vercel__next.js/examples/with-temporal/temporal/src/activities.ts

import fetch from "node-fetch";

export type ChargeResult = {
  status: string;
  errorMessage?: string;
};

export async function chargeUser(
  userId: string,
  itemId: string,
  quantity: number,
): Promise<ChargeResult> {
  // TODO send request to the payments service that looks up the user's saved
  // payment info and the cost of the item and attempts to charge their payment
  // method.
  console.log(`Charging user ${userId} for ${quantity} of item ${itemId}`);
  try {
    const response = await fetch("http://httpbin.org/get?status=success");
    const body: any = await response.json();
    return { status: body.args.status };
  } catch (e: any) {
    return { status: "failure", errorMessage: e.message };
  }
}

export async function checkAndDecrementInventory(
  itemId: string,
  quantity: number,
): Promise<boolean> {
  // TODO a database request that—in a single operation or transaction—checks
  // whether there are `quantity` items remaining, and if so, decreases the
  // total. Something like:
  // const result = await db.collection('items').updateOne(
  //   { _id: itemId, numAvailable: { $gte: quantity } },
  //   { $inc: { numAvailable: -quantity } }
  // )
  // return result.modifiedCount === 1
  console.log(`Reserving ${quantity} of item ${itemId}`);
  return true;
}

export async function incrementInventory(
  itemId: string,
  quantity: number,
): Promise<boolean> {
  // TODO increment inventory:
  // const result = await db.collection('items').updateOne(
  //   { _id: itemId },
  //   { $inc: { numAvailable: quantity } }
  // )
  // return result.modifiedCount === 1
  console.log(`Incrementing ${itemId} inventory by ${quantity}`);
  return true;
}