'default' => $route_namespace,
							),
							'context'   => array(
								'default' => 'view',
							),
						),
					),
				)
			);
		}

		// Associative to avoid double-registration.
		$this->namespaces[ $route_namespace ][ $route ] = true;

		$route_args['namespace'] = $route_namespace;

		if ( $override || empty( $this->endpoints[ $route ] ) ) {
			$this->endpoints[ $route ] = $route_args;
		} else {
			$this->endpoints[ $route ] = array_merge( $this->endpoints[ $route ], $route_args );
		}
	}

	/**
	 * Retrieves the route map.
	 *
	 * The route map is an associative array with path regexes as the keys. The
	 * value is an indexed array with the callback function/method as the first
	 * item, and a bitmask of HTTP methods as the second item (see the class
	 * constants).
	 *
	 * Each route can be mapped to more than one callback by using an array of
	 * the indexed arrays. This allows mapping e.g. GET requests to one callback
	 * and POST requests to another.
	 *
	 * Note that the path regexes (array keys) must have @ escaped, as this is
	 * used as the delimiter with preg_match()
	 *
	 * @since 4.4.0
	 * @since 5.4.0 Added `$route_namespace` parameter.
	 *
	 * @param string $route_namespace Optionally, only return routes in the given namespace.
	 * @return array `'/path/regex' => array( $callback, $bitmask )` or
	 *               `'/path/regex' => array( array( $callback, $bitmask ), ...)`.
	 */
	public function get_routes( $route_namespace = '' ) {
		$endpoints = $this->endpoints;

		if ( $route_namespace ) {
			$endpoints = wp_list_filter( $endpoints, array( 'namespace' => $route_namespace ) );
		}

		/**
		 * Filters the array of available REST API endpoints.
		 *
		 * @since 4.4.0
		 *
		 * @param array $endpoints The available endpoints. An array of matching regex patterns, each mapped
		 *                         to an array of callbacks for the endpoint. These take the format
		 *                         `'/path/regex' => array( $callback, $bitmask )` or
		 *                         `'/path/regex' => array( array( $callback, $bitmask ).
		 */
		$endpoints = apply_filters( 'rest_endpoints', $endpoints );

		// Normalize the endpoints.
		$defaults = array(
			'methods'       => '',
			'accept_json'   => false,
			'accept_raw'    => false,
			'show_in_index' => true,
			'args'          => array(),
		);

		foreach ( $endpoints as $route => &$handlers ) {

			if ( isset( $handlers['callback'] ) ) {
				// Single endpoint, add one deeper.
				$handlers = array( $handlers );
			}

			if ( ! isset( $this->route_options[ $route ] ) ) {
				$this->route_options[ $route ] = array();
			}

			foreach ( $handlers as $key => &$handler ) {

				if ( ! is_numeric( $key ) ) {
					// Route option, move it to the options.
					$this->route_options[ $route ][ $key ] = $handler;
					unset( $handlers[ $key ] );
					continue;
				}

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

				// Allow comma-separated HTTP methods.
				if ( is_string( $handler['methods'] ) ) {
					$methods = explode( ',', $handler['methods'] );
				} elseif ( is_array( $handler['methods'] ) ) {
					$methods = $handler['methods'];
				} else {
					$methods = array();
				}

				$handler['methods'] = array();

				foreach ( $methods as $method ) {
					$method                        = strtoupper( trim( $method ) );
					$handler['methods'][ $method ] = true;
				}
			}
		}

		return $endpoints;
	}

	/**
	 * Retrieves namespaces registered on the server.
	 *
	 * @since 4.4.0
	 *
	 * @return string[] List of registered namespaces.
	 */
	public function get_namespaces() {
		return array_keys( $this->namespaces );
	}

	/**
	 * Retrieves specified options for a route.
	 *
	 * @since 4.4.0
	 *
	 * @param string $route Route pattern to fetch options for.
	 * @return array|null Data as an associative array if found, or null if not found.
	 */
	public function get_route_options( $route ) {
		if ( ! isset( $this->route_options[ $route ] ) ) {
			return null;
		}

		return $this->route_options[ $route ];
	}

	/**
	 * Matches the request to a callback and call it.
	 *
	 * @since 4.4.0
	 *
	 * @param WP_REST_Request $request Request to attempt dispatching.
	 * @return WP_REST_Response Response returned by the callback.
	 */
	public function dispatch( $request ) {
		/**
		 * Filters the pre-calculated result of a REST API dispatch request.
		 *
		 * Allow hijacking the request before dispatching by returning a non-empty. The returned value
		 * will be used to serve the request instead.
		 *
		 * @since 4.4.0
		 *
		 * @param mixed           $result  Response to replace the requested version with. Can be anything
		 *                                 a normal endpoint can return, or null to not hijack the request.
		 * @param WP_REST_Server  $server  Server instance.
		 * @param WP_REST_Request $request Request used to generate the response.
		 */
		$result = apply_filters( 'rest_pre_dispatch', null, $this, $request );

		if ( ! empty( $result ) ) {

			// Normalize to either WP_Error or WP_REST_Response...
			$result = rest_ensure_response( $result );

			// ...then convert WP_Error across.
			if ( is_wp_error( $result ) ) {
				$result = $this->error_to_response( $result );
			}

			return $result;
		}

		$error   = null;
		$matched = $this->match_request_to_handler( $request );

		if ( is_wp_error( $matched ) ) {
			return $this->error_to_response( $matched );
		}

		list( $route, $handler ) = $matched;

		if ( ! is_callable( $handler['callback'] ) ) {
			$error = new WP_Error(
				'rest_invalid_handler',
				__( 'The handler for the route is invalid.' ),
				array( 'status' => 500 )
			);
		}

		if ( ! is_wp_error( $error ) ) {
			$check_required = $request->has_valid_params();
			if ( is_wp_error( $check_required ) ) {
				$error = $check_required;
			} else {
				$check_sanitized = $request->sanitize_params();
				if ( is_wp_error( $check_sanitized ) ) {
					$error = $check_sanitized;
				}
			}
		}

		return $this->respond_to_request( $request, $route, $handler, $error );
	}

	/**
	 * Matches a request object to its handler.
	 *
	 * @access private
	 * @since 5.6.0
	 *
	 * @param WP_REST_Request $request The request object.
	 * @return array|WP_Error The route and request handler on success or a WP_Error instance if no handler was found.
	 */
	protected function match_request_to_handler( $request ) {
		$method = $request->get_method();
		$path   = $request->get_route();

		$with_namespace = array();

		foreach ( $this->get_namespaces() as $namespace ) {
			if ( str_starts_with( trailingslashit( ltrim( $path, '/' ) ), $namespace ) ) {
				$with_namespace[] = $this->get_routes( $namespace );
			}
		}

		if ( $with_namespace ) {
			$routes = array_merge( ...$with_namespace );
		} else {
			$routes = $this->get_routes();
		}

		foreach ( $routes as $route => $handlers ) {
			$match = preg_match( '@^' . $route . '$@i', $path, $matches );

			if ( ! $match ) {
				continue;
			}

			$args = array();

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

			foreach ( $handlers as $handler ) {
				$callback = $handler['callback'];
				$response = null;

				// Fallback to GET method if no HEAD method is registered.
				$checked_method = $method;
				if ( 'HEAD' === $method && empty( $handler['methods']['HEAD'] ) ) {
					$checked_method = 'GET';
				}
				if ( empty( $handler['methods'][ $checked_method ] ) ) {
					continue;
				}

				if ( ! is_callable( $callback ) ) {
					return array( $route, $handler );
				}

				$request->set_url_params( $args );
				$request->set_attributes( $handler );

				$defaults = array();

				foreach ( $handler['args'] as $arg => $options ) {
					if ( isset( $options['default'] ) ) {
						$defaults[ $arg ] = $options['default'];
					}
				}

