* @since  3.0.0
	 * @param  WP_REST_Request $request Request data.
	 * @return WP_Error|WP_REST_Response
	 */
	public function update_item( $request ) {
		$setting = $this->get_setting( $request['group_id'], $request['id'] );

		if ( is_wp_error( $setting ) ) {
			return $setting;
		}

		if ( is_callable( array( $this, 'validate_setting_' . $setting['type'] . '_field' ) ) ) {
			$value = $this->{'validate_setting_' . $setting['type'] . '_field'}( $request['value'], $setting );
		} else {
			$value = $this->validate_setting_text_field( $request['value'], $setting );
		}

		if ( is_wp_error( $value ) ) {
			return $value;
		}

		if ( is_array( $setting['option_key'] ) ) {
			$setting['value']       = $value;
			$option_key             = $setting['option_key'];
			$prev                   = get_option( $option_key[0], null ) ?? array();
			$prev[ $option_key[1] ] = $request['value'];
			update_option( $option_key[0], $prev );
		} else {
			$update_data                           = array();
			$update_data[ $setting['option_key'] ] = $value;
			$setting['value']                      = $value;
			WC_Admin_Settings::save_fields( array( $setting ), $update_data );
		}

		$response = $this->prepare_item_for_response( $setting, $request );

		return rest_ensure_response( $response );
	}

	/**
	 * Prepare a single setting object for response.
	 *
	 * @since  3.0.0
	 * @param object          $item Setting object.
	 * @param WP_REST_Request $request Request object.
	 * @return WP_REST_Response $response Response data.
	 */
	public function prepare_item_for_response( $item, $request ) {
		unset( $item['option_key'] );
		$data     = $this->filter_setting( $item );
		$data     = $this->add_additional_fields_to_object( $data, $request );
		$data     = $this->filter_response_by_context( $data, empty( $request['context'] ) ? 'view' : $request['context'] );
		$response = rest_ensure_response( $data );
		$response->add_links( $this->prepare_links( $data['id'], $request['group_id'] ) );
		return $response;
	}

	/**
	 * Prepare links for the request.
	 *
	 * @since  3.0.0
	 * @param string $setting_id Setting ID.
	 * @param string $group_id Group ID.
	 * @return array Links for the given setting.
	 */
	protected function prepare_links( $setting_id, $group_id ) {
		$base  = str_replace( '(?P<group_id>[\w-]+)', $group_id, $this->rest_base );
		$links = array(
			'self'       => array(
				'href' => rest_url( sprintf( '/%s/%s/%s', $this->namespace, $base, $setting_id ) ),
			),
			'collection' => array(
				'href' => rest_url( sprintf( '/%s/%s', $this->namespace, $base ) ),
			),
		);

		return $links;
	}

	/**
	 * Makes sure the current user has access to READ the settings APIs.
	 *
	 * @since  3.0.0
	 * @param WP_REST_Request $request Full data about the request.
	 * @return WP_Error|boolean
	 */
	public function get_items_permissions_check( $request ) {
		if ( ! wc_rest_check_manager_permissions( 'settings', 'read' ) ) {
			return new WP_Error( 'woocommerce_rest_cannot_view', __( 'Sorry, you cannot list resources.', 'woocommerce' ), array( 'status' => rest_authorization_required_code() ) );
		}

		return true;
	}

	/**
	 * Makes sure the current user has access to WRITE the settings APIs.
	 *
	 * @since  3.0.0
	 * @param WP_REST_Request $request Full data about the request.
	 * @return WP_Error|boolean
	 */
	public function update_items_permissions_check( $request ) {
		if ( ! wc_rest_check_manager_permissions( 'settings', 'edit' ) ) {
			return new WP_Error( 'woocommerce_rest_cannot_edit', __( 'Sorry, you cannot edit this resource.', 'woocommerce' ), array( 'status' => rest_authorization_required_code() ) );
		}

		return true;
	}

	/**
	 * Filters out bad values from the settings array/filter so we
	 * only return known values via the API.
	 *
	 * @since 3.0.0
	 * @param  array $setting Settings.
	 * @return array
	 */
	public function filter_setting( $setting ) {
		$setting = array_intersect_key(
			$setting,
			array_flip( array_filter( array_keys( $setting ), array( $this, 'allowed_setting_keys' ) ) )
		);

		if ( empty( $setting['options'] ) ) {
			unset( $setting['options'] );
		}

		if ( 'image_width' === $setting['type'] ) {
			$setting = $this->cast_image_width( $setting );
		}

