smc-hub/client/license/index.ts

CoCalc: Backend webserver component

/*
 *  This file is part of CoCalc: Copyright © 2020 Sagemath, Inc.
 *  License: AGPLv3 s.t. "Commons Clause" – see LICENSE.md for details
 */

/*
Handle purchasing a licenses by customers. This is the server side of
   smc-webapp/site-licenses/purchase/

What this does:

- stores the request object in a table in the database
- if the request is for a quote, sends an email
- if the request is to make a purchase, makes that purchase and creates the license
*/

import { PostgreSQL } from "../../postgres/types";
import {
  PurchaseInfo,
  sanity_checks,
} from "smc-webapp/site-licenses/purchase/util";
import { charge_user_for_license, set_purchase_metadata } from "./charge";
import { create_license } from "./create-license";
import { StripeClient } from "../../stripe/client";
import { callback2 } from "smc-util/async-utils";
import { delay } from "awaiting";

// Does what should be done, and returns the license_id of the license that was created
// and has user added to as a manager.

// We don't allow a user to attempt a purchase more than once every THROTTLE_S seconds.
// This is just standard good practice, and avoids "double clicks" and probably some
// sort of attacks...
const THROTTLE_S = 15;
const last_attempt: { [account_id: string]: number } = {};

export async function purchase_license(
  database: PostgreSQL,
  stripe: StripeClient,
  account_id: string,
  info: PurchaseInfo,
  dbg: (...args) => void
): Promise<string> {
  dbg(`purchase_license: got info=${JSON.stringify(info)} for ${account_id}`);

  const now = new Date().valueOf();
  if (now - (last_attempt[account_id] ?? 0) <= THROTTLE_S * 1000) {
    throw Error(
      "You must wait at least " +
        THROTTLE_S.toString() +
        " seconds between license purchases."
    );
  }
  last_attempt[account_id] = now;

  dbg("purchase_license: running sanity checks...");
  sanity_checks(info);

  dbg("purchase_license: charging user for license...");
  const purchase = await charge_user_for_license(stripe, info, (...args) =>
    dbg("charge_user_for_license", ...args)
  );

  dbg("purchase_license: creating the license...");
  const license_id = await create_license(
    database,
    account_id,
    info,
    (...args) => dbg("create_license", ...args)
  );

  dbg("purchase_license: set metadata on purchase...");
  await set_purchase_metadata(stripe, purchase, { license_id, account_id });

  // We have to try a few times, since the metadata sometimes doesn't appear
  // when querying stripe for the customer, even after it was written in the
  // above line.  Also, this gives the credit card a first chance to work.
  for (let i = 0; i < 3; i++) {
    const customer = await callback2(database.stripe_update_customer, {
      account_id,
    });
    const data = customer?.subscriptions?.data;
    if (data != null) {
      for (const sub of data) {
        if (sub.metadata?.license_id == license_id && sub.status == "active") {
          // metadata is set and status is active -- yes
          break;
        }
      }
    }
    await delay(2000);
  }

  // Sets the license expire date if the subscription is NOT active at this point (e.g., due to credit card failure).
  await database.sync_site_license_subscriptions(account_id);

  return license_id;
}