99 Bottles Solution 1

99_bottles_example.rb

class Bottles
  def song
    verses(99, 0)
  end

  def verses(*verses)
    output = (verses[1]..verses[0]).to_a.reverse.map { |n| verse(n) }
    output.join("\n")
  end

  def verse(num)
    new_qty = if (num - 1 == 1)
                "1 bottle"
              else
                "#{num - 1} bottles"
              end

    case num
    when 0
      <<-VERSE_0
No more bottles of beer on the wall, no more bottles of beer.
Go to the store and buy some more, 99 bottles of beer on the wall.
      VERSE_0
    when 1
      <<-VERSE_1
1 bottle of beer on the wall, 1 bottle of beer.
Take it down and pass it around, no more bottles of beer on the wall.
      VERSE_1
    else
      <<-VERSE_X
#{num} bottles of beer on the wall, #{num} bottles of beer.
Take one down and pass it around, #{new_qty} of beer on the wall.
      VERSE_X
    end
  end
end