"""Number to Russian words converter"""


class NumberToWords:
    """Convert numbers to Russian words in nominative case"""

    def __init__(self):
        self.ones = ['', 'один', 'два', 'три', 'четыре', 'пять', 'шесть', 'семь', 'восемь', 'девять']
        self.tens = ['', '', 'двадцать', 'тридцать', 'сорок', 'пятьдесят', 'шестьдесят', 'семьдесят', 'восемьдесят', 'девяносто']
        self.teens = ['десять', 'одиннадцать', 'двенадцать', 'тринадцать', 'четырнадцать', 'пятнадцать',
                      'шестнадцать', 'семнадцать', 'восемнадцать', 'девятнадцать']
        self.hundreds = ['', 'сто', 'двести', 'триста', 'четыреста', 'пятьсот', 'шестьсот', 'семьсот', 'восемьсот', 'девятьсот']
        self.thousands = ['', 'одна', 'две', 'три', 'четыре', 'пять', 'шесть', 'семь', 'восемь', 'девять']

    def _convert_hundreds(self, num: int) -> str:
        """Convert number 0-999 to words"""
        if num == 0:
            return ''

        result = []

        # Hundreds
        hundred = num // 100
        if hundred > 0:
            result.append(self.hundreds[hundred])

        # Tens and ones
        remainder = num % 100
        if 10 <= remainder <= 19:
            result.append(self.teens[remainder - 10])
        else:
            ten = remainder // 10
            one = remainder % 10
            if ten > 0:
                result.append(self.tens[ten])
            if one > 0:
                result.append(self.ones[one])

        return ' '.join(result)

    def _convert_thousands(self, num: int) -> str:
        """Convert thousands part (0-999) to words with feminine forms"""
        if num == 0:
            return ''

        result = []

        # Hundreds
        hundred = num // 100
        if hundred > 0:
            result.append(self.hundreds[hundred])

        # Tens and ones (with feminine forms for thousands)
        remainder = num % 100
        if 10 <= remainder <= 19:
            result.append(self.teens[remainder - 10])
        else:
            ten = remainder // 10
            one = remainder % 10
            if ten > 0:
                result.append(self.tens[ten])
            if one > 0:
                result.append(self.thousands[one])

        return ' '.join(result)

    def _thousand_word(self, num: int) -> str:
        """Get correct grammatical form of 'thousand' word"""
        if num % 100 in [11, 12, 13, 14]:
            return 'тысяч'
        last_digit = num % 10
        if last_digit == 1:
            return 'тысяча'
        elif last_digit in [2, 3, 4]:
            return 'тысячи'
        else:
            return 'тысяч'

    def convert(self, num: int) -> str:
        """
        Convert integer to Russian words in nominative case

        Args:
            num: Integer number to convert

        Returns:
            String representation of the number in Russian
        """
        if num == 0:
            return 'ноль'

        if num < 0:
            return 'минус ' + self.convert(-num)

        result = []

        # Millions
        millions = num // 1000000
        if millions > 0:
            result.append(self._convert_hundreds(millions))
            if millions % 100 in [11, 12, 13, 14]:
                result.append('миллионов')
            elif millions % 10 == 1:
                result.append('миллион')
            elif millions % 10 in [2, 3, 4]:
                result.append('миллиона')
            else:
                result.append('миллионов')

        # Thousands
        thousands = (num % 1000000) // 1000
        if thousands > 0:
            result.append(self._convert_thousands(thousands))
            result.append(self._thousand_word(thousands))

        # Hundreds
        hundreds = num % 1000
        if hundreds > 0:
            result.append(self._convert_hundreds(hundreds))

        return ' '.join(result)