rest-api.php

<?php
/**
 * REST API functions.
 *
 * @package WordPress
 * @subpackage REST_API
 * @since 4.4.0
 */

/**
 * Version number for our API.
 *
 * @var string
 */
define( 'REST_API_VERSION', '2.0' );

/**
 * Registers a REST API route.
 *
 * Note: Do not use before the {@see 'rest_api_init'} hook.
 *
 * @since 4.4.0
 * @since 5.1.0 Added a `_doing_it_wrong()` notice when not called on or after the `rest_api_init` hook.
 * @since 5.5.0 Added a `_doing_it_wrong()` notice when the required `permission_callback` argument is not set.
 *
 * @param string $route_namespace The first URL segment after core prefix. Should be unique to your package/plugin.
 * @param string $route           The base URL for route you are adding.
 * @param array  $args            Optional. Either an array of options for the endpoint, or an array of arrays for
 *                                multiple methods. Default empty array.
 * @param bool   $override        Optional. If the route already exists, should we override it? True overrides,
 *                                false merges (with newer overriding if duplicate keys exist). Default false.
 * @return bool True on success, false on error.
 */
function register_rest_route( $route_namespace, $route, $args = array(), $override = false ) {
	if ( empty( $route_namespace ) ) {
		/*
		 * Non-namespaced routes are not allowed, with the exception of the main
		 * and namespace indexes. If you really need to register a
		 * non-namespaced route, call `WP_REST_Server::register_route` directly.
		 */
		_doing_it_wrong(
			__FUNCTION__,
			sprintf(
				/* translators: 1: string value of the namespace, 2: string value of the route. */
				__( 'Routes must be namespaced with plugin or theme name and version. Instead there seems to be an empty namespace \'%1$s\' for route \'%2$s\'.' ),
				'<code>' . $route_namespace . '</code>',
				'<code>' . $route . '</code>'
			),
			'4.4.0'
		);
		return false;
	} elseif ( empty( $route ) ) {
		_doing_it_wrong(
			__FUNCTION__,
			sprintf(
				/* translators: 1: string value of the namespace, 2: string value of the route. */
				__( 'Route must be specified. Instead within the namespace \'%1$s\', there seems to be an empty route \'%2$s\'.' ),
				'<code>' . $route_namespace . '</code>',
				'<code>' . $route . '</code>'
			),
			'4.4.0'
		);
		return false;
	}

	$clean_namespace = trim( $route_namespace, '/' );

	if ( $clean_namespace !== $route_namespace ) {
		_doing_it_wrong(
			__FUNCTION__,
			sprintf(
				/* translators: 1: string value of the namespace, 2: string value of the route. */
				__( 'Namespace must not start or end with a slash. Instead namespace \'%1$s\' for route \'%2$s\' seems to contain a slash.' ),
				'<code>' . $route_namespace . '</code>',
				'<code>' . $route . '</code>'
			),
			'5.4.2'
		);
	}

	if ( ! did_action( 'rest_api_init' ) ) {
		_doing_it_wrong(
			__FUNCTION__,
			sprintf(
				/* translators: 1: rest_api_init, 2: string value of the route, 3: string value of the namespace. */
				__( 'REST API routes must be registered on the %1$s action. Instead route \'%2$s\' with namespace \'%3$s\' was not registered on this action.' ),
				'<code>rest_api_init</code>',
				'<code>' . $route . '</code>',
				'<code>' . $route_namespace . '</code>'
			),
			'5.1.0'
		);
	}

	if ( isset( $args['args'] ) ) {
		$common_args = $args['args'];
		unset( $args['args'] );
	} else {
		$common_args = array();
	}

	if ( isset( $args['callback'] ) ) {
		// Upgrade a single set to multiple.
		$args = array( $args );
	}

	$defaults = array(
		'methods'  => 'GET',
		'callback' => null,
		'args'     => array(),
	);

	foreach ( $args as $key => &$arg_group ) {
		if ( ! is_numeric( $key ) ) {
			// Route option, skip here.
			continue;
		}