				$request->set_default_params( $defaults );

				return array( $route, $handler );
			}
		}

		return new WP_Error(
			'rest_no_route',
			__( 'No route was found matching the URL and request method.' ),
			array( 'status' => 404 )
		);
	}

	/**
	 * Dispatches the request to the callback handler.
	 *
	 * @access private
	 * @since 5.6.0
	 *
	 * @param WP_REST_Request $request  The request object.
	 * @param string          $route    The matched route regex.
	 * @param array           $handler  The matched route handler.
	 * @param WP_Error|null   $response The current error object if any.
	 * @return WP_REST_Response
	 */
	protected function respond_to_request( $request, $route, $handler, $response ) {
		/**
		 * Filters the response before executing any REST API callbacks.
		 *
		 * Allows plugins to perform additional validation after a
		 * request is initialized and matched to a registered route,
		 * but before it is executed.
		 *
		 * Note that this filter will not be called for requests that
		 * fail to authenticate or match to a registered route.
		 *
		 * @since 4.7.0
		 *
		 * @param WP_REST_Response|WP_HTTP_Response|WP_Error|mixed $response Result to send to the client.
		 *                                                                   Usually a WP_REST_Response or WP_Error.
		 * @param array                                            $handler  Route handler used for the request.
		 * @param WP_REST_Request                                  $request  Request used to generate the response.
		 */
		$response = apply_filters( 'rest_request_before_callbacks', $response, $handler, $request );

		// Check permission specified on the route.
		if ( ! is_wp_error( $response ) && ! empty( $handler['permission_callback'] ) ) {
			$permission = call_user_func( $handler['permission_callback'], $request );

			if ( is_wp_error( $permission ) ) {
				$response = $permission;
			} elseif ( false === $permission || null === $permission ) {
				$response = new WP_Error(
					'rest_forbidden',
					__( 'Sorry, you are not allowed to do that.' ),
					array( 'status' => rest_authorization_required_code() )
				);
			}
		}

		if ( ! is_wp_error( $response ) ) {
			/**
			 * Filters the REST API dispatch request result.
			 *
			 * Allow plugins to override dispatching the request.
			 *
			 * @since 4.4.0
			 * @since 4.5.0 Added `$route` and `$handler` parameters.
			 *
			 * @param mixed           $dispatch_result Dispatch result, will be used if not empty.
			 * @param WP_REST_Request $request         Request used to generate the response.
			 * @param string          $route           Route matched for the request.
			 * @param array           $handler         Route handler used for the request.
			 */
			$dispatch_result = apply_filters( 'rest_dispatch_request', null, $request, $route, $handler );

			// Allow plugins to halt the request via this filter.
			if ( null !== $dispatch_result ) {
				$response = $dispatch_result;
			} else {
				$response = call_user_func( $handler['callback'], $request );
			}
		}

		/**
		 * Filters the response immediately after executing any REST API
		 * callbacks.
		 *
		 * Allows plugins to perform any needed cleanup, for example,
		 * to undo changes made during the {@see 'rest_request_before_callbacks'}
		 * filter.
		 *
		 * Note that this filter will not be called for requests that
		 * fail to authenticate or match to a registered route.
		 *
		 * Note that an endpoint's `permission_callback` can still be
		 * called after this filter - see `rest_send_allow_header()`.
		 *
		 * @since 4.7.0
		 *
		 * @param WP_REST_Response|WP_HTTP_Response|WP_Error|mixed $response Result to send to the client.
		 *                                                                   Usually a WP_REST_Response or WP_Error.
		 * @param array                                            $handler  Route handler used for the request.
		 * @param WP_REST_Request                                  $request  Request used to generate the response.
		 */
		$response = apply_filters( 'rest_request_after_callbacks', $response, $handler, $request );

		if ( is_wp_error( $response ) ) {
			$response = $this->error_to_response( $response );
		} else {
			$response = rest_ensure_response( $response );
		}

		$response->set_matched_route( $route );
		$response->set_matched_handler( $handler );

		return $response;
	}

	/**
	 * Returns if an error occurred during most recent JSON encode/decode.
	 *
	 * Strings to be translated will be in format like
	 * "Encoding error: Maximum stack depth exceeded".
	 *
	 * @since 4.4.0
	 *
	 * @return false|string Boolean false or string error message.
	 */
	protected function get_json_last_error() {
		$last_error_code = json_last_error();

		if ( JSON_ERROR_NONE === $last_error_code || empty( $last_error_code ) ) {
			return false;
		}

		return json_last_error_msg();
	}

	/**
	 * Retrieves the site index.
	 *
	 * This endpoint describes the capabilities of the site.
	 *
	 * @since 4.4.0
	 *
	 * @param array $request {
	 *     Request.
	 *
	 *     @type string $context Context.
	 * }
	 * @return WP_REST_Response The API root index data.
	 */
	public function get_index( $request ) {
		// General site data.
		$available = array(
			'name'            => get_option( 'blogname' ),
			'description'     => get_option( 'blogdescription' ),
			'url'             => get_option( 'siteurl' ),
			'home'            => home_url(),
			'gmt_offset'      => get_option( 'gmt_offset' ),
			'timezone_string' => get_option( 'timezone_string' ),
			'namespaces'      => array_keys( $this->namespaces ),
			'authentication'  => array(),
			'routes'          => $this->get_data_for_routes( $this->get_routes(), $request['context'] ),
		);

		$response = new WP_REST_Response( $available );
		$response->add_link( 'help', 'https://developer.wordpress.org/rest-api/' );
		$this->add_active_theme_link_to_index( $response );
		$this->add_site_logo_to_index( $response );
		$this->add_site_icon_to_index( $response );

		/**
		 * Filters the REST API root index data.
		 *
		 * This contains the data describing the API. This includes information
		 * about supported authentication schemes, supported namespaces, routes
		 * available on the API, and a small amount of data about the site.
		 *
		 * @since 4.4.0
		 * @since 6.0.0 Added `$request` parameter.
		 *
		 * @param WP_REST_Response $response Response data.
		 * @param WP_REST_Request  $request  Request data.
		 */
		return apply_filters( 'rest_index', $response, $request );
	}

	/**
	 * Adds a link to the active theme for users who have proper permissions.
	 *
	 * @since 5.7.0
	 *
	 * @param WP_REST_Response $response REST API response.
	 */
	protected function add_active_theme_link_to_index( WP_REST_Response $response ) {
		$should_add = current_user_can( 'switch_themes' ) || current_user_can( 'manage_network_themes' );

		if ( ! $should_add && current_user_can( 'edit_posts' ) ) {
			$should_add = true;
		}

		if ( ! $should_add ) {
			foreach ( get_post_types( array( 'show_in_rest' => true ), 'objects' ) as $post_type ) {
				if ( current_user_can( $post_type->cap->edit_posts ) ) {
					$should_add = true;
					break;
				}
			}
		}

		if ( $should_add ) {
			$theme = wp_get_theme();
			$response->add_link( 'https://api.w.org/active-theme', rest_url( 'wp/v2/themes/' . $theme->get_stylesheet() ) );
		}
	}

	/**
	 * Exposes the site logo through the WordPress REST API.
	 *
	 * This is used for fetching this information when user has no rights
	 * to update settings.
	 *
	 * @since 5.8.0
	 *
	 * @param WP_REST_Response $response REST API response.
	 */
	protected function add_site_logo_to_index( WP_REST_Response $response ) {
		$site_logo_id = get_theme_mod( 'custom_logo', 0 );

