finance-app/src/__tests__/integration/transaction-owner.test.ts

import { describe, it, expect, beforeAll } from "vitest";
import type { NextRequest } from "next/server";
import { queryRaw, queryRow } from "../../lib/db";

/**
 * Changing who paid.
 *
 * Owner was write-once for every ingestion path — a pantry receipt hardcodes
 * DEFAULT_OWNER_ID, and no route, modal or bulk action could correct it, so a
 * shop the other person paid for was permanently filed as yours. There was not
 * a single `UPDATE ... SET owner_id` anywhere in src/.
 *
 * Two things make this more than a field edit, and both are tested here:
 *
 *  1. **It is a one-way door.** Access is "owner OR holds a split"
 *     (canAccessTransactions), so handing a row over while holding no split on
 *     it removes it from your list and 404s every route that could put it back.
 *     Only the new owner can undo it.
 *  2. **It moves money between two ledgers.** Splits record shares, not
 *     direction — getParticipantBalances derives who owes whom from ownership —
 *     so the same 50/50 rows flip sides untouched.
 */

type Ctx = { params: Promise<{ id: string }> };
type Handler = (req: NextRequest, ctx: Ctx) => Promise<Response>;

let txPATCH: Handler;
let stmtPATCH: Handler;

/** Enough of a NextRequest for these routes: the auth header and the body. */
const req = (email: string | null, body: unknown) =>
  ({
    headers: { get: (h: string) => (h.toLowerCase() === "x-forwarded-user" ? email : null) },
    json: async () => body,
  }) as unknown as NextRequest;

const ctx = (id: number) => ({ params: Promise.resolve({ id: String(id) }) });

let me = 0;
let them = 0;
let meEmail = "";
let themEmail = "";

beforeAll(async () => {
  ({ PATCH: txPATCH } = await import("../../app/api/transactions/[id]/route"));
  ({ PATCH: stmtPATCH } = await import("../../app/api/statements/[id]/route"));

  // Fixtures are named, not random, so a re-run is idempotent. `participants`
  // has a unique email and no cascade from `transactions.owner_id`, so the
  // teardown order is rows → statements → people.
  await queryRaw(`DELETE FROM transactions WHERE description LIKE 'Owner fixture — %'`);
  await queryRaw(`DELETE FROM statements WHERE bank_name = 'Owner Fixture Bank'`);
  await queryRaw(`DELETE FROM participants WHERE email LIKE 'owner-fixture-%@example.test'`);

  const mk = async (label: string) => {
    const email = `owner-fixture-${label}@example.test`;
    const row = await queryRow<{ id: number }>(
      `INSERT INTO participants (name, email) VALUES ($1, $2) RETURNING id`,
      [`Owner fixture — ${label}`, email]
    );
    return { id: row!.id, email };
  };
  const a = await mk("me");
  const b = await mk("them");
  me = a.id;
  meEmail = a.email;
  them = b.id;
  themEmail = b.email;
});

/** A manual transaction owned by `owner`, with optional splits. */
async function manualTxn(label: string, owner: number, splits: [number, number][] = []) {
  const row = await queryRow<{ id: number }>(
    `INSERT INTO transactions (transaction_date, description, amount, transaction_type, category, owner_id)
     VALUES ('2026-06-01', $1, 100.00, 'debit', 'groceries', $2) RETURNING id`,
    [`Owner fixture — ${label}`, owner]
  );
  for (const [pid, pct] of splits) {
    await queryRaw(
      `INSERT INTO transaction_splits (transaction_id, participant_id, share_percent) VALUES ($1,$2,$3)`,
      [row!.id, pid, pct]
    );
  }
  return row!.id;
}

const ownerOf = async (id: number) =>
  (await queryRow<{ owner_id: number | null }>(`SELECT owner_id FROM transactions WHERE id = $1`, [id]))!
    .owner_id;

describe("PATCH /api/transactions/[id] — owner", () => {
  it("reassigns a manual row when I hold a split on it", async () => {
    const id = await manualTxn("shared shop", me, [[me, 50], [them, 50]]);
    const res = await txPATCH(req(meEmail, { owner_id: them }), ctx(id));
    expect(res.status).toBe(200);
    expect(await ownerOf(id)).toBe(them);
  });

