1<?php
  2/**
  3 * Block Bindings API: WP_Block_Bindings_Registry class.
  4 *
  5 * Supports overriding content in blocks by connecting them to different sources.
  6 *
  7 * @package WordPress
  8 * @subpackage Block Bindings
  9 * @since 6.5.0
 10 */
 11
 12/**
 13 * Core class used for interacting with block bindings sources.
 14 *
 15 * @since 6.5.0
 16 */
 17final class WP_Block_Bindings_Registry {
 18
 19	/**
 20	 * Holds the registered block bindings sources, keyed by source identifier.
 21	 *
 22	 * @since 6.5.0
 23	 * @var WP_Block_Bindings_Source[]
 24	 */
 25	private $sources = array();
 26
 27	/**
 28	 * Container for the main instance of the class.
 29	 *
 30	 * @since 6.5.0
 31	 * @var WP_Block_Bindings_Registry|null
 32	 */
 33	private static $instance = null;
 34
 35	/**
 36	 * Supported source properties that can be passed to the registered source.
 37	 *
 38	 * @since 6.5.0
 39	 * @var string[]
 40	 */
 41	private $allowed_source_properties = array(
 42		'label',
 43		'get_value_callback',
 44		'uses_context',
 45	);
 46
 47	/**
 48	 * Supported blocks that can use the block bindings API.
 49	 *
 50	 * @since 6.5.0
 51	 * @var string[]
 52	 */
 53	private $supported_blocks = array(
 54		'core/paragraph',
 55		'core/heading',
 56		'core/image',
 57		'core/button',
 58	);
 59
 60	/**
 61	 * Registers a new block bindings source.
 62	 *
 63	 * This is a low-level method. For most use cases, it is recommended to use
 64	 * the `register_block_bindings_source()` function instead.
 65	 *
 66	 * @see register_block_bindings_source()
 67	 *
 68	 * Sources are used to override block's original attributes with a value
 69	 * coming from the source. Once a source is registered, it can be used by a
 70	 * block by setting its `metadata.bindings` attribute to a value that refers
 71	 * to the source.
 72	 *
 73	 * @since 6.5.0
 74	 *
 75	 * @param string $source_name       The name of the source. It must be a string containing a namespace prefix, i.e.
 76	 *                                  `my-plugin/my-custom-source`. It must only contain lowercase alphanumeric
 77	 *                                  characters, the forward slash `/` and dashes.
 78	 * @param array  $source_properties {
 79	 *     The array of arguments that are used to register a source.
 80	 *
 81	 *     @type string   $label              The label of the source.
 82	 *     @type callable $get_value_callback A callback executed when the source is processed during block rendering.
 83	 *                                        The callback should have the following signature:
 84	 *
 85	 *                                        `function( $source_args, $block_instance, $attribute_name ): mixed`
 86	 *                                            - @param array    $source_args    Array containing source arguments
 87	 *                                                                              used to look up the override value,
 88	 *                                                                              i.e. {"key": "foo"}.
 89	 *                                            - @param WP_Block $block_instance The block instance.
 90	 *                                            - @param string   $attribute_name The name of the target attribute.
 91	 *                                        The callback has a mixed return type; it may return a string to override
 92	 *                                        the block's original value, null, false to remove an attribute, etc.
 93	 *     @type string[] $uses_context       Optional. Array of values to add to block `uses_context` needed by the source.
 94	 * }
 95	 * @return WP_Block_Bindings_Source|false Source when the registration was successful, or `false` on failure.
 96	 */
 97	public function register( string $source_name, array $source_properties ) {
 98		if ( ! is_string( $source_name ) ) {
 99			_doing_it_wrong(
100				__METHOD__,
101				__( 'Block bindings source name must be a string.' ),
102				'6.5.0'
103			);
104			return false;
105		}
106
107		if ( preg_match( '/[A-Z]+/', $source_name ) ) {
108			_doing_it_wrong(
109				__METHOD__,
110				__( 'Block bindings source names must not contain uppercase characters.' ),
111				'6.5.0'
112			);
113			return false;
114		}
115
116		$name_matcher = '/^[a-z0-9-]+\/[a-z0-9-]+$/';
117		if ( ! preg_match( $name_matcher, $source_name ) ) {
118			_doing_it_wrong(
119				__METHOD__,
120				__( 'Block bindings source names must contain a namespace prefix. Example: my-plugin/my-custom-source' ),
121				'6.5.0'
122			);
123			return false;
124		}
125
126		if ( $this->is_registered( $source_name ) ) {
127			_doing_it_wrong(
128				__METHOD__,
129				/* translators: %s: Block bindings source name. */
130				sprintf( __( 'Block bindings source "%s" already registered.' ), $source_name ),
131				'6.5.0'
132			);
133			return false;
134		}
135
136		// Validates that the source properties contain the label.
