import contextlib
from collections.abc import Iterator

from sqlalchemy.orm import Session


class SessionMixin:
    _session: Session | None = None

    @contextlib.contextmanager
    def _set_session(self, session: Session) -> Iterator[None]:
        """Set the current session."""
        self._session = session
        try:
            yield
        finally:
            self._session = None

    def _get_session(self) -> Session:
        """Get the current session."""
        if self._session is None:
            raise LookupError("Session is not started.")
        return self._session

    def _has_session(self) -> bool:
        """Check if the current session is started."""
        return self._session is not None