arbret/backend/exceptions.py

"""Standardized API exception classes for consistent error responses.

Note: These exceptions use string detail for backward compatibility with existing tests.
Future refactoring could standardize on structured error responses.
"""

from fastapi import HTTPException, status


class APIError(HTTPException):
    """Base API error with consistent structure.

    Uses string detail for backward compatibility with existing tests.
    """

    def __init__(
        self,
        status_code: int,
        message: str,
    ):
        super().__init__(status_code=status_code, detail=message)


class NotFoundError(APIError):
    """Resource not found error (404)."""

    def __init__(self, resource: str):
        super().__init__(
            status_code=status.HTTP_404_NOT_FOUND,
            message=f"{resource} not found",
        )


class ConflictError(APIError):
    """Conflict error (409)."""

    def __init__(self, message: str):
        super().__init__(
            status_code=status.HTTP_409_CONFLICT,
            message=message,
        )


class BadRequestError(APIError):
    """Bad request error (400)."""

    def __init__(self, message: str):
        super().__init__(
            status_code=status.HTTP_400_BAD_REQUEST,
            message=message,
        )


class UnauthorizedError(APIError):
    """Unauthorized error (401)."""

    def __init__(self, message: str = "Not authenticated"):
        super().__init__(
            status_code=status.HTTP_401_UNAUTHORIZED,
            message=message,
        )


class ServiceUnavailableError(APIError):
    """Service unavailable error (503)."""

    def __init__(self, message: str):
        super().__init__(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            message=message,
        )


class ValidationError(HTTPException):
    """Validation error (422) with field-specific errors."""

    def __init__(self, message: str, field_errors: dict[str, str] | None = None):
        detail: dict[str, str | dict[str, str]] = {"message": message}
        if field_errors:
            detail["field_errors"] = field_errors
        super().__init__(
            status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
            detail=detail,
        )