#!/usr/bin/env ruby

NTW = {
1 => "one",
2 => "two",
3 => "three",
4 => "four",
5 => "five",
6 => "six",
7 => "seven",
8 => "eight",
9 => "nine",
10 => "ten",
100 => "hundred",
1000 => "thousand",
1000000 => "million",
1000000000 => "billion",
1000000000000 => "trillion"
}

class IntegerToBetterEnglish
  class << self
    def convert(number)
      return "zero" if number == 0
      word_representation_accumulator = []
      number_digits_reversed = number.to_s.reverse
      digit_count = 0
      number_digits_reversed.chars.each_with_index do |digit, index|
        digit_as_number = Integer(digit)
        skip_zero(digit_as_number) do
          multiplier = 10**digit_count
          word_representation = "#{NTW[digit_as_number]}"
          word_representation += " #{NTW[multiplier]}" if multiplier > 1 && NTW[multiplier]
          word_representation_accumulator << word_representation
        end
        digit_count += 1
      end
      word_representation_accumulator.reverse.join(" ")
    end

    def skip_zero(digit)
      if digit != 0
        yield
      end
    end
  end
end

if __FILE__ == $0
  puts IntegerToBetterEnglish.convert(0)
  puts IntegerToBetterEnglish.convert(1)
  puts IntegerToBetterEnglish.convert(3)
  puts IntegerToBetterEnglish.convert(5)
  puts IntegerToBetterEnglish.convert(11)
  puts IntegerToBetterEnglish.convert(15)
  puts IntegerToBetterEnglish.convert(25)
  puts IntegerToBetterEnglish.convert(71)
  puts IntegerToBetterEnglish.convert(40)
  puts IntegerToBetterEnglish.convert(100)
  puts IntegerToBetterEnglish.convert(101)
  puts IntegerToBetterEnglish.convert(112)
  puts IntegerToBetterEnglish.convert(123)
  puts IntegerToBetterEnglish.convert(457)
  puts IntegerToBetterEnglish.convert(999)
  puts IntegerToBetterEnglish.convert(1000)
  puts IntegerToBetterEnglish.convert(1001)
  puts IntegerToBetterEnglish.convert(1010)
  puts IntegerToBetterEnglish.convert(1011)
  puts IntegerToBetterEnglish.convert(2117)
  puts IntegerToBetterEnglish.convert(3001)
  puts IntegerToBetterEnglish.convert(13101)
  puts IntegerToBetterEnglish.convert(14001)
  puts IntegerToBetterEnglish.convert(16000)
  puts IntegerToBetterEnglish.convert(25119)
  puts IntegerToBetterEnglish.convert(65009)
  puts IntegerToBetterEnglish.convert(315119)
  puts IntegerToBetterEnglish.convert(1000001)
  puts IntegerToBetterEnglish.convert(1315119)
  puts IntegerToBetterEnglish.convert(11315119)
  puts IntegerToBetterEnglish.convert(74315119)
  puts IntegerToBetterEnglish.convert(174315119)
  puts IntegerToBetterEnglish.convert(1174315119)
  puts IntegerToBetterEnglish.convert(15174315119)
  puts IntegerToBetterEnglish.convert(35174315119)
  puts IntegerToBetterEnglish.convert(935174315119)
  puts IntegerToBetterEnglish.convert(2935174315119)
end