"""Context variables for tracking request-specific data."""

from contextlib import contextmanager
from contextvars import ContextVar, Token
from typing import Generator, Literal, overload

from . import constants
from .errors import ERROR_CTX_USER_ID_NOT_SET

ctx_user_id: ContextVar[str | None] = ContextVar('user_id', default=None)


@overload
def get_user_id(strict: Literal[True]) -> str: ...
@overload
def get_user_id(strict: Literal[False] | None = None) -> str | None: ...
def get_user_id(strict: bool | None = None) -> str | None:
    """Get the current user ID from context.

    Args:
         strict:
             If `True`, raises error when `user_id` is `None`.
             If `False`, returns `None` silently.
             If `None` (default), uses `STRICT_CONTEXT_VALIDATION` setting.
    """
    use_strict = constants.STRICT_CONTEXT_VALIDATION if strict is None else strict
    user_id = ctx_user_id.get()
    if user_id is None and use_strict:
        raise ValueError(ERROR_CTX_USER_ID_NOT_SET)
    return user_id


@contextmanager
def set_user_context(user_id: str | None) -> Generator[None, None, None]:
    """Context manager to temporarily set user ID.

    Usage:
    ```python
    with set_user_context('user_123'):
        model.soft_delete()  # Automatically tracked to user_123
    ```
    """
    token = ctx_user_id.set(user_id)
    try:
        yield
    finally:
        ctx_user_id.reset(token)


def set_user_id(user_id: str | None) -> Token[str | None]:
    """Set the context user ID."""
    return ctx_user_id.set(user_id)