"""Input validation utilities."""

import re
from datetime import time
from typing import Optional, Tuple


def validate_time_format(time_str: str) -> Optional[time]:
    """
    Validate and parse time string in HH:MM format.

    Args:
        time_str: Time string to validate

    Returns:
        time object if valid, None otherwise
    """
    # Remove extra whitespace
    time_str = time_str.strip()

    # Check format with regex
    pattern = r'^([0-1]?[0-9]|2[0-3]):([0-5][0-9])$'
    match = re.match(pattern, time_str)

    if not match:
        return None

    try:
        hours = int(match.group(1))
        minutes = int(match.group(2))

        if 0 <= hours <= 23 and 0 <= minutes <= 59:
            return time(hour=hours, minute=minutes)
    except (ValueError, AttributeError):
        pass

    return None


def validate_days_interval(days_str: str) -> Optional[int]:
    """
    Validate and parse days interval.

    Args:
        days_str: Days interval string to validate

    Returns:
        Integer days if valid (>0), None otherwise
    """
    try:
        days = int(days_str.strip())
        if days > 0:
            return days
    except (ValueError, AttributeError):
        pass

    return None


def format_time_for_display(time_obj: time) -> str:
    """
    Format time object for display.

    Args:
        time_obj: time object

    Returns:
        Formatted time string (HH:MM)
    """
    return time_obj.strftime("%H:%M")