		$this->add_image_to_index( $response, $site_logo_id, 'site_logo' );
	}

	/**
	 * Exposes the site icon through the WordPress REST API.
	 *
	 * This is used for fetching this information when user has no rights
	 * to update settings.
	 *
	 * @since 5.9.0
	 *
	 * @param WP_REST_Response $response REST API response.
	 */
	protected function add_site_icon_to_index( WP_REST_Response $response ) {
		$site_icon_id = get_option( 'site_icon', 0 );

		$this->add_image_to_index( $response, $site_icon_id, 'site_icon' );

		$response->data['site_icon_url'] = get_site_icon_url();
	}

	/**
	 * Exposes an image through the WordPress REST API.
	 * This is used for fetching this information when user has no rights
	 * to update settings.
	 *
	 * @since 5.9.0
	 *
	 * @param WP_REST_Response $response REST API response.
	 * @param int              $image_id Image attachment ID.
	 * @param string           $type     Type of Image.
	 */
	protected function add_image_to_index( WP_REST_Response $response, $image_id, $type ) {
		$response->data[ $type ] = (int) $image_id;
		if ( $image_id ) {
			$response->add_link(
				'https://api.w.org/featuredmedia',
				rest_url( rest_get_route_for_post( $image_id ) ),
				array(
					'embeddable' => true,
					'type'       => $type,
				)
			);
		}
	}

	/**
	 * Retrieves the index for a namespace.
	 *
	 * @since 4.4.0
	 *
	 * @param WP_REST_Request $request REST request instance.
	 * @return WP_REST_Response|WP_Error WP_REST_Response instance if the index was found,
	 *                                   WP_Error if the namespace isn't set.
	 */
	public function get_namespace_index( $request ) {
		$namespace = $request['namespace'];

		if ( ! isset( $this->namespaces[ $namespace ] ) ) {
			return new WP_Error(
				'rest_invalid_namespace',
				__( 'The specified namespace could not be found.' ),
				array( 'status' => 404 )
			);
		}

		$routes    = $this->namespaces[ $namespace ];
		$endpoints = array_intersect_key( $this->get_routes(), $routes );

		$data     = array(
			'namespace' => $namespace,
			'routes'    => $this->get_data_for_routes( $endpoints, $request['context'] ),
		);
		$response = rest_ensure_response( $data );

		// Link to the root index.
		$response->add_link( 'up', rest_url( '/' ) );

		/**
		 * Filters the REST API namespace index data.
		 *
		 * This typically is just the route data for the namespace, but you can
		 * add any data you'd like here.
		 *
		 * @since 4.4.0
		 *
		 * @param WP_REST_Response $response Response data.
		 * @param WP_REST_Request  $request  Request data. The namespace is passed as the 'namespace' parameter.
		 */
		return apply_filters( 'rest_namespace_index', $response, $request );
	}

	/**
	 * Retrieves the publicly-visible data for routes.
	 *
	 * @since 4.4.0
	 *
	 * @param array  $routes  Routes to get data for.
	 * @param string $context Optional. Context for data. Accepts 'view' or 'help'. Default 'view'.
	 * @return array[] Route data to expose in indexes, keyed by route.
	 */
	public function get_data_for_routes( $routes, $context = 'view' ) {
		$available = array();

		// Find the available routes.
		foreach ( $routes as $route => $callbacks ) {
			$data = $this->get_data_for_route( $route, $callbacks, $context );
			if ( empty( $data ) ) {
				continue;
			}

			/**
			 * Filters the publicly-visible data for a single REST API route.
			 *
			 * @since 4.4.0
			 *
			 * @param array $data Publicly-visible data for the route.
			 */
			$available[ $route ] = apply_filters( 'rest_endpoints_description', $data );
		}

		/**
		 * Filters the publicly-visible data for REST API routes.
		 *
		 * This data is exposed on indexes and can be used by clients or
		 * developers to investigate the site and find out how to use it. It
		 * acts as a form of self-documentation.
		 *
		 * @since 4.4.0
		 *
		 * @param array[] $available Route data to expose in indexes, keyed by route.
		 * @param array   $routes    Internal route data as an associative array.
		 */
		return apply_filters( 'rest_route_data', $available, $routes );
	}

	/**
	 * Retrieves publicly-visible data for the route.
	 *
	 * @since 4.4.0
	 *
	 * @param string $route     Route to get data for.
	 * @param array  $callbacks Callbacks to convert to data.
	 * @param string $context   Optional. Context for the data. Accepts 'view' or 'help'. Default 'view'.
	 * @return array|null Data for the route, or null if no publicly-visible data.
	 */
	public function get_data_for_route( $route, $callbacks, $context = 'view' ) {
		$data = array(
			'namespace' => '',
			'methods'   => array(),
			'endpoints' => array(),
		);

		$allow_batch = false;

		if ( isset( $this->route_options[ $route ] ) ) {
			$options = $this->route_options[ $route ];

			if ( isset( $options['namespace'] ) ) {
				$data['namespace'] = $options['namespace'];
			}

			$allow_batch = isset( $options['allow_batch'] ) ? $options['allow_batch'] : false;

			if ( isset( $options['schema'] ) && 'help' === $context ) {
				$data['schema'] = call_user_func( $options['schema'] );
			}
		}

		$allowed_schema_keywords = array_flip( rest_get_allowed_schema_keywords() );

		$route = preg_replace( '#\(\?P<(\w+?)>.*?\)#', '{$1}', $route );

		foreach ( $callbacks as $callback ) {
			// Skip to the next route if any callback is hidden.
			if ( empty( $callback['show_in_index'] ) ) {
				continue;
			}

			$data['methods'] = array_merge( $data['methods'], array_keys( $callback['methods'] ) );
			$endpoint_data   = array(
				'methods' => array_keys( $callback['methods'] ),
			);

			$callback_batch = isset( $callback['allow_batch'] ) ? $callback['allow_batch'] : $allow_batch;

			if ( $callback_batch ) {
				$endpoint_data['allow_batch'] = $callback_batch;
			}

			if ( isset( $callback['args'] ) ) {
				$endpoint_data['args'] = array();

				foreach ( $callback['args'] as $key => $opts ) {
					if ( is_string( $opts ) ) {
						$opts = array( $opts => 0 );
					} elseif ( ! is_array( $opts ) ) {
						$opts = array();
					}
					$arg_data             = array_intersect_key( $opts, $allowed_schema_keywords );
					$arg_data['required'] = ! empty( $opts['required'] );

					$endpoint_data['args'][ $key ] = $arg_data;
				}
			}

			$data['endpoints'][] = $endpoint_data;

			// For non-variable routes, generate links.
			if ( ! str_contains( $route, '{' ) ) {
				$data['_links'] = array(
					'self' => array(
						array(
							'href' => rest_url( $route ),
						),
					),
				);
			}
		}

		if ( empty( $data['methods'] ) ) {
			// No methods supported, hide the route.
			return null;
		}

		return $data;
	}

	/**
	 * Gets the maximum number of requests that can be included in a batch.
	 *
	 * @since 5.6.0
	 *
	 * @return int The maximum requests.
	 */
	protected function get_max_batch_size() {
		/**
		 * Filters the maximum number of REST API requests that can be included in a batch.
		 *
		 * @since 5.6.0
		 *
		 * @param int $max_size The maximum size.
		 */
		return apply_filters( 'rest_get_max_batch_size', 25 );
	}

