import contextvars
import logging

_tracking_id: contextvars.ContextVar[str] = contextvars.ContextVar("tracking_id", default="")


def set_tracking_id(task_id: str) -> contextvars.Token:
    return _tracking_id.set(task_id)


def get_tracking_id() -> str:
    return _tracking_id.get()


class TrackingFilter(logging.Filter):
    """Logging filter that injects the current tracking ID into every log record."""

    def filter(self, record: logging.LogRecord) -> bool:
        tid = _tracking_id.get()
        record.tracking_id = f"[{tid}] " if tid else ""
        return True