<?php

/**

 * WP_Navigation_Fallback class

 *

 * Manages fallback behavior for Navigation menus.

 *

 * @package WordPress

 * @subpackage Navigation

 * @since 6.3.0

 */

/**

 * Manages fallback behavior for Navigation menus.

 *

 * @access public

 * @since 6.3.0

 */

class WP_Navigation_Fallback {

	/**

	 * Updates the wp_navigation custom post type schema, in order to expose

	 * additional fields in the embeddable links of WP_REST_Navigation_Fallback_Controller.

	 *

	 * The Navigation Fallback endpoint may embed the full Navigation Menu object

	 * into the response as the `self` link. By default, the Posts Controller

	 * will only expose a limited subset of fields but the editor requires

	 * additional fields to be available in order to utilize the menu.

	 *

	 * Used with the `rest_wp_navigation_item_schema` hook.

	 *

	 * @since 6.4.0

	 *

	 * @param array $schema The schema for the `wp_navigation` post.

	 * @return array The modified schema.

	 */

	public static function update_wp_navigation_post_schema( $schema ) {

		// Expose top level fields.

		$schema['properties']['status']['context']  = array_merge( $schema['properties']['status']['context'], array( 'embed' ) );

		$schema['properties']['content']['context'] = array_merge( $schema['properties']['content']['context'], array( 'embed' ) );

		/*

		 * Exposes sub properties of content field.

		 * These sub properties aren't exposed by the posts controller by default,

		 * for requests where context is `embed`.

		 *

		 * @see WP_REST_Posts_Controller::get_item_schema()

		 */

		$schema['properties']['content']['properties']['raw']['context']           = array_merge( $schema['properties']['content']['properties']['raw']['context'], array( 'embed' ) );

		$schema['properties']['content']['properties']['rendered']['context']      = array_merge( $schema['properties']['content']['properties']['rendered']['context'], array( 'embed' ) );

		$schema['properties']['content']['properties']['block_version']['context'] = array_merge( $schema['properties']['content']['properties']['block_version']['context'], array( 'embed' ) );

		/*

		 * Exposes sub properties of title field.

		 * These sub properties aren't exposed by the posts controller by default,

		 * for requests where context is `embed`.

		 *

		 * @see WP_REST_Posts_Controller::get_item_schema()

		 */

		$schema['properties']['title']['properties']['raw']['context'] = array_merge( $schema['properties']['title']['properties']['raw']['context'], array( 'embed' ) );

		return $schema;

	}

	/**

	 * Gets (and/or creates) an appropriate fallback Navigation Menu.

	 *

	 * @since 6.3.0

	 *

	 * @return WP_Post|null the fallback Navigation Post or null.

	 */

	public static function get_fallback() {

		/**

		 * Filters whether or not a fallback should be created.

		 *

		 * @since 6.3.0

		 *

		 * @param bool $create Whether to create a fallback navigation menu. Default true.

		 */

		$should_create_fallback = apply_filters( 'wp_navigation_should_create_fallback', true );

		$fallback = static::get_most_recently_published_navigation();

		if ( $fallback || ! $should_create_fallback ) {

			return $fallback;

		}

		$fallback = static::create_classic_menu_fallback();

		if ( $fallback && ! is_wp_error( $fallback ) ) {

			// Return the newly created fallback post object which will now be the most recently created navigation menu.

			return $fallback instanceof WP_Post ? $fallback : static::get_most_recently_published_navigation();

		}

		$fallback = static::create_default_fallback();

		if ( $fallback && ! is_wp_error( $fallback ) ) {

			// Return the newly created fallback post object which will now be the most recently created navigation menu.

			return $fallback instanceof WP_Post ? $fallback : static::get_most_recently_published_navigation();

		}

		return null;

	}

	/**

	 * Finds the most recently published `wp_navigation` post type.

	 *

	 * @since 6.3.0

	 *

	 * @return WP_Post|null the first non-empty Navigation or null.

	 */

	private static function get_most_recently_published_navigation() {

		$parsed_args = array(

			'post_type'              => 'wp_navigation',

			'no_found_rows'          => true,

			'update_post_meta_cache' => false,

			'update_post_term_cache' => false,

			'order'                  => 'DESC',

			'orderby'                => 'date',

			'post_status'            => 'publish',

			'posts_per_page'         => 1,

		);

		$navigation_post = new WP_Query( $parsed_args );

		if ( count( $navigation_post->posts ) > 0 ) {

			return $navigation_post->posts[0];

		}

		return null;

	}

	/**

	 * Creates a Navigation Menu post from a Classic Menu.

	 *

	 * @since 6.3.0

	 *

	 * @return int|WP_Error The post ID of the default fallback menu or a WP_Error object.

	 */

	private static function create_classic_menu_fallback() {

		// See if we have a classic menu.

