from cryptography.fernet import Fernet

from app.config import settings

_fernet: Fernet | None = (
    Fernet(settings.token_encryption_key.encode()) if settings.token_encryption_key else None
)


def _require_fernet() -> Fernet:
    if _fernet is None:
        raise RuntimeError("TOKEN_ENCRYPTION_KEY is not configured")
    return _fernet


def encrypt(value: str | None) -> str | None:
    if value is None:
        return None
    return _require_fernet().encrypt(value.encode()).decode()


def decrypt(value: str | None) -> str | None:
    if value is None:
        return None
    return _require_fernet().decrypt(value.encode()).decode()