	/**
	 * Serves the batch/v1 request.
	 *
	 * @since 5.6.0
	 *
	 * @param WP_REST_Request $batch_request The batch request object.
	 * @return WP_REST_Response The generated response object.
	 */
	public function serve_batch_request_v1( WP_REST_Request $batch_request ) {
		$requests = array();

		foreach ( $batch_request['requests'] as $args ) {
			$parsed_url = wp_parse_url( $args['path'] );

			if ( false === $parsed_url ) {
				$requests[] = new WP_Error( 'parse_path_failed', __( 'Could not parse the path.' ), array( 'status' => 400 ) );

				continue;
			}

			$single_request = new WP_REST_Request( isset( $args['method'] ) ? $args['method'] : 'POST', $parsed_url['path'] );

			if ( ! empty( $parsed_url['query'] ) ) {
				$query_args = null; // Satisfy linter.
				wp_parse_str( $parsed_url['query'], $query_args );
				$single_request->set_query_params( $query_args );
			}

			if ( ! empty( $args['body'] ) ) {
				$single_request->set_body_params( $args['body'] );
			}

			if ( ! empty( $args['headers'] ) ) {
				$single_request->set_headers( $args['headers'] );
			}

			$requests[] = $single_request;
		}

		$matches    = array();
		$validation = array();
		$has_error  = false;

		foreach ( $requests as $single_request ) {
			$match     = $this->match_request_to_handler( $single_request );
			$matches[] = $match;
			$error     = null;

			if ( is_wp_error( $match ) ) {
				$error = $match;
			}

			if ( ! $error ) {
				list( $route, $handler ) = $match;

				if ( isset( $handler['allow_batch'] ) ) {
					$allow_batch = $handler['allow_batch'];
				} else {
					$route_options = $this->get_route_options( $route );
					$allow_batch   = isset( $route_options['allow_batch'] ) ? $route_options['allow_batch'] : false;
				}

				if ( ! is_array( $allow_batch ) || empty( $allow_batch['v1'] ) ) {
					$error = new WP_Error(
						'rest_batch_not_allowed',
						__( 'The requested route does not support batch requests.' ),
						array( 'status' => 400 )
					);
				}
			}

			if ( ! $error ) {
				$check_required = $single_request->has_valid_params();
				if ( is_wp_error( $check_required ) ) {
					$error = $check_required;
				}
			}

			if ( ! $error ) {
				$check_sanitized = $single_request->sanitize_params();
				if ( is_wp_error( $check_sanitized ) ) {
					$error = $check_sanitized;
				}
			}

			if ( $error ) {
				$has_error    = true;
				$validation[] = $error;
			} else {
				$validation[] = true;
			}
		}

		$responses = array();

		if ( $has_error && 'require-all-validate' === $batch_request['validation'] ) {
			foreach ( $validation as $valid ) {
				if ( is_wp_error( $valid ) ) {
					$responses[] = $this->envelope_response( $this->error_to_response( $valid ), false )->get_data();
				} else {
					$responses[] = null;
				}
			}

			return new WP_REST_Response(
				array(
					'failed'    => 'validation',
					'responses' => $responses,
				),
				WP_Http::MULTI_STATUS
			);
		}

		foreach ( $requests as $i => $single_request ) {
			$clean_request = clone $single_request;
			$clean_request->set_url_params( array() );
			$clean_request->set_attributes( array() );
			$clean_request->set_default_params( array() );

			/** This filter is documented in wp-includes/rest-api/class-wp-rest-server.php */
			$result = apply_filters( 'rest_pre_dispatch', null, $this, $clean_request );

			if ( empty( $result ) ) {
				$match = $matches[ $i ];
				$error = null;

				if ( is_wp_error( $validation[ $i ] ) ) {
					$error = $validation[ $i ];
				}

				if ( is_wp_error( $match ) ) {
					$result = $this->error_to_response( $match );
				} else {
					list( $route, $handler ) = $match;

					if ( ! $error && ! is_callable( $handler['callback'] ) ) {
						$error = new WP_Error(
							'rest_invalid_handler',
							__( 'The handler for the route is invalid' ),
							array( 'status' => 500 )
						);
					}

					$result = $this->respond_to_request( $single_request, $route, $handler, $error );
				}
			}

			/** This filter is documented in wp-includes/rest-api/class-wp-rest-server.php */
			$result = apply_filters( 'rest_post_dispatch', rest_ensure_response( $result ), $this, $single_request );

			$responses[] = $this->envelope_response( $result, false )->get_data();
		}

		return new WP_REST_Response( array( 'responses' => $responses ), WP_Http::MULTI_STATUS );
	}

	/**
	 * Sends an HTTP status code.
	 *
	 * @since 4.4.0
	 *
	 * @param int $code HTTP status.
	 */
	protected function set_status( $code ) {
		status_header( $code );
	}

	/**
	 * Sends an HTTP header.
	 *
	 * @since 4.4.0
	 *
	 * @param string $key Header key.
	 * @param string $value Header value.
	 */
	public function send_header( $key, $value ) {
		/*
		 * Sanitize as per RFC2616 (Section 4.2):
		 *
		 * Any LWS that occurs between field-content MAY be replaced with a
		 * single SP before interpreting the field value or forwarding the
		 * message downstream.
		 */
		$value = preg_replace( '/\s+/', ' ', $value );
		header( sprintf( '%s: %s', $key, $value ) );
	}

	/**
	 * Sends multiple HTTP headers.
	 *
	 * @since 4.4.0
	 *
	 * @param array $headers Map of header name to header value.
	 */
	public function send_headers( $headers ) {
		foreach ( $headers as $key => $value ) {
			$this->send_header( $key, $value );
		}
	}

	/**
	 * Removes an HTTP header from the current response.
	 *
	 * @since 4.8.0
	 *
	 * @param string $key Header key.
	 */
	public function remove_header( $key ) {
		header_remove( $key );
	}

	/**
	 * Retrieves the raw request entity (body).
	 *
	 * @since 4.4.0
	 *
	 * @global string $HTTP_RAW_POST_DATA Raw post data.
	 *
	 * @return string Raw request data.
	 */
	public static function get_raw_data() {
		// phpcs:disable PHPCompatibility.Variables.RemovedPredefinedGlobalVariables.http_raw_post_dataDeprecatedRemoved
		global $HTTP_RAW_POST_DATA;

		// $HTTP_RAW_POST_DATA was deprecated in PHP 5.6 and removed in PHP 7.0.
		if ( ! isset( $HTTP_RAW_POST_DATA ) ) {
			$HTTP_RAW_POST_DATA = file_get_contents( 'php://input' );
		}

		return $HTTP_RAW_POST_DATA;
		// phpcs:enable
	}

	/**
	 * Extracts headers from a PHP-style $_SERVER array.
	 *
	 * @since 4.4.0
	 *
	 * @param array $server Associative array similar to `$_SERVER`.
	 * @return array Headers extracted from the input.
	 */
	public function get_headers( $server ) {
		$headers = array();

		// CONTENT_* headers are not prefixed with HTTP_.
		$additional = array(
			'CONTENT_LENGTH' => true,
			'CONTENT_MD5'    => true,
			'CONTENT_TYPE'   => true,
		);

		foreach ( $server as $key => $value ) {
			if ( str_starts_with( $key, 'HTTP_' ) ) {
				$headers[ substr( $key, 5 ) ] = $value;
			} elseif ( 'REDIRECT_HTTP_AUTHORIZATION' === $key && empty( $server['HTTP_AUTHORIZATION'] ) ) {
				/*
				 * In some server configurations, the authorization header is passed in this alternate location.
				 * Since it would not be passed in in both places we do not check for both headers and resolve.
				 */
				$headers['AUTHORIZATION'] = $value;
			} elseif ( isset( $additional[ $key ] ) ) {
				$headers[ $key ] = $value;
			}
		}

		return $headers;
	}
}
 into item, and cut out non-keys for meta
		$columns = $this->get_column_names();
		$data    = array_merge( $item, $data );
		$meta    = array_diff_key( $data, $columns );
		$save    = array_intersect_key( $data, $columns );

		// Maybe save meta keys
		if ( ! empty( $meta ) ) {
			$this->save_extra_item_meta( $item_id, $meta );
		}

		// Bail if no change
		if ( (array) $save === (array) $item ) {
			return true;
		}

