Rock Paper Scissors

rps.ex

defmodule Rps do
  def run(input) do
    player1 = String.split(input, "")
    player2 = Enum.shuffle(["r", "p", "s"])
    result =
      [player1, player2]
      |> Enum.zip()
      |> Enum.map(&result/1)
      |> Enum.sum()
      |> case do
           0 -> "Draw"
           result when result > 0 -> "Win"
           result when result < 0 -> "Lose"
         end

    "#{player2}#{result}"
  end

  def result({a, a}), do: 0
  def result({"r", "p"}), do: -1
  def result({"p", "s"}), do: -1
  def result({"s", "r"}), do: -1
  def result({"r", "s"}), do: 1
  def result({"p", "r"}), do: 1
  def result({"s", "p"}), do: 1
  def result(_), do: raise "Invalid play"
end

IO.gets("Input: ")
|> String.trim()
|> Rps.run()
|> IO.puts()