  it("refuses to hand away a row I hold no split on", async () => {
    const id = await manualTxn("nothing of mine", me);
    const res = await txPATCH(req(meEmail, { owner_id: them }), ctx(id));
    expect(res.status).toBe(409);
    expect((await res.json()).code).toBe("would_lose_access");
    // Unchanged — a refusal must not half-apply.
    expect(await ownerOf(id)).toBe(me);
  });

  it("hands it away when the release is explicit", async () => {
    const id = await manualTxn("given away", me);
    const res = await txPATCH(req(meEmail, { owner_id: them, release: true }), ctx(id));
    expect(res.status).toBe(200);
    expect(await ownerOf(id)).toBe(them);
  });

  it("never blocks taking onto my ledger a row I can already see", async () => {
    // No `release` needed: I end up the owner, so there is no door to close
    // behind me. The split is what lets me see it in the first place.
    const id = await manualTxn("taken on", them, [[me, 50], [them, 50]]);
    const res = await txPATCH(req(meEmail, { owner_id: me }), ctx(id));
    expect(res.status).toBe(200);
    expect(await ownerOf(id)).toBe(me);
  });

  it("cannot claim a row I cannot see", async () => {
    // Their transaction, no split of mine — canAccessTransactions rejects
    // before any owner logic runs. Reassignment is a correction to a row you
    // already have, never a way to reach one you do not.
    const id = await manualTxn("out of reach", them);
    const res = await txPATCH(req(meEmail, { owner_id: me }), ctx(id));
    expect(res.status).toBe(404);
    expect(await ownerOf(id)).toBe(them);
  });

  it("refuses a statement row and says where to change it", async () => {
    const stmt = await queryRow<{ id: number }>(
      `INSERT INTO statements (bank_name, account_number, billing_end_date, currency, filename, owner_id)
       VALUES ('Owner Fixture Bank','1111','2026-06-30','AUD','owner-fixture-1.pdf',$1) RETURNING id`,
      [me]
    );
    const row = await queryRow<{ id: number }>(
      `INSERT INTO transactions (statement_id, transaction_date, description, amount, transaction_type)
       VALUES ($1,'2026-06-02','Owner fixture — statement row', 40.00, 'debit') RETURNING id`,
      [stmt!.id]
    );
    const res = await txPATCH(req(meEmail, { owner_id: them }), ctx(row!.id));
    expect(res.status).toBe(400);
    expect((await res.json()).code).toBe("statement_owned");
  });

  it("rejects a participant that does not exist", async () => {
    const id = await manualTxn("bad participant", me, [[me, 100]]);
    const res = await txPATCH(req(meEmail, { owner_id: 999999 }), ctx(id));
    expect(res.status).toBe(400);
    expect(await ownerOf(id)).toBe(me);
  });

  it("leaves splits untouched — they record shares, not direction", async () => {
    const id = await manualTxn("shares survive", me, [[me, 50], [them, 50]]);
    await txPATCH(req(meEmail, { owner_id: them }), ctx(id));
    const splits = await queryRaw<{ participant_id: number; share_percent: string; settled: boolean }>(
      `SELECT participant_id, share_percent, settled FROM transaction_splits
        WHERE transaction_id = $1 ORDER BY participant_id`,
      [id]
    );
    expect(splits.map((s) => [s.participant_id, Number(s.share_percent)])).toEqual([
      [me, 50],
      [them, 50],
    ]);
    expect(splits.every((s) => s.settled === false)).toBe(true);
  });

  it("flips which side of the balance the same rows sit on", async () => {
    const id = await manualTxn("balance flip", me, [[me, 50], [them, 50]]);

