<?php

/**

 * Post API: Walker_PageDropdown class

 *

 * @package WordPress

 * @subpackage Post

 * @since 4.4.0

 */

/**

 * Core class used to create an HTML drop-down list of pages.

 *

 * @since 2.1.0

 *

 * @see Walker

 */

class Walker_PageDropdown extends Walker {

	/**

	 * What the class handles.

	 *

	 * @since 2.1.0

	 * @var string

	 *

	 * @see Walker::$tree_type

	 */

	public $tree_type = 'page';

	/**

	 * Database fields to use.

	 *

	 * @since 2.1.0

	 * @var string[]

	 *

	 * @see Walker::$db_fields

	 * @todo Decouple this

	 */

	public $db_fields = array(

		'parent' => 'post_parent',

		'id'     => 'ID',

	);

	/**

	 * Starts the element output.

	 *

	 * @since 2.1.0

	 * @since 5.9.0 Renamed `$page` to `$data_object` and `$id` to `$current_object_id`

	 *              to match parent class for PHP 8 named parameter support.

	 *

	 * @see Walker::start_el()

	 *

	 * @param string  $output            Used to append additional content. Passed by reference.

	 * @param WP_Post $data_object       Page data object.

	 * @param int     $depth             Optional. Depth of page in reference to parent pages.

	 *                                   Used for padding. Default 0.

	 * @param array   $args              Optional. Uses 'selected' argument for selected page to

	 *                                   set selected HTML attribute for option element. Uses

	 *                                   'value_field' argument to fill "value" attribute.

	 *                                   See wp_dropdown_pages(). Default empty array.

	 * @param int     $current_object_id Optional. ID of the current page. Default 0.

	 */

	public function start_el( &$output, $data_object, $depth = 0, $args = array(), $current_object_id = 0 ) {

		// Restores the more descriptive, specific name for use within this method.

		$page = $data_object;

		$pad = str_repeat( ' ', $depth * 3 );

		if ( ! isset( $args['value_field'] ) || ! isset( $page->{$args['value_field']} ) ) {

			$args['value_field'] = 'ID';

		}

		$output .= "\t<option class=\"level-$depth\" value=\"" . esc_attr( $page->{$args['value_field']} ) . '"';

		if ( $page->ID === (int) $args['selected'] ) {

			$output .= ' selected="selected"';

		}

		$output .= '>';

		$title = $page->post_title;

		if ( '' === $title ) {

			/* translators: %d: ID of a post. */

			$title = sprintf( __( '#%d (no title)' ), $page->ID );

		}

		/**

		 * Filters the page title when creating an HTML drop-down list of pages.

		 *

		 * @since 3.1.0

		 *

		 * @param string  $title Page title.

		 * @param WP_Post $page  Page data object.

		 */

		$title = apply_filters( 'list_pages', $title, $page );

		$output .= $pad . esc_html( $title );

		$output .= "</option>\n";

	}

}