		return $setting;
	}

	/**
	 * For image_width, Crop can return "0" instead of false -- so we want
	 * to make sure we return these consistently the same we accept them.
	 *
	 * @todo remove in 4.0
	 * @since 3.0.0
	 * @param  array $setting Settings.
	 * @return array
	 */
	public function cast_image_width( $setting ) {
		foreach ( array( 'default', 'value' ) as $key ) {
			if ( isset( $setting[ $key ] ) ) {
				$setting[ $key ]['width']  = intval( $setting[ $key ]['width'] );
				$setting[ $key ]['height'] = intval( $setting[ $key ]['height'] );
				$setting[ $key ]['crop']   = (bool) $setting[ $key ]['crop'];
			}
		}
		return $setting;
	}

	/**
	 * Callback for allowed keys for each setting response.
	 *
	 * @since  3.0.0
	 * @param  string $key Key to check.
	 * @return boolean
	 */
	public function allowed_setting_keys( $key ) {
		return in_array(
			$key,
			array(
				'id',
				'label',
				'description',
				'default',
				'tip',
				'placeholder',
				'type',
				'options',
				'value',
				'option_key',
			),
			true
		);
	}

	/**
	 * Boolean for if a setting type is a valid supported setting type.
	 *
	 * @since  3.0.0
	 * @param  string $type Type.
	 * @return bool
	 */
	public function is_setting_type_valid( $type ) {
		return in_array(
			$type,
			array(
				'text',         // Validates with validate_setting_text_field.
				'email',        // Validates with validate_setting_text_field.
				'number',       // Validates with validate_setting_text_field.
				'color',        // Validates with validate_setting_text_field.
				'password',     // Validates with validate_setting_text_field.
				'textarea',     // Validates with validate_setting_textarea_field.
				'select',       // Validates with validate_setting_select_field.
				'multiselect',  // Validates with validate_setting_multiselect_field.
				'radio',        // Validates with validate_setting_radio_field (-> validate_setting_select_field).
				'checkbox',     // Validates with validate_setting_checkbox_field.
				'image_width',  // Validates with validate_setting_image_width_field.
				'thumbnail_cropping', // Validates with validate_setting_text_field.
			),
			true
		);
	}

	/**
	 * Get the settings schema, conforming to JSON Schema.
	 *
	 * @since 3.0.0
	 * @return array
	 */
	public function get_item_schema() {
		$schema = array(
			'$schema'    => 'http://json-schema.org/draft-04/schema#',
			'title'      => 'setting',
			'type'       => 'object',
			'properties' => array(
				'id'          => array(
					'description' => __( 'A unique identifier for the setting.', 'woocommerce' ),
					'type'        => 'string',
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_title',
					),
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'label'       => array(
					'description' => __( 'A human readable label for the setting used in interfaces.', 'woocommerce' ),
					'type'        => 'string',
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_text_field',
					),
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'description' => array(
					'description' => __( 'A human readable description for the setting used in interfaces.', 'woocommerce' ),
					'type'        => 'string',
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_text_field',
					),
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'value'       => array(
					'description' => __( 'Setting value.', 'woocommerce' ),
					'type'        => 'mixed',
					'context'     => array( 'view', 'edit' ),
				),
				'default'     => array(
					'description' => __( 'Default value for the setting.', 'woocommerce' ),
					'type'        => 'mixed',
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'tip'         => array(
					'description' => __( 'Additional help text shown to the user about the setting.', 'woocommerce' ),
					'type'        => 'string',
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_text_field',
					),
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'placeholder' => array(
					'description' => __( 'Placeholder text to be displayed in text inputs.', 'woocommerce' ),
					'type'        => 'string',
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_text_field',
					),
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
				'type'        => array(
					'description' => __( 'Type of setting.', 'woocommerce' ),
					'type'        => 'string',
					'arg_options' => array(
						'sanitize_callback' => 'sanitize_text_field',
					),
					'context'     => array( 'view', 'edit' ),
					'enum'        => array( 'text', 'email', 'number', 'color', 'password', 'textarea', 'select', 'multiselect', 'radio', 'image_width', 'checkbox', 'thumbnail_cropping' ),
					'readonly'    => true,
				),
				'options'     => array(
					'description' => __( 'Array of options (key value pairs) for inputs such as select, multiselect, and radio buttons.', 'woocommerce' ),
					'type'        => 'object',
					'context'     => array( 'view', 'edit' ),
					'readonly'    => true,
				),
			),
		);

		return $this->add_additional_fields_schema( $schema );
	}
}