		// Unset the primary key from data to save
		unset( $save[ $primary ] );

		// If date-modified is empty, use the current time
		$modified = $this->get_column_by( array( 'modified' => true ) );
		if ( ! empty( $modified ) ) {
			$save[ $modified->name ] = $this->get_current_time();
		}

		// Try to update
		$table  = $this->get_table_name();
		$reduce = $this->reduce_item( 'update', $save );
		$save   = $this->validate_item( $reduce );
		$where  = array( $primary => $item_id );
		$result = ! empty( $save )
			? $this->get_db()->update( $table, $save, $where )
			: false;

		// Bail on failure
		if ( ! $this->is_success( $result ) ) {
			return false;
		}

		// Use get item to prime caches
		$this->update_item_cache( $item_id );

		// Transition item data
		$this->transition_item( $save, $item );

		// Return result
		return $result;
	}

	/**
	 * Delete an item from the database.
	 *
	 * @since 1.0.0
	 *
	 * @param int $item_id
	 * @return bool
	 */
	public function delete_item( $item_id = 0 ) {

		// Bail if no item ID
		$item_id = $this->shape_item_id( $item_id );
		if ( empty( $item_id ) ) {
			return false;
		}

		// Get the primary column name
		$primary = $this->get_primary_column_name();

		// Get item (before it's deleted)
		$item = $this->get_item_raw( $primary, $item_id );

		// Bail if item does not exist to delete
		if ( empty( $item ) ) {
			return false;
		}

		// Attempt to reduce this item
		$item = $this->reduce_item( 'delete', $item );

		// Bail if item was reduced to nothing
		if ( empty( $item ) ) {
			return false;
		}

		// Try to delete
		$table  = $this->get_table_name();
		$where  = array( $primary => $item_id );
		$result = $this->get_db()->delete( $table, $where );

		// Bail on failure
		if ( ! $this->is_success( $result ) ) {
			return false;
		}

		// Clean caches on successful delete
		$this->delete_all_item_meta( $item_id );
		$this->clean_item_cache( $item );

		// Return result
		return $result;
	}

	/**
	 * Filter an item before it is inserted of updated in the database.
	 *
	 * This method is public to allow subclasses to perform JIT manipulation
	 * of the parameters passed into it.
	 *
	 * @since 1.0.0
	 *
	 * @param array $item
	 * @return array
	 */
	public function filter_item( $item = array() ) {
		return (array) apply_filters_ref_array( $this->apply_prefix( "filter_{$this->item_name}_item" ), array( $item, &$this ) );
	}

	/**
	 * Shape an item from the database into the type of object it always wanted
	 * to be when it grew up.
	 *
	 * @since 1.0.0
	 *
	 * @param mixed ID of item, or row from database
	 * @return mixed False on error, Object of single-object class type on success
	 */
	private function shape_item( $item = 0 ) {

		// Get the item from an ID
		if ( is_numeric( $item ) ) {
			$item = $this->get_item( $item );
		}

		// Return the item if it's already shaped
		if ( $item instanceof $this->item_shape ) {
			return $item;
		}

		// Shape the item as needed
		$item = ! empty( $this->item_shape )
			? new $this->item_shape( $item )
			: (object) $item;

		// Return the item object
		return $item;
	}

	/**
	 * Validate an item before it is updated in or added to the database.
	 *
	 * @since 1.0.0
	 *
	 * @param array $item
	 * @return array|false False on error, Array of validated values on success
	 */
	private function validate_item( $item = array() ) {

		// Bail if item is empty or not an array
		if ( empty( $item ) || ! is_array( $item ) ) {
			return $item;
		}

		// Loop through item attributes
		foreach ( $item as $key => $value ) {

			// Strip slashes from all strings
			/*if ( is_string( $value ) ) {
				$value = stripslashes( $value );// We removed this line at PR #3847 to solve if the content has backslash.
			}*/

			// Get the column
			$column = $this->get_column_by( array( 'name' => $key ) );

			// Null value is special for all item keys
			if ( is_null( $value ) ) {

				// Bail if null is not allowed
				if ( false === $column->allow_null ) {
					return false;
				}

			// Attempt to validate
			} elseif ( ! empty( $column->validate ) && is_callable( $column->validate ) ) {
				$validated = call_user_func( $column->validate, $value );

				// Bail if error
				if ( is_wp_error( $validated ) ) {
					return false;
				}

				// Update the value
				$item[ $key ] = $validated;

			/**
			 * Fallback to using the raw value.
			 *
			 * Note: This may change at a later date, so do not rely on this.
			 *       Please always validate all data.
			 */
			} else {
				$item[ $key ] = $value;
			}
		}

		// Return the validated item
		return $this->filter_item( $item );
	}

	/**
	 * Reduce an item down to the keys and values the current user has the
	 * appropriate capabilities to select|insert|update|delete.
	 *
	 * Note that internally, this method works with both arrays and objects of
	 * any type, and also resets the key values. It looks weird, but is
	 * currently by design to protect the integrity of the return value.
	 *
	 * @since 1.0.0
	 *
	 * @param string $method select|insert|update|delete
	 * @param mixed  $item   Object|Array of keys/values to reduce
	 *
	 * @return mixed Object|Array without keys the current user does not have caps for
	 */
	private function reduce_item( $method = 'update', $item = array() ) {

		// Bail if item is empty
		if ( empty( $item ) ) {
			return $item;
		}

		// Loop through item attributes
		foreach ( $item as $key => $value ) {

			// Get capabilities for this column
			$caps = $this->get_column_field( array( 'name' => $key ), 'caps' );

			// Unset if not explicitly allowed
			if ( empty( $caps[ $method ] ) || ! current_user_can( $caps[ $method ] ) ) {
				if ( is_array( $item ) ) {
					unset( $item[ $key ] );
				} elseif ( is_object( $item ) ) {
					$item->{$key} = null;
				}

			// Set if explicitly allowed
			} elseif ( is_array( $item ) ) {
				$item[ $key ] = $value;
			} elseif ( is_object( $item ) ) {
				$item->{$key} = $value;
			}
		}

		// Return the reduced item
		return $item;
	}

	/**
	 * Return an item comprised of all default values.
	 *
	 * This is used by `add_item()` to populate known default values, to ensure
	 * new item data is always what we expect it to be.
	 *
	 * @since 1.0.0
	 *
	 * @return array
	 */
	private function default_item() {

		// Default return value
		$retval   = array();

		// Get the column names and their defaults
		$names    = $this->get_columns( array(), 'and', 'name'    );
		$defaults = $this->get_columns( array(), 'and', 'default' );

		// Put together an item using default values
		foreach ( $names as $key => $name ) {
			$retval[ $name ] = $defaults[ $key ];
		}

		// Return
		return $retval;
	}

	/**
	 * Transition an item when adding or updating.
	 *
	 * This method takes the data being saved, looks for any columns that are
	 * known to transition between values, and fires actions on them.
	 *
	 * @since 1.0.0
	 *
	 * @param array $item
	 * @return array
	 */
	private function transition_item( $new_data = array(), $old_data = array() ) {

		// Look for transition columns
		$columns = $this->get_columns( array( 'transition' => true ), 'and', 'name' );

		// Bail if no columns to transition
		if ( empty( $columns ) ) {
			return;
		}

		// Get the item ID
		$item_id = $this->shape_item_id( $old_data );

		// Bail if item ID cannot be retrieved
		if ( empty( $item_id ) ) {
			return;
		}

		// If no old value(s), it's new
		if ( ! is_array( $old_data ) ) {
			$old_data = $new_data;

			// Set all old values to "new"
			foreach ( $old_data as $key => $value ) {
				$value            = 'new';
				$old_data[ $key ] = $value;
			}
		}

