<?php
/*
Plugin Name: Auto Subpage Menu
Plugin URI: https://wordpress.org/plugins/auto-subpage-menu/
Description: Automatically add child page (subpage) into menus, also update hierarchy / remove / restore subpage on menu for you.
Version: 1.1.5
Author: Nathachai Thongniran
Author URI: http://jojoee.com/
Text Domain: asm
License: GPLv2
*/

class Auto_Subpage_Menu {

  function __construct() {
    add_action( 'post_updated', array( &$this, 'when_update_page' ), 10, 4 );
    add_action( 'wp_trash_post', '_wp_delete_post_menu_item' );
  }

  function dd( $var, $die = true ) {
    echo '<pre>';
    print_r( $var );
    echo '</pre>';

    if ( $die ) { die(); }
  }

  function da( $var ) {
    $this->dd( $var, false );
  }

  function is_restore( $page_after_status, $page_before_status ) {
    if ( ( $page_after_status === 'publish' ) &&
      ( $page_before_status === 'trash' ) ) {
      return true;
    }

    return false;
  }

  function is_parent_change( $page_parent_after, $page_parent_before ) {
    if ( $page_parent_after !== $page_parent_before ) {
      return true;
    }

    return false;
  }

    function is_reorder( $page_order_after, $page_order_before ) {
        if ( $page_order_after !== $page_order_before ) {
          return true;
        }

        return false;
    }

  /**
   * Check the theme, support menu or not
   *
   * @see https://codex.wordpress.org/Function_Reference/current_theme_supports
   *
   * @return boolean
   */
  function is_support_menus() {
    if ( ! current_theme_supports( 'menus' ) ) {
      return false;
    }

    return true;
  }

  /**
   * Check the page, has page parent or not
   *
   * @param  integer $page_id
   * @return boolean
   */
  function has_parent( $page_id ) {
    $post = get_post( $page_id );
    if ( ! $post->post_parent ) {
      return false;
    }

    return true;
  }

  /**
   * Check menus, set `Automatically add new top-level pages to this menu` (auto_add) or not
   *
   * @see https://codex.wordpress.org/Appearance_Menus_Screen
   *
   * @return boolean
   */
  function has_auto_add() {
    $auto_add = get_option( 'nav_menu_options' );
    if ( ! is_array( $auto_add ) || empty( $auto_add ) ||
      ! isset( $auto_add['auto_add'] ) || ! is_array( $auto_add['auto_add'] ) || empty( $auto_add['auto_add'] ) ) {
      return false;
    }

    return true;
  }

  function get_auto_add() {
    $auto_add = get_option( 'nav_menu_options' );

    return $auto_add['auto_add'];
  }

  function remove_page_from_menu( $object_id ) {
    global $wpdb,
      $table_prefix;

    $query = sprintf( 'DELETE FROM %s_term_relationships WHERE object_id = %d',
      $table_prefix,
      $object_id
    );

    $wpdb->get_results( $query, OBJECT );
  }

  function remove_page_from_menus( $menu_ids, $page ) {
    foreach ( $menu_ids as $menu_id ) {
      $menu_items = wp_get_nav_menu_items( $menu_id, array( 'post_status' => 'publish' ) );

      if ( ! is_array( $menu_items ) ) {
        continue;

      } else {
        foreach ( $menu_items as $menu_item ) {
          // if page's existed in menu, then remove it from menu
          if ( $menu_item->object_id == $page->ID ) { $this->remove_page_from_menu( $menu_item->ID ); }
        }
      }
    }
  }

    function update_items_order( $menu_ids, $page ) {
        foreach ( $menu_ids as $menu_id ) {
          $menu_items = wp_get_nav_menu_items( $menu_id, array( 'post_status' => 'publish' ) );

          if ( ! is_array( $menu_items ) ) {
            continue;

