NeoCom/DEVELOPMENT_GUIDE.md

# Development Guide: Bank Transactions & Payment Recording

Complete implementation of bank transaction CSV import and AR invoice payment recording for the ERP platform.

## Quick Links

### Documentation
- **API_ENDPOINTS.md** - Complete API reference with examples
- **IMPLEMENTATION_SUMMARY.md** - Technical architecture and implementation details
- **EXAMPLE_CSVs.md** - Sample CSV files and testing guide
- **FRONTEND_INTEGRATION_GUIDE.md** - Frontend code examples and patterns

### Code Files
- **API: Bank Transaction Import** - `/src/app/api/bank-transactions/import/route.ts`
- **API: CSV Parser** - `/src/app/api/bank-transactions/parse-csv/route.ts`
- **UI: AR Invoice Detail** - `/src/app/(dashboard)/finance/ar/invoice/[invoiceId]/page.tsx`
- **UI: AR List Page** - `/src/app/(dashboard)/finance/ar/page.tsx`

## What Was Built

### Task 1: Bank Transaction CSV Import Endpoint

Two new API endpoints for importing bank transactions from CSV files:

1. **POST `/api/bank-transactions/parse-csv`**
   - Accept CSV file upload
   - Parse and validate
   - Return preview of transactions
   - No external dependencies (pure TypeScript CSV parser)

2. **POST `/api/bank-transactions/import`**
   - Bulk import validated transactions
   - Atomic operation (all or nothing)
   - Verify bank account ownership
   - Return count of imported transactions

**Features:**
- Supports 2 CSV formats (Amount or Debit/Credit columns)
- Handles quoted fields with commas
- Handles escaped quotes
- Auto-detects CSV format
- Comprehensive validation
- Organization isolation

### Task 2: AR Invoice Payment Recording

Enhanced AR invoice detail page with payment recording capability:

1. **Payment Recording Modal**
   - Form for entering payment details
   - Payment amount (validated > 0)
   - Payment date (date picker)
   - Payment method (dropdown with 7 options)
   - Error handling and loading states

2. **Integration with Existing Payment API**
   - Uses existing `/api/payments` endpoint
   - Automatically updates invoice balances
   - Updates invoice status (PAID or PARTIALLY_PAID)
   - Creates payment allocations

3. **AR List Page Integration**
   - "Record Payment" action in context menu
   - Navigates to invoice detail with auto-opening modal
   - Direct payment entry from list

**Features:**
- Modal auto-opens with query parameter `?action=payment`
- Form validation on client and server
- Error display with helpful messages
- Loading state during submission
- Auto-refresh after successful payment
- Maintains invoice context

## Architecture

### Authentication & Multi-Tenancy
- All endpoints use `getOrganization()` for tenant isolation
- Bank account ownership verified before import
- Organization ID included in all queries

### Error Handling
- Standard HTTP status codes
- Descriptive error messages
- Input validation on both client and server
- Proper exception handling with try-catch

### Data Flow

#### CSV Import
```
User uploads CSV
    ↓
Parse endpoint validates and extracts transactions
    ↓
UI displays preview of parsed transactions
    ↓
User confirms import
    ↓
Import endpoint validates and bulk inserts
    ↓
Success response with transaction count
    ↓
Transactions appear in bank account
```

#### Payment Recording
```
User clicks "Record Payment" button
    ↓
Modal form opens
    ↓
User enters payment details
    ↓
User submits form
    ↓
Payment endpoint creates payment record
    ↓
Invoice balances updated
    ↓
Invoice status updated
    ↓
Modal closes, page refreshes
```

## API Reference

### Parse CSV
```bash
POST /api/bank-transactions/parse-csv
Content-Type: multipart/form-data

file: [CSV file]
```

Response:
```json
{
  "success": true,
  "count": 100,
  "transactions": [
    {
      "transactionDate": "2024-01-15",
      "description": "Office Supplies",
      "transactionType": "DEBIT",
      "amount": 150.50
    }
  ]
}
```

### Import Transactions
```bash
POST /api/bank-transactions/import
Content-Type: application/json

{
  "bankAccountId": "uuid",
  "transactions": [...]
}
```

Response:
```json
{
  "success": true,
  "imported": 100,
  "message": "Successfully imported 100 transaction(s)"
}
```

### Record Payment
```bash
POST /api/payments
Content-Type: application/json

{
  "paymentDate": "2024-01-20",
  "paymentMethod": "ACH",
  "paymentAmount": 1500.00,
  "customerId": "uuid",
  "invoiceId": "uuid",
  "paymentAllocations": [...]
}
```

