rock_paper_scissors_context.ex

rock_paper_scissors_context.ex

defmodule RPS do
  defmodule Score, do: defstruct player: 0, computer: 0
  
  defmodule Context do
    defstruct [
      score: %Score{},
      rounds_to_play: 3,
      valid_moves: [:rock, :paper, :scissors],
      win_conditions: %{rock: :scissors, paper: :rock, scissors: :paper},
      io: IO
    ]
  end

  def play(rounds \\ 3) do
    %Context{rounds_to_play: rounds}
    |> Stream.iterate(&play_round/1)
    |> Enum.at(rounds)
    |> announce_winner()
    |> maybe_play_again()
  end

  defp play_round(ctx) do
    with {:ok, player} <- get_move(ctx),
         computer = get_computer_move(ctx) do
      ctx.io.puts("Computer chose: #{computer}")
      
      winner = determine_winner(ctx, player, computer)
      ctx.io.puts(format_result(winner, player, computer))
      
      update_score(ctx, winner)
    else
      {:error, msg} -> 
        ctx.io.puts(msg)
        play_round(ctx)
    end
  end

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

  defp get_computer_move(ctx) do
    Enum.random(ctx.valid_moves)
  end

  defp determine_winner(ctx, player, computer) do
    cond do
      player == computer -> :draw
      ctx.win_conditions[player] == computer -> :player
      true -> :computer
    end
  end

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

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

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

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