protected function update_order( $request ) {
		try {
			$order = $this->prepare_item_for_database( $request );
			$order->save();

			// Handle set paid.
			if ( $order->needs_payment() && true === $request['set_paid'] ) {
				$order->payment_complete( $request['transaction_id'] );
			}

			// If items have changed, recalculate order totals.
			if ( isset( $request['billing'] ) || isset( $request['shipping'] ) || isset( $request['line_items'] ) || isset( $request['shipping_lines'] ) || isset( $request['fee_lines'] ) || isset( $request['coupon_lines'] ) ) {
				$order->calculate_totals();
			}

			return $order->get_id();
		} catch ( WC_Data_Exception $e ) {
			return new WP_Error( $e->getErrorCode(), $e->getMessage(), $e->getErrorData() );
		} catch ( WC_REST_Exception $e ) {
			return new WP_Error( $e->getErrorCode(), $e->getMessage(), array( 'status' => $e->getCode() ) );
		}
	}