		$arg_group         = array_merge( $defaults, $arg_group );
		$arg_group['args'] = array_merge( $common_args, $arg_group['args'] );

		if ( ! isset( $arg_group['permission_callback'] ) ) {
			_doing_it_wrong(
				__FUNCTION__,
				sprintf(
					/* translators: 1: The REST API route being registered, 2: The argument name, 3: The suggested function name. */
					__( 'The REST API route definition for %1$s is missing the required %2$s argument. For REST API routes that are intended to be public, use %3$s as the permission callback.' ),
					'<code>' . $clean_namespace . '/' . trim( $route, '/' ) . '</code>',
					'<code>permission_callback</code>',
					'<code>__return_true</code>'
				),
				'5.5.0'
			);
		}

		foreach ( $arg_group['args'] as $arg ) {
			if ( ! is_array( $arg ) ) {
				_doing_it_wrong(
					__FUNCTION__,
					sprintf(
						/* translators: 1: $args, 2: The REST API route being registered. */
						__( 'REST API %1$s should be an array of arrays. Non-array value detected for %2$s.' ),
						'<code>$args</code>',
						'<code>' . $clean_namespace . '/' . trim( $route, '/' ) . '</code>'
					),
					'6.1.0'
				);
				break; // Leave the foreach loop once a non-array argument was found.
			}
		}
	}

	$full_route = '/' . $clean_namespace . '/' . trim( $route, '/' );
	rest_get_server()->register_route( $clean_namespace, $full_route, $args, $override );
	return true;
}

/**
 * Registers a new field on an existing WordPress object type.
 *
 * @since 4.7.0
 *
 * @global array $wp_rest_additional_fields Holds registered fields, organized
 *                                          by object type.
 *
 * @param string|array $object_type Object(s) the field is being registered to,
 *                                  "post"|"term"|"comment" etc.
 * @param string       $attribute   The attribute name.
 * @param array        $args {
 *     Optional. An array of arguments used to handle the registered field.
 *
 *     @type callable|null $get_callback    Optional. The callback function used to retrieve the field value. Default is
 *                                          'null', the field will not be returned in the response. The function will
 *                                          be passed the prepared object data.
 *     @type callable|null $update_callback Optional. The callback function used to set and update the field value. Default
 *                                          is 'null', the value cannot be set or updated. The function will be passed
 *                                          the model object, like WP_Post.
 *     @type array|null $schema             Optional. The schema for this field.
 *                                          Default is 'null', no schema entry will be returned.
 * }
 */
function register_rest_field( $object_type, $attribute, $args = array() ) {
	global $wp_rest_additional_fields;

	$defaults = array(
		'get_callback'    => null,
		'update_callback' => null,
		'schema'          => null,
	);

	$args = wp_parse_args( $args, $defaults );

	$object_types = (array) $object_type;

	foreach ( $object_types as $object_type ) {
		$wp_rest_additional_fields[ $object_type ][ $attribute ] = $args;
	}
}

/**
 * Registers rewrite rules for the REST API.
 *
 * @since 4.4.0
 *
 * @see rest_api_register_rewrites()
 * @global WP $wp Current WordPress environment instance.
 */
function rest_api_init() {
	rest_api_register_rewrites();

	global $wp;
	$wp->add_query_var( 'rest_route' );
}

/**
 * Adds REST rewrite rules.
 *
 * @since 4.4.0
 *
 * @see add_rewrite_rule()
 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
 */
function rest_api_register_rewrites() {
	global $wp_rewrite;

	add_rewrite_rule( '^' . rest_get_url_prefix() . '/?$', 'index.php?rest_route=/', 'top' );
	add_rewrite_rule( '^' . rest_get_url_prefix() . '/(.*)?', 'index.php?rest_route=/$matches[1]', 'top' );
	add_rewrite_rule( '^' . $wp_rewrite->index . '/' . rest_get_url_prefix() . '/?$', 'index.php?rest_route=/', 'top' );
	add_rewrite_rule( '^' . $wp_rewrite->index . '/' . rest_get_url_prefix() . '/(.*)?', 'index.php?rest_route=/$matches[1]', 'top' );
}