		// Compare
		$keys = array_flip( $columns );
		$new  = array_intersect_key( $new_data, $keys );
		$old  = array_intersect_key( $old_data, $keys );

		// Get the difference
		$diff = array_diff( $new, $old );

		// Bail if nothing is changing
		if ( empty( $diff ) ) {
			return;
		}

		// Do the actions
		foreach ( $diff as $key => $value ) {
			$old_value  = $old_data[ $key ];
			$new_value  = $new_data[ $key ];
			$key_action = $this->apply_prefix( "transition_{$this->item_name}_{$key}" );

			/**
			 * Fires after an object value has transitioned.
			 *
			 * @since 1.0.0
			 *
			 * @param mixed $old_value The value being transitioned FROM.
			 * @param mixed $new_value The value being transitioned TO.
			 * @param int   $item_id   The ID of the item that is transitioning.
			 */
			do_action( $key_action, $old_value, $new_value, $item_id );
		}
	}

	/** Meta ******************************************************************/

	/**
	 * Add meta data to an item.
	 *
	 * @since 1.0.0
	 *
	 * @param int    $item_id
	 * @param string $meta_key
	 * @param string $meta_value
	 * @param string $unique
	 * @return int|false The meta ID on success, false on failure.
	 */
	protected function add_item_meta( $item_id = 0, $meta_key = '', $meta_value = '', $unique = false ) {

		// Bail if no meta was returned
		$item_id = $this->shape_item_id( $item_id );
		if ( empty( $item_id ) || empty( $meta_key ) ) {
			return false;
		}

		// Bail if no meta table exists
		if ( false === $this->get_meta_table_name() ) {
			return false;
		}

		// Get the meta type
		$meta_type = $this->get_meta_type();

		// Return results of adding meta data
		return add_metadata( $meta_type, $item_id, $meta_key, $meta_value, $unique );
	}

	/**
	 * Get meta data for an item.
	 *
	 * @since 1.0.0
	 *
	 * @param int     $item_id
	 * @param string  $meta_key
	 * @param bool    $single
	 * @return mixed Single metadata value, or array of values
	 */
	protected function get_item_meta( $item_id = 0, $meta_key = '', $single = false ) {

		// Bail if no meta was returned
		$item_id = $this->shape_item_id( $item_id );
		if ( empty( $item_id ) || empty( $meta_key ) ) {
			return false;
		}

		// Bail if no meta table exists
		if ( false === $this->get_meta_table_name() ) {
			return false;
		}

		// Get the meta type
		$meta_type = $this->get_meta_type();

		// Return results of getting meta data
		return get_metadata( $meta_type, $item_id, $meta_key, $single );
	}

	/**
	 * Update meta data for an item.
	 *
	 * @since 1.0.0
	 *
	 * @param int    $item_id
	 * @param string $meta_key
	 * @param string $meta_value
	 * @param string $prev_value
	 * @return bool True on successful update, false on failure.
	 */
	protected function update_item_meta( $item_id = 0, $meta_key = '', $meta_value = '', $prev_value = '' ) {

		// Bail if no meta was returned
		$item_id = $this->shape_item_id( $item_id );
		if ( empty( $item_id ) || empty( $meta_key ) ) {
			return false;
		}

		// Bail if no meta table exists
		if ( false === $this->get_meta_table_name() ) {
			return false;
		}

		// Get the meta type
		$meta_type = $this->get_meta_type();

		// Return results of updating meta data
		return update_metadata( $meta_type, $item_id, $meta_key, $meta_value, $prev_value );
	}

	/**
	 * Delete meta data for an item.
	 *
	 * @since 1.0.0
	 *
	 * @param int    $item_id
	 * @param string $meta_key
	 * @param string $meta_value
	 * @param string $delete_all
	 * @return bool True on successful delete, false on failure.
	 */
	protected function delete_item_meta( $item_id = 0, $meta_key = '', $meta_value = '', $delete_all = false ) {

		// Bail if no meta was returned
		$item_id = $this->shape_item_id( $item_id );
		if ( empty( $item_id ) || empty( $meta_key ) ) {
			return false;
		}

		// Bail if no meta table exists
		if ( false === $this->get_meta_table_name() ) {
			return false;
		}

		// Get the meta type
		$meta_type = $this->get_meta_type();

		// Return results of deleting meta data
		return delete_metadata( $meta_type, $item_id, $meta_key, $meta_value, $delete_all );
	}

	/**
	 * Get registered meta data keys.
	 *
	 * @since 1.0.0
	 *
	 * @param string $object_subtype The sub-type of meta keys
	 *
	 * @return array
	 */
	private function get_registered_meta_keys( $object_subtype = '' ) {

		// Get the object type
		$object_type = $this->get_meta_type();

		// Return the keys
		return get_registered_meta_keys( $object_type, $object_subtype );
	}

	/**
	 * Maybe update meta values on item update/save.
	 *
	 * @since 1.0.0
	 *
	 * @param array $meta
	 */
	private function save_extra_item_meta( $item_id = 0, $meta = array() ) {

		// Bail if there is no bulk meta to save
		$item_id = $this->shape_item_id( $item_id );
		if ( empty( $item_id ) || empty( $meta ) ) {
			return;
		}

		// Bail if no meta table exists
		if ( false === $this->get_meta_table_name() ) {
			return;
		}

		// Only save registered keys
		$keys = $this->get_registered_meta_keys();
		$meta = array_intersect_key( $meta, $keys );

		// Bail if no registered meta keys
		if ( empty( $meta ) ) {
			return;
		}

		// Save or delete meta data
		foreach ( $meta as $key => $value ) {
			! empty( $value )
				? $this->update_item_meta( $item_id, $key, $value )
				: $this->delete_item_meta( $item_id, $key );
		}
	}

	/**
	 * Delete all meta data for an item.
	 *
	 * @since 1.0.0
	 *
	 * @param int $item_id
	 */
	private function delete_all_item_meta( $item_id = 0 ) {

		// Bail if no meta was returned
		$item_id = $this->shape_item_id( $item_id );
		if ( empty( $item_id ) ) {
			return;
		}

		// Get the meta table name
		$table = $this->get_meta_table_name();

		// Bail if no meta table exists
		if ( empty( $table ) ) {
			return;
		}

		// Guess the item ID column for the meta table
		$primary_id     = $this->get_primary_column_name();
		$item_id_column = $this->apply_prefix( "{$this->item_name}_{$primary_id}" );

		// Get meta IDs
		$query    = "SELECT meta_id FROM {$table} WHERE {$item_id_column} = %d";
		$prepared = $this->get_db()->prepare( $query, $item_id );
		$meta_ids = $this->get_db()->get_col( $prepared );

		// Bail if no meta IDs to delete
		if ( empty( $meta_ids ) ) {
			return;
		}

		// Get the meta type
		$meta_type = $this->get_meta_type();

		// Delete all meta data for this item ID
		foreach ( $meta_ids as $mid ) {
			delete_metadata_by_mid( $meta_type, $mid );
		}
	}

	/**
	 * Get the meta table for this query.
	 *
	 * Forked from WordPress\_get_meta_table() so it can be more accurately
	 * predicted in a future iteration and default to returning false.
	 *
	 * @since 1.0.0
	 *
	 * @return mixed Table name if exists, False if not
	 */
	private function get_meta_table_name() {

		// Get the meta-type
		$type       = $this->get_meta_type();

		// Append "meta" to end of meta-type
		$table_name = "{$type}meta";

		// Variable'ize the database interface, to use inside empty()
		$db         = $this->get_db();

		// If not empty, return table name
		if ( ! empty( $db->{$table_name} ) ) {
			return $table_name;
		}

