import datetime as dt
from typing import Optional

DATE_FORMAT = '%d.%m.%Y'
TODAY = dt.date.today()


class Calculator:

    def __init__(self, limit):
        self.limit = limit
        self.records = []

    def add_record(self, record):
        self.records.append(record)

    def get_today_stats(self):
        return sum(record.amount for record in self.records if
                   record.date == TODAY)

    def get_week_stats(self):
        week_ago = TODAY - dt.timedelta(days=7)
        return sum(record.amount for record in self.records if
                   week_ago < record.date <= TODAY)

    def remained(self):
        return self.limit - self.get_today_stats()


class Record:
    def __init__(self, amount, comment, date: Optional[str] = None):
        self.amount = abs(amount)
        self.comment = comment
        if date is not None:
            self.date = dt.datetime.strptime(date, DATE_FORMAT).date()
        else:
            self.date = dt.date.today()


class CaloriesCalculator(Calculator):
    def get_calories_remained(self):
        calories_remained = self.remained()
        if calories_remained <= 0:
            return 'Хватит есть!'
        else:
            return ('Сегодня можно съесть что-нибудь ещё, но с общей '
                    f'калорийностью не более {calories_remained} кКал'
                    .format(calories_remained=self.remained))


class CashCalculator(Calculator):
    USD_RATE = 60.0
    EURO_RATE = 70.0
    RUB_RATE = 1.0

    def get_today_cash_remained(self, currency):
        cash_remained = self.remained()
        money = {
            'eur': ('Euro', self.EURO_RATE),
            'usd': ('USD', self.USD_RATE),
            'rub': ('руб', self.RUB_RATE),
        }
        sign, rate = money[currency]
        if currency not in money:
            raise KeyError('Валюта не найдена')
        cash_remained = round(cash_remained / rate, 2)
        if cash_remained > 0:
            return f'На сегодня осталось {cash_remained} {sign}'
        if cash_remained < 0:
            cash_remained = abs(cash_remained)
            return f'Денег нет, держись: твой долг - {cash_remained} {sign}'
        else:
            return 'Денег нет, держись'