SkyMoney/api/tests/variable-categories.manual-rebalance.test.ts

import request from "supertest";
import { describe, it, expect, beforeAll, afterAll, beforeEach } from "vitest";
import appFactory from "./appFactory";
import { prisma, resetUser, ensureUser, U, cid, closePrisma } from "./helpers";
import type { FastifyInstance } from "fastify";

let app: FastifyInstance;

beforeAll(async () => {
  app = await appFactory();
});

afterAll(async () => {
  if (app) await app.close();
  await closePrisma();
});

async function seedBasics() {
  await resetUser(U);
  await ensureUser(U);
  await prisma.variableCategory.createMany({
    data: [
      { id: cid("s"), userId: U, name: "savings", percent: 30, priority: 1, isSavings: true, balanceCents: 3000n },
      { id: cid("f"), userId: U, name: "food", percent: 20, priority: 2, isSavings: false, balanceCents: 2000n },
      { id: cid("g"), userId: U, name: "gas", percent: 30, priority: 3, isSavings: false, balanceCents: 3000n },
      { id: cid("m"), userId: U, name: "misc", percent: 20, priority: 4, isSavings: false, balanceCents: 2000n },
    ],
  });
  await prisma.budgetSession.create({
    data: {
      userId: U,
      periodStart: new Date("2026-03-01T00:00:00Z"),
      periodEnd: new Date("2026-04-01T00:00:00Z"),
      totalBudgetCents: 10_000n,
      allocatedCents: 0n,
      fundedCents: 0n,
      availableCents: 10_000n,
    },
  });
}

describe("manual rebalance", () => {
  beforeEach(async () => {
    await seedBasics();
  });

  it("uses live category balances when session availableCents is stale", async () => {
    await prisma.budgetSession.updateMany({
      where: { userId: U },
      data: { availableCents: 1234n },
    });

    const getRes = await request(app.server)
      .get("/variable-categories/manual-rebalance")
      .set("x-user-id", U);

    expect(getRes.statusCode).toBe(200);
    expect(getRes.body?.availableCents).toBe(10_000);

    const cats = await prisma.variableCategory.findMany({ where: { userId: U }, orderBy: { priority: "asc" } });
    const targets = cats.map((c) => ({ id: c.id, targetCents: 2500 })); // 4 * 2500 = 10000
    const postRes = await request(app.server)
      .post("/variable-categories/manual-rebalance")
      .set("x-user-id", U)
      .send({ targets });

    expect(postRes.statusCode).toBe(200);
    expect(postRes.body?.availableCents).toBe(10_000);

    const session = await prisma.budgetSession.findFirst({
      where: { userId: U },
      orderBy: { periodStart: "desc" },
      select: { availableCents: true },
    });
    expect(Number(session?.availableCents ?? 0n)).toBe(10_000);
  });

  it("rebalances when sums match available", async () => {
    const cats = await prisma.variableCategory.findMany({ where: { userId: U }, orderBy: { priority: "asc" } });
    const targets = cats.map((c) => ({ id: c.id, targetCents: 2500 })); // 4 * 2500 = 10000

    const res = await request(app.server)
      .post("/variable-categories/manual-rebalance")
      .set("x-user-id", U)
      .send({ targets });

    expect(res.statusCode).toBe(200);
    expect(res.body?.ok).toBe(true);
    const updated = await prisma.variableCategory.findMany({ where: { userId: U } });
    expect(updated.every((c) => Number(c.balanceCents) === 2500)).toBe(true);
  });

  it("rejects sum mismatch", async () => {
    const cats = await prisma.variableCategory.findMany({ where: { userId: U }, orderBy: { priority: "asc" } });
    const targets = cats.map((c, i) => ({ id: c.id, targetCents: i === 0 ? 5000 : 1000 })); // 5000 + 3*1000 = 8000

    const res = await request(app.server)
      .post("/variable-categories/manual-rebalance")
      .set("x-user-id", U)
      .send({ targets });

    expect(res.statusCode).toBe(400);
    expect(res.body?.code).toBe("SUM_MISMATCH");
  });

  it("requires savings confirmation when lowering below floor", async () => {
    const cats = await prisma.variableCategory.findMany({ where: { userId: U }, orderBy: { priority: "asc" } });
    // savings to 500 (below 20% of 10000 = 2000)
    const targets = cats.map((c) => ({ id: c.id, targetCents: c.isSavings ? 500 : 3166 })); // 500 + 3*3166 = 9998 -> adjust
    targets[1].targetCents += 2; // total 10000

    const res = await request(app.server)
      .post("/variable-categories/manual-rebalance")
      .set("x-user-id", U)
      .send({ targets });

    expect(res.statusCode).toBe(400);
    expect(res.body?.code).toBe("SAVINGS_FLOOR");

    const resOk = await request(app.server)
      .post("/variable-categories/manual-rebalance")
      .set("x-user-id", U)
      .send({ targets, forceLowerSavings: true });

    expect(resOk.statusCode).toBe(200);
  });

  it("blocks >80% single category", async () => {
    const cats = await prisma.variableCategory.findMany({ where: { userId: U }, orderBy: { priority: "asc" } });
    const targets = cats.map((c, i) => ({ id: c.id, targetCents: i === 0 ? 9000 : 333 }));
    targets[1].targetCents += 1; // sum 10000

    const res = await request(app.server)
      .post("/variable-categories/manual-rebalance")
      .set("x-user-id", U)
      .send({ targets });

    expect(res.statusCode).toBe(400);
    expect(res.body?.code).toBe("OVER_80_PERCENT");
  });
});