1<?php
  2/**
  3 * WP_Navigation_Fallback class
  4 *
  5 * Manages fallback behavior for Navigation menus.
  6 *
  7 * @package WordPress
  8 * @subpackage Navigation
  9 * @since 6.3.0
 10 */
 11
 12/**
 13 * Manages fallback behavior for Navigation menus.
 14 *
 15 * @since 6.3.0
 16 */
 17class WP_Navigation_Fallback {
 18
 19	/**
 20	 * Updates the wp_navigation custom post type schema, in order to expose
 21	 * additional fields in the embeddable links of WP_REST_Navigation_Fallback_Controller.
 22	 *
 23	 * The Navigation Fallback endpoint may embed the full Navigation Menu object
 24	 * into the response as the `self` link. By default, the Posts Controller
 25	 * will only expose a limited subset of fields but the editor requires
 26	 * additional fields to be available in order to utilize the menu.
 27	 *
 28	 * Used with the `rest_wp_navigation_item_schema` hook.
 29	 *
 30	 * @since 6.4.0
 31	 *
 32	 * @param array $schema The schema for the `wp_navigation` post.
 33	 * @return array The modified schema.
 34	 */
 35	public static function update_wp_navigation_post_schema( $schema ) {
 36		// Expose top level fields.
 37		$schema['properties']['status']['context']  = array_merge( $schema['properties']['status']['context'], array( 'embed' ) );
 38		$schema['properties']['content']['context'] = array_merge( $schema['properties']['content']['context'], array( 'embed' ) );
 39
 40		/*
 41		 * Exposes sub properties of content field.
 42		 * These sub properties aren't exposed by the posts controller by default,
 43		 * for requests where context is `embed`.
 44		 *
 45		 * @see WP_REST_Posts_Controller::get_item_schema()
 46		 */
 47		$schema['properties']['content']['properties']['raw']['context']           = array_merge( $schema['properties']['content']['properties']['raw']['context'], array( 'embed' ) );
 48		$schema['properties']['content']['properties']['rendered']['context']      = array_merge( $schema['properties']['content']['properties']['rendered']['context'], array( 'embed' ) );
 49		$schema['properties']['content']['properties']['block_version']['context'] = array_merge( $schema['properties']['content']['properties']['block_version']['context'], array( 'embed' ) );
 50
 51		/*
 52		 * Exposes sub properties of title field.
 53		 * These sub properties aren't exposed by the posts controller by default,
 54		 * for requests where context is `embed`.
 55		 *
 56		 * @see WP_REST_Posts_Controller::get_item_schema()
 57		 */
 58		$schema['properties']['title']['properties']['raw']['context'] = array_merge( $schema['properties']['title']['properties']['raw']['context'], array( 'embed' ) );
 59
 60		return $schema;
 61	}
 62
 63	/**
 64	 * Gets (and/or creates) an appropriate fallback Navigation Menu.
 65	 *
 66	 * @since 6.3.0
 67	 *
 68	 * @return WP_Post|null the fallback Navigation Post or null.
 69	 */
 70	public static function get_fallback() {
 71		/**
 72		 * Filters whether or not a fallback should be created.
 73		 *
 74		 * @since 6.3.0
 75		 *
 76		 * @param bool $create Whether to create a fallback navigation menu. Default true.
 77		 */
 78		$should_create_fallback = apply_filters( 'wp_navigation_should_create_fallback', true );
 79
 80		$fallback = static::get_most_recently_published_navigation();
 81
 82		if ( $fallback || ! $should_create_fallback ) {
 83			return $fallback;
 84		}
 85
 86		$fallback = static::create_classic_menu_fallback();
 87
 88		if ( $fallback && ! is_wp_error( $fallback ) ) {
 89			// Return the newly created fallback post object which will now be the most recently created navigation menu.
 90			return $fallback instanceof WP_Post ? $fallback : static::get_most_recently_published_navigation();
 91		}
 92
 93		$fallback = static::create_default_fallback();
 94
 95		if ( $fallback && ! is_wp_error( $fallback ) ) {
 96			// Return the newly created fallback post object which will now be the most recently created navigation menu.
 97			return $fallback instanceof WP_Post ? $fallback : static::get_most_recently_published_navigation();
 98		}
 99
100		return null;
101	}
102
103	/**
104	 * Finds the most recently published `wp_navigation` post type.
105	 *
106	 * @since 6.3.0
107	 *
108	 * @return WP_Post|null the first non-empty Navigation or null.
109	 */
110	private static function get_most_recently_published_navigation() {
111
112		$parsed_args = array(
113			'post_type'              => 'wp_navigation',
114			'no_found_rows'          => true,
115			'update_post_meta_cache' => false,
116			'update_post_term_cache' => false,
117			'order'                  => 'DESC',
118			'orderby'                => 'date',
119			'post_status'            => 'publish',
120			'posts_per_page'         => 1,
121		);
122
123		$navigation_post = new WP_Query( $parsed_args );
124
125		if ( count( $navigation_post->posts ) > 0 ) {
126			return $navigation_post->posts[0];
127		}
128
129		return null;
130	}
131
132	/**
133	 * Creates a Navigation Menu post from a Classic Menu.
134	 *
135	 * @since 6.3.0
136	 *
137	 * @return int|WP_Error The post ID of the default fallback menu or a WP_Error object.
138	 */
139	private static function create_classic_menu_fallback() {
140		// See if we have a classic menu.
