# Temporal Logic Test Scenarios

## Test Case 1: Add New Product

### Frontend Behavior:
- **Default valid_from**: Today's date (e.g., 2025-01-15)
- **User constraint**: Can edit to any date <= today
- **Date picker**: max="2025-01-15", no min restriction

### API Call:
```json
POST /products/
{
  "name": "New Milk",
  "category_id": 1,
  "weight": 1000,
  "valid_from": "2025-01-10"  // User chose 5 days ago
}
```

### Backend Validation:
- ✅ valid_from <= today (2025-01-10 <= 2025-01-15)

### Database Result:
```sql
products: id=1, name="New Milk", weight=1000, valid_from='2025-01-10', valid_to='9999-12-31'
```

---

## Test Case 2: Edit Existing Product

### Current State:
```sql
products: id=1, name="Milk", weight=1000, valid_from='2025-01-10', valid_to='9999-12-31'
```

### Frontend Behavior:
- **Fetch current valid_from**: API call to `/products/1/valid-from` → "2025-01-10"
- **Default valid_from**: Today's date (2025-01-15)
- **User constraint**: Can edit to any date > 2025-01-10 AND <= today
- **Date picker**: min="2025-01-10", max="2025-01-15"

### API Call:
```json
PUT /products/1
{
  "weight": 1200,
  "valid_from": "2025-01-12"  // User chose 2 days after current valid_from
}
```

### Backend Validation:
- ✅ valid_from <= today (2025-01-12 <= 2025-01-15)
- ✅ valid_from > current_valid_from (2025-01-12 > 2025-01-10)

### Backend Processing:
1. **Manual versioning** (since valid_from was specified):
   - Create history record with old data
   - Set history.valid_to = new.valid_from

### Database Result:
```sql
-- History table gets the old version
products_history: 
  id=1, name="Milk", weight=1000, 
  valid_from='2025-01-10', valid_to='2025-01-12', operation='U'

-- Current table gets updated version  
products: 
  id=1, name="Milk", weight=1200, 
  valid_from='2025-01-12', valid_to='9999-12-31'
```

---

## Test Case 3: Edit Without Custom Date (Automatic Versioning)

### Current State:
```sql
products: id=1, name="Milk", weight=1200, valid_from='2025-01-12', valid_to='9999-12-31'
```

### API Call (no valid_from specified):
```json
PUT /products/1
{
  "name": "Organic Milk"
}
```

### Backend Processing:
1. **Automatic versioning** (trigger handles it):
   - Trigger detects OLD.valid_from = NEW.valid_from
   - Trigger creates history with valid_to = CURRENT_DATE
   - Trigger sets NEW.valid_from = CURRENT_DATE

### Database Result:
```sql
-- History table gets the old version (trigger created)
products_history: 
  id=1, name="Milk", weight=1200, 
  valid_from='2025-01-12', valid_to='2025-01-15', operation='U'

-- Current table gets updated version (trigger set dates)
products: 
  id=1, name="Organic Milk", weight=1200, 
  valid_from='2025-01-15', valid_to='9999-12-31'
```

---

## Validation Rules Summary

### For New Products:
- ✅ Frontend: valid_from <= today
- ✅ Backend: valid_from <= today

### For Existing Products:
- ✅ Frontend: current_valid_from < valid_from <= today  
- ✅ Backend: current_valid_from < valid_from <= today
- ✅ Manual versioning: history.valid_to = new.valid_from
- ✅ Automatic versioning: history.valid_to = CURRENT_DATE

### Database Trigger Logic:
- **Manual versioning**: When OLD.valid_from ≠ NEW.valid_from (app handles history)
- **Automatic versioning**: When OLD.valid_from = NEW.valid_from (trigger handles history)