shorter.ex

rock_paper_scissors_short.ex

defmodule RPS do
  defmodule Score, do: defstruct player: 0, computer: 0

  def play do
    %Score{}
    |> Stream.iterate(&play_round/1)
    |> Enum.at(3)
    |> announce_winner()
    |> maybe_play_again()
  end

  defp play_round(score) do
    with {:ok, player} <- get_move("Enter move (rock/paper/scissors): "),
         computer = Enum.random([:rock, :paper, :scissors]) do
      IO.puts("Computer chose: #{computer}")
      {winner, move1, move2} = determine_winner(player, computer)
      IO.puts(format_result(winner, move1, move2))
      update_score(winner, score)
    else
      {:error, msg} -> IO.puts(msg); play_round(score)
    end
  end

  defp get_move(prompt) do
    case IO.gets(prompt) |> String.trim() |> String.downcase() do
      "rock" -> {:ok, :rock}
      "paper" -> {:ok, :paper}
      "scissors" -> {:ok, :scissors}
      _ -> {:error, "Invalid move"}
    end
  end

  defp determine_winner(player, computer) do
    wins = %{rock: :scissors, paper: :rock, scissors: :paper}
    cond do
      player == computer -> {:draw, player, computer}
      wins[player] == computer -> {:player, player, computer}
      true -> {:computer, computer, player}
    end
  end

  defp format_result(:draw, move, _), do: "Draw! Both threw #{move}"
  defp format_result(:player, threw, beat), do: "You won with #{threw} against #{beat}"
  defp format_result(:computer, threw, beat), do: "Computer won with #{threw} against #{beat}"

  defp update_score(:player, score), do: %{score | player: score.player + 1}
  defp update_score(:computer, score), do: %{score | computer: score.computer + 1}
  defp update_score(:draw, score), do: score

  defp announce_winner(score = %Score{player: p, computer: c}) do
    IO.puts("\nFinal Score - You: #{p}, Computer: #{c}")
    IO.puts(if p > c, do: "You win!", else: if(p < c, do: "Computer wins!", else: "Draw!"))
    score
  end

  defp maybe_play_again(_) do
    if String.starts_with?(IO.gets("\nPlay again? (y/n): ") |> String.downcase(), "y") do
      play()
    else
      IO.puts("Thanks for playing!")
    end
  end
end