<?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;

	}

}