/**
 * Registers the default REST API filters.
 *
 * Attached to the {@see 'rest_api_init'} action
 * to make testing and disabling these filters easier.
 *
 * @since 4.4.0
 */
function rest_api_default_filters() {
	if ( wp_is_serving_rest_request() ) {
		// Deprecated reporting.
		add_action( 'deprecated_function_run', 'rest_handle_deprecated_function', 10, 3 );
		add_filter( 'deprecated_function_trigger_error', '__return_false' );
		add_action( 'deprecated_argument_run', 'rest_handle_deprecated_argument', 10, 3 );
		add_filter( 'deprecated_argument_trigger_error', '__return_false' );
		add_action( 'doing_it_wrong_run', 'rest_handle_doing_it_wrong', 10, 3 );
		add_filter( 'doing_it_wrong_trigger_error', '__return_false' );
	}

	// Default serving.
	add_filter( 'rest_pre_serve_request', 'rest_send_cors_headers' );
	add_filter( 'rest_post_dispatch', 'rest_send_allow_header', 10, 3 );
	add_filter( 'rest_post_dispatch', 'rest_filter_response_fields', 10, 3 );

	add_filter( 'rest_pre_dispatch', 'rest_handle_options_request', 10, 3 );
	add_filter( 'rest_index', 'rest_add_application_passwords_to_index' );
}

/**
 * Registers default REST API routes.
 *
 * @since 4.7.0
 */
function create_initial_rest_routes() {
	foreach ( get_post_types( array( 'show_in_rest' => true ), 'objects' ) as $post_type ) {
		$controller = $post_type->get_rest_controller();

		if ( ! $controller ) {
			continue;
		}

		if ( ! $post_type->late_route_registration ) {
			$controller->register_routes();
		}

		$revisions_controller = $post_type->get_revisions_rest_controller();
		if ( $revisions_controller ) {
			$revisions_controller->register_routes();
		}

		$autosaves_controller = $post_type->get_autosave_rest_controller();
		if ( $autosaves_controller ) {
			$autosaves_controller->register_routes();
		}

		if ( $post_type->late_route_registration ) {
			$controller->register_routes();
		}
	}

	// Post types.
	$controller = new WP_REST_Post_Types_Controller();
	$controller->register_routes();

	// Post statuses.
	$controller = new WP_REST_Post_Statuses_Controller();
	$controller->register_routes();

	// Taxonomies.
	$controller = new WP_REST_Taxonomies_Controller();
	$controller->register_routes();

	// Terms.
	foreach ( get_taxonomies( array( 'show_in_rest' => true ), 'object' ) as $taxonomy ) {
		$controller = $taxonomy->get_rest_controller();

		if ( ! $controller ) {
			continue;
		}

		$controller->register_routes();
	}

	// Users.
	$controller = new WP_REST_Users_Controller();
	$controller->register_routes();

	// Application Passwords
	$controller = new WP_REST_Application_Passwords_Controller();
	$controller->register_routes();

	// Comments.
	$controller = new WP_REST_Comments_Controller();
	$controller->register_routes();

	$search_handlers = array(
		new WP_REST_Post_Search_Handler(),
		new WP_REST_Term_Search_Handler(),
		new WP_REST_Post_Format_Search_Handler(),
	);

	/**
	 * Filters the search handlers to use in the REST search controller.
	 *
	 * @since 5.0.0
	 *
	 * @param array $search_handlers List of search handlers to use in the controller. Each search
	 *                               handler instance must extend the `WP_REST_Search_Handler` class.
	 *                               Default is only a handler for posts.
	 */
	$search_handlers = apply_filters( 'wp_rest_search_handlers', $search_handlers );

	$controller = new WP_REST_Search_Controller( $search_handlers );
	$controller->register_routes();

	// Block Renderer.
	$controller = new WP_REST_Block_Renderer_Controller();
	$controller->register_routes();

	// Block Types.
	$controller = new WP_REST_Block_Types_Controller();
	$controller->register_routes();

	// Settings.
	$controller = new WP_REST_Settings_Controller();
	$controller->register_routes();

	// Themes.
	$controller = new WP_REST_Themes_Controller();
	$controller->register_routes();

