99bottles.rb

class Bottles

  def verses(start, last)
    start.downto(last).map.map{|v| verse(v) }.join("\n")
  end

  def verse(num_bottles)
    "#{bottles_of_beer_on_the_wall(num_bottles).capitalize} of beer on the wall, #{bottles_of_beer_on_the_wall(num_bottles)} of beer.
#{action(num_bottles)}.
"
  end

  def song
    verses(99, 0)
  end

  private

  def action(n)
    if n == 0
      "Go to the store and buy some more, 99 bottles of beer on the wall"
    else
      "Take #{it_or_one(n)} down and pass it around, #{bottles_left(n)} of beer on the wall"
    end
  end

  def pluralise_bottle(n)
    n < 2 ? "bottle" : "bottles"
  end

  def it_or_one(n)
    n == 1 ? "it" : "one"
  end

  def bottles_of_beer_on_the_wall(n)
    if n < 1
      "no more bottles"
    else
      "#{n} #{pluralise_bottle(n)}"
    end
  end

  def bottles_left(n)
    if n > 2
      "#{n-1} bottles"
    elsif n == 1
      "no more bottles"
    else
      "1 bottle"
    end
  end
end

Here's this in Elixir for some reason: https://gist.github.com/ciaran/097dec82cf85d849954d30269d23504c