Response: Created payment object with payment number and allocations

## Development Workflow

### 1. Testing CSV Import

**Prepare Test Data:**
1. Create or download CSV file (see EXAMPLE_CSVs.md)
2. Ensure correct format with Date, Description, Amount columns
3. Verify bank account exists in system

**Test Parse Endpoint:**
```bash
curl -X POST http://localhost:3000/api/bank-transactions/parse-csv \
  -F "file=@test.csv"
```

**Test Import Endpoint:**
```bash
curl -X POST http://localhost:3000/api/bank-transactions/import \
  -H "Content-Type: application/json" \
  -d '{
    "bankAccountId": "your-account-id",
    "transactions": [... parsed transactions ...]
  }'
```

### 2. Testing Payment Recording

**Manual Testing:**
1. Log into application
2. Navigate to AR invoices
3. Click on any open invoice
4. Click "Record Payment" button
5. Enter payment details
6. Submit form
7. Verify invoice status updates

**Test with Query Parameter:**
```
/finance/ar/invoice/{invoiceId}?action=payment
```
Should auto-open payment modal.

### 3. Frontend Integration

Build the CSV import UI using FRONTEND_INTEGRATION_GUIDE.md as reference:
- File upload component
- CSV preview table
- Bank account selector
- Import confirmation

## CSV Format Examples

### Format 1: Date, Description, Amount
```csv
Date,Description,Amount
2024-01-15,Office Supplies,150.50
2024-01-16,Client Payment,2500.00
```

### Format 2: Date, Description, Debit, Credit
```csv
Date,Description,Debit,Credit
2024-01-15,Office Supplies,150.50,0
2024-01-16,Client Payment,0,2500.00
```

### Format 3: With Quoted Descriptions
```csv
Date,Description,Amount
2024-01-15,"Office Supplies, Inc., Springfield",150.50
2024-01-16,"Client Payment, Invoice #INV-123",2500.00
```

See EXAMPLE_CSVs.md for more examples and bank-specific formats.

## Common Issues & Troubleshooting

### CSV Not Parsing
- Check column headers (Date, Description required)
- Verify file is valid CSV format
- Check for special characters in descriptions
- Ensure amounts are numeric without currency symbols

### Import Fails
- Verify bank account ID is correct
- Check organization ownership
- Validate transaction types are DEBIT or CREDIT
- Ensure amounts are positive numbers

### Payment Not Recording
- Verify customer exists
- Verify invoice exists and belongs to customer
- Check invoice status (some statuses may be readonly)
- Verify payment amount is greater than 0

### Modal Not Opening
- Check URL has `?action=payment` query parameter
- Verify invoice detail page loads successfully
- Check browser console for JavaScript errors
- Clear browser cache and reload

## Performance Considerations

### CSV Import
- Supports files up to 10MB (50,000+ transactions)
- Bulk import in single database operation
- No row-by-row processing overhead
- Consider pagination for preview if 1000+ transactions

### Payment Recording
- Modal form lightweight component
- Single API call per payment
- Invoice refetch may take few seconds
- Fallback to page refresh if needed

## Security Notes

### Authentication
- All endpoints require valid session
- Organization isolation enforced
- Bank account ownership verified

### Input Validation
- Transaction amounts must be positive
- Transaction types must be valid enum
- Bank account must belong to organization
- Customer and invoice must exist and match organization

### Data Protection
- CSV data validated before import
- Transactions created with status PENDING
- Organization ID required for all queries
- Proper HTTP status codes for errors

## Future Enhancements

1. **CSV Column Mapping**
   - Allow users to map custom CSV columns
   - Save mappings for future imports

2. **Batch Payment Import**
   - Import payments from CSV
   - Auto-match to invoices
   - Reconciliation matching

3. **Payment Verification**
   - Confirm payment details (routing numbers, etc.)
   - Store payment references
   - Payment reconciliation workflow

4. **Webhook Support**
   - Receive payment notifications
   - Auto-create payment records
   - Real-time reconciliation

5. **Advanced Reporting**
   - Import history and audit trail
   - Failed transaction log
   - Reconciliation reports

## Support & Questions

For questions about implementation, refer to:
1. **API_ENDPOINTS.md** - API specifications
2. **IMPLEMENTATION_SUMMARY.md** - Technical details
3. **FRONTEND_INTEGRATION_GUIDE.md** - Code examples
4. **EXAMPLE_CSVs.md** - CSV format guide

All code follows existing ERP platform patterns and conventions.