<?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 array

	 *

	 * @see Walker::$db_fields

	 * @todo Decouple this

	 */

	public $db_fields = array( 'parent' => 'post_parent', 'id' => 'ID' );

	/**

	 * Starts the element output.

	 *

	 * @since 2.1.0

	 *

	 * @see Walker::start_el()

	 *

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

	 * @param WP_Post $page   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     $id     Optional. ID of the current page. Default 0 (unused).

	 */

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

		$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 == $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 object $page  Page data object.

		 */

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

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

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

	}

}