order );

		/**
		 * Process the payment and return the results.
		 */
		$payment_result = $this->order->needs_payment() ? $this->process_payment( $request ) : $this->process_without_payment( $request );

		return $this->prepare_item_for_response(
			(object) [
				'order'          => wc_get_order( $this->order ),
				'payment_result' => $payment_result,
			],
			$request
		);
	}

	/**
	 * Get route response when something went wrong.
	 *
	 * @param string $error_code String based error code.
	 * @param string $error_message User facing error message.
	 * @param int    $http_status_code HTTP status. Defaults to 500.
	 * @param array  $additional_data  Extra data (key value pairs) to expose in the error response.
	 * @return WP_Error WP Error object.
	 */
	protected function get_route_error_response( $error_code, $error_message, $http_status_code = 500, $additional_data = [] ) {
		$error_from_message = new WP_Error(
			$error_code,
			$error_message
		);
		switch ( $http_status_code ) {
			case 409:
				// 409 is when there was a conflict, so we return the cart so the client can resolve it.
				return $this->add_data_to_error_object( $error_from_message, $additional_data, $http_status_code, true );
		}
		return $this->add_data_to_error_object( $error_from_message, $additional_data, $http_status_code );
	}

	/**
	 * Get route response when something went wrong.
	 *
	 * @param WP_Error $error_object User facing error message.
	 * @param int      $http_status_code HTTP status. Defaults to 500.
	 * @param array    $additional_data  Extra data (key value pairs) to expose in the error response.
	 * @return WP_Error WP Error object.
	 */
	protected function get_route_error_response_from_object( $error_object, $http_status_code = 500, $additional_data = [] ) {
		switch ( $http_status_code ) {
			case 409:
				// 409 is when there was a conflict, so we return the cart so the client can resolve it.
				return $this->add_data_to_error_object( $error_object, $additional_data, $http_status_code, true );
		}
		return $this->add_data_to_error_object( $error_object, $additional_data, $http_status_code );
	}

	/**
	 * Adds additional data to the WP_Error object.
	 *
	 * @param WP_Error $error The error object to add the cart to.
	 * @param array    $data The data to add to the error object.
	 * @param int      $http_status_code The HTTP status code this error should return.
	 * @param bool     $include_cart Whether the cart should be included in the error data.
	 * @returns WP_Error The WP_Error with the cart added.
	 */
	private function add_data_to_error_object( $error, $data, $http_status_code, bool $include_cart = false ) {
		$data = array_merge( $data, [ 'status' => $http_status_code ] );
		if ( $include_cart ) {
			$data = array_merge( $data, [ 'cart' => wc()->api->get_endpoint_data( '/wc/store/cart' ) ] );
		}
		$error->add_data( $data );
		return $error;
	}

	/**
	 * Gets draft order data from the customer session.
	 *
	 * @return array
	 */
	private function get_draft_order_id() {
		return wc()->session->get( 'store_api_draft_order', 0 );
	}

	/**
	 * Updates draft order data in the customer session.
	 *
	 * @param integer $order_id Draft order ID.
	 */
	private function set_draft_order_id( $order_id ) {
		wc()->session->set( 'store_api_draft_order', $order_id );
	}

	/**
	 * Whether the passed argument is a draft order or an order that is
	 * pending/failed and the cart hasn't changed.
	 *
	 * @param \WC_Order $order_object Order object to check.
	 * @return boolean Whether the order is valid as a draft order.
	 */
	private function is_valid_draft_order( $order_object ) {
		if ( ! $order_object instanceof \WC_Order ) {
			return false;
		}

		// Draft orders are okay.
		if ( $order_object->has_status( 'checkout-draft' ) ) {
			return true;
		}

		// Pending and failed orders can be retried if the cart hasn't changed.
		if ( $order_object->needs_payment() && $order_object->has_cart_hash( wc()->cart->get_cart_hash() ) ) {
			return true;
		}

		return false;
	}

	/**
	 * Create or update a draft order based on the cart.
	 *
	 * @throws RouteException On error.
	 */
	private function create_or_update_draft_order() {
		$this->order = $this->get_draft_order_id() ? wc_get_order( $this->get_draft_order_id() ) : null;

		if ( ! $this->is_valid_draft_order( $this->order ) ) {
			$this->order = $this->order_controller->create_order_from_cart();
		} else {
			$this->order_controller->update_order_from_cart( $this->order );
		}