	// Plugins.
	$controller = new WP_REST_Plugins_Controller();
	$controller->register_routes();

	// Sidebars.
	$controller = new WP_REST_Sidebars_Controller();
	$controller->register_routes();

	// Widget Types.
	$controller = new WP_REST_Widget_Types_Controller();
	$controller->register_routes();

	// Widgets.
	$controller = new WP_REST_Widgets_Controller();
	$controller->register_routes();

	// Block Directory.
	$controller = new WP_REST_Block_Directory_Controller();
	$controller->register_routes();

	// Pattern Directory.
	$controller = new WP_REST_Pattern_Directory_Controller();
	$controller->register_routes();

	// Block Patterns.
	$controller = new WP_REST_Block_Patterns_Controller();
	$controller->register_routes();

	// Block Pattern Categories.
	$controller = new WP_REST_Block_Pattern_Categories_Controller();
	$controller->register_routes();

	// Site Health.
	$site_health = WP_Site_Health::get_instance();
	$controller  = new WP_REST_Site_Health_Controller( $site_health );
	$controller->register_routes();

	// URL Details.
	$controller = new WP_REST_URL_Details_Controller();
	$controller->register_routes();

	// Menu Locations.
	$controller = new WP_REST_Menu_Locations_Controller();
	$controller->register_routes();

	// Site Editor Export.
	$controller = new WP_REST_Edit_Site_Export_Controller();
	$controller->register_routes();

	// Navigation Fallback.
	$controller = new WP_REST_Navigation_Fallback_Controller();
	$controller->register_routes();

	// Font Collections.
	$font_collections_controller = new WP_REST_Font_Collections_Controller();
	$font_collections_controller->register_routes();

	// Abilities.
	$abilities_categories_controller = new WP_REST_Abilities_V1_Categories_Controller();
	$abilities_categories_controller->register_routes();
	$abilities_run_controller = new WP_REST_Abilities_V1_Run_Controller();
	$abilities_run_controller->register_routes();
	$abilities_list_controller = new WP_REST_Abilities_V1_List_Controller();
	$abilities_list_controller->register_routes();
}

/**
 * Loads the REST API.
 *
 * @since 4.4.0
 *
 * @global WP $wp Current WordPress environment instance.
 */
function rest_api_loaded() {
	if ( empty( $GLOBALS['wp']->query_vars['rest_route'] ) ) {
		return;
	}

	// Return an error message if query_var is not a string.
	if ( ! is_string( $GLOBALS['wp']->query_vars['rest_route'] ) ) {
		$rest_type_error = new WP_Error(
			'rest_path_invalid_type',
			__( 'The REST route parameter must be a string.' ),
			array( 'status' => 400 )
		);
		wp_die( $rest_type_error );
	}

	/**
	 * Whether this is a REST Request.
	 *
	 * @since 4.4.0
	 * @var bool
	 */
	define( 'REST_REQUEST', true );

	// Initialize the server.
	$server = rest_get_server();

	// Fire off the request.
	$route = untrailingslashit( $GLOBALS['wp']->query_vars['rest_route'] );
	if ( empty( $route ) ) {
		$route = '/';
	}
	$server->serve_request( $route );

	// We're done.
	die();
}

/**
 * Retrieves the URL prefix for any API resource.
 *
 * @since 4.4.0
 *
 * @return string Prefix.
 */
function rest_get_url_prefix() {
	/**
	 * Filters the REST URL prefix.
	 *
	 * @since 4.4.0
	 *
	 * @param string $prefix URL prefix. Default 'wp-json'.
	 */
	return apply_filters( 'rest_url_prefix', 'wp-json' );
}

/**
 * Retrieves the URL to a REST endpoint on a site.
 *
 * Note: The returned URL is NOT escaped.
 *
 * @since 4.4.0
 *
 * @todo Check if this is even necessary
 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
 *
 * @param int|null $blog_id Optional. Blog ID. Default of null returns URL for current blog.
 * @param string   $path    Optional. REST route. Default '/'.
 * @param string   $scheme  Optional. Sanitization scheme. Default 'rest'.
 * @return string Full URL to the endpoint.
 */
function get_rest_url( $blog_id = null, $path = '/', $scheme = 'rest' ) {
	if ( empty( $path ) ) {
		$path = '/';
	}

