<?php

/**

 * REST API: WP_REST_Meta_Fields class

 *

 * @package WordPress

 * @subpackage REST_API

 * @since 4.7.0

 */

/**

 * Core class to manage meta values for an object via the REST API.

 *

 * @since 4.7.0

 */

abstract class WP_REST_Meta_Fields {

	/**

	 * Retrieves the object meta type.

	 *

	 * @since 4.7.0

	 *

	 * @return string One of 'post', 'comment', 'term', 'user', or anything

	 *                else supported by `_get_meta_table()`.

	 */

	abstract protected function get_meta_type();

	/**

	 * Retrieves the object meta subtype.

	 *

	 * @since 4.9.8

	 *

	 * @return string Subtype for the meta type, or empty string if no specific subtype.

	 */

	protected function get_meta_subtype() {

		return '';

	}

	/**

	 * Retrieves the object type for register_rest_field().

	 *

	 * @since 4.7.0

	 *

	 * @return string The REST field type, such as post type name, taxonomy name, 'comment', or `user`.

	 */

	abstract protected function get_rest_field_type();

	/**

	 * Registers the meta field.

	 *

	 * @since 4.7.0

	 *

	 * @see register_rest_field()

	 */

	public function register_field() {

	}

	/**

	 * Retrieves the meta field value.

	 *

	 * @since 4.7.0

	 *

	 * @param int             $object_id Object ID to fetch meta for.

	 * @param WP_REST_Request $request   Full details about the request.

	 * @return WP_Error|object Object containing the meta values by name, otherwise WP_Error object.

	 */

	public function get_value( $object_id, $request ) {

		$fields   = $this->get_registered_fields();

		$response = array();

		foreach ( $fields as $meta_key => $args ) {

			$all_values = get_metadata( $this->get_meta_type(), $object_id, $meta_key, false );

			if ( $args['single'] ) {

				if ( empty( $all_values ) ) {

					$value = $args['schema']['default'];

				} else {

					$value = $all_values[0];

				}

				$value = $this->prepare_value_for_response( $value, $request, $args );

			} else {

				$value = array();

				foreach ( $all_values as $row ) {

					$value[] = $this->prepare_value_for_response( $row, $request, $args );

				}

			}

			$response[ $name ] = $value;

		}

		return $response;

	}

	/**

	 * Prepares a meta value for a response.

	 *

	 * This is required because some native types cannot be stored correctly

	 * in the database, such as booleans. We need to cast back to the relevant

	 * type before passing back to JSON.

	 *

	 * @since 4.7.0

	 *

	 * @param mixed           $value   Meta value to prepare.

	 * @param WP_REST_Request $request Current request object.

	 * @param array           $args    Options for the field.

	 * @return mixed Prepared value.

	 */

	protected function prepare_value_for_response( $value, $request, $args ) {

		if ( ! empty( $args['prepare_callback'] ) ) {

			$value = call_user_func( $args['prepare_callback'], $value, $request, $args );

		}

		return $value;

	}

	/**

	 * Updates meta values.

	 *

	 * @since 4.7.0

	 *

	 * @param array           $meta      Array of meta parsed from the request.

	 * @param int             $object_id Object ID to fetch meta for.

	 * @return WP_Error|null WP_Error if one occurs, null on success.

	 */

	public function update_value( $meta, $object_id ) {

		$fields = $this->get_registered_fields();

		foreach ( $fields as $meta_key => $args ) {

			$name = $args['name'];

			if ( ! array_key_exists( $name, $meta ) ) {

				continue;

			}

			/*

			 * A null value means reset the field, which is essentially deleting it

			 * from the database and then relying on the default value.

			 */

			if ( is_null( $meta[ $name ] ) ) {

				$result = $this->delete_meta_value( $object_id, $meta_key, $name );

				if ( is_wp_error( $result ) ) {

					return $result;

				}

				continue;

			}

			$is_valid = rest_validate_value_from_schema( $meta[ $name ], $args['schema'], 'meta.' . $name );

			if ( is_wp_error( $is_valid ) ) {

				$is_valid->add_data( array( 'status' => 400 ) );

				return $is_valid;

			}

			$value = rest_sanitize_value_from_schema( $meta[ $name ], $args['schema'] );

			if ( $args['single'] ) {

				$result = $this->update_meta_value( $object_id, $meta_key, $name, $value );

			} else {

				$result = $this->update_multi_meta_value( $object_id, $meta_key, $name, $value );

			}

			if ( is_wp_error( $result ) ) {

				return $result;

			}

		}

		return null;

	}

	/**

	 * Deletes a meta value for an object.

	 *

	 * @since 4.7.0

	 *

	 * @param int    $object_id Object ID the field belongs to.

	 * @param string $meta_key  Key for the field.

	 * @param string $name      Name for the field that is exposed in the REST API.

	 * @return bool|WP_Error True if meta field is deleted, WP_Error otherwise.

	 */

	protected function delete_meta_value( $object_id, $meta_key, $name ) {

		$meta_type = $this->get_meta_type();

		if ( ! current_user_can( "delete_{$meta_type}_meta", $object_id, $meta_key ) ) {

			return new WP_Error(

				'rest_cannot_delete',

				/* translators: %s: custom field key */

				sprintf( __( 'Sorry, you are not allowed to edit the %s custom field.' ), $name ),

			);

		}

		if ( ! delete_metadata( $meta_type, $object_id, wp_slash( $meta_key ) ) ) {

			return new WP_Error(

				'rest_meta_database_error',

				__( 'Could not delete meta value from database.' ),

			);

		}

		return true;

	}

	/**

	 * Updates multiple meta values for an object.

	 *

	 * Alters the list of values in the database to match the list of provided values.

