pong-game/PongGame/Hubs/PongRoom.cs

using System.ComponentModel;
using Microsoft.AspNetCore.SignalR;

namespace PongGame.Hubs;

public class PongRoom {
    public string ID { get; }
    private readonly ILogger Logger;
    private const string JOIN_LOG_TEMPLATE = "[{ID}] {Player} joined pong room as player {Number}!";
    private const string LEAVE_LOG_TEMPLATE = "[{ID}] Player {Number} {Player} left pong room!";
    private const string DIRECTION_LOG_TEMPLATE = "[{ID}] Player {Number} {player} moves paddle in direction: {direction}!";

    public PongRoom(string id, ILogger logger) {
        ID = id;
        Logger = logger;
        gameWorker.DoWork += GameLoop;
    }

    public PongPlayer? Player1 { get; private set; }
    public PongPlayer? Player2 { get; private set; }
    public bool IsEmpty => Player1 is null && Player2 is null;

    private PongGameState State = PongGameState.Initial;

    public void Join(PongPlayer player) {
        // TODO: synchronize this
        if (Player1 is null) {
            Player1 = player;
            Logger.LogInformation(JOIN_LOG_TEMPLATE, ID, player, 1);
        } else if (Player2 is null) {
            Player2 = player;
            Logger.LogInformation(JOIN_LOG_TEMPLATE, ID, player, 1);
        } else
            throw new HubException($"Lobby [{ID}] is already full!");
        _ = Task.Run(PlayersChanged);
        player.ConnectedRoom = this;
    }

    public void Leave(PongPlayer player) {
        if (Player1 == player) {
            Player1 = null;
            Logger.LogInformation(LEAVE_LOG_TEMPLATE, ID, 1, player);
        } else if (Player2 == player) {
            Player2 = null;
            Logger.LogInformation(LEAVE_LOG_TEMPLATE, ID, 2, player);
        }
        player.ConnectedRoom = null;
        _ = Task.Run(PlayersChanged);
    }

    private readonly BackgroundWorker gameWorker = new() {
        WorkerSupportsCancellation = true
    };

    private void GameLoop(object? sender, DoWorkEventArgs e) {
        while (!gameWorker.CancellationPending
            && Player1 is PongPlayer p1
            && Player2 is PongPlayer p2
            && State.Status is GameStatus.InProgress) {
            PongGameState.Update(ref State);
            _ = Task.Run(() => Task.WhenAll(
                p1.Client.ReceiveGameState(State),
                p2.Client.ReceiveGameState(State)));
            Thread.Sleep(1000 / 60);
        }
    }

    private Task PlayersChanged() {
        if (Player1 is PongPlayer player1 && Player2 is PongPlayer player2) {
            Logger.LogInformation("[{ID}] Pong game started: {player1} vs. {player2}", ID, player1, player2);
            ResumeGame();
        } else if (IsEmpty) {
            CloseRoom();
        } else
            PauseGame();
        return Task.CompletedTask;
    }

    private void ResumeGame() {
        State.Status = GameStatus.InProgress;
        if (!gameWorker.IsBusy) gameWorker.RunWorkerAsync();
    }

    private void PauseGame() => State.Status = GameStatus.Paused;
    private void CloseRoom() => State.Status = GameStatus.Finished;

    public override string ToString() => $"[{ID}]";

    public Task MovePaddle(PongPlayer player, PongPaddleDirection direction) {
        if (Player1 == player) {
            State.Paddle1.Direction = direction;
            Logger.LogDebug(DIRECTION_LOG_TEMPLATE, ID, 1, player, direction);
        } else if (Player2 == player) {
            State.Paddle2.Direction = direction;
            Logger.LogDebug(DIRECTION_LOG_TEMPLATE, ID, 2, player, direction);
        } else
            throw new InvalidOperationException("Player is not in this room, but moved! Assumably players room wasn't deleted.");
        return Task.CompletedTask;
    }
}