from __future__ import annotations

from datetime import date

from app.models import PaymentInfo


def payment_banner(payment: PaymentInfo, today: date | None = None) -> str | None:
    today = today or date.today()
    due = payment.due_date(today.year, today.month)
    days = (due - today).days
    if days < 0:
        next_month = 1 if today.month == 12 else today.month + 1
        next_year = today.year + 1 if today.month == 12 else today.year
        due = payment.due_date(next_year, next_month)
        days = (due - today).days
    if days > 5:
        return None
    if days == 0:
        return f"Сегодня день оплаты · {payment.monthly_price_rub} ₽"
    return f"Оплата через {days} дн. · {due.strftime('%-d.%m')} · {payment.monthly_price_rub} ₽"


def month_key(today: date | None = None) -> str:
    today = today or date.today()
    return f"{today.year:04d}-{today.month:02d}"