"""Date and time utilities for API analysis."""

from datetime import datetime, timedelta, timezone


def get_date_range(days: int) -> tuple[str, str]:
    """Calculate date range from current time.

    Args:
        days: Number of days to go back from now

    Returns:
        Tuple of (starting_at, ending_at) in ISO 8601 format
    """
    ending_at_dt = datetime.now(timezone.utc)
    starting_at_dt = ending_at_dt - timedelta(days=days)

    starting_at = starting_at_dt.isoformat().replace('+00:00', 'Z')
    ending_at = ending_at_dt.isoformat().replace('+00:00', 'Z')

    return starting_at, ending_at


def normalize_time_period(timestamp: str, grouping: str) -> str:
    """Normalize timestamp to time period string.

    Args:
        timestamp: ISO 8601 timestamp
        grouping: Time grouping ('day' or 'month')

    Returns:
        Normalized time period string (e.g., '2025-10-10' or '2025-10')
    """
    if not timestamp:
        return 'unknown'

    try:
        dt = datetime.fromisoformat(timestamp.replace('Z', '+00:00'))

        if grouping == 'day':
            return dt.strftime('%Y-%m-%d')
        elif grouping == 'month':
            return dt.strftime('%Y-%m')
        else:
            return 'total'
    except Exception:
        return 'unknown'