"""Date utility functions for todo management."""

from datetime import datetime, timezone, timedelta
from typing import Tuple, Optional


def get_timezone_aware_now() -> datetime:
    """Get current time in UTC timezone."""
    return datetime.now(timezone.utc)


def get_date_range_today() -> Tuple[datetime, datetime]:
    """Get start and end of today in UTC."""
    now = get_timezone_aware_now()
    start_of_day = now.replace(hour=0, minute=0, second=0, microsecond=0)
    end_of_day = now.replace(hour=23, minute=59, second=59, microsecond=999999)
    return start_of_day, end_of_day


def get_date_range_this_week() -> Tuple[datetime, datetime]:
    """Get start and end of current week (Monday to Sunday) in UTC."""
    now = get_timezone_aware_now()
    start_of_week = now - timedelta(days=now.weekday())
    start_of_week = start_of_week.replace(hour=0, minute=0, second=0, microsecond=0)
    end_of_week = start_of_week + timedelta(
        days=6, hours=23, minutes=59, seconds=59, microseconds=999999
    )
    return start_of_week, end_of_week


def get_date_range_next_week() -> Tuple[datetime, datetime]:
    """Get start and end of next week (Monday to Sunday) in UTC."""
    now = get_timezone_aware_now()
    days_until_next_monday = 7 - now.weekday()
    start_of_next_week = now + timedelta(days=days_until_next_monday)
    start_of_next_week = start_of_next_week.replace(
        hour=0, minute=0, second=0, microsecond=0
    )
    end_of_next_week = start_of_next_week + timedelta(
        days=6, hours=23, minutes=59, seconds=59, microseconds=999999
    )
    return start_of_next_week, end_of_next_week


def get_date_range_next_days(days: int) -> Tuple[datetime, datetime]:
    """Get start and end of next N days in UTC."""
    now = get_timezone_aware_now()
    start_time = now
    end_time = now + timedelta(days=days)
    return start_time, end_time


def get_overdue_cutoff() -> datetime:
    """Get cutoff datetime for overdue todos (current time)."""
    return get_timezone_aware_now()


def get_due_soon_cutoff(days: int = 7) -> datetime:
    """Get cutoff datetime for due soon todos (next N days)."""
    return get_timezone_aware_now() + timedelta(days=days)


def is_overdue(due_date: Optional[datetime], completed: bool = False) -> bool:
    """Check if a todo is overdue."""
    if due_date is None or completed:
        return False
    return get_timezone_aware_now() > due_date


def is_due_today(due_date: Optional[datetime]) -> bool:
    """Check if a todo is due today."""
    if due_date is None:
        return False
    today_start, today_end = get_date_range_today()
    return today_start <= due_date <= today_end


def is_due_soon(
    due_date: Optional[datetime], days: int = 7, completed: bool = False
) -> bool:
    """Check if a todo is due within the next N days."""
    if due_date is None or completed:
        return False
    cutoff = get_due_soon_cutoff(days)
    now = get_timezone_aware_now()
    return now <= due_date <= cutoff