<?php
/**
*
* Adapted from Edward McIntyre's wp_bootstrap_navwalker class.
* Removed support for glyphicon and added support for Font Awesome
*
*/
/**
 * Class Name: wp_bootstrap_navwalker
 * GitHub URI: https://github.com/twittem/wp-bootstrap-navwalker
 * Description: A custom WordPress nav walker class to implement the Bootstrap 3 navigation style in a custom theme using the WordPress built in menu manager.
 * Version: 2.0.4
 * Author: Edward McIntyre - @twittem
 * License: GPL-2.0+
 * License URI: http://www.gnu.org/licenses/gpl-2.0.txt
  * @package understrap
 */
//exit if accessed directly
if(!defined('ABSPATH')) exit;
class wp_bootstrap_navwalker extends Walker_Nav_Menu {
  /**
   * @see Walker::start_lvl()
   * @since 3.0.0
   *
   * @param string $output Passed by reference. Used to append additional content.
   * @param int $depth Depth of page. Used for padding.
   */
  public function start_lvl( &$output, $depth = 0, $args = array() ) {
    $indent = str_repeat( "\t", $depth );
    $output .= "\n$indent<ul class=\" dropdown-menu\" role=\"menu\">\n";
  }
  /**
   * @see Walker::start_el()
   * @since 3.0.0
   *
   * @param string $output Passed by reference. Used to append additional content.
   * @param object $item Menu item data object.
   * @param int $depth Depth of menu item. Used for padding.
   * @param int $current_page Menu item ID.
   * @param object $args
   */
  public function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
    $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';
    /**
     * Dividers, Headers or Disabled
     * =============================
     * Determine whether the item is a Divider, Header, Disabled or regular
     * menu item. To prevent errors we use the strcasecmp() function to so a
     * comparison that is not case sensitive. The strcasecmp() function returns
     * a 0 if the strings are equal.
     */
    if ( strcasecmp( $item->attr_title, 'divider' ) == 0 && $depth === 1 ) {
      $output .= $indent . '<li class="divider" role="presentation">';
    } else if ( strcasecmp( $item->title, 'divider') == 0 && $depth === 1 ) {
      $output .= $indent . '<li class="divider" role="presentation">';
    } else if ( strcasecmp( $item->attr_title, 'dropdown-header') == 0 && $depth === 1 ) {
      $output .= $indent . '<li class="dropdown-header" role="presentation">' . esc_attr( $item->title );
    } else if ( strcasecmp($item->attr_title, 'disabled' ) == 0 ) {
      $output .= $indent . '<li class="disabled" role="presentation"><a href="#">' . esc_attr( $item->title ) . '</a>';
    } else {
      $class_names = $value = '';
      $classes = empty( $item->classes ) ? array() : (array) $item->classes;
      $classes[] = 'nav-item menu-item-' . $item->ID;
      $class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args ) );
      /*
      if ( $args->has_children )
        $class_names .= ' dropdown';
      */
      if($args->has_children && $depth === 0) { $class_names .= ' dropdown'; } elseif($args->has_children && $depth > 0) { $class_names .= ' dropdown-submenu'; }
      if ( in_array( 'current-menu-item', $classes ) )
        $class_names .= ' active';
      // remove Font Awesome icon from classes array and save the icon
      // we will add the icon back in via a <span> below so it aligns with
      // the menu item
      if ( in_array('fa', $classes)) {
        $key = array_search('fa', $classes);
        $icon = $classes[$key + 1];
        $class_names = str_replace($classes[$key+1], '', $class_names);
        $class_names = str_replace($classes[$key], '', $class_names);
      }

      $class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';
      $id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args );
      $id = $id ? ' id="' . esc_attr( $id ) . '"' : '';
      $output .= $indent . '<li' . $id . $value . $class_names .'>';
      $atts = array();
      $atts['title']  = ! empty( $item->title )	? $item->title	: '';
      $atts['target'] = ! empty( $item->target )	? $item->target	: '';
      $atts['rel']    = ! empty( $item->xfn )		? $item->xfn	: '';
      // If item has_children add atts to a.

      if ( $args->has_children && $depth === 0 ) {
        $atts['href']   		= '#';
        $atts['data-toggle']	= 'dropdown';
        $atts['class']			= 'nav-link dropdown-toggle';
      } else {
        $atts['href'] = ! empty( $item->url ) ? $item->url : '';
        $atts['class']			= 'nav-link';
      }
      $atts = apply_filters( 'nav_menu_link_attributes', $atts, $item, $args );
      $attributes = '';
      foreach ( $atts as $attr => $value ) {
        if ( ! empty( $value ) ) {
          $value = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );
          $attributes .= ' ' . $attr . '="' . $value . '"';
        }
      }
      $item_output = $args->before;
      // Font Awesome icons
      if ( ! empty( $icon ) )
        $item_output .= '<a'. $attributes .'><span class="fa ' . esc_attr( $icon ) . '"></span>&nbsp;';
      else
        $item_output .= '<a'. $attributes .'>';
      $item_output .= $args->link_before . apply_filters( 'the_title', $item->title, $item->ID ) . $args->link_after;
      $item_output .= ( $args->has_children && 0 === $depth ) ? ' <span class="caret"></span></a>' : '</a>';
      $item_output .= $args->after;
      $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
    }
  }
  /**
   * Traverse elements to create list from elements.
   *
   * Display one element if the element doesn't have any children otherwise,
   * display the element and its children. Will only traverse up to the max
   * depth and no ignore elements under that depth.
   *
   * This method shouldn't be called directly, use the walk() method instead.
   *
   * @see Walker::start_el()
   * @since 2.5.0
   *
   * @param object $element Data object
   * @param array $children_elements List of elements to continue traversing.
   * @param int $max_depth Max depth to traverse.
   * @param int $depth Depth of current element.
   * @param array $args
   * @param string $output Passed by reference. Used to append additional content.
   * @return null Null on failure with no changes to parameters.
   */
  public function display_element( $element, &$children_elements, $max_depth, $depth, $args, &$output ) {
        if ( ! $element )
            return;
        $id_field = $this->db_fields['id'];
        // Display this element.
        if ( is_object( $args[0] ) )
           $args[0]->has_children = ! empty( $children_elements[ $element->$id_field ] );
        parent::display_element( $element, $children_elements, $max_depth, $depth, $args, $output );
    }
  /**
   * Menu Fallback
   * =============
   * If this function is assigned to the wp_nav_menu's fallback_cb variable
   * and a manu has not been assigned to the theme location in the WordPress
   * menu manager the function with display nothing to a non-logged in user,
   * and will add a link to the WordPress menu manager if logged in as an admin.
   *
   * @param array $args passed from the wp_nav_menu function.
   *
   */
  public static function fallback( $args ) {
    if ( current_user_can( 'manage_options' ) ) {
      extract( $args );
      $fb_output = null;
      if ( $container ) {
        $fb_output = '<' . $container;
        if ( $container_class )
          $fb_output .= ' class="' . $container_class . '"';
        if ( $container_id )
          $fb_output .= ' id="' . $container_id . '"';
        $fb_output .= '>';
      }
      $fb_output .= '<ul';
      if ( $menu_class )
        $fb_output .= ' class="' . $menu_class . '"';
        if ( $menu_id )
          $fb_output .= ' id="' . $menu_id . '"';
      $fb_output .= '>';
      $fb_output .= '<li><a href="' . admin_url( 'nav-menus.php' ) . '">Add a menu</a></li>';
      $fb_output .= '</ul>';
      if ( $container )
        $fb_output .= '</' . $container . '>';
      echo $fb_output;
    }
  }
}