		/**
		 * WooCommerce Blocks Checkout Update Order Meta (experimental).
		 *
		 * This hook gives extensions the chance to add or update meta data on the $order.
		 *
		 * This is similar to existing core hook woocommerce_checkout_update_order_meta.
		 * We're using a new action:
		 * - To keep the interface focused (only pass $order, not passing request data).
		 * - This also explicitly indicates these orders are from checkout block/StoreAPI.
		 *
		 * @see https://github.com/woocommerce/woocommerce-gutenberg-products-block/pull/3686
		 * @internal This Hook is experimental and may change or be removed.
		 *
		 * @param WC_Order $order Order object.
		 */
		do_action( '__experimental_woocommerce_blocks_checkout_update_order_meta', $this->order );

		// Confirm order is valid before proceeding further.
		if ( ! $this->order instanceof WC_Order ) {
			throw new RouteException(
				'woocommerce_rest_checkout_missing_order',
				__( 'Unable to create order', 'woocommerce' ),
				500
			);
		}

		// Store order ID to session.
		$this->set_draft_order_id( $this->order->get_id() );

		// Try to reserve stock for 10 mins, if available.
		try {
			$reserve_stock = new ReserveStock();
			$reserve_stock->reserve_stock_for_order( $this->order, 10 );
		} catch ( ReserveStockException $e ) {
			$error_data = $e->getErrorData();
			throw new RouteException(
				$e->getErrorCode(),
				$e->getMessage(),
				$e->getCode()
			);
		}
	}

	/**
	 * Updates the current customer session using data from the request (e.g. address data).
	 *
	 * Address session data is synced to the order itself later on by OrderController::update_order_from_cart()
	 *
	 * @param WP_REST_Request $request Full details about the request.
	 */
	private function update_customer_from_request( WP_REST_Request $request ) {
		$customer = wc()->customer;

		if ( isset( $request['billing_address'] ) ) {
			foreach ( $request['billing_address'] as $key => $value ) {
				if ( is_callable( [ $customer, "set_billing_$key" ] ) ) {
					$customer->{"set_billing_$key"}( $value );
				}
			}
		}

		if ( isset( $request['shipping_address'] ) ) {
			foreach ( $request['shipping_address'] as $key => $value ) {
				if ( is_callable( [ $customer, "set_shipping_$key" ] ) ) {
					$customer->{"set_shipping_$key"}( $value );
				}
			}
		}

		$customer->save();
	}

	/**
	 * Update the current order using the posted values from the request.
	 *
	 * @param WP_REST_Request $request Full details about the request.
	 */
	private function update_order_from_request( WP_REST_Request $request ) {
		if ( isset( $request['customer_note'] ) ) {
			$this->order->set_customer_note( $request['customer_note'] );
		}
		$this->order->set_payment_method( $this->order->needs_payment() ? $this->get_request_payment_method( $request ) : '' );
		$this->order->save();
	}

	/**
	 * For orders which do not require payment, just update status.
	 *
	 * @param WP_REST_Request $request Request object.
	 * @return PaymentResult
	 */
	private function process_without_payment( WP_REST_Request $request ) {
		$this->order->payment_complete();

		$result = new PaymentResult( 'success' );
		$result->set_redirect_url( $this->order->get_checkout_order_received_url() );

		return $result;
	}

	/**
	 * Fires an action hook instructing active payment gateways to process the payment for an order and provide a result.
	 *
	 * @throws RouteException On error.
	 * @param WP_REST_Request $request Request object.
	 * @return PaymentResult
	 */
	private function process_payment( WP_REST_Request $request ) {
		try {
			$result  = new PaymentResult();
			$context = new PaymentContext();
			$context->set_payment_method( $this->get_request_payment_method_id( $request ) );
			$context->set_payment_data( $this->get_request_payment_data( $request ) );

			// Orders are made pending before attempting payment.
			$this->order->update_status( 'pending' );
			$context->set_order( $this->order );

