cms/src/checkout/paypal-order.ts

import type { Order } from "../../types";
import { calculateTotalProductPrice } from "./pricing";
import { vatIncludedDecimal } from "./vat";

// The PayPal order that PayPalApi.createSessionOrThrow creates, built without the PayPal SDK so it can be unit tested.
// String literals stand in for the SDK enums, with the values of @paypal/paypal-server-sdk 0.6.1.

export type PayPalMoney = {
	currencyCode: string;
	value: string;
};

export type PayPalOrderItem = {
	name: string;
	unitAmount: PayPalMoney;
	tax: PayPalMoney;
	quantity: string;
};

export type PayPalOrderRequest = {
	/** CheckoutPaymentIntent.Capture */
	intent: "CAPTURE";
	purchaseUnits: {
		referenceId: string;
		amount: PayPalMoney & {
			breakdown: {
				itemTotal: PayPalMoney;
				taxTotal: PayPalMoney;
				shipping: PayPalMoney | undefined;
			};
		};
		shipping: {
			name: { fullName: string };
			address: { addressLine1: string; postalCode: string; adminArea2: string; countryCode: string };
		};
		customId: string;
		invoiceId: string;
	}[];
	applicationContext: {
		returnUrl: string;
		cancelUrl: string;
		/** OrderApplicationContextShippingPreference.SetProvidedAddress */
		shippingPreference: "SET_PROVIDED_ADDRESS";
	};
};

/**
 * The part of PayPalApi.createSessionOrThrow that runs before its try block, so nothing thrown here is logged there.
 * Rejects an order without a total, then computes one item per cart line. The items are not sent to PayPal, but computing
 * them throws a TypeError for a cart line without a product.
 */
export const buildPayPalOrderItems = (order: Order): PayPalOrderItem[] => {
	if (!order.total) throw new Error("Cart is empty or has no total");

	return order.cart.map((item) => {
		const totalProductPrice = calculateTotalProductPrice(item.product);
		const amount = totalProductPrice / vatIncludedDecimal;
		const tax = totalProductPrice - amount;

		return {
			name: item.product.name,
			unitAmount: {
				currencyCode: "EUR",
				value: amount.toFixed(2)
			},
			tax: {
				currencyCode: "EUR",
				value: tax.toFixed(2)
			},
			quantity: item.count.toString()
		};
	});
};

/**
 * The order request body PayPalApi.createSessionOrThrow sends. It is built inside that try block, so whatever throws here is logged there.
 */
export const buildPayPalOrderRequest = (returnUrl: string, order: Order): PayPalOrderRequest => ({
	intent: "CAPTURE",
	purchaseUnits: [
		{
			// items: computed by buildPayPalOrderItems, but not sent
			referenceId: order.uuid,
			amount: {
				currencyCode: "EUR",
				value: order.total.toFixed(2),
				breakdown: {
					itemTotal: {
						currencyCode: "EUR",
						value: (Math.round((order.subtotal / vatIncludedDecimal) * 100) / 100).toFixed(2)
					},
					taxTotal: {
						currencyCode: "EUR",
						value: order.VAT.toFixed(2)
					},
					shipping: order.delivery
						? {
								currencyCode: "EUR",
								value: order.delivery.price.toFixed(2)
							}
						: undefined
				}
			},
			shipping: {
				name: {
					fullName: order.deliveryAddress.split("\n")[0]
				},
				address: {
					addressLine1: order.deliveryAddress.split("\n")[1],
					postalCode: order.deliveryAddress.split("\n")[2].slice(0, 5),
					adminArea2: order.deliveryAddress.split("\n")[2].slice(6),
					countryCode: "DE"
				}
			},
			customId: order.uuid,
			invoiceId: order.invoiceNumber
		}
	],
	applicationContext: {
		returnUrl: returnUrl,
		cancelUrl: returnUrl,
		shippingPreference: "SET_PROVIDED_ADDRESS"
	}
});