from datetime import datetime, timezone
from typing import Optional


def parse_hs_date(value: Optional[str]) -> Optional[datetime]:
    if not value:
        return None
    try:
        dt = datetime.fromisoformat(value.replace("Z", "+00:00"))

        if dt.tzinfo is None:
            return dt.replace(tzinfo=timezone.utc)

        return dt.astimezone(timezone.utc)
    except ValueError:
        return None