		// Default return false
		return false;
	}

	/**
	 * Get the meta type for this query.
	 *
	 * This method exists to reduce some duplication for now. Future iterations
	 * will likely use Column::relationships to
	 *
	 * @since 1.1.0
	 *
	 * @return string
	 */
	private function get_meta_type() {
		return $this->apply_prefix( $this->item_name );
	}

	/** Cache *****************************************************************/

	/**
	 * Get cache key from query_vars and query_var_defaults.
	 *
	 * @since 1.0.0
	 *
	 * @return string
	 */
	private function get_cache_key( $group = '' ) {

		// Slice query vars
		$slice = wp_array_slice_assoc( $this->query_vars, array_keys( $this->query_var_defaults ) );

		// Unset `fields` so it does not effect the cache key
		unset( $slice['fields'] );

		// Setup key & last_changed
		$key          = md5( serialize( $slice ) );
		$last_changed = $this->get_last_changed_cache( $group );

		// Concatenate and return cache key
		return "get_{$this->item_name_plural}:{$key}:{$last_changed}";
	}

	/**
	 * Get the cache group, or fallback to the primary one.
	 *
	 * @since 1.0.0
	 *
	 * @param string $group
	 * @return string
	 */
	private function get_cache_group( $group = '' ) {

		// Get the primary column
		$primary = $this->get_primary_column_name();

		// Default return value
		$retval  = $this->cache_group;

		// Only allow non-primary groups
		if ( ! empty( $group ) && ( $group !== $primary ) ) {
			$retval = $group;
		}

		// Return the group
		return $retval;
	}

	/**
	 * Get array of which database columns have uniquely cached groups.
	 *
	 * @since 1.0.0
	 *
	 * @return array
	 */
	private function get_cache_groups() {

		// Return value
		$cache_groups = array();

		// Get the cache groups
		$groups = $this->get_columns( array( 'cache_key' => true ), 'and', 'name' );

		if ( ! empty( $groups ) ) {

			// Get the primary column name
			$primary = $this->get_primary_column_name();

			// Setup return values
			foreach ( $groups as $name ) {
				if ( $primary !== $name ) {
					$cache_groups[ $name ] = "{$this->cache_group}-by-{$name}";
				} else {
					$cache_groups[ $name ] = $this->cache_group;
				}
			}
		}

		// Return cache groups array
		return $cache_groups;
	}

	/**
	 * Maybe prime item & item-meta caches by querying 1 time for all un-cached
	 * items.
	 *
	 * Accepts a single ID, or an array of IDs.
	 *
	 * The reason this accepts only IDs is because it gets called immediately
	 * after an item is inserted in the database, but before items have been
	 * "shaped" into proper objects, so object properties may not be set yet.
	 *
	 * @since 1.0.0
	 *
	 * @param array $item_ids
	 * @param bool  $force
	 *
	 * @return bool False if empty
	 */
	private function prime_item_caches( $item_ids = array(), $force = false ) {

		// Bail if no items to cache
		if ( empty( $item_ids ) ) {
			return false;
		}

		// Accepts single values, so cast to array
		$item_ids = (array) $item_ids;

		// Update item caches
		if ( ! empty( $force ) || ! empty( $this->query_vars['update_item_cache'] ) ) {

			// Look for non-cached IDs
			$ids = $this->get_non_cached_ids( $item_ids, $this->cache_group );

			// Bail if IDs are cached
			if ( empty( $ids ) ) {
				return false;
			}

			// Get query parts
			$table   = $this->get_table_name();
			$primary = $this->get_primary_column_name();

			// Query database
			$query   = "SELECT * FROM {$table} WHERE {$primary} IN (%s)";
			$ids     = implode( ',', array_map( 'absint', $ids ) );
			$prepare = sprintf( $query, $ids );
			$results = $this->get_db()->get_results( $prepare );

			// Update item caches
			$this->update_item_cache( $results );
		}

		// Update meta data caches
		if ( ! empty( $this->query_vars['update_meta_cache'] ) ) {
			$singular = rtrim( $this->table_name, 's' ); // sic
			update_meta_cache( $singular, $item_ids );
		}
	}

	/**
	 * Update the cache for an item. Does not update item-meta cache.
	 *
	 * Accepts a single object, or an array of objects.
	 *
	 * The reason this does not accept ID's is because this gets called
	 * after an item is already updated in the database, so we want to avoid
	 * querying for it again. It's just safer this way.
	 *
	 * @since 1.0.0
	 *
	 * @param array $items
	 */
	private function update_item_cache( $items = array() ) {

		// Maybe query for single item
		if ( is_numeric( $items ) ) {
			$primary = $this->get_primary_column_name();
			$items   = $this->get_item_raw( $primary, $items );
		}

		// Bail if no items to cache
		if ( empty( $items ) ) {
			return false;
		}

		// Make sure items are an array (without casting objects to arrays)
		if ( ! is_array( $items ) ) {
			$items = array( $items );
		}

		// Get the cache groups
		$groups = $this->get_cache_groups();

		// Loop through all items and cache them
		foreach ( $items as $item ) {

			// Skip if item is not an object
			if ( ! is_object( $item ) ) {
				continue;
			}

			// Loop through groups and set cache
			if ( ! empty( $groups ) ) {
				foreach ( $groups as $key => $group ) {
					$this->cache_set( $item->{$key}, $item, $group );
				}
			}
		}

		// Update last changed
		$this->update_last_changed_cache();
	}

	/**
	 * Clean the cache for an item. Does not clean item-meta.
	 *
	 * Accepts a single object, or an array of objects.
	 *
	 * The reason this does not accept ID's is because this gets called
	 * after an item is already deleted from the database, so it cannot be
	 * queried and may not exist in the cache. It's just safer this way.
	 *
	 * @since 1.0.0
	 *
	 * @param mixed $items Single object item, or Array of object items
	 *
	 * @return bool
	 */
	private function clean_item_cache( $items = array() ) {

		// Bail if no items to clean
		if ( empty( $items ) ) {
			return false;
		}

		// Make sure items are an array
		if ( ! is_array( $items ) ) {
			$items = array( $items );
		}

		// Get the cache groups
		$groups = $this->get_cache_groups();

		// Loop through all items and clean them
		foreach ( $items as $item ) {

			// Skip if item is not an object
			if ( ! is_object( $item ) ) {
				continue;
			}

			// Loop through groups and delete cache
			if ( ! empty( $groups ) ) {
				foreach ( $groups as $key => $group ) {
					$this->cache_delete( $item->{$key}, $group );
				}
			}
		}

		// Update last changed
		$this->update_last_changed_cache();
	}

	/**
	 * Update the last_changed key for the cache group.
	 *
	 * @since 1.0.0
	 *
	 * @return string The last time a cache group was changed.
	 */
	private function update_last_changed_cache( $group = '' ) {

		// Fallback to microtime
		if ( empty( $this->last_changed ) ) {
			$this->set_last_changed();
		}

		// Set the last changed time for this cache group
		$this->cache_set( 'last_changed', $this->last_changed, $group );

		// Return the last changed time
		return $this->last_changed;
	}

	/**
	 * Get the last_changed key for a cache group.
	 *
	 * @since 1.0.0
	 *
	 * @param string $group Cache group. Defaults to $this->cache_group
	 *
	 * @return string The last time a cache group was changed.
	 */
	private function get_last_changed_cache( $group = '' ) {

		// Get the last changed cache value
		$last_changed = $this->cache_get( 'last_changed', $group );

		// Maybe update the last changed value
		if ( false === $last_changed ) {
			$last_changed = $this->update_last_changed_cache( $group );
		}

		// Return the last changed value for the cache group
		return $last_changed;
	}

	/**
	 * Get array of non-cached item IDs.
	 *
	 * @since 1.0.0
	 *
	 * @param array  $item_ids Array of item IDs
	 * @param string $group    Cache group. Defaults to $this->cache_group
	 *
	 * @return array
	 */
	private function get_non_cached_ids( $item_ids = array(), $group = '' ) {
		$retval = array();

