"""Domain exceptions for business logic errors.

This module defines the exception hierarchy for domain layer errors.
All domain exceptions inherit from DomainException base class.
"""


class DomainException(Exception):
    """Base exception for domain layer.

    All domain-specific exceptions should inherit from this class.
    Provides a consistent interface for error messages.

    Attributes:
        message: Human-readable error description.

    Example:
        >>> raise DomainException("Business rule violated")
    """

    def __init__(self, message: str) -> None:
        """Initialize domain exception.

        Args:
            message: Error message describing the exception.
        """
        self.message = message
        super().__init__(self.message)


class ValidationException(DomainException):
    """Raised when validation fails.

    Used when entity or value object validation does not pass.

    Example:
        >>> raise ValidationException("Title is too long")
    """


class NotFoundException(DomainException):
    """Raised when an entity is not found.

    Used when requesting an entity that does not exist in the repository.

    Example:
        >>> raise NotFoundException("Post with id 123 not found")
    """


class AlreadyExistsException(DomainException):
    """Raised when trying to create an entity that already exists.

    Used when attempting to create a duplicate entity.

    Example:
        >>> raise AlreadyExistsException("Post with this slug already exists")
    """


class UnauthorizedException(DomainException):
    """Raised when user is not authorized.

    Used when authentication is required but not provided or invalid.

    Example:
        >>> raise UnauthorizedException("Authentication required")
    """


class ForbiddenException(DomainException):
    """Raised when access is forbidden.

    Used when authenticated user lacks required permissions.

    Example:
        >>> raise ForbiddenException("Only admins can delete posts")
    """