# Penalty System - Implementation Summary

## What Was Implemented

A comprehensive penalty system for loan management with both automatic and manual penalty application capabilities.

## Key Features

### 1. Dual Penalty Modes
- **Automatic**: System applies penalties daily via Celery tasks
- **Manual**: Admins apply penalties through the UI

### 2. Flexible Penalty Frequencies
- Daily penalties (e.g., 2% per day)
- Weekly penalties (e.g., 5% per week)
- Monthly penalties (e.g., 10% per month)

### 3. Smart Penalty Tracking
- Distinguishes between automatic and manual penalties
- Records who applied manual penalties
- Stores reason for each penalty
- Prevents duplicate penalties on same day
- Complete audit trail

### 4. User-Friendly Interface
- Enhanced loan detail page with penalty section
- Modal for easy penalty application
- Suggested penalty calculations
- Visual indicators for penalty type (Auto/Manual)
- Penalty history view

## Files Created/Modified

### New Files
1. `loans/migrations/0016_add_penalty_mode.py` - Database migration
2. `loans/tasks.py` - Celery tasks for automatic penalties
3. `loans/penalty_views.py` - Views for penalty management
4. `branch_system/celery.py` - Celery configuration
5. `branch_system/__init__.py` - Celery app initialization
6. `templates/loans/penalty_section.html` - Enhanced penalty UI
7. `setup_penalty_system.py` - Setup script
8. `PENALTY_SYSTEM_IMPLEMENTATION.md` - Full documentation
9. `PENALTY_SYSTEM_QUICK_REFERENCE.md` - Quick reference guide

### Modified Files
1. `loans/models.py` - Added penalty fields to LoanProduct and PenaltyCharge
2. `loans/urls.py` - Added penalty management routes
3. `payments/views.py` - Updated manual payment matching to use loans
4. `templates/payments/callbacks.html` - Updated to show loan selection

## Database Changes

### LoanProduct Table
```sql
ALTER TABLE loan_products ADD COLUMN penalty_mode VARCHAR(10) DEFAULT 'auto';
ALTER TABLE loan_products ADD COLUMN penalty_frequency VARCHAR(10) DEFAULT 'daily';
```

### PenaltyCharge Table
```sql
ALTER TABLE penalty_charges ADD COLUMN is_automatic BOOLEAN DEFAULT TRUE;
ALTER TABLE penalty_charges ADD COLUMN applied_by_id UUID NULL;
ALTER TABLE penalty_charges ADD COLUMN reason TEXT;
```

## Setup Steps

### 1. Run Migrations
```bash
python manage.py migrate
```

### 2. Configure Loan Products
```bash
python setup_penalty_system.py
```

### 3. Install Dependencies
```bash
pip install celery redis
```

### 4. Start Services
```bash
# Terminal 1: Redis
redis-server

# Terminal 2: Celery Worker
celery -A branch_system worker -l info

# Terminal 3: Celery Beat
celery -A branch_system beat -l info
```

## How It Works

### Automatic Penalties

1. **Celery Beat** triggers `apply_automatic_penalties` task daily at 1:00 AM
2. Task finds all active overdue loans with `penalty_mode='auto'`
3. Calculates penalty based on:
   - Outstanding amount
   - Penalty rate
   - Days/weeks/months overdue
   - Penalty frequency
4. Creates PenaltyCharge record with `is_automatic=True`
5. Creates audit log entry
6. Prevents duplicate penalties on same day

### Manual Penalties

1. Admin navigates to overdue loan
2. Clicks "Apply Penalty" button
3. System shows suggested penalty amount
4. Admin enters amount and reason
5. System creates PenaltyCharge with `is_automatic=False`
6. Records admin who applied penalty
7. Creates audit log entry

## Penalty Calculation Examples

### Daily Penalty (Boost)
- Outstanding: KES 10,000
- Rate: 2% daily
- Days overdue: 5
- **Penalty: KES 1,000** (10,000 × 0.02 × 5)