		// Bail if no item IDs
		if ( empty( $item_ids ) ) {
			return $retval;
		}

		// Loop through item IDs
		foreach ( $item_ids as $id ) {
			$id = $this->shape_item_id( $id );

			if ( false === $this->cache_get( $id, $group ) ) {
				$retval[] = $id;
			}
		}

		// Return array of IDs
		return $retval;
	}

	/**
	 * Add a cache value for a key and group.
	 *
	 * @since 1.0.0
	 *
	 * @param string $key    Cache key.
	 * @param mixed  $value  Cache value.
	 * @param string $group  Cache group. Defaults to $this->cache_group
	 * @param int    $expire Expiration.
	 */
	private function cache_add( $key = '', $value = '', $group = '', $expire = 0 ) {

		// Bail if cache invalidation is suspended
		if ( wp_suspend_cache_addition() ) {
			return;
		}

		// Bail if no cache key
		if ( empty( $key ) ) {
			return;
		}

		// Get the cache group
		$group = $this->get_cache_group( $group );

		// Add to the cache
		wp_cache_add( $key, $value, $group, $expire );
	}

	/**
	 * Get a cache value for a key and group.
	 *
	 * @since 1.0.0
	 *
	 * @param string  $key   Cache key.
	 * @param string  $group Cache group. Defaults to $this->cache_group
	 * @param bool    $force
	 */
	private function cache_get( $key = '', $group = '', $force = false ) {

		// Bail if no cache key
		if ( empty( $key ) ) {
			return;
		}

		// Get the cache group
		$group = $this->get_cache_group( $group );

		// Return from the cache
		return wp_cache_get( $key, $group, $force );
	}

	/**
	 * Set a cache value for a key and group.
	 *
	 * @since 1.0.0
	 *
	 * @param string $key    Cache key.
	 * @param mixed  $value  Cache value.
	 * @param string $group  Cache group. Defaults to $this->cache_group
	 * @param int    $expire Expiration.
	 */
	private function cache_set( $key = '', $value = '', $group = '', $expire = 0 ) {

		// Bail if cache invalidation is suspended
		if ( wp_suspend_cache_addition() ) {
			return;
		}

		// Bail if no cache key
		if ( empty( $key ) ) {
			return;
		}

		// Get the cache group
		$group = $this->get_cache_group( $group );

		// Update the cache
		wp_cache_set( $key, $value, $group, $expire );
	}

	/**
	 * Delete a cache key for a group.
	 *
	 * @since 1.0.0
	 *
	 * @global bool $_wp_suspend_cache_invalidation
	 *
	 * @param string $key   Cache key.
	 * @param string $group Cache group. Defaults to $this->cache_group
	 */
	private function cache_delete( $key = '', $group = '' ) {
		global $_wp_suspend_cache_invalidation;

		// Bail if cache invalidation is suspended
		if ( ! empty( $_wp_suspend_cache_invalidation ) ) {
			return;
		}

		// Bail if no cache key
		if ( empty( $key ) ) {
			return;
		}

		// Get the cache group
		$group = $this->get_cache_group( $group );

		// Delete the cache
		wp_cache_delete( $key, $group );
	}

	/**
	 * Fetch raw results directly from the database.
	 *
	 * @since 1.0.0
	 *
	 * @param array  $cols       Columns for `SELECT`.
	 * @param array  $where_cols Where clauses. Each key-value pair in the array
	 *                           represents a column and a comparison.
	 * @param int    $limit      Optional. LIMIT value. Default 25.
	 * @param null   $offset     Optional. OFFSET value. Default null.
	 * @param string $output     Optional. Any of ARRAY_A | ARRAY_N | OBJECT | OBJECT_K constants.
	 *                           Default OBJECT.
	 *                           With one of the first three, return an array of
	 *                           rows indexed from 0 by SQL result row number.
	 *                           Each row is an associative array (column => value, ...),
	 *                           a numerically indexed array (0 => value, ...),
	 *                           or an object. ( ->column = value ), respectively.
	 *                           With OBJECT_K, return an associative array of
	 *                           row objects keyed by the value of each row's
	 *                           first column's value.
	 *
	 * @return array|object|null Database query results.
	 */
	public function get_results( $cols = array(), $where_cols = array(), $limit = 25, $offset = null, $output = OBJECT ) {

		// Bail if no columns have been passed
		if ( empty( $cols ) ) {
			return null;
		}

		// Fetch all the columns for the table being queried
		$column_names = $this->get_column_names();

		// Ensure valid column names have been passed for the `SELECT` clause
		foreach ( $cols as $index => $column ) {
			if ( ! array_key_exists( $column, $column_names ) ) {
				unset( $cols[ $index ] );
			}
		}

		// Columns to retrieve
		$columns = implode( ',', $cols );

		// Get the table name
		$table = $this->get_table_name();

		// Setup base query
		$query = implode( ' ', array(
			"SELECT",
			$columns,
			"FROM {$table} {$this->table_alias}",
			"WHERE 1=1"
		) );

		// Ensure valid columns have been passed for the `WHERE` clause
		if ( ! empty( $where_cols ) ) {

			// Get keys from where columns
			$columns = array_keys( $where_cols );

			// Loop through columns and unset any invalid names
			foreach ( $columns as $index => $column ) {
				if ( ! array_key_exists( $column, $column_names ) ) {
					unset( $where_cols[ $index ] );
				}
			}

			// Parse WHERE clauses
			foreach ( $where_cols as $column => $compare ) {

				// Basic WHERE clause
				if ( ! is_array( $compare ) ) {
					$pattern   = $this->get_column_field( array( 'name' => $column ), 'pattern', '%s' );
					$statement = " AND {$this->table_alias}.{$column} = {$pattern} ";
					$query    .= $this->get_db()->prepare( $statement, $compare );

				// More complex WHERE clause
				} else {
					$value = isset( $compare['value'] )
						? $compare['value']
						: false;

					// Skip if a value was not provided
					if ( false === $value ) {
						continue;
					}

					// Default compare clause to equals
					$compare_clause = isset( $compare['compare_query'] )
						? trim( strtoupper( $compare['compare_query'] ) )
						: '=';

					// Array (unprepared)
					if ( is_array( $compare['value'] ) ) {

						// Default to IN if clause not specified
						if ( ! in_array( $compare_clause, array( 'IN', 'NOT IN', 'BETWEEN' ), true ) ) {
							$compare_clause = 'IN';
						}

						// Parse & escape for IN and NOT IN
						if ( 'IN' === $compare_clause || 'NOT IN' === $compare_clause ) {
							$value = "('" . implode( "','", $this->get_db()->_escape( $compare['value'] ) ) . "')";

						// Parse & escape for BETWEEN
						} elseif ( is_array( $value ) && 2 === count( $value ) && 'BETWEEN' === $compare_clause ) {
							$_this = $this->get_db()->_escape( $value[0] );
							$_that = $this->get_db()->_escape( $value[1] );
							$value = " {$_this} AND {$_that} ";
						}
					}

					// Add WHERE clause
					$query .= " AND {$this->table_alias}.{$column} {$compare_clause} {$value} ";
				}
			}
		}

		// Maybe set an offset
		if ( ! empty( $offset ) ) {
			$values = explode( ',', $offset );
			$values = array_filter( $values, 'intval' );
			$offset = implode( ',', $values );
			$query .= " OFFSET {$offset} ";
		}

		// Maybe set a limit
		if ( ! empty( $limit ) && ( $limit > 0 ) ) {
			$limit  = intval( $limit );
			$query .= " LIMIT {$limit} ";
		}

		// Execute query
		$results = $this->get_db()->get_results( $query, $output );

		// Return results
		return $results;
	}
}