"""Domain exceptions for Aegis business logic.

These exceptions are raised by service-layer code and automatically
mapped to HTTP responses by the error-handler middleware registered
in ``app.main``.  This keeps the service layer free from any HTTP
or framework coupling.
"""


class DomainException(Exception):
    """Base for all domain exceptions."""

    def __init__(self, message: str, code: str = "DOMAIN_ERROR"):
        self.message = message
        self.code = code
        super().__init__(message)


class EntityNotFoundError(DomainException):
    """Raised when a requested entity does not exist."""

    def __init__(self, entity: str, identifier: str):
        super().__init__(f"{entity} not found: {identifier}", "NOT_FOUND")
        self.entity = entity
        self.identifier = identifier


class DuplicateEntityError(DomainException):
    """Raised when creating an entity that already exists."""

    def __init__(self, entity: str, field: str, value: str):
        super().__init__(
            f"{entity} with {field}='{value}' already exists",
            "DUPLICATE",
        )


class InvalidTransitionError(DomainException):
    """Raised when a state-machine transition is not allowed."""

    def __init__(
        self,
        current_state: str,
        target_state: str,
        valid_transitions: list[str] | None = None,
    ):
        msg = f"Cannot transition from '{current_state}' to '{target_state}'"
        if valid_transitions:
            msg += f". Valid transitions: {valid_transitions}"
        super().__init__(msg, "INVALID_TRANSITION")
        self.current_state = current_state
        self.target_state = target_state
        self.valid_transitions = valid_transitions or []


class InvalidOperationError(DomainException):
    """Raised when an operation is invalid in the current context."""

    def __init__(self, message: str):
        super().__init__(message, "INVALID_OPERATION")


class AuthorizationError(DomainException):
    """Raised when the user lacks permissions for an action."""

    def __init__(self, message: str = "Insufficient permissions"):
        super().__init__(message, "FORBIDDEN")