	$path = '/' . ltrim( $path, '/' );

	if ( is_multisite() && get_blog_option( $blog_id, 'permalink_structure' ) || get_option( 'permalink_structure' ) ) {
		global $wp_rewrite;

		if ( $wp_rewrite->using_index_permalinks() ) {
			$url = get_home_url( $blog_id, $wp_rewrite->index . '/' . rest_get_url_prefix(), $scheme );
		} else {
			$url = get_home_url( $blog_id, rest_get_url_prefix(), $scheme );
		}

		$url .= $path;
	} else {
		$url = trailingslashit( get_home_url( $blog_id, '', $scheme ) );
		/*
		 * nginx only allows HTTP/1.0 methods when redirecting from / to /index.php.
		 * To work around this, we manually add index.php to the URL, avoiding the redirect.
		 */
		if ( ! str_ends_with( $url, 'index.php' ) ) {
			$url .= 'index.php';
		}

		$url = add_query_arg( 'rest_route', $path, $url );
	}

	if ( is_ssl() && isset( $_SERVER['SERVER_NAME'] ) ) {
		// If the current host is the same as the REST URL host, force the REST URL scheme to HTTPS.
		if ( parse_url( get_home_url( $blog_id ), PHP_URL_HOST ) === $_SERVER['SERVER_NAME'] ) {
			$url = set_url_scheme( $url, 'https' );
		}
	}

	if ( is_admin() && force_ssl_admin() ) {
		/*
		 * In this situation the home URL may be http:, and `is_ssl()` may be false,
		 * but the admin is served over https: (one way or another), so REST API usage
		 * will be blocked by browsers unless it is also served over HTTPS.
		 */
		$url = set_url_scheme( $url, 'https' );
	}

	/**
	 * Filters the REST URL.
	 *
	 * Use this filter to adjust the url returned by the get_rest_url() function.
	 *
	 * @since 4.4.0
	 *
	 * @param string   $url     REST URL.
	 * @param string   $path    REST route.
	 * @param int|null $blog_id Blog ID.
	 * @param string   $scheme  Sanitization scheme.
	 */
	return apply_filters( 'rest_url', $url, $path, $blog_id, $scheme );
}

/**
 * Retrieves the URL to a REST endpoint.
 *
 * Note: The returned URL is NOT escaped.
 *
 * @since 4.4.0
 *
 * @param string $path   Optional. REST route. Default empty.
 * @param string $scheme Optional. Sanitization scheme. Default 'rest'.
 * @return string Full URL to the endpoint.
 */
function rest_url( $path = '', $scheme = 'rest' ) {
	return get_rest_url( null, $path, $scheme );
}

/**
 * Do a REST request.
 *
 * Used primarily to route internal requests through WP_REST_Server.
 *
 * @since 4.4.0
 *
 * @param WP_REST_Request|string $request Request.
 * @return WP_REST_Response REST response.
 */
function rest_do_request( $request ) {
	$request = rest_ensure_request( $request );
	return rest_get_server()->dispatch( $request );
}

/**
 * Retrieves the current REST server instance.
 *
 * Instantiates a new instance if none exists already.
 *
 * @since 4.5.0
 *
 * @global WP_REST_Server $wp_rest_server REST server instance.
 *
 * @return WP_REST_Server REST server instance.
 */
function rest_get_server() {
	/* @var WP_REST_Server $wp_rest_server */
	global $wp_rest_server;

	if ( empty( $wp_rest_server ) ) {
		/**
		 * Filters the REST Server Class.
		 *
		 * This filter allows you to adjust the server class used by the REST API, using a
		 * different class to handle requests.
		 *
		 * @since 4.4.0
		 *
		 * @param string $class_name The name of the server class. Default 'WP_REST_Server'.
		 */
		$wp_rest_server_class = apply_filters( 'wp_rest_server_class', 'WP_REST_Server' );
		$wp_rest_server       = new $wp_rest_server_class();

