playground

pub type Move {
  Rock
  Paper
  Scissors
}

type GameResult {
  Player1Wins(threw: Move, beat: Move)
  Player2Wins(threw: Move, beat: Move)
  Draw(Move)
}

fn move_to_string(move: Move) {
  case move {
    Rock -> "Rock"
    Paper -> "Paper"
    Scissors -> "Scissors"
  }
}

fn game_result_to_string(result) {
  case result {
    Player1Wins(threw, beat) ->
      "Player 1 won by throwing "
      <> move_to_string(threw)
      <> " against "
      <> move_to_string(beat)
    Player2Wins(threw, beat) ->
      "Player 2 won by throwing "
      <> move_to_string(threw)
      <> " against "
      <> move_to_string(beat)
    Draw(move) -> "Draw! Both players threw " <> move_to_string(move) <> "s"
  }
}

pub fn play(player_1_move: Move, player_2_move: Move) {
  case player_1_move, player_2_move {
    Rock, Scissors -> Player1Wins(Rock, Scissors)
    Rock, Paper -> Player2Wins(Paper, Rock)
    Paper, Rock -> Player1Wins(Rock, Paper)
    Paper, Scissors -> Player2Wins(Scissors, Paper)
    Scissors, Rock -> Player2Wins(Rock, Scissors)
    Scissors, Paper -> Player1Wins(Scissors, Paper)
    _, _ -> Draw(player_1_move)
  }
  |> game_result_to_string
}