99bottles.ex

defmodule Bottles do
  def song do
    verses(99, 0)
  end

  def verses(first, last) do
    first..last
    |> Enum.map_join("\n", &verse(&1))
  end

  def verse(n) do
    "#{bottles(n, :capital)} of beer on the wall, #{bottles(n)} of beer.\n" <>
    case n do
      0 -> "Go to the store and buy some more, 99 bottles of beer on the wall.\n"
      1 -> "Take it down and pass it around, no more bottles of beer on the wall.\n"
      _ -> "Take one down and pass it around, #{bottles(n-1)} of beer on the wall.\n"
    end
  end

  defp bottles(n, case \\ :lower)
  defp bottles(0, :capital), do: "No more bottles"
  defp bottles(0, :lower),   do: "no more bottles"
  defp bottles(1, _), do: "1 bottle"
  defp bottles(n, _), do: "#{n} bottles"

end