<?php
/**
* Taxonomy API: Walker_CategoryDropdown class
*
* @package WordPress
* @subpackage Template
* @since 4.4.0
*/

/**
* Core class used to create an HTML dropdown list of Categories.
*
* @since 2.1.0
*
* @see Walker
*/
class Walker_CategoryDropdown extends Walker {

/**
* What the class handles.
*
* @since 2.1.0
* @var string
*
* @see Walker::$tree_type
*/
public $tree_type = 'category';

/**
* Database fields to use.
*
* @since 2.1.0
* @todo Decouple this
* @var string[]
*
* @see Walker::$db_fields
*/
public $db_fields = array(
'parent' => 'parent',
'id' => 'term_id',
);

/**
* Starts the element output.
*
* @since 2.1.0
* @since 5.9.0 Renamed `$category` to `$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_Term $data_object Category data object.
* @param int $depth Depth of category. Used for padding.
* @param array $args Uses 'selected', 'show_count', and 'value_field' keys, if they exist.
* See wp_dropdown_categories().
* @param int $current_object_id Optional. ID of the current category. Default 0.
*/
public function start_el( &$output, $data_object, $depth = 0, $args = array(), $current_object_id = 0 ) {
// Restores the more descriptive, specific name for use within this method.
$category = $data_object;

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

/** This filter is documented in wp-includes/category-template.php */
$cat_name = apply_filters( 'list_cats', $category->name, $category );

if ( isset( $args['value_field'] ) && isset( $category->{$args['value_field']} ) ) {
$value_field = $args['value_field'];
} else {
$value_field = 'term_id';
}

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

// Type-juggling causes false matches, so we force everything to a string.
if ( (string) $category->{$value_field} === (string) $args['selected'] ) {
$output .= ' selected="selected"';
}
$output .= '>';
$output .= $pad . $cat_name;
if ( $args['show_count'] ) {
$output .= '&nbsp;&nbsp;(' . number_format_i18n( $category->count ) . ')';
}
$output .= "</option>\n";
}
}