# ACH Banking System Updates

## ACH Logic Management

As requested by the client, the following changes have been implemented to the banking information management system:

### Business Rules

1. **Primary Bank Account**
   - Only one bank account per employee can be designated as primary
   - When a new account is set as primary, all other accounts for that employee are automatically set as non-primary
   - When updating an existing account to be primary, all other accounts are automatically updated to non-primary

2. **Direct Deposit Enablement**
   - Only one bank account per employee can have direct deposit enabled
   - When a new account has direct deposit enabled, all other accounts for that employee automatically have direct deposit disabled
   - When updating an existing account to enable direct deposit, all other accounts automatically have direct deposit disabled

### Implementation Details

These business rules are enforced in the following controller methods:

- `addBankingInfo`: When adding a new bank account
- `updateBankingInfo`: When updating an existing bank account
- `deleteBankingInfo`: When deleting a bank account (if the deleted account was primary, another account is automatically promoted to primary)

### Technical Implementation

1. **Database Structure**:
   - The `employee_banking_info` table includes `is_primary` and `direct_deposit_enabled` boolean fields
   - These fields default to `TRUE` for new accounts
   - Foreign key constraints ensure data integrity

2. **Business Logic**:
   - Before inserting or updating records, the system checks for existing primary and direct deposit accounts
   - Updates are performed in a transaction to ensure data consistency
   - When setting an account as primary or direct deposit enabled, all other accounts are automatically updated accordingly

3. **API Endpoints**:
   - `POST /api/employees/:id/banking` - Add new banking information
   - `PUT /api/employees/:id/banking/:bankingId` - Update existing banking information
   - `DELETE /api/employees/:id/banking/:bankingId` - Delete banking information
   - `GET /api/employees/:id/banking` - List all banking records for an employee
   - `GET /api/employees/:id/banking/:bankingId` - Get specific banking record details

### Security

- Account and routing numbers are encrypted in the database
- Sensitive data is never returned in API responses - only masked versions (e.g., "XXXX1234")
- Validation is performed to ensure account and routing numbers meet required formats