module NumeriRomani

# File lib/numeri_romani.rb, line 22
def to_decimal(roman_number)
  raise ArgumentError.new('Not valid roman number') unless roman_number.match?(REGEXP)
  result = roman_number.scan(/#{(DIGITS.keys + FRACTIONS.keys).join('|')}/).sum { |let| DIGITS[let] || FRACTIONS[let] }
  roman_number.match?(/\*/) ? result + roman_number.count('*') * 1/12r : result
end

# File lib/numeri_romani.rb, line 5
def to_roman(decimal_number)
  unless [Integer, Float, Rational].include?(decimal_number.class)
    raise ArgumentError.new('Number should be an Integer/Float/Rational')
  end
  unless decimal_number.between?(1/12r, 3_999_999 + 11/12r)
    raise ArgumentError.new('Number should be in interval [(1/12)..3_999_999(11/12)]')
  end
  integer = decimal_number.to_i
  fract = (decimal_number - integer).to_r
  fract = Rational((12.0 * fract.numerator / fract.denominator).round, 12)
  roman = DIGITS.map do |letter, value|
    count, integer = integer.divmod(value)
    [letter * count]
  end
  (roman << FRACTIONS.key(fract)).join
end