RockPaperScissors

import java.io.*;
import java.util.Random;
import java.util.Scanner;

public class App {
    public static void main(String[] args) {
        try (Scanner input = new Scanner(System.in)) {
            Game game = initializeGame(input);
            startGameLoop(input, game);
            endGame(input, game);
        }
    }

    private static Game initializeGame(Scanner input) {
        System.out.println("Welcome to Rock Paper Scissors!");
        System.out.println("Do you want to start a new game or resume a saved game? (new/resume)");
        String choice = input.nextLine().toLowerCase();
        if (choice.equals("resume")) {
            Game game = Game.loadGame();
            if (game == null) {
                System.out.println("No saved game found. Starting a new game.");
                return startNewGame(input);
            }
            return game;
        }
        return startNewGame(input);
    }

    private static Game startNewGame(Scanner input) {
        System.out.println("Enter the series length (e.g., 3 for best of 3): ");
        int seriesLength = input.nextInt();
        input.nextLine();
        return new Game(seriesLength);
    }

    private static void startGameLoop(Scanner input, Game game) {
        System.out.println("Press Enter to get started!");
        input.nextLine();
        System.out.println("-------");

        boolean play = true;
        while (play) {
            System.out.println("\nPlease choose rock, paper, or scissors. Enter 0 to quit, save to save the game.");
            String userChoice = input.nextLine().toLowerCase();
            play = handleUserChoice(input, game, userChoice);
        }
    }

    private static boolean handleUserChoice(Scanner input, Game game, String userChoice) {
        if (userChoice.equals("0")) {
            return false;
        } else if (userChoice.equals("save")) {
            game.saveGame();
            System.out.println("Game saved. You can resume later.");
        } else {
            System.out.println(game.play(userChoice));
            if (game.isSeriesOver()) {
                System.out.println("\n-------");
                System.out.println(game.finalResult());
                return false;
            }
        }
        return true;
    }

    private static void endGame(Scanner input, Game game) {
        System.out.println("\n-------");
        System.out.println(game.gameScore());
        System.out.println(game.finalResult());
    }
}

class Game implements Serializable {
    private static final long serialVersionUID = 1L;
    private static final String[] CHOICES = {"rock", "paper", "scissors"};
    private static final String INVALID_CHOICE_MESSAGE = "Invalid choice. Please choose rock, paper, or scissors.";

    private int userScore;
    private int botScore;
    private int seriesLength;
    private transient Random random;

    public Game(int seriesLength) {
        userScore = 0;
        botScore = 0;
        this.seriesLength = (seriesLength % 2 == 0) ? seriesLength + 1 : seriesLength;
        random = RandomSingleton.getInstance();
    }

    public String play(String userChoice) {
        if (!isValidChoice(userChoice)) {
            return INVALID_CHOICE_MESSAGE;
        }

        String botChoice = getBotChoice();
        String result = "Bot chose " + botChoice + ". " + determineWinner(userChoice, botChoice);

        return result;
    }

    private boolean isValidChoice(String choice) {
        for (String validChoice : CHOICES) {
            if (validChoice.equals(choice)) {
                return true;
            }
        }
        return false;
    }

    private String getBotChoice() {
        return CHOICES[random.nextInt(CHOICES.length)];
    }

    private String determineWinner(String userChoice, String botChoice) {
        if (userChoice.equals(botChoice)) {
            return "It's a tie!";
        }

        if ((userChoice.equals("rock") && botChoice.equals("scissors")) ||
            (userChoice.equals("paper") && botChoice.equals("rock")) ||
            (userChoice.equals("scissors") && botChoice.equals("paper"))) {
            userScore++;
            return "You win this round!";
        } else {
            botScore++;
            return "You lose this round!";
        }
    }

    public String gameScore() {
        return "Current Score - You: " + userScore + ", Bot: " + botScore;
    }

    public String finalResult() {
        if (userScore > botScore) {
            return "You won the series!";
        } else if (userScore < botScore) {
            return "You lost the series.";
        } else {
            return "The series is tied.";
        }
    }

    public boolean isSeriesOver() {
        return userScore > seriesLength / 2 || botScore > seriesLength / 2;
    }

    public void saveGame() {
        try (ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("game.dat"))) {
            out.writeObject(this);
        } catch (IOException e) {
            System.out.println("Error saving game: " + e.getMessage());
        }
    }

    public static Game loadGame() {
        try (ObjectInputStream in = new ObjectInputStream(new FileInputStream("game.dat"))) {
            Game game = (Game) in.readObject();
            game.random = RandomSingleton.getInstance();
            return game;
        } catch (IOException | ClassNotFoundException e) {
            return null;
        }
    }
}

class RandomSingleton {
    private static final Random INSTANCE = new Random();

    private RandomSingleton() {}

    public static Random getInstance() {
        return INSTANCE;
    }
}