<?php

/**

 * Nav Menu API: Walker_Nav_Menu class

 *

 * @package WordPress

 * @subpackage Nav_Menus

 * @since 4.6.0

 */

/**

 * Core class used to implement an HTML list of nav menu items.

 *

 * @since 3.0.0

 *

 * @see Walker

 */

class Walker_Nav_Menu extends Walker {

	/**

	 * What the class handles.

	 *

	 * @since 3.0.0

	 * @var string

	 *

	 * @see Walker::$tree_type

	 */

	public $tree_type = array( 'post_type', 'taxonomy', 'custom' );

	/**

	 * Database fields to use.

	 *

	 * @since 3.0.0

	 * @todo Decouple this.

	 * @var array

	 *

	 * @see Walker::$db_fields

	 */

	/**

	 * Starts the list before the elements are added.

	 *

	 * @since 3.0.0

	 *

	 * @see Walker::start_lvl()

	 *

	 * @param string   $output Used to append additional content (passed by reference).

	 * @param int      $depth  Depth of menu item. Used for padding.

	 * @param stdClass $args   An object of wp_nav_menu() arguments.

	 */

	public function start_lvl( &$output, $depth = 0, $args = array() ) {

		if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {

			$t = '';

			$n = '';

		} else {

			$t = "\t";

			$n = "\n";

		}

		$indent = str_repeat( $t, $depth );

		// Default class.

		$classes = array( 'sub-menu' );

		/**

		 * Filters the CSS class(es) applied to a menu list element.

		 *

		 * @since 4.8.0

		 *

		 * @param stdClass $args    An object of `wp_nav_menu()` arguments.

		 * @param int      $depth   Depth of menu item. Used for padding.

		 */

		$class_names = join( ' ', apply_filters( 'nav_menu_submenu_css_class', $classes, $args, $depth ) );

		$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';

		$output .= "{$n}{$indent}<ul$class_names>{$n}";

	}

	/**

	 * Ends the list of after the elements are added.

	 *

	 * @since 3.0.0

	 *

	 * @see Walker::end_lvl()

	 *

	 * @param string   $output Used to append additional content (passed by reference).

	 * @param int      $depth  Depth of menu item. Used for padding.

	 * @param stdClass $args   An object of wp_nav_menu() arguments.

	 */

	public function end_lvl( &$output, $depth = 0, $args = array() ) {

		if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {

			$t = '';

			$n = '';

		} else {

			$t = "\t";

			$n = "\n";

		}

		$output .= "$indent</ul>{$n}";

	}

	/**

	 * Starts the element output.

	 *

	 * @since 3.0.0

	 * @since 4.4.0 The {@see 'nav_menu_item_args'} filter was added.

	 *

	 * @see Walker::start_el()

	 *

	 * @param string   $output Used to append additional content (passed by reference).

	 * @param WP_Post  $item   Menu item data object.

	 * @param int      $depth  Depth of menu item. Used for padding.

	 * @param stdClass $args   An object of wp_nav_menu() arguments.

	 * @param int      $id     Current item ID.

	 */

	public function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {

		if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {

			$t = '';

			$n = '';

		} else {

			$t = "\t";

			$n = "\n";

		}

		$indent = ( $depth ) ? str_repeat( $t, $depth ) : '';

		$classes[] = 'menu-item-' . $item->ID;

		/**

		 * Filters the arguments for a single nav menu item.

		 *

		 * @since 4.4.0

		 *

		 * @param stdClass $args  An object of wp_nav_menu() arguments.

		 * @param WP_Post  $item  Menu item data object.

		 * @param int      $depth Depth of menu item. Used for padding.

		 */

		$args = apply_filters( 'nav_menu_item_args', $args, $item, $depth );

		/**

		 *

		 * @since 3.0.0

		 * @since 4.1.0 The `$depth` parameter was added.

		 *

		 * @param WP_Post  $item    The current menu item.

		 * @param stdClass $args    An object of wp_nav_menu() arguments.

		 * @param int      $depth   Depth of menu item. Used for padding.

		 */

		$class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args, $depth ) );

		$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';

		/**

		 * Filters the ID applied to a menu item's list item element.

		 *

		 * @since 3.0.1

		 * @since 4.1.0 The `$depth` parameter was added.

		 *

		 * @param string   $menu_id The ID that is applied to the menu item's `<li>` element.

		 * @param WP_Post  $item    The current menu item.

		 * @param stdClass $args    An object of wp_nav_menu() arguments.

		 * @param int      $depth   Depth of menu item. Used for padding.

		 */

		$id = $id ? ' id="' . esc_attr( $id ) . '"' : '';

		$atts['title']  = ! empty( $item->attr_title ) ? $item->attr_title : '';

		/**

		 * Filters the HTML attributes applied to a menu item's anchor element.

		 *

		 * @since 3.6.0

		 * @since 4.1.0 The `$depth` parameter was added.

		 *

		 * @param array $atts {

		 *     The HTML attributes applied to the menu item's `<a>` element, empty strings are ignored.

		 *

		 * }

		 * @param WP_Post  $item  The current menu item.

		 * @param stdClass $args  An object of wp_nav_menu() arguments.

		 * @param int      $depth Depth of menu item. Used for padding.

		 */

		$atts = apply_filters( 'nav_menu_link_attributes', $atts, $item, $args, $depth );

		$attributes = '';

		foreach ( $atts as $attr => $value ) {

			if ( ! empty( $value ) ) {

				$attributes .= ' ' . $attr . '="' . $value . '"';

			}

		}

		/** This filter is documented in wp-includes/post-template.php */

		$title = apply_filters( 'the_title', $item->title, $item->ID );

		/**

		 * Filters a menu item's title.

		 *

		 * @since 4.4.0

		 *

		 * @param string   $title The menu item's title.

		 * @param WP_Post  $item  The current menu item.

		 * @param stdClass $args  An object of wp_nav_menu() arguments.

		 * @param int      $depth Depth of menu item. Used for padding.

		 */

		$title = apply_filters( 'nav_menu_item_title', $title, $item, $args, $depth );

		$item_output .= $args->link_before . $title . $args->link_after;

		$item_output .= '</a>';

		$item_output .= $args->after;

		/**

		 * Filters a menu item's starting output.

		 *

		 * The menu item's starting output only includes `$args->before`, the opening `<a>`,

		 * the menu item's title, the closing `</a>`, and `$args->after`. Currently, there is

		 * no filter for modifying the opening and closing `<li>` for a menu item.

		 *

		 * @since 3.0.0

		 *

		 * @param string   $item_output The menu item's starting HTML output.

		 * @param WP_Post  $item        Menu item data object.

		 * @param int      $depth       Depth of menu item. Used for padding.

		 * @param stdClass $args        An object of wp_nav_menu() arguments.

		 */

		$output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );

	}

	/**

	 * Ends the element output, if needed.

	 *

	 * @since 3.0.0

	 *

	 * @see Walker::end_el()

	 *

	 * @param string   $output Used to append additional content (passed by reference).

	 * @param WP_Post  $item   Page data object. Not used.

	 * @param int      $depth  Depth of page. Not Used.

	 * @param stdClass $args   An object of wp_nav_menu() arguments.

	 */

	public function end_el( &$output, $item, $depth = 0, $args = array() ) {

		if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {

			$t = '';

			$n = '';

		} else {

			$t = "\t";

			$n = "\n";

		}

		$output .= "</li>{$n}";

	}

} // Walker_Nav_Menu