		/**
		 * Fires when preparing to serve a REST API request.
		 *
		 * Endpoint objects should be created and register their hooks on this action rather
		 * than another action to ensure they're only loaded when needed.
		 *
		 * @since 4.4.0
		 *
		 * @param WP_REST_Server $wp_rest_server Server object.
		 */
		do_action( 'rest_api_init', $wp_rest_server );
	}

	return $wp_rest_server;
}

/**
 * Ensures request arguments are a request object (for consistency).
 *
 * @since 4.4.0
 * @since 5.3.0 Accept string argument for the request path.
 *
 * @param array|string|WP_REST_Request $request Request to check.
 * @return WP_REST_Request REST request instance.
 */
function rest_ensure_request( $request ) {
	if ( $request instanceof WP_REST_Request ) {
		return $request;
	}

	if ( is_string( $request ) ) {
		return new WP_REST_Request( 'GET', $request );
	}

	return new WP_REST_Request( 'GET', '', $request );
}

/**
 * Ensures a REST response is a response object (for consistency).
 *
 * This implements WP_REST_Response, allowing usage of `set_status`/`header`/etc
 * without needing to double-check the object. Will also allow WP_Error to indicate error
 * responses, so users should immediately check for this value.
 *
 * @since 4.4.0
 *
 * @param WP_REST_Response|WP_Error|WP_HTTP_Response|mixed $response Response to check.
 * @return WP_REST_Response|WP_Error If response generated an error, WP_Error, if response
 *                                   is already an instance, WP_REST_Response, otherwise
 *                                   returns a new WP_REST_Response instance.
 */
function rest_ensure_response( $response ) {
	if ( is_wp_error( $response ) ) {
		return $response;
	}

	if ( $response instanceof WP_REST_Response ) {
		return $response;
	}

	/*
	 * While WP_HTTP_Response is the base class of WP_REST_Response, it doesn't provide
	 * all the required methods used in WP_REST_Server::dispatch().
	 */
	if ( $response instanceof WP_HTTP_Response ) {
		return new WP_REST_Response(
			$response->get_data(),
			$response->get_status(),
			$response->get_headers()
		);
	}

	return new WP_REST_Response( $response );
}

/**
 * Handles _deprecated_function() errors.
 *
 * @since 4.4.0
 *
 * @param string $function_name The function that was called.
 * @param string $replacement   The function that should have been called.
 * @param string $version       Version.
 */
function rest_handle_deprecated_function( $function_name, $replacement, $version ) {
	if ( ! WP_DEBUG || headers_sent() ) {
		return;
	}
	if ( ! empty( $replacement ) ) {
		/* translators: 1: Function name, 2: WordPress version number, 3: New function name. */
		$string = sprintf( __( '%1$s (since %2$s; use %3$s instead)' ), $function_name, $version, $replacement );
	} else {
		/* translators: 1: Function name, 2: WordPress version number. */
		$string = sprintf( __( '%1$s (since %2$s; no alternative available)' ), $function_name, $version );
	}

	header( sprintf( 'X-WP-DeprecatedFunction: %s', $string ) );
}

/**
 * Handles _deprecated_argument() errors.
 *
 * @since 4.4.0
 *
 * @param string $function_name The function that was called.
 * @param string $message       A message regarding the change.
 * @param string $version       Version.
 */
function rest_handle_deprecated_argument( $function_name, $message, $version ) {
	if ( ! WP_DEBUG || headers_sent() ) {
		return;
	}
	if ( $message ) {
		/* translators: 1: Function name, 2: WordPress version number, 3: Error message. */
		$string = sprintf( __( '%1$s (since %2$s; %3$s)' ), $function_name, $version, $message );
	} else {
		/* translators: 1: Function name, 2: WordPress version number. */
		$string = sprintf( __( '%1$s (since %2$s; no alternative available)' ), $function_name, $version );
	}