          } else {
            foreach ( $menu_items as $menu_item ) {
              // if page's existed in menu, then remove it from menu
              if ( $menu_item->object_id == $page->ID ) {

                  wp_update_nav_menu_item( $menu_id, $menu_item->db_id, array(
                      'menu-item-db-id'       => $menu_item->db_id,
                      'menu-item-object-id'   => $menu_item->object_id,
                      'menu-item-object'      => $menu_item->object,
                      'menu-item-parent-id'   => $menu_item->menu_item_parent,
                      'menu-item-position'    => $page->menu_order,
                      'menu-item-type'        => $menu_item->type,
                      'menu-item-title'       => $menu_item->title,
                      'menu-item-url'         => $menu_item->url,
                      'menu-item-description' => $menu_item->description,
                      'menu-item-attr-title'  => $menu_item->attr_title,
                      'menu-item-target'      => $menu_item->target,
                      'menu-item-classes'     => implode($menu_item->classes, ' '),
                      'menu-item-xfn'         => $menu_item->xfn,
                      'menu-item-status'      => 'publish'
                    ) );

              }
            }
          }
        }
      }

  function add_page_into_menu( $menu_id, $page_id, $post_type, $page_parent_id = 0, $menu_order ) {
    wp_update_nav_menu_item( $menu_id, 0, array(
      'menu-item-object-id'   => $page_id,
      'menu-item-object'      => $post_type,
      'menu-item-parent-id'   => $page_parent_id,
      'menu-item-position'    => $menu_order,
      'menu-item-type'        => 'post_type',
      'menu-item-status'      => 'publish'
    ) );
  }

  function add_page_into_submenu( $menu_id, $page, $page_parent ) {
    $this->add_page_into_menu( $menu_id, $page->ID, $page->post_type, $page_parent->ID, $page->menu_order );
  }

  function add_page_into_topmenu( $menu_id, $page ) {
    $this->add_page_into_menu( $menu_id, $page->ID, $page->post_type, 0, $page->menu_order );
  }

  function update_submenu( $menu_ids, $page ) {
    // loop through each menu
    foreach ( $menu_ids as $menu_id ) {
      $page_parent = null;
      $menu_items = wp_get_nav_menu_items( $menu_id, array( 'post_status' => 'publish' ) );

      if ( ! is_array( $menu_items ) ) {
        continue;

      } else {
        // loop through each menu item
        foreach ( $menu_items as $menu_item ) {
          // if page's existed in this menu, then ignore
          if ( $menu_item->object_id == $page->ID ) {
            continue;
          }

          // if page parent's existed in this menu, then get this menu item
          if ( $menu_item->object_id == $page->post_parent ) {
            $page_parent = $menu_item;
          }
        }
      }

      // if page has parent page, then add page into sub-menu under page parent
      if ( ! is_null( $page_parent ) ) {
        $this->add_page_into_submenu( $menu_id, $page, $page_parent );
      }
    }
  }

  function update_topmenu( $menu_ids, $page ) {
    foreach ( $menu_ids as $menu_id ) {
      $this->add_page_into_topmenu( $menu_id, $page );
    }
  }

  function when_update_page( $page_id, $page_after, $page_before ) {
    // if support menu and has auto_add
    if ( $this->is_support_menus() && $this->has_auto_add() ) {
      $page = $page_after;
      $menu_ids = $this->get_auto_add();

      $is_restore = $this->is_restore( $page_after->post_status, $page_before->post_status );
      $is_parent_change = $this->is_parent_change( $page_after->post_parent, $page_before->post_parent);
        $is_reorder = $this->is_reorder( $page_after->menu_order, $page_before->menu_order );

      // if it's restored or its page parent's changed
      if ( $is_restore || $is_parent_change ) {
        $this->remove_page_from_menus( $menu_ids, $page );

        if ( $this->has_parent( $page_id ) ) {
          $this->update_submenu( $menu_ids, $page );

        } else {
          $this->update_topmenu( $menu_ids, $page );
        }

      } elseif ( $is_reorder ) {
          $this->update_items_order( $menu_ids, $page );
      }
    }
  }
}

$auto_subpage_menu = new Auto_Subpage_Menu();