from datetime import datetime, timezone
from typing import Any, Optional

UTC = timezone.utc


def utcnow() -> datetime:
    return datetime.now(tz=UTC)


def isoformat(dt: Optional[datetime]) -> Optional[str]:
    if dt is None:
        return None
    return dt.astimezone(UTC).isoformat()


def parse_datetime(value: Optional[str]) -> Optional[datetime]:
    if not value:
        return None
    return datetime.fromisoformat(value)


def parse_int(value: Any, default: int) -> int:
    try:
        return int(value)
    except (TypeError, ValueError):
        return default