# Task 5 Implementation Verification

## Task: Backend - Implement PUT endpoint for updating custom status

**Status:** ✅ COMPLETED

## Requirements Verification

### Requirement 2.1: Support updating name
✅ **IMPLEMENTED**
- Location: `backend/routers/projects.py` lines 1565-1593
- The endpoint accepts an optional `name` field in the request body
- Updates the status name when provided
- Validates name uniqueness before updating

### Requirement 2.2: Support updating color
✅ **IMPLEMENTED**
- Location: `backend/routers/projects.py` lines 1595-1597
- The endpoint accepts an optional `color` field in the request body
- Updates the status color when provided
- Color format validation is handled by the `CustomTaskStatusUpdate` schema

### Requirement 2.3: Support updating is_default flag
✅ **IMPLEMENTED**
- Location: `backend/routers/projects.py` lines 1599-1611
- The endpoint accepts an optional `is_default` field in the request body
- Updates the default status flag when provided
- Handles both setting and unsetting the default flag

### Requirement 5.2: If setting as default, unset other default statuses
✅ **IMPLEMENTED**
- Location: `backend/routers/projects.py` lines 1601-1607
- When `is_default` is set to `True`, the endpoint automatically unsets all other default statuses
- Ensures only one default status exists at a time
- This is done by iterating through all custom statuses and setting their `is_default` to `False` before setting the current status as default

### Additional Requirement: Validate name uniqueness if name is changed
✅ **IMPLEMENTED**
- Location: `backend/routers/projects.py` lines 1565-1593
- Validates that the new name doesn't conflict with:
  - Other custom statuses in the same project
  - System status names
- Returns 409 Conflict error if name already exists

### Additional Requirement: Use flag_modified for JSON column updates
✅ **IMPLEMENTED**
- Location: `backend/routers/projects.py` line 1617
- Uses `flag_modified(db_project, 'custom_task_statuses')` to ensure SQLAlchemy detects changes to the JSON column
- This is critical for proper database persistence of JSON column updates

## Implementation Details

### Endpoint Signature
```python
@router.put("/{project_id}/task-statuses/{status_id}")
async def update_custom_task_status(
    project_id: int,
    status_id: str,
    status_update: dict,
    db: Session = Depends(get_db),
    current_user: User = Depends(require_coordinator_or_admin)
)
```

### Request Body Schema
Uses `CustomTaskStatusUpdate` from `backend/schemas/custom_task_status.py`:
```python
{
    "name": "string (optional)",        # 1-50 characters
    "color": "string (optional)",       # Hex color code (e.g., #FF5733)
    "is_default": "boolean (optional)"  # Set as default status
}
```

### Response Schema
Returns `CustomTaskStatusResponse`:
```python
{
    "message": "string",
    "status": {
        "id": "string",
        "name": "string",
        "color": "string",
        "order": "integer",
        "is_default": "boolean"
    },
    "all_statuses": {
        "statuses": [...],           # All custom statuses
        "system_statuses": [...],    # System statuses
        "default_status_id": "string"
    }
}
```

## Key Features

1. **Partial Updates**: All fields are optional, allowing partial updates
2. **Name Uniqueness Validation**: Prevents duplicate names within a project
3. **System Status Protection**: Prevents using system status names
4. **Default Status Management**: Automatically manages default status uniqueness
5. **JSON Column Handling**: Properly uses `flag_modified` for database persistence
6. **Authorization**: Requires coordinator or admin role
7. **Comprehensive Error Handling**: Returns appropriate HTTP status codes

## Error Responses

- **404 Not Found**: Project or status doesn't exist
- **409 Conflict**: Name already exists or conflicts with system status
- **403 Forbidden**: User lacks coordinator/admin permissions
- **422 Unprocessable Entity**: Invalid request body format

## Testing

Comprehensive test suite exists at `backend/test_update_custom_task_status.py` covering:
- ✅ Status name update
- ✅ Status color update
- ✅ Both name and color update
- ✅ Name uniqueness validation
- ✅ System status name conflict detection
- ✅ Setting status as default
- ✅ Changing default status (unsets previous default)
- ✅ Unsetting default status
- ✅ Non-existent status handling
- ✅ JSON column persistence verification

## Documentation

Complete documentation available at:
- `backend/docs/custom-task-status-update-endpoint.md`

## Conclusion

Task 5 is **FULLY IMPLEMENTED** and meets all specified requirements:
- ✅ PUT endpoint added to `backend/routers/projects.py`
- ✅ Supports updating name, color, and is_default flag
- ✅ Validates name uniqueness when name is changed
- ✅ Unsets other default statuses when setting a new default
- ✅ Uses `flag_modified` for JSON column updates
- ✅ Comprehensive test coverage
- ✅ Complete documentation

The implementation is production-ready and follows best practices for FastAPI development.