"""Shared utilities for Video Library Manager."""

from datetime import datetime, timezone


def utc_now() -> datetime:
    """Return current UTC time (timezone-aware)."""
    return datetime.now(timezone.utc)


def ensure_utc(dt: datetime) -> datetime:
    """Ensure datetime is timezone-aware UTC (for backward compatibility with naive ISO strings)."""
    if dt.tzinfo is None:
        return dt.replace(tzinfo=timezone.utc)
    return dt.astimezone(timezone.utc)


def format_size(size_bytes: int) -> str:
    """Format file size in human-readable format (e.g. 1.5 GB, 234.2 MB)."""
    for unit in ["B", "KB", "MB", "GB", "TB"]:
        if size_bytes < 1024.0:
            return f"{size_bytes:.1f} {unit}"
        size_bytes /= 1024.0
    return f"{size_bytes:.1f} PB"