137		if ( ! isset( $source_properties['label'] ) ) {
138			_doing_it_wrong(
139				__METHOD__,
140				__( 'The $source_properties must contain a "label".' ),
141				'6.5.0'
142			);
143			return false;
144		}
145
146		// Validates that the source properties contain the get_value_callback.
147		if ( ! isset( $source_properties['get_value_callback'] ) ) {
148			_doing_it_wrong(
149				__METHOD__,
150				__( 'The $source_properties must contain a "get_value_callback".' ),
151				'6.5.0'
152			);
153			return false;
154		}
155
156		// Validates that the get_value_callback is a valid callback.
157		if ( ! is_callable( $source_properties['get_value_callback'] ) ) {
158			_doing_it_wrong(
159				__METHOD__,
160				__( 'The "get_value_callback" parameter must be a valid callback.' ),
161				'6.5.0'
162			);
163			return false;
164		}
165
166		// Validates that the uses_context parameter is an array.
167		if ( isset( $source_properties['uses_context'] ) && ! is_array( $source_properties['uses_context'] ) ) {
168			_doing_it_wrong(
169				__METHOD__,
170				__( 'The "uses_context" parameter must be an array.' ),
171				'6.5.0'
172			);
173			return false;
174		}
175
176		if ( ! empty( array_diff( array_keys( $source_properties ), $this->allowed_source_properties ) ) ) {
177			_doing_it_wrong(
178				__METHOD__,
179				__( 'The $source_properties array contains invalid properties.' ),
180				'6.5.0'
181			);
182			return false;
183		}
184
185		$source = new WP_Block_Bindings_Source(
186			$source_name,
187			$source_properties
188		);
189
190		$this->sources[ $source_name ] = $source;
191
192		return $source;
193	}
194
195	/**
196	 * Unregisters a block bindings source.
197	 *
198	 * @since 6.5.0
199	 *
200	 * @param string $source_name Block bindings source name including namespace.
201	 * @return WP_Block_Bindings_Source|false The unregistered block bindings source on success and `false` otherwise.
202	 */
203	public function unregister( string $source_name ) {
204		if ( ! $this->is_registered( $source_name ) ) {
205			_doing_it_wrong(
206				__METHOD__,
207				/* translators: %s: Block bindings source name. */
208				sprintf( __( 'Block binding "%s" not found.' ), $source_name ),
209				'6.5.0'
210			);
211			return false;
212		}
213
214		$unregistered_source = $this->sources[ $source_name ];
215		unset( $this->sources[ $source_name ] );
216
217		return $unregistered_source;
218	}
219
220	/**
221	 * Retrieves the list of all registered block bindings sources.
222	 *
223	 * @since 6.5.0
224	 *
225	 * @return WP_Block_Bindings_Source[] The array of registered sources.
226	 */
227	public function get_all_registered() {
228		return $this->sources;
229	}
230
231	/**
232	 * Retrieves a registered block bindings source.
233	 *
234	 * @since 6.5.0
235	 *
236	 * @param string $source_name The name of the source.
237	 * @return WP_Block_Bindings_Source|null The registered block bindings source, or `null` if it is not registered.
238	 */
239	public function get_registered( string $source_name ) {
240		if ( ! $this->is_registered( $source_name ) ) {
241			return null;
242		}
243
244		return $this->sources[ $source_name ];
245	}
246
247	/**
248	 * Checks if a block bindings source is registered.
249	 *
250	 * @since 6.5.0
251	 *
252	 * @param string|null $source_name The name of the source.
253	 * @return bool `true` if the block bindings source is registered, `false` otherwise.
254	 */
255	public function is_registered( $source_name ) {
256		return isset( $source_name, $this->sources[ $source_name ] );
257	}
258
259	/**
260	 * Wakeup magic method.
261	 *
262	 * @since 6.5.0
263	 */
264	public function __wakeup() {
265		if ( ! $this->sources ) {
266			return;
267		}
268		if ( ! is_array( $this->sources ) ) {
269			throw new UnexpectedValueException();
270		}
271		foreach ( $this->sources as $value ) {
272			if ( ! $value instanceof WP_Block_Bindings_Source ) {
273				throw new UnexpectedValueException();
274			}
275		}
276	}
277
278	/**
279	 * Utility method to retrieve the main instance of the class.
280	 *
281	 * The instance will be created if it does not exist yet.
282	 *
283	 * @since 6.5.0
284	 *
285	 * @return WP_Block_Bindings_Registry The main instance.
286	 */
287	public static function get_instance() {
288		if ( null === self::$instance ) {
289			self::$instance = new self();
290		}
291
292		return self::$instance;
293	}
294}
295