<?php

/**
 * 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
 */
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 role=\"menu\" class=\" dropdown-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 role="presentation" class="divider">';
        } else if ( strcasecmp( $item->title, 'divider' ) == 0 && $depth === 1 ) {
            $output .= $indent . '<li role="presentation" class="divider">';
        } else if ( strcasecmp( $item->attr_title, 'dropdown-header' ) == 0 && $depth === 1 ) {
            $output .= $indent . '<li role="presentation" class="dropdown-header">' . esc_attr( $item->title );
        } else if ( strcasecmp( $item->attr_title, 'disabled' ) == 0 ) {
            $output .= $indent . '<li role="presentation" class="disabled"><a href="#">' . esc_attr( $item->title ) . '</a>';
        } else {

            $class_names = $value = '';

            $classes = empty( $item->classes ) ? array() : ( array ) $item->classes;
            $classes[] = '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 ( in_array( 'current-menu-item', $classes ) ) {
                $class_names .= ' active';
            }

            $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'] = 'dropdown-toggle';
            } else {
                $atts['href'] = !empty( $item->url ) ? $item->url : '';
            }

            $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;

            /*
             * Glyphicons
             * ===========
             * Since the the menu item is NOT a Divider or Header we check the see
             * if there is a value in the attr_title property. If the attr_title
             * property is NOT null we apply it as the class name for the glyphicon.
             */

            if ( !empty( $item->attr_title ) ) {
                $item_output .= '<a' . $attributes . '><span class="glyphicon ' . esc_attr( $item->attr_title ) . '"></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 && $depth === 0) ? ' <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_id ) {
                    $fb_output .= ' id="' . $container_id . '"';
                }

                if ( $container_class ) {
                    $fb_output .= ' class="' . $container_class . '"';
                }

                $fb_output .= '>';
            }

            $fb_output .= '<ul';

            if ( $menu_id ) {
                $fb_output .= ' id="' . $menu_id . '"';
            }

            if ( $menu_class ) {
                $fb_output .= ' class="' . $menu_class . '"';
            }

            $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;
        }
    }

}

?>