walker( $class, $menu_id ) {

      global $wp_version;

      if( version_compare( $wp_version, '5.4.0', '<' ) ) {

        if ( ! class_exists( 'ULF_Walker_Nav_Menu_Edit' ) ) {
          ULF::include_plugin_file( 'functions/walker.php' );
        }

        return 'ULF_Walker_Nav_Menu_Edit';

      }

      return $class;

    }

    // get default value
    public function get_default( $field ) {

      $default = ( isset( $field['default'] ) ) ? $field['default'] : '';
      $default = ( isset( $this->args['defaults'][$field['id']] ) ) ? $this->args['defaults'][$field['id']] : $default;

      return $default;

    }

    // get meta value
    public function get_meta_value( $menu_item_id, $field ) {

      $value = null;

      if ( ! empty( $menu_item_id ) && ! empty( $field['id'] ) ) {

        if ( $this->args['data_type'] !== 'serialize' ) {
          $meta  = get_post_meta( $menu_item_id, $field['id'] );
          $value = ( isset( $meta[0] ) ) ? $meta[0] : null;
        } else {
          $meta  = get_post_meta( $menu_item_id, $this->unique, true );
          $value = ( isset( $meta[$field['id']] ) ) ? $meta[$field['id']] : null;
        }

      }

      $default = ( isset( $field['id'] ) ) ? $this->get_default( $field ) : '';
      $value   = ( isset( $value ) ) ? $value : $default;

      return $value;

    }

    //
    public function wp_nav_menu_item_custom_fields( $menu_item_id, $item, $depth, $args ) {

      $errors = ( ! empty( $menu_item_id ) ) ? get_post_meta( $menu_item_id, '_ulf_errors_'. $this->unique, true ) : array();
      $errors = ( ! empty( $errors ) ) ? $errors : array();
      $class  = ( $this->args['class'] ) ? ' '. $this->args['class'] : '';

      if ( ! empty( $errors ) ) {
        delete_post_meta( $menu_item_id, '_ulf_errors_'. $this->unique );
      }

      echo '<div class="ulf ulf-nav-menu-options'. esc_attr( $class ) .'">';

        foreach ( $this->sections as $section ) {

          $section_icon  = ( ! empty( $section['icon'] ) ) ? '<i class="ulf-nav-menu-icon '. esc_attr( $section['icon'] ) .'"></i>' : '';
          $section_title = ( ! empty( $section['title'] ) ) ? $section['title'] : '';

          echo '<div class="ulf-fields">';

          echo ( $section_title || $section_icon ) ? '<div class="ulf-nav-menu-title"><h4>'. $section_icon . $section_title .'</h4></div>' : '';
          echo ( ! empty( $section['description'] ) ) ? '<div class="ulf-field ulf-section-description">'. $section['description'] .'</div>' : '';

          if ( ! empty( $section['fields'] ) ) {

            foreach ( $section['fields'] as $field ) {

              if ( ! empty( $field['id'] ) && ! empty( $errors['fields'][$field['id']] ) ) {
                $field['_error'] = $errors['fields'][$field['id']];
              }

              if ( ! empty( $field['id'] ) ) {
                $field['default'] = $this->get_default( $field );
              }

              ULF::field( $field, $this->get_meta_value( $menu_item_id, $field ), $this->unique .'['. $menu_item_id .']', 'menu' );

            }

          }

          echo '</div>';

        }

      echo '</div>';

    }

    public function wp_update_nav_menu_item( $menu_id, $menu_item_db_id, $menu_item_args ) {

      $count    = 1;
      $data     = array();
      $errors   = array();
      $noncekey = 'update-nav-menu-nonce';
      $nonce    = ( ! empty( $_POST[ $noncekey ] ) ) ? sanitize_text_field( wp_unslash( $_POST[ $noncekey ] ) ) : '';

      if ( ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) || ! wp_verify_nonce( $nonce, 'update-nav_menu' ) ) {
        return $menu_item_db_id;
      }

      // XSS ok.
      // No worries, This "POST" requests is sanitizing in the below foreach.
      $request = ( ! empty( $_POST[ $this->unique ][ $menu_item_db_id ] ) ) ? $_POST[ $this->unique ][ $menu_item_db_id ] : array();

      if ( ! empty( $request ) ) {

        foreach ( $this->sections as $section ) {

          if ( ! empty( $section['fields'] ) ) {

            foreach ( $section['fields'] as $field ) {

              if ( ! empty( $field['id'] ) ) {

                $field_id    = $field['id'];
                $field_value = isset( $request[$field_id] ) ? $request[$field_id] : '';

                // Sanitize "post" request of field.
                if ( ! isset( $field['sanitize'] ) ) {

                  if( is_array( $field_value ) ) {
                    $data[$field_id] = wp_kses_post_deep( $field_value );
                  } else {
                    $data[$field_id] = wp_kses_post( $field_value );
                  }

                } else if( isset( $field['sanitize'] ) && is_callable( $field['sanitize'] ) ) {

                  $data[$field_id] = call_user_func( $field['sanitize'], $field_value );

                } else {

                  $data[$field_id] = $field_value;

                }

                // Validate "post" request of field.
                if ( isset( $field['validate'] ) && is_callable( $field['validate'] ) ) {

                  $has_validated = call_user_func( $field['validate'], $field_value );

                  if ( ! empty( $has_validated ) ) {

                    $errors['sections'][$count] = true;
                    $errors['fields'][$field_id] = $has_validated;
                    $data[$field_id] = $this->get_meta_value( $menu_item_db_id, $field );

                  }

                }

              }

            }

          }

          $count++;

        }

      }

      $data = apply_filters( "ulf_{$this->unique}_save", $data, $menu_item_db_id, $this );

      do_action( "ulf_{$this->unique}_save_before", $data, $menu_item_db_id, $this );

      if ( empty( $data ) ) {

        if ( $this->args['data_type'] !== 'serialize' ) {
          foreach ( $this->pre_fields as $field ) {
            if ( ! empty( $field['id'] ) ) {
              delete_post_meta( $menu_item_db_id, $field['id'] );
            }
          }
        } else {
          delete_post_meta( $menu_item_db_id, $this->unique );
        }

      } else {

        if ( $this->args['data_type'] !== 'serialize' ) {
          foreach ( $data as $key => $value ) {
            update_post_meta( $menu_item_db_id, $key, $value );
          }
        } else {
          update_post_meta( $menu_item_db_id, $this->unique, $data );
        }

        if ( ! empty( $errors ) ) {
          update_post_meta( $menu_item_db_id, '_ulf_errors_'. $this->unique, $errors );
        }

      }

      do_action( "ulf_{$this->unique}_saved", $data, $menu_item_db_id, $this );

      do_action( "ulf_{$this->unique}_save_after", $data, $menu_item_db_id, $this );

    }

  }
}
