Ninety Nine Bottles of Beer

99bottles.rb

require 'pp'

@unique_number_words = {
  1 => "one", 2 => "two", 3 => "three", 
  4 => "four", 5 => "five", 6 => "six", 
  7 => "seven", 8 => "eight", 9 => "nine", 
  10 => "ten", 11 => "eleven", 12 => "twelve", 13 => "thirteen"
}

@compound_number_words = {
  10 => "teen", 20 => "twenty", 30 => "thirty", 40 => "forty",
  50 => "fifty", 60 => "sixty", 70 => "seventy", 80 => "eighty", 90 => "ninety",
}

@lyrics = {
  :line_one => " bottles of beer on the wall, ",
  :line_two => " bottles of beer,\n",
  :line_three => "take one down pass it around, ",
  :line_four => " bottles of beer on the wall.\n\n"
}

def get_written_number(index)
 case 
 when index == 0
   "zero"
 when index <= 13
   return @unique_number_words[index]
 when index > 13 && index < 20
   return "#{@unique_number_words[index % 10]} #{@compound_number_words[(index / 10) * 10]}"
 when index > 13
   return "#{@compound_number_words[(index / 10) * 10]} #{@unique_number_words[index % 10]}"
 end
end

def print_lyrics(index)
  string = ""
  string += get_written_number(index) + @lyrics[:line_one]
  string += get_written_number(index) + @lyrics[:line_two]
  string += @lyrics[:line_three]
  string += get_written_number(index - 1) + @lyrics[:line_four]
end

99.times do |index|
  reverse_index = 99 - index
  puts print_lyrics(reverse_index)
end