Arb Alert Discord Bot

1// Arb Alert Discord Bot — economy
2//
3// Every balance change goes through this module, and every one of them runs
4// inside a Prisma transaction that re-reads the row first. That is what stops
5// the classic Discord economy exploit: fire /pay twice in the same tick and
6// spend the same coins on both.
7 
8import { prisma } from "../../lib/db.js";
9 
10export type Wallet = {
11  wallet: number;
12  bank: number;
13  bankCap: number;
14  totalEarned: number;
15  totalSpent: number;
16  dailyStreak: number;
17};
18 
19export const JOBS = [
20  { name: "wrote a cron job that actually worked", min: 120, max: 320 },
21  { name: "reviewed a 900-line pull request", min: 180, max: 420 },
22  { name: "answered the ticket nobody wanted", min: 90, max: 260 },
23  { name: "fixed the flaky test for real this time", min: 200, max: 500 },
24  { name: "migrated the database with no downtime", min: 260, max: 620 },
25] as const;
26 
27export const DAILY_COOLDOWN_MS = 22 * 60 * 60 * 1000;
28export const WORK_COOLDOWN_MS = 60 * 60 * 1000;
29export const ROB_COOLDOWN_MS = 2 * 60 * 60 * 1000;
30export const JAIL_MS = 30 * 60 * 1000;
31 
32export function randomBetween(min: number, max: number): number {
33  return min + Math.floor(Math.random() * (max - min + 1));
34}
35 
36export async function ensureWallet(guildId: string, userId: string) {
37  const existing = await prisma.economy.findUnique({
38    where: { guildId_userId: { guildId, userId } },
39  });
40  if (existing) return existing;
41 
42  const guild = await prisma.guild.upsert({
43    where: { id: guildId },
44    update: {},
45    create: { id: guildId },
46  });
47 
48  return prisma.economy.create({
49    data: { guildId, userId, wallet: guild.startingWallet },
50  });
51}
52 
53export type SpendResult =
54  | { ok: true; wallet: number }
55  | { ok: false; reason: "insufficient"; wallet: number };
56 
57/**
58 * Takes money out of a wallet, or reports that it could not.
59 *
60 * The read and the write are in one transaction, so two concurrent purchases
61 * cannot both see the same starting balance.
62 */
63export async function debit(
64  guildId: string,
65  userId: string,
66  amount: number
67): Promise<SpendResult> {
68  await ensureWallet(guildId, userId);
69 
70  return prisma.$transaction(async (tx) => {
71    const row = await tx.economy.findUniqueOrThrow({
72      where: { guildId_userId: { guildId, userId } },
73    });
74 
75    if (row.wallet < amount) {
76      return { ok: false as const, reason: "insufficient" as const, wallet: row.wallet };
77    }
78 
79    const updated = await tx.economy.update({
80      where: { guildId_userId: { guildId, userId } },
81      data: { wallet: { decrement: amount }, totalSpent: { increment: amount } },
82    });
83 
84    return { ok: true as const, wallet: updated.wallet };
85  });
86}
87 
88export async function credit(
89  guildId: string,
90  userId: string,
91  amount: number
92): Promise<number> {
93  await ensureWallet(guildId, userId);
94 
95  const updated = await prisma.economy.update({
96    where: { guildId_userId: { guildId, userId } },
97    data: { wallet: { increment: amount }, totalEarned: { increment: amount } },
98  });
99  return updated.wallet;
100}