"""
Date utility functions for TODO MCP server.
"""

from datetime import datetime, timedelta
from typing import Optional


def parse_relative_date(relative_days: int) -> str:
    """
    Convert a relative day offset to an absolute date string.

    Args:
        relative_days: Number of days relative to today
                      0 = today
                      +1 = tomorrow
                      -1 = yesterday
                      +7 = one week from now

    Returns:
        Date string in YYYY-MM-DD format

    Examples:
        >>> parse_relative_date(0)  # today
        '2025-12-18'
        >>> parse_relative_date(1)  # tomorrow
        '2025-12-19'
        >>> parse_relative_date(-1)  # yesterday
        '2025-12-17'
    """
    target_date = datetime.now() + timedelta(days=relative_days)
    return target_date.strftime("%Y-%m-%d")


def get_date_for_query(relative_days: Optional[int]) -> Optional[str]:
    """
    Convert relative days to date string for queries, or return None if not specified.

    Args:
        relative_days: Optional relative day offset

    Returns:
        Date string in YYYY-MM-DD format, or None if relative_days is None
    """
    if relative_days is None:
        return None
    return parse_relative_date(relative_days)