    // "They owe me": their split on a row I own.
    const owedToMe = async () =>
      Number(
        (await queryRow<{ v: string | null }>(
          `SELECT COALESCE(SUM(t.amount * ts.share_percent / 100), 0) AS v
             FROM transaction_splits ts JOIN transactions t ON t.id = ts.transaction_id
            WHERE t.id = $1 AND t.owner_id = $2 AND ts.participant_id <> $2`,
          [id, me]
        ))!.v ?? 0
      );
    // "I owe them": my split on a row they own.
    const owedByMe = async () =>
      Number(
        (await queryRow<{ v: string | null }>(
          `SELECT COALESCE(SUM(t.amount * ts.share_percent / 100), 0) AS v
             FROM transaction_splits ts JOIN transactions t ON t.id = ts.transaction_id
            WHERE t.id = $1 AND t.owner_id <> $2 AND ts.participant_id = $2`,
          [id, me]
        ))!.v ?? 0
      );

    expect(await owedToMe()).toBe(50);
    expect(await owedByMe()).toBe(0);

    await txPATCH(req(meEmail, { owner_id: them }), ctx(id));

    expect(await owedToMe()).toBe(0);
    expect(await owedByMe()).toBe(50);
  });

  it("rejects an unauthenticated caller", async () => {
    const id = await manualTxn("no auth", me, [[me, 100]]);
    const res = await txPATCH(req("nobody@example.test", { owner_id: them }), ctx(id));
    expect(res.status).toBe(403);
    expect(await ownerOf(id)).toBe(me);
  });
});

describe("PATCH /api/statements/[id] — owner", () => {
  async function statementWithRows(label: string, owner: number) {
    const stmt = await queryRow<{ id: number }>(
      `INSERT INTO statements (bank_name, account_number, billing_end_date, currency, filename, owner_id)
       VALUES ('Owner Fixture Bank', $1, '2026-06-30','AUD', $2, $3) RETURNING id`,
      [label, `owner-fixture-${label}.pdf`, owner]
    );
    // One row inheriting the owner (owner_id NULL) and one carrying its own
    // copy — the live table holds 1,803 and 2,194 of these respectively, and
    // updating `statements` alone would move only the first kind.
    const inheriting = await queryRow<{ id: number }>(
      `INSERT INTO transactions (statement_id, transaction_date, description, amount, transaction_type)
       VALUES ($1,'2026-06-03','Owner fixture — inheriting', 10.00, 'debit') RETURNING id`,
      [stmt!.id]
    );
    const carrying = await queryRow<{ id: number }>(
      `INSERT INTO transactions (statement_id, transaction_date, description, amount, transaction_type, owner_id)
       VALUES ($1,'2026-06-04','Owner fixture — carrying', 20.00, 'debit', $2) RETURNING id`,
      [stmt!.id, owner]
    );
    return { stmtId: stmt!.id, inheriting: inheriting!.id, carrying: carrying!.id };
  }

  /** The owner the app actually reads: COALESCE(t.owner_id, s.owner_id). */
  const effectiveOwner = async (id: number) =>
    (await queryRow<{ v: number }>(
      `SELECT COALESCE(t.owner_id, s.owner_id) AS v FROM transactions t
         LEFT JOIN statements s ON s.id = t.statement_id WHERE t.id = $1`,
      [id]
    ))!.v;

  it("moves the statement and every row on it, both kinds", async () => {
    const { stmtId, inheriting, carrying } = await statementWithRows("move", me);
    const res = await stmtPATCH(req(meEmail, { owner_id: them }), ctx(stmtId));
    expect(res.status).toBe(200);
    expect((await res.json()).rows_moved).toBe(1); // only the one carrying a copy

    expect(await effectiveOwner(inheriting)).toBe(them);
    expect(await effectiveOwner(carrying)).toBe(them);
  });

  it("refuses a caller who does not own it", async () => {
    const { stmtId, carrying } = await statementWithRows("not-mine", me);
    const res = await stmtPATCH(req(themEmail, { owner_id: them }), ctx(stmtId));
    expect(res.status).toBe(404);
    expect(await effectiveOwner(carrying)).toBe(me);
  });

  it("rejects a participant that does not exist", async () => {
    const { stmtId, carrying } = await statementWithRows("bad-participant", me);
    const res = await stmtPATCH(req(meEmail, { owner_id: 999999 }), ctx(stmtId));
    expect(res.status).toBe(400);
    expect(await effectiveOwner(carrying)).toBe(me);
  });

  it("is a no-op when the owner is unchanged", async () => {
    const { stmtId } = await statementWithRows("same-owner", me);
    const res = await stmtPATCH(req(meEmail, { owner_id: me }), ctx(stmtId));
    expect(res.status).toBe(200);
    expect((await res.json()).rows_moved).toBe(0);
  });
});