			/**
			 * Process payment with context.
			 *
			 * @hook woocommerce_rest_checkout_process_payment_with_context
			 *
			 * @throws Exception If there is an error taking payment, an Exception object can be thrown
			 *                                     with an error message.
			 *
			 * @param PaymentContext $context Holds context for the payment, including order ID and payment method.
			 * @param PaymentResult  $result Result object for the transaction.
			 */
			do_action_ref_array( 'woocommerce_rest_checkout_process_payment_with_context', [ $context, &$result ] );

			if ( ! $result instanceof PaymentResult ) {
				throw new RouteException( 'woocommerce_rest_checkout_invalid_payment_result', __( 'Invalid payment result received from payment method.', 'woocommerce' ), 500 );
			}

			return $result;
		} catch ( Exception $e ) {
			throw new RouteException( 'woocommerce_rest_checkout_process_payment_error', $e->getMessage(), 400 );
		}
	}

	/**
	 * Gets the chosen payment method ID from the request.
	 *
	 * @throws RouteException On error.
	 * @param WP_REST_Request $request Request object.
	 * @return string
	 */
	private function get_request_payment_method_id( WP_REST_Request $request ) {
		$payment_method_id = isset( $request['payment_method'] )
			? wc_clean( wp_unslash( $request['payment_method'] ) )
			: '';

		if ( empty( $payment_method_id ) ) {
			throw new RouteException(
				'woocommerce_rest_checkout_missing_payment_method',
				__( 'No payment method provided.', 'woocommerce' ),
				400
			);
		}

		return $payment_method_id;
	}

	/**
	 * Gets the chosen payment method from the request.
	 *
	 * @throws RouteException On error.
	 * @param WP_REST_Request $request Request object.
	 * @return \WC_Payment_Gateway
	 */
	private function get_request_payment_method( WP_REST_Request $request ) {
		$payment_method_id  = $this->get_request_payment_method_id( $request );
		$available_gateways = WC()->payment_gateways->get_available_payment_gateways();

		if ( ! isset( $available_gateways[ $payment_method_id ] ) ) {
			throw new RouteException(
				'woocommerce_rest_checkout_payment_method_disabled',
				__( 'This payment gateway is not available.', 'woocommerce' ),
				400
			);
		}

		return $available_gateways[ $payment_method_id ];
	}

	/**
	 * Gets and formats payment request data.
	 *
	 * @param WP_REST_Request $request Request object.
	 * @return array
	 */
	private function get_request_payment_data( WP_REST_Request $request ) {
		static $payment_data = [];
		if ( ! empty( $payment_data ) ) {
			return $payment_data;
		}
		if ( ! empty( $request['payment_data'] ) ) {
			foreach ( $request['payment_data'] as $data ) {
				$payment_data[ sanitize_key( $data['key'] ) ] = wc_clean( $data['value'] );
			}
		}

		return $payment_data;
	}

	/**
	 * Order processing relating to customer account.
	 *
	 * Creates a customer account as needed (based on request & store settings) and  updates the order with the new customer ID.
	 * Updates the order with user details (e.g. address).
	 *
	 * @internal CreateAccount class includes feature gating logic (i.e. this may not create an account depending on build).
	 * @internal Checkout signup is feature gated to WooCommerce 4.7 and newer; Because it requires updated my-account/lost-password screen in 4.7+ for setting initial password.
	 *
	 * @throws RouteException API error object with error details.
	 * @param WP_REST_Request $request Request object.
	 */
	private function process_customer( WP_REST_Request $request ) {
		if ( defined( 'WC_VERSION' ) && version_compare( WC_VERSION, '4.7', '>=' ) ) {
			try {
				$create_account = Package::container()->get( CreateAccount::class );
				$create_account->from_order_request( $request );
				$this->order->set_customer_id( get_current_user_id() );
				$this->order->save();
			} catch ( Exception $error ) {
				switch ( $error->getMessage() ) {
					case 'registration-error-invalid-email':
						throw new RouteException(
							'registration-error-invalid-email',
							__( 'Please provide a valid email address.', 'woocommerce' ),
							400
						);
					case 'registration-error-email-exists':
						throw new RouteException(
							'registration-error-email-exists',
							__( 'An account is already registered with your email address. Please log in before proceeding.', 'woocommerce' ),
							400
						);
				}
			}
		}

		// Persist customer address data to account.
		$this->order_controller->sync_customer_data_with_order( $this->order );
	}

}