	header( sprintf( 'X-WP-DeprecatedParam: %s', $string ) );
}

/**
 * Handles _doing_it_wrong errors.
 *
 * @since 5.5.0
 *
 * @param string      $function_name The function that was called.
 * @param string      $message       A message explaining what has been done incorrectly.
 * @param string|null $version       The version of WordPress where the message was added.
 */
function rest_handle_doing_it_wrong( $function_name, $message, $version ) {
	if ( ! WP_DEBUG || headers_sent() ) {
		return;
	}

	if ( $version ) {
		/* translators: Developer debugging message. 1: PHP function name, 2: WordPress version number, 3: Explanatory message. */
		$string = __( '%1$s (since %2$s; %3$s)' );
		$string = sprintf( $string, $function_name, $version, $message );
	} else {
		/* translators: Developer debugging message. 1: PHP function name, 2: Explanatory message. */
		$string = __( '%1$s (%2$s)' );
		$string = sprintf( $string, $function_name, $message );
	}

	header( sprintf( 'X-WP-DoingItWrong: %s', $string ) );
}

/**
 * Sends Cross-Origin Resource Sharing headers with API requests.
 *
 * @since 4.4.0
 *
 * @param mixed $value Response data.
 * @return mixed Response data.
 */
function rest_send_cors_headers( $value ) {
	$origin = get_http_origin();

	if ( $origin ) {
		// Requests from file:// and data: URLs send "Origin: null".
		if ( 'null' !== $origin ) {
			$origin = sanitize_url( $origin );
		}
		header( 'Access-Control-Allow-Origin: ' . $origin );
		header( 'Access-Control-Allow-Methods: OPTIONS, GET, POST, PUT, PATCH, DELETE' );
		header( 'Access-Control-Allow-Credentials: true' );
		header( 'Vary: Origin', false );
	} elseif ( ! headers_sent() && 'GET' === $_SERVER['REQUEST_METHOD'] && ! is_user_logged_in() ) {
		header( 'Vary: Origin', false );
	}

	return $value;
}

/**
 * Handles OPTIONS requests for the server.
 *
 * This is handled outside of the server code, as it doesn't obey normal route
 * mapping.
 *
 * @since 4.4.0
 *
 * @param mixed           $response Current response, either response or `null` to indicate pass-through.
 * @param WP_REST_Server  $handler  ResponseHandler instance (usually WP_REST_Server).
 * @param WP_REST_Request $request  The request that was used to make current response.
 * @return WP_REST_Response Modified response, either response or `null` to indicate pass-through.
 */
function rest_handle_options_request( $response, $handler, $request ) {
	if ( ! empty( $response ) || $request->get_method() !== 'OPTIONS' ) {
		return $response;
	}

	$response = new WP_REST_Response();
	$data     = array();

	foreach ( $handler->get_routes() as $route => $endpoints ) {
		$match = preg_match( '@^' . $route . '$@i', $request->get_route(), $matches );

		if ( ! $match ) {
			continue;
		}

		$args = array();
		foreach ( $matches as $param => $value ) {
			if ( ! is_int( $param ) ) {
				$args[ $param ] = $value;
			}
		}

		foreach ( $endpoints as $endpoint ) {
			$request->set_url_params( $args );
			$request->set_attributes( $endpoint );
		}

		$data = $handler->get_data_for_route( $route, $endpoints, 'help' );
		$response->set_matched_route( $route );
		break;
	}

	$response->set_data( $data );
	return $response;
}

/**
 * Sends the "Allow" header to state all methods that can be sent to the current route.
 *
 * @since 4.4.0
 *
 * @param WP_REST_Response $response Current response being served.
 * @param WP_REST_Server   $server   ResponseHandler instance (usually WP_REST_Server).
 * @param WP_REST_Request  $request  The request that was used to make current response.
 * @return WP_REST_Response Response to be served, with "Allow" header if route has allowed methods.
 */
function rest_send_allow_header( $response, $server, $request ) {
	$matched_route = $response->get_matched_route();

	if ( ! $matched_route ) {
		return $response;
	}

	$routes = $server->get_routes();

	$allowed_methods = array();

	// Get the allowed methods across the routes.
	foreach ( $routes[ $matched_route ] as $_handler ) {
		foreach ( $_handler['methods'] as $handler_method => $value ) {

			if ( ! empty( $_handler['permission_callback'] ) ) {

				$permission = call_user_func( $_handler['permission_callback'], $request );

