// File: server/modules/sales/sales.service.js (original, line ~186)
function deleteSale(id, isDecoy) {
    var stmt = db.prepare('UPDATE sales SET is_deleted = 1, updated_at = datetime(\'now\', \'localtime\') WHERE id = ? AND is_decoy = ?');
    stmt.run(id, isDecoy ? 1 : 0);
    logger.info('Sales', 'Sale deleted: ID ' + id + (isDecoy ? ' [DECOY]' : ''));
    return true;
}

// File: server/modules/sales/sales.service.js (lines 441–487)
function deleteSale(id, isDecoy) {
    var sale = getSaleById(id, isDecoy);
    if (!sale) return false;

    var transaction = db.transaction(function() {
        var deletedInvoiceNo = sale.invoice_no + '-DEL-' + Date.now();
        db.prepare('UPDATE sales SET is_deleted = 1, invoice_no = ?, updated_at = datetime(\'now\', \'localtime\') WHERE id = ?')
            .run(deletedInvoiceNo, id);

        if (sale.customer_account_id) {
            db.prepare('UPDATE accounts SET current_balance = current_balance - ?, updated_at = datetime(\'now\', \'localtime\') WHERE id = ?')
                .run(sale.total, sale.customer_account_id);
        }

        db.prepare('UPDATE transactions SET is_deleted = 1 WHERE linked_sale_id = ?').run(id);

        var payments = db.prepare('SELECT * FROM payments WHERE sale_id = ? AND is_decoy = ? AND is_deleted = 0').all(id, isDecoy ? 1 : 0);
        payments.forEach(function(payment) {
            var assetAccount = payment.mode === 'cash'
                ? accountsService.getDefaultCashAccount(isDecoy)
                : accountsService.getDefaultBankAccount(isDecoy);
            if (assetAccount) {
                var assetRevert = payment.type === 'in' ? -payment.amount : payment.amount;
                db.prepare('UPDATE accounts SET current_balance = current_balance + ?, updated_at = datetime(\'now\', \'localtime\') WHERE id = ?')
                    .run(assetRevert, assetAccount.id);
            }

            if (payment.type === 'in' && sale.id) {
                db.prepare('UPDATE sales SET amount_paid = amount_paid - ?, updated_at = datetime(\'now\', \'localtime\') WHERE id = ?')
                    .run(payment.amount, sale.id);
            }

            db.prepare('UPDATE payments SET is_deleted = 1 WHERE id = ?').run(payment.id);
        });

        return true;
    });

    transaction();
    logger.info('Sales', 'Sale deleted: ID ' + id + (isDecoy ? ' [DECOY]' : ''));
    return true;
}

UPDATE transactions SET is_deleted = 1
WHERE linked_sale_id IN (SELECT id FROM sales WHERE is_deleted = 1);

// File: tests/double-entry.test.js (lines 830–887)
// Arrange — create a valid sale first to establish baseline
const saleResponse = await request(app)
    .post('/api/v1/sales')
    .set('Cookie', cookies)
    .send({ customer_account_id: testCustomerId, total: 1000, amount_paid: 1000, date: '2026-04-29' });
expect(saleResponse.status).toBe(201);

// Count transactions before the bad operation
const db = new Database(TEST_DB_PATH);
db.pragma(`key = '${TEST_DB_KEY}'`);
const countBefore = db.prepare(
    'SELECT COUNT(*) as count FROM transactions WHERE is_deleted = 0'
).get().count;
db.close();

// Act — try to create a sale with a NEGATIVE amount
// The API should reject this, but will it leave ghost entries?
const invalidSaleData = {
    customer_account_id: testCustomerId,
    total: -500,
    amount_paid: -500,
    date: '2026-04-29'
};

const failResponse = await request(app)
    .post('/api/v1/sales')
    .set('Cookie', cookies)
    .send(invalidSaleData);

expect(failResponse.status).toBe(400);

// Assert — verify the transaction count is EXACTLY the same
// If even ONE extra row exists, the books are now corrupted
const db2 = new Database(TEST_DB_PATH);
db2.pragma(`key = '${TEST_DB_KEY}'`);
const countAfter = db2.prepare(
    'SELECT COUNT(*) as count FROM transactions WHERE is_deleted = 0'
).get().count;
db2.close();

// THIS is the assertion that matters
expect(countAfter).toBe(countBefore);

expect(countAfter).toBe(countBefore);

// File: tests/crash-simulation.test.js (lines 228–258)
test('partial writes should not persist after crash', () => {
    let writeCount = 0;
    const mockStmt = {
        run: jest.fn().mockImplementation(() => {
            writeCount++;
            if (writeCount === 2) {
                throw new Error('SIGKILL: Process terminated during second write');
            }
            return { changes: 1, lastInsertRowid: writeCount };
        })
    };
    mockDb.prepare.mockReturnValue(mockStmt);

    const transactionFn = mockDb.transaction(function() {
        mockDb.prepare('INSERT INTO sales (total) VALUES (?)').run(1000);
        mockDb.prepare('INSERT INTO transactions (amount) VALUES (?)').run(1000);
    });

    expect(() => { transactionFn(); }).toThrow('SIGKILL: Process terminated during second write');
    expect(writeCount).toBe(2);
});

// File: tests/double-entry.test.js (lines 1–22)
/**
 * Double-Entry Enforcement Tests — Hisaab Pro
 *
 * Acceptance Criteria:
 * 1. Every transaction MUST create balanced journal entries (debit = credit)
 * 2. Failed transactions must not create partial ledger entries
 * 3. Updated transactions must maintain balance (old deleted, new balanced)
 * 4. Multiple transactions each maintain independent double-entry
 *
 * Following AAA Pattern: Arrange → Act → Assert
 */