rock paper scissors

game.ex

defmodule Game do
  @win_combinations [rock: :scissors, paper: :rock, scissors: :paper]
  @valid_options [:rock, :paper, :scissors]

  def play(player1, player2) do
    with {player1, player2} = plays <- validate_params({player1, player2}) do
      winner(plays)
    else
      _ -> "Tiraste fruta"
    end
  end

  defp winner(plays) when plays in @win_combinations do
    "Player1"
  end

  defp winner({player1, player2}) when player1 == player2 do
    "Draw"
  end

  defp winner(_plays) do
    "Player2"
  end

  defp validate_params(plays) do
    case plays do
      {player1, player2} when player1 in @valid_options and player2 in @valid_options ->
        plays

      _ ->
        "Invalid play"
    end
  end
end

Game.play(:rock, :scissors)
Game.play(:paper, :scissors)
Game.play(:paper, :paper)
Game.play(:lagarto, :spok)