rock-paper-scissors

rps.py

#!/usr/bin/env python3

import random
from enum import Enum


class Choice(Enum):
    ROCK = 0
    PAPER = 1
    SCISSORS = 2

    @classmethod
    def from_str(cls, s: str) -> "Choice":
        try:
            return {
                "r": cls.ROCK,
                "rock": cls.ROCK,
                "p": cls.PAPER,
                "paper": cls.PAPER,
                "s": cls.SCISSORS,
                "scissors": cls.SCISSORS
            }[s.strip().lower()]
        except KeyError:
            raise ValueError(f"{s!r} is not a valid {cls.__name__}")

    def __str__(self) -> str:
        return self.name.lower()

    def beats(self, other: "Choice") -> bool:
        return (self.value - other.value) % 3 == 1


class RockPaperScissors:
    def __init__(self):
        self.wins = 0
        self.losses = 0
        self.ties = 0
        self.choices = list(Choice)

    def random_choice(self) -> Choice:
        return random.choice(self.choices)

    def player_choice(self) -> Choice:
        prompt = ("\nChoices are 'rock', 'paper', or 'scissors'.\n"
                  "Which do you choose? ")
        while True:
            try:
                return Choice.from_str(input(prompt))
            except ValueError:
                print("Invalid input, try again!")

    def check_win(self, player_choice: Choice, opponent_choice: Choice):
        if player_choice == opponent_choice:
            self.ties += 1
            print("The game is a tie! You are a most worthy opponent!")
        elif player_choice.beats(opponent_choice):
            self.wins += 1
            print("You win! My honor demands a rematch!")
        else:
            self.losses += 1
            print("Haha, I am victorious! Dare you challenge me again?")

    def print_score(self):
        print(f"You have {self.wins} wins, {self.losses} losses, and "
              f"{self.ties} ties.")

    def play_round(self):
        player_choice = self.player_choice()
        opponent_choice = self.random_choice()
        print(f"\nYou picked {player_choice}, and I picked {opponent_choice}.")
        self.check_win(player_choice, opponent_choice)
        self.print_score()

    def player_wants_to_play_again(self) -> bool:
        prompt = "\nDo you wish to play again? (y/n): "
        valid_choices = ("y", "n")
        while True:
            user_choice = input(prompt).strip().lower()
            if user_choice in valid_choices:
                return user_choice == "y"

            print("Invalid input!")

    def run_game(self):
        while True:
            self.play_round()
            if not self.player_wants_to_play_again():
                print("You are weak!")
                break


if __name__ == "__main__":
    game = RockPaperScissors()
    game.run_game()