### Weekly Penalty (Mwamba)
- Outstanding: KES 50,000
- Rate: 5% weekly
- Days overdue: 14 (2 weeks)
- **Penalty: KES 5,000** (50,000 × 0.05 × 2)

### Monthly Penalty (Imara)
- Outstanding: KES 100,000
- Rate: 10% monthly
- Days overdue: 45 (2 months)
- **Penalty: KES 20,000** (100,000 × 0.10 × 2)

## User Interface Features

### Loan Detail Page
- Penalty mode badge (Auto/Manual)
- Total penalties display
- Suggested penalty for overdue loans
- List of all penalties with type indicators
- Apply penalty button (staff only)
- Delete button for manual penalties
- View history link

### Apply Penalty Modal
- Pre-filled suggested amount
- Loan information display
- Amount input field
- Reason text area (required)
- Apply/Cancel buttons

### Penalty List
- Amount in red
- Type badge (Auto/Manual)
- Penalty rate and days overdue
- Outstanding amount at time of penalty
- Applied by (for manual penalties)
- Reason (for manual penalties)
- Date and time
- Delete button (manual penalties only)

## API Endpoints

```
POST /loans/<loan_id>/penalty/apply/          - Apply manual penalty
GET  /loans/<loan_id>/penalty/calculate/      - Calculate suggested penalty
GET  /loans/<loan_id>/penalty/history/        - View penalty history
POST /loans/penalty/<penalty_id>/delete/      - Delete manual penalty
```

## Monitoring & Maintenance

### Check System Status
```bash
# Celery workers
celery -A branch_system inspect active

# Recent penalties
SELECT * FROM penalty_charges 
WHERE DATE(applied_date) = CURDATE()
ORDER BY applied_date DESC;
```

### View Logs
- Celery logs: Check terminal output or `/var/log/celery/`
- Audit logs: Admin panel → Audit Logs
- Application logs: Django logs

## Security & Compliance

- ✅ Only staff can apply/delete penalties
- ✅ Complete audit trail for all penalties
- ✅ Automatic penalties cannot be deleted
- ✅ Manual penalties require reason
- ✅ Duplicate prevention on same day
- ✅ All actions logged with user and timestamp

## Testing

### Test Automatic Penalties
```bash
# Dry run
python manage.py apply_penalties --dry-run

# Or in shell
python manage.py shell
>>> from loans.tasks import apply_automatic_penalties
>>> result = apply_automatic_penalties()
>>> print(result)
```

### Test Manual Penalties
1. Create overdue loan
2. Navigate to loan detail
3. Click "Apply Penalty"
4. Enter amount and reason
5. Verify penalty appears in list
6. Check audit log

## Benefits

1. **Automated Compliance**: Ensures penalties are applied consistently
2. **Flexibility**: Supports both automatic and manual workflows
3. **Transparency**: Clear audit trail of all penalties
4. **User-Friendly**: Easy-to-use interface for staff
5. **Configurable**: Different settings per loan product
6. **Scalable**: Handles large numbers of loans efficiently
7. **Reliable**: Prevents duplicates and errors

## Next Steps

1. ✅ Run migrations
2. ✅ Configure loan products
3. ✅ Install Celery and Redis
4. ✅ Start Celery services
5. ✅ Test with sample loans
6. ✅ Monitor for first week
7. ✅ Train staff on manual penalty application
8. ✅ Set up production monitoring

## Support & Documentation

- **Full Guide**: `PENALTY_SYSTEM_IMPLEMENTATION.md`
- **Quick Reference**: `PENALTY_SYSTEM_QUICK_REFERENCE.md`
- **Setup Script**: `setup_penalty_system.py`
- **Code**: `loans/tasks.py`, `loans/penalty_views.py`

---

**Status**: ✅ Fully Implemented  
**Version**: 1.0  
**Date**: March 2026