		$classic_nav_menu = static::get_fallback_classic_menu();

		if ( ! $classic_nav_menu ) {

			return new WP_Error( 'no_classic_menus', __( 'No Classic Menus found.' ) );

		}

		// If there is a classic menu then convert it to blocks.

		$classic_nav_menu_blocks = WP_Classic_To_Block_Menu_Converter::convert( $classic_nav_menu );

		if ( is_wp_error( $classic_nav_menu_blocks ) ) {

			return $classic_nav_menu_blocks;

		}

		if ( empty( $classic_nav_menu_blocks ) ) {

			return new WP_Error( 'cannot_convert_classic_menu', __( 'Unable to convert Classic Menu to blocks.' ) );

		}

		// Create a new navigation menu from the classic menu.

		$classic_menu_fallback = wp_insert_post(

			array(

				'post_content' => $classic_nav_menu_blocks,

				'post_title'   => $classic_nav_menu->name,

				'post_name'    => $classic_nav_menu->slug,

				'post_status'  => 'publish',

				'post_type'    => 'wp_navigation',

			),

			true // So that we can check whether the result is an error.

		);

		return $classic_menu_fallback;

	}

	/**

	 * Determines the most appropriate classic navigation menu to use as a fallback.

	 *

	 * @since 6.3.0

	 *

	 * @return WP_Term|null The most appropriate classic navigation menu to use as a fallback.

	 */

	private static function get_fallback_classic_menu() {

		$classic_nav_menus = wp_get_nav_menus();

		if ( ! $classic_nav_menus || is_wp_error( $classic_nav_menus ) ) {

			return null;

		}

		$nav_menu = static::get_nav_menu_at_primary_location();

		if ( $nav_menu ) {

			return $nav_menu;

		}

		$nav_menu = static::get_nav_menu_with_primary_slug( $classic_nav_menus );

		if ( $nav_menu ) {

			return $nav_menu;

		}

		return static::get_most_recently_created_nav_menu( $classic_nav_menus );

	}

	/**

	 * Sorts the classic menus and returns the most recently created one.

	 *

	 * @since 6.3.0

	 *

	 * @param WP_Term[] $classic_nav_menus Array of classic nav menu term objects.

	 * @return WP_Term The most recently created classic nav menu.

	 */

	private static function get_most_recently_created_nav_menu( $classic_nav_menus ) {

		usort(

			$classic_nav_menus,

			static function ( $a, $b ) {

				return $b->term_id - $a->term_id;

			}

		);

		return $classic_nav_menus[0];

	}

	/**

	 * Returns the classic menu with the slug `primary` if it exists.

	 *

	 * @since 6.3.0

	 *

	 * @param WP_Term[] $classic_nav_menus Array of classic nav menu term objects.

	 * @return WP_Term|null The classic nav menu with the slug `primary` or null.

	 */

	private static function get_nav_menu_with_primary_slug( $classic_nav_menus ) {

		foreach ( $classic_nav_menus as $classic_nav_menu ) {

			if ( 'primary' === $classic_nav_menu->slug ) {

				return $classic_nav_menu;

			}

		}

		return null;

	}

	/**

	 * Gets the classic menu assigned to the `primary` navigation menu location

	 * if it exists.

	 *

	 * @since 6.3.0

	 *

	 * @return WP_Term|null The classic nav menu assigned to the `primary` location or null.

	 */

	private static function get_nav_menu_at_primary_location() {

		$locations = get_nav_menu_locations();

		if ( isset( $locations['primary'] ) ) {

			$primary_menu = wp_get_nav_menu_object( $locations['primary'] );

			if ( $primary_menu ) {

				return $primary_menu;

			}

		}

		return null;

	}

	/**

	 * Creates a default Navigation Block Menu fallback.

	 *

	 * @since 6.3.0

	 *

	 * @return int|WP_Error The post ID of the default fallback menu or a WP_Error object.

	 */

	private static function create_default_fallback() {

		$default_blocks = static::get_default_fallback_blocks();

		// Create a new navigation menu from the fallback blocks.

		$default_fallback = wp_insert_post(

			array(

				'post_content' => $default_blocks,

				'post_title'   => _x( 'Navigation', 'Title of a Navigation menu' ),

				'post_name'    => 'navigation',

				'post_status'  => 'publish',

				'post_type'    => 'wp_navigation',

			),

			true // So that we can check whether the result is an error.

		);

		return $default_fallback;

	}

	/**

	 * Gets the rendered markup for the default fallback blocks.

	 *

	 * @since 6.3.0

	 *

	 * @return string default blocks markup to use a the fallback.

	 */

	private static function get_default_fallback_blocks() {

		$registry = WP_Block_Type_Registry::get_instance();

		// If `core/page-list` is not registered then use empty blocks.

		return $registry->is_registered( 'core/page-list' ) ? '<!-- wp:page-list /-->' : '';

	}

}