141		$classic_nav_menu = static::get_fallback_classic_menu();
142
143		if ( ! $classic_nav_menu ) {
144			return new WP_Error( 'no_classic_menus', __( 'No Classic Menus found.' ) );
145		}
146
147		// If there is a classic menu then convert it to blocks.
148		$classic_nav_menu_blocks = WP_Classic_To_Block_Menu_Converter::convert( $classic_nav_menu );
149
150		if ( is_wp_error( $classic_nav_menu_blocks ) ) {
151			return $classic_nav_menu_blocks;
152		}
153
154		if ( empty( $classic_nav_menu_blocks ) ) {
155			return new WP_Error( 'cannot_convert_classic_menu', __( 'Unable to convert Classic Menu to blocks.' ) );
156		}
157
158		// Create a new navigation menu from the classic menu.
159		$classic_menu_fallback = wp_insert_post(
160			array(
161				'post_content' => $classic_nav_menu_blocks,
162				'post_title'   => $classic_nav_menu->name,
163				'post_name'    => $classic_nav_menu->slug,
164				'post_status'  => 'publish',
165				'post_type'    => 'wp_navigation',
166			),
167			true // So that we can check whether the result is an error.
168		);
169
170		return $classic_menu_fallback;
171	}
172
173	/**
174	 * Determines the most appropriate classic navigation menu to use as a fallback.
175	 *
176	 * @since 6.3.0
177	 *
178	 * @return WP_Term|null The most appropriate classic navigation menu to use as a fallback.
179	 */
180	private static function get_fallback_classic_menu() {
181		$classic_nav_menus = wp_get_nav_menus();
182
183		if ( ! $classic_nav_menus || is_wp_error( $classic_nav_menus ) ) {
184			return null;
185		}
186
187		$nav_menu = static::get_nav_menu_at_primary_location();
188
189		if ( $nav_menu ) {
190			return $nav_menu;
191		}
192
193		$nav_menu = static::get_nav_menu_with_primary_slug( $classic_nav_menus );
194
195		if ( $nav_menu ) {
196			return $nav_menu;
197		}
198
199		return static::get_most_recently_created_nav_menu( $classic_nav_menus );
200	}
201
202
203	/**
204	 * Sorts the classic menus and returns the most recently created one.
205	 *
206	 * @since 6.3.0
207	 *
208	 * @param WP_Term[] $classic_nav_menus Array of classic nav menu term objects.
209	 * @return WP_Term The most recently created classic nav menu.
210	 */
211	private static function get_most_recently_created_nav_menu( $classic_nav_menus ) {
212		usort(
213			$classic_nav_menus,
214			static function ( $a, $b ) {
215				return $b->term_id - $a->term_id;
216			}
217		);
218
219		return $classic_nav_menus[0];
220	}
221
222	/**
223	 * Returns the classic menu with the slug `primary` if it exists.
224	 *
225	 * @since 6.3.0
226	 *
227	 * @param WP_Term[] $classic_nav_menus Array of classic nav menu term objects.
228	 * @return WP_Term|null The classic nav menu with the slug `primary` or null.
229	 */
230	private static function get_nav_menu_with_primary_slug( $classic_nav_menus ) {
231		foreach ( $classic_nav_menus as $classic_nav_menu ) {
232			if ( 'primary' === $classic_nav_menu->slug ) {
233				return $classic_nav_menu;
234			}
235		}
236
237		return null;
238	}
239
240
241	/**
242	 * Gets the classic menu assigned to the `primary` navigation menu location
243	 * if it exists.
244	 *
245	 * @since 6.3.0
246	 *
247	 * @return WP_Term|null The classic nav menu assigned to the `primary` location or null.
248	 */
249	private static function get_nav_menu_at_primary_location() {
250		$locations = get_nav_menu_locations();
251
252		if ( isset( $locations['primary'] ) ) {
253			$primary_menu = wp_get_nav_menu_object( $locations['primary'] );
254
255			if ( $primary_menu ) {
256				return $primary_menu;
257			}
258		}
259
260		return null;
261	}
262
263	/**
264	 * Creates a default Navigation Block Menu fallback.
265	 *
266	 * @since 6.3.0
267	 *
268	 * @return int|WP_Error The post ID of the default fallback menu or a WP_Error object.
269	 */
270	private static function create_default_fallback() {
271
272		$default_blocks = static::get_default_fallback_blocks();
273
274		// Create a new navigation menu from the fallback blocks.
275		$default_fallback = wp_insert_post(
276			array(
277				'post_content' => $default_blocks,
278				'post_title'   => _x( 'Navigation', 'Title of a Navigation menu' ),
279				'post_name'    => 'navigation',
280				'post_status'  => 'publish',
281				'post_type'    => 'wp_navigation',
282			),
283			true // So that we can check whether the result is an error.
284		);
285
286		return $default_fallback;
287	}
288
289	/**
290	 * Gets the rendered markup for the default fallback blocks.
291	 *
292	 * @since 6.3.0
293	 *
294	 * @return string default blocks markup to use a the fallback.
295	 */
296	private static function get_default_fallback_blocks() {
297		$registry = WP_Block_Type_Registry::get_instance();
298
299		// If `core/page-list` is not registered then use empty blocks.
300		return $registry->is_registered( 'core/page-list' ) ? '<!-- wp:page-list /-->' : '';
301	}
302}
303