"""Schema helpers."""

from datetime import date
from datetime import datetime


def convert_to_date(value: datetime | date | None) -> date | None:
    """Ensure that the value is a date, converting if need be.

    Args:
        value (datetime | date | None): Value to validate
    Returns:
        date | None: Validated date
    Raises:
        ValueError: If the value isn't convertable to date
    """
    if isinstance(value, datetime):
        return value.date()
    if isinstance(value, date) or value is None:
        return value
    if isinstance(value, str):
        return datetime.strptime(value, '%Y-%m-%d').date()

    raise ValueError(f"'{value}' is not a date-ish value")