<?php
/**
* WP_Classic_To_Block_Menu_Converter class
*
* @package WordPress
* @since 6.3.0
*/

/**
* Converts a Classic Menu to Block Menu blocks.
*
* @since 6.3.0
* @access public
*/
class WP_Classic_To_Block_Menu_Converter {

/**
* Converts a Classic Menu to blocks.
*
* @since 6.3.0
*
* @param WP_Term $menu The Menu term object of the menu to convert.
* @return string|WP_Error The serialized and normalized parsed blocks on success,
* an empty string when there are no menus to convert,
* or WP_Error on invalid menu.
*/
public static function convert( $menu ) {

if ( ! is_nav_menu( $menu ) ) {
return new WP_Error(
'invalid_menu',
__( 'The menu provided is not a valid menu.' )
);
}

$menu_items = wp_get_nav_menu_items( $menu->term_id, array( 'update_post_term_cache' => false ) );

if ( empty( $menu_items ) ) {
return '';
}

// Set up the $menu_item variables.
// Adds the class property classes for the current context, if applicable.
_wp_menu_item_classes_by_context( $menu_items );

$menu_items_by_parent_id = static::group_by_parent_id( $menu_items );

$first_menu_item = isset( $menu_items_by_parent_id[0] )
? $menu_items_by_parent_id[0]
: array();

$inner_blocks = static::to_blocks(
$first_menu_item,
$menu_items_by_parent_id
);

return serialize_blocks( $inner_blocks );
}

/**
* Returns an array of menu items grouped by the id of the parent menu item.
*
* @since 6.3.0
*
* @param array $menu_items An array of menu items.
* @return array
*/
private static function group_by_parent_id( $menu_items ) {
$menu_items_by_parent_id = array();

foreach ( $menu_items as $menu_item ) {
$menu_items_by_parent_id[ $menu_item->menu_item_parent ][] = $menu_item;
}

return $menu_items_by_parent_id;
}

/**
* Turns menu item data into a nested array of parsed blocks
*
* @since 6.3.0
*
* @param array $menu_items An array of menu items that represent
* an individual level of a menu.
* @param array $menu_items_by_parent_id An array keyed by the id of the
* parent menu where each element is an
* array of menu items that belong to
* that parent.
* @return array An array of parsed block data.
*/
private static function to_blocks( $menu_items, $menu_items_by_parent_id ) {

if ( empty( $menu_items ) ) {
return array();
}

$blocks = array();

foreach ( $menu_items as $menu_item ) {
$class_name = ! empty( $menu_item->classes ) ? implode( ' ', (array) $menu_item->classes ) : null;
$id = ( null !== $menu_item->object_id && 'custom' !== $menu_item->object ) ? $menu_item->object_id : null;
$opens_in_new_tab = null !== $menu_item->target && '_blank' === $menu_item->target;
$rel = ( null !== $menu_item->xfn && '' !== $menu_item->xfn ) ? $menu_item->xfn : null;
$kind = null !== $menu_item->type ? str_replace( '_', '-', $menu_item->type ) : 'custom';

$block = array(
'blockName' => isset( $menu_items_by_parent_id[ $menu_item->ID ] ) ? 'core/navigation-submenu' : 'core/navigation-link',
'attrs' => array(
'className' => $class_name,
'description' => $menu_item->description,
'id' => $id,
'kind' => $kind,
'label' => $menu_item->title,
'opensInNewTab' => $opens_in_new_tab,
'rel' => $rel,
'title' => $menu_item->attr_title,
'type' => $menu_item->object,
'url' => $menu_item->url,
),
);

$block['innerBlocks'] = isset( $menu_items_by_parent_id[ $menu_item->ID ] )
? static::to_blocks( $menu_items_by_parent_id[ $menu_item->ID ], $menu_items_by_parent_id )
: array();
$block['innerContent'] = array_map( 'serialize_block', $block['innerBlocks'] );

$blocks[] = $block;
}

return $blocks;
}
}