ecommerce-escalation v2

service.js

import _ from 'lodash';

export class InsufficientStock extends Error {
  constructor(message) {
    super(message);
    this.name = 'InsufficientStock';
  }
}

export default (repository) => {
  return {
    async checkout(lineItems, shippingAddress, paymentDetails) {
      return repository.checkoutTransaction(async (session) => {
        const productSkus = _.map(lineItems, 'productSku');
        const inventory = await session.findInventoryByProuctSkus(productSkus);
        const inventoryStockByProductSku = _(inventory)
          .keyBy('productSku')
          .mapValues('stock')
          .value();

        const inventoryStockUpdates = [];
        for (const {productSku, quantity} of lineItems) {
          const remainingStock = inventoryStockByProductSku[productSku];
          if (remainingStock < quantity) {
            throw new InsufficientStock({
              productSku,
              remainingStock,
              requestedStock: quantity
            });
          }
          inventoryStockUpdates.push({
            productSku,
            stock: remainingStock - quantity
          });
        }
        await session.updateInventoryStock(inventoryStockUpdates);

        const orderID = await session.createOrder({
          lineItems,
          shippingAddress,
          paymentDetails
        });
        return orderID;
      });
    }
  };
};