from __future__ import annotations

from datetime import datetime, timedelta, timezone

# India Standard Time is a fixed UTC+05:30 offset (no DST).
IST = timezone(timedelta(hours=5, minutes=30))


def now_ist() -> datetime:
    """Return a timezone-aware datetime in IST."""
    return datetime.now(IST)


def ensure_ist(value: datetime) -> datetime:
    """Coerce a datetime to IST.

    If naive, assume it represents IST wall-clock time.

    Note: SQLite often strips tzinfo even when timezone-aware datetimes are provided.
    """
    if value.tzinfo is None:
        value = value.replace(tzinfo=IST)
    return value.astimezone(IST)


def iso_now_ist() -> str:
    """Return an ISO-8601 timestamp string in IST, truncated to seconds."""
    return now_ist().replace(microsecond=0).isoformat()