bottles.rb

class Bottles
  def word_part(n)
    case n
    when 0
      "no more bottles"
    when 1
      "1 bottle"
    else
      "#{n} bottles"
    end
  end

  def numbered_pronoun(n)
    if n == 1
      "it"
    else
      "one"
    end
  end

  def line_one(n)
    "#{word_part(n).capitalize} of beer on the wall, #{word_part(n)} of beer.\n"
  end

  def line_two(n)
    if n == 0
      "Go to the store and buy some more, 99 bottles of beer on the wall.\n"
    else
      "Take #{numbered_pronoun(n)} down and pass it around, #{word_part(n - 1)} of beer on the wall.\n"
    end
  end

  def verse(n)
    line_one(n) + line_two(n)
  end

  def verses(a, b)
    parts = []
    a.downto b do |i|
      parts << verse(i)
    end
    parts.join("\n")
  end

  def song
    verses(99, 0)
  end
end