				$allowed_methods[ $handler_method ] = true === $permission;
			} else {
				$allowed_methods[ $handler_method ] = true;
			}
		}
	}

	// Strip out all the methods that are not allowed (false values).
	$allowed_methods = array_filter( $allowed_methods );

	if ( $allowed_methods ) {
		$response->header( 'Allow', implode( ', ', array_map( 'strtoupper', array_keys( $allowed_methods ) ) ) );
	}

	return $response;
}

/**
 * Recursively computes the intersection of arrays using keys for comparison.
 *
 * @since 5.3.0
 *
 * @param array $array1 The array with master keys to check.
 * @param array $array2 An array to compare keys against.
 * @return array An associative array containing all the entries of array1 which have keys
 *               that are present in all arguments.
 */
function _rest_array_intersect_key_recursive( $array1, $array2 ) {
	$array1 = array_intersect_key( $array1, $array2 );
	foreach ( $array1 as $key => $value ) {
		if ( is_array( $value ) && is_array( $array2[ $key ] ) ) {
			$array1[ $key ] = _rest_array_intersect_key_recursive( $value, $array2[ $key ] );
		}
	}
	return $array1;
}

/**
 * Filters the REST API response to include only an allow-listed set of response object fields.
 *
 * @since 4.8.0
 *
 * @param WP_REST_Response $response Current response being served.
 * @param WP_REST_Server   $server   ResponseHandler instance (usually WP_REST_Server).
 * @param WP_REST_Request  $request  The request that was used to make current response.
 * @return WP_REST_Response Response to be served, trimmed down to contain a subset of fields.
 */
function rest_filter_response_fields( $response, $server, $request ) {
	if ( ! isset( $request['_fields'] ) || $response->is_error() ) {
		return $response;
	}

	$data = $response->get_data();

	$fields = wp_parse_list( $request['_fields'] );

	if ( 0 === count( $fields ) ) {
		return $response;
	}

	// Trim off outside whitespace from the comma delimited list.
	$fields = array_map( 'trim', $fields );

	// Create nested array of accepted field hierarchy.
	$fields_as_keyed = array();
	foreach ( $fields as $field ) {
		$parts = explode( '.', $field );
		$ref   = &$fields_as_keyed;
		while ( count( $parts ) > 1 ) {
			$next = array_shift( $parts );
			if ( isset( $ref[ $next ] ) && true === $ref[ $next ] ) {
				// Skip any sub-properties if their parent prop is already marked for inclusion.
				break 2;
			}
			$ref[ $next ] = isset( $ref[ $next ] ) ? $ref[ $next ] : array();
			$ref          = &$ref[ $next ];
		}
		$last         = array_shift( $parts );
		$ref[ $last ] = true;
	}

	if ( wp_is_numeric_array( $data ) ) {
		$new_data = array();
		foreach ( $data as $item ) {
			$new_data[] = _rest_array_intersect_key_recursive( $item, $fields_as_keyed );
		}
	} else {
		$new_data = _rest_array_intersect_key_recursive( $data, $fields_as_keyed );
	}

	$response->set_data( $new_data );

	return $response;
}

/**
 * Given an array of fields to include in a response, some of which may be
 * `nested.fields`, determine whether the provided field should be included
 * in the response body.
 *
 * If a parent field is passed in, the presence of any nested field within
 * that parent will cause the method to return `true`. For example "title"
 * will return true if any of `title`, `title.raw` or `title.rendered` is
 * provided.
 *
 * @since 5.3.0
 *
 * @param string $field  A field to test for inclusion in the response body.
 * @param array  $fields An array of string fields supported by the endpoint.
 * @return bool Whether to include the field or not.
 */
function rest_is_field_included( $field, $fields ) {
	if ( in_array( $field, $fields, true ) ) {
		return true;
	}

	foreach ( $fields as $accepted_field ) {
		/*
		 * Check to see if $field is the parent of any item in $fields.
		 * A field "parent" should be accepted if "parent.child" is accepted.