nav_breadcrumbs.php

<?php

class CustomMenuBreadcrumbs {
  
  public $menu_location = '';
  public $menu = false;
  public $menu_items = array();

  public function __construct( $menu_location = '' ) {

    $this->menu_location = $menu_location;

    // for convenience everything is built on Menu location (e.g. user changes out an entire Menu)
    $menu_locations = get_nav_menu_locations();

    // make sure the location exists
    if ( isset( $menu_locations[ $this->menu_location ] ) ) {
      $this->menu = wp_get_nav_menu_object( $menu_locations[ $this->menu_location ] );
      $this->menu_items = wp_get_nav_menu_items( $this->menu->term_id );
    }
  }

  /**
   * Format a URL such that we can compare it easily. Escapes, removes protocol, and removes trailing slash
   *
   * @since       1.0.0
   * @param       string          $url URL to format
   * @return      mixed|string    Formatted URL (no protocol or trailing slash)
   */
  public function format_url( $url = '' ) {
    $url = esc_url( $url );
    $url = str_replace( array( 'http://', 'https://' ), '', strtolower( $url ) );
    $url = rtrim( $url, '/' );

    return $url;
  }

  /**
   * Check to see if the page being viewed matches the submitted URL. Requires that we're viewing a WordPress permalink.
   *
   * @since       1.0.0
   * @param       string $url     The URL to check against the current URL
   * @return      bool            Whether we are viewing the submitted URL
   */
  public function is_at_url( $url = '' ) {
    global $post;

    if ( empty( $url ) ) {
      return false;
    }

    $url = $this->format_url( $url );
    $current_url = $this->format_url( get_permalink( $post->ID ) );

    return $current_url == $url;

  }

  /**
   * Retrieve the current Menu item object for the current Menu.
   *
   * @since       1.0.0
   * @return      bool|WP_Post    The current Menu item
   */
  public function get_current_menu_item_object() {

    $current_menu_item = false;

    if ( empty( $this->menu_items ) ) {
      return $current_menu_item;
    }

    // loop through the entire nav menu and determine whether any have a class="current" or are the current URL (e.g. a Custom Link was used)
    foreach ( $this->menu_items as $menu_item ) {

      // if WordPress was able to detect the current page
      if ( is_array( $menu_item->classes ) && in_array( 'current', $menu_item->classes ) ) {
        $current_menu_item = $menu_item;
      }

      // if the current URL matches a Custom Link
      if ( ! $current_menu_item && isset( $menu_item->url ) && $this->is_at_url( $menu_item->url ) ) {
        $current_menu_item = $menu_item;
      }

      if ( $current_menu_item ) {
        break;
      }
    }

    return $current_menu_item;
  }

  /**
   * Retrieve the current Menu item object's parent Menu item object
   *
   * @since       1.0.0
   * @param       WP_Post $current_menu_item      The current Menu item object
   * @return      bool|WP_post                    The parent Menu object
   */
  public function get_parent_menu_item_object( $current_menu_item ) {

    $parent_menu_item = false;

    if ( empty( $this->menu_items ) ) {
      return $current_menu_item;
    }

    foreach ( $this->menu_items as $menu_item ) {
      if ( absint( $current_menu_item->menu_item_parent ) == absint( $menu_item->ID ) ) {
        $parent_menu_item = $menu_item;
        break;
      }
    }

    return $parent_menu_item;
  }

  /**
   * Generate an array of WP_Post objects that constitutes a breadcrumb trail based on a Menu
   *
   * @since       1.0.0
   * @return      array|string    Breadcrumb of WP_Post objects
   */
  public function generate_trail() {
    $current_menu_item = $this->get_current_menu_item_object();
    
    if ( empty( $current_menu_item ) ) {
      return '';
    }

    // there's at least one level
    $breadcrumb = array( $current_menu_item );

    // work backwards from the current menu item all the way to the top
    while ( $current_menu_item = $this->get_parent_menu_item_object( $current_menu_item ) ) {
      $breadcrumb[] = $current_menu_item;
    }

    // since we worked backwards, we need to reverse everything
    $breadcrumb = array_reverse( $breadcrumb );

    // add a level for each breadcrumb object
    $i = 1;
    foreach ( $breadcrumb as $key => $val ) {
      if ( ! isset( $val->menu_breadcrumb_level ) ) {
        $val->menu_breadcrumb_level = $i;
        $breadcrumb[ $key ] = $val;
      }
      $i++;
    }
    
    array_pop( $breadcrumb );

    return $breadcrumb;
  }

}



function add_menu_breadcrumbs( $crumbs ){
  
  // dump( $crumbs );
  
  $menu_breadcrumbs = new CustomMenuBreadcrumbs( 'primary_menu' );
  $breadcrumbs = $menu_breadcrumbs->generate_trail();
  
  if ( empty( $breadcrumbs ) ) {
    return $crumbs;
  }
  
  $last_crumb = array_pop( $crumbs );
  
  
  foreach ( $breadcrumbs as $key => $breadcrumb ) {
      
    $_url = $breadcrumb->url;
    if( $_url == '#' ) $_url = '';
    
    $crumbs[] = array(
      'text'       => $breadcrumb->title,
      'url'        => $_url,
      'allow_html' => false,
    );
  }
  
  $crumbs[] = $last_crumb;
  
  return $crumbs;
}
add_filter( 'wpseo_breadcrumb_links', 'add_menu_breadcrumbs', 10, 1 );