## Implementation Analysis

* Code style reference examples
    * Service layer pattern: `services/user_service.py`
    * View layer style: `views/user_views.py`
    * Model usage: How to use `User.objects.filter()`
    * Exception handling: Using custom Exception classes
* Implementation details
    * Create `services/auth_service.py` containing `AuthService` class
    * Implement `authenticate()` and `register_user()` methods
    * Content to move includes:
        * Password validation logic
        * JWT token generation logic
        * User registration validation (email format, password strength, etc.)
        * Database queries and user creation
    * Service layer returns `ServiceResult` object (using dataclass)
    * View layer retains:
        * HTTP request parameter retrieval and basic validation
        * Calling service layer methods
        * Returning HTTP responses based on service layer results (200/400/401/500)
    * No database migration needed, no API format changes needed
* Data format examples
    ```python
    # Service layer returned object structure
    @dataclass
    class ServiceResult:
        success: bool
        data: Optional[Dict[str, Any]] = None
        error: Optional[str] = None
        error_code: Optional[str] = None

    # Login success example
    ServiceResult(
        success=True,
        data={
            'user_id': 123,
            'username': 'john_doe',
            'token': 'eyJhbGciOiJIUzI1NiIs...',
            'expires_at': 1728012345
        }
    )

    # Login failure example
    ServiceResult(
        success=False,
        error='Invalid credentials',
        error_code='AUTH_INVALID_CREDENTIALS'
    )

    # View layer JSON response (maintain existing format)
    {
        "success": true,
        "data": {
            "user_id": 123,
            "username": "john_doe",
            "token": "eyJhbGciOiJIUzI1NiIs...",
            "expires_at": 1728012345
        }
    }
    ```

### 📋 Development Task Breakdown

#### Task 1: Create service layer foundation
- [ ] **Dev 1.1**: Create `services/auth_service.py`, define `AuthService` class
- [ ] **Dev 1.2**: Create `services/models.py`, define `ServiceResult` dataclass
- [ ] **Dev 1.3**: Create `services/exceptions.py`, define custom exception classes
- [ ] **commit**: Write commit message strictly following existing commit message style
- [ ] **Update**: Check completed items, update md file if necessary

#### Task 2: Implement authentication business logic
- [ ] **Dev 2.1**: Implement `AuthService.authenticate()` method
- [ ] **Dev 2.2**: Move password validation logic to service layer
- [ ] **Dev 2.3**: Move JWT token generation logic to service layer
- [ ] **commit**: Write commit message strictly following existing commit message style
- [ ] **Update**: Check completed items, update md file if necessary

#### Task 3: Implement registration business logic
- [ ] **Dev 3.1**: Implement `AuthService.register_user()` method
- [ ] **Dev 3.2**: Move email and password validation logic
- [ ] **Dev 3.3**: Move user creation logic
- [ ] **commit**: Write commit message strictly following existing commit message style
- [ ] **Update**: Check completed items, update md file if necessary

#### Task 4: Refactor View layer
- [ ] **Dev 4.1**: Modify `login_view()` to call service layer methods
- [ ] **Dev 4.2**: Modify `register_view()` to call service layer methods
- [ ] **Dev 4.3**: Simplify view layer logic, keep only HTTP handling
- [ ] **commit**: Write commit message strictly following existing commit message style
- [ ] **Update**: Check completed items, update md file if necessary

#### Task 5: Write comprehensive tests
- [ ] **Dev 5.1**: Create `tests/unit/test_auth_service.py`
- [ ] **Dev 5.2**: Test `authenticate()` method (success/failure scenarios)
- [ ] **Dev 5.3**: Test `register_user()` method (various validation scenarios)
- [ ] **Dev 5.4**: Test edge cases and exception handling
- [ ] **Dev 5.5**: Run integration tests to ensure API behavior unchanged
- [ ] **commit**: Write commit message strictly following existing commit message style
- [ ] **Update**: Check completed items, update md file if necessary