	 *

	 * @since 4.7.0

	 *

	 * @param int    $object_id Object ID to update.

	 * @param string $meta_key  Key for the custom field.

	 * @param string $name      Name for the field that is exposed in the REST API.

	 * @param array  $values    List of values to update to.

	 * @return bool|WP_Error True if meta fields are updated, WP_Error otherwise.

	 */

	protected function update_multi_meta_value( $object_id, $meta_key, $name, $values ) {

		$meta_type = $this->get_meta_type();

		if ( ! current_user_can( "edit_{$meta_type}_meta", $object_id, $meta_key ) ) {

			return new WP_Error(

				'rest_cannot_update',

				/* translators: %s: custom field key */

				sprintf( __( 'Sorry, you are not allowed to edit the %s custom field.' ), $name ),

			);

		}

		$current = get_metadata( $meta_type, $object_id, $meta_key, false );

		$to_remove = $current;

		$to_add    = $values;

		foreach ( $to_add as $add_key => $value ) {

			$remove_keys = array_keys( $to_remove, $value, true );

			if ( empty( $remove_keys ) ) {

				continue;

			}

			if ( count( $remove_keys ) > 1 ) {

				// To remove, we need to remove first, then add, so don't touch.

				continue;

			}

			$remove_key = $remove_keys[0];

			unset( $to_remove[ $remove_key ] );

			unset( $to_add[ $add_key ] );

		}

		// `delete_metadata` removes _all_ instances of the value, so only call once.

		$to_remove = array_unique( $to_remove );

		foreach ( $to_remove as $value ) {

			if ( ! delete_metadata( $meta_type, $object_id, wp_slash( $meta_key ), wp_slash( $value ) ) ) {

				return new WP_Error(

					'rest_meta_database_error',

					__( 'Could not update meta value in database.' ),

				);

			}

		}

		foreach ( $to_add as $value ) {

			if ( ! add_metadata( $meta_type, $object_id, wp_slash( $meta_key ), wp_slash( $value ) ) ) {

				return new WP_Error(

					'rest_meta_database_error',

					__( 'Could not update meta value in database.' ),

				);

			}

		}

		return true;

	}

	/**

	 * Updates a meta value for an object.

	 *

	 * @since 4.7.0

	 *

	 * @param int    $object_id Object ID to update.

	 * @param string $meta_key  Key for the custom field.

	 * @param string $name      Name for the field that is exposed in the REST API.

	 * @param mixed  $value     Updated value.

	 * @return bool|WP_Error True if the meta field was updated, WP_Error otherwise.

	 */

	protected function update_meta_value( $object_id, $meta_key, $name, $value ) {

		$meta_type = $this->get_meta_type();

			return new WP_Error(

				'rest_cannot_update',

				/* translators: %s: custom field key */

				sprintf( __( 'Sorry, you are not allowed to edit the %s custom field.' ), $name ),

			);

		}

		// Do the exact same check for a duplicate value as in update_metadata() to avoid update_metadata() returning false.

		$old_value = get_metadata( $meta_type, $object_id, $meta_key );

		if ( 1 === count( $old_value ) ) {

				return true;

			}

		}

			return new WP_Error(

				'rest_meta_database_error',

				__( 'Could not update meta value in database.' ),

			);

		}

		return true;

	}

	/**

	 * Retrieves all the registered meta fields.

	 *

	 * @since 4.7.0

	 *

	 * @return array Registered fields.

	 */

	protected function get_registered_fields() {

		$registered = array();

		$meta_type    = $this->get_meta_type();

		$meta_subtype = $this->get_meta_subtype();

		$meta_keys = get_registered_meta_keys( $meta_type );

		if ( ! empty( $meta_subtype ) ) {

			$meta_keys = array_merge( $meta_keys, get_registered_meta_keys( $meta_type, $meta_subtype ) );

		}

		foreach ( $meta_keys as $name => $args ) {

			if ( empty( $args['show_in_rest'] ) ) {

				continue;

			}

			$rest_args = array();

			if ( is_array( $args['show_in_rest'] ) ) {

				$rest_args = $args['show_in_rest'];

			}

			$default_args = array(

				'name'             => $name,

				'single'           => $args['single'],

				'type'             => ! empty( $args['type'] ) ? $args['type'] : null,

				'schema'           => array(),

				'prepare_callback' => array( $this, 'prepare_value' ),

			);

			$default_schema = array(

				'type'        => $default_args['type'],

				'description' => empty( $args['description'] ) ? '' : $args['description'],

				'default'     => isset( $args['default'] ) ? $args['default'] : null,

			);

			$rest_args['schema'] = array_merge( $default_schema, $rest_args['schema'] );

			$type = ! empty( $rest_args['type'] ) ? $rest_args['type'] : null;

			$type = ! empty( $rest_args['schema']['type'] ) ? $rest_args['schema']['type'] : $type;

			if ( ! in_array( $type, array( 'string', 'boolean', 'integer', 'number' ) ) ) {

				continue;

			}

			if ( empty( $rest_args['single'] ) ) {

				$rest_args['schema']['items'] = array(

					'type' => $rest_args['type'],

				);

			}

			$registered[ $name ] = $rest_args;

		}

		return $registered;

	}

	/**

	 * Retrieves the object's meta schema, conforming to JSON Schema.

	 *

	 * @since 4.7.0

	 *

	 * @return array Field schema data.

	 */

	public function get_field_schema() {

		$fields = $this->get_registered_fields();

		$schema = array(

			'description' => __( 'Meta fields.' ),

			'type'        => 'object',

			'context'     => array( 'view', 'edit' ),

			'properties'  => array(),

			'arg_options' => array(

				'sanitize_callback' => null,