MauMau-Server/Mau/Game.cs

using System.Text.Json;
using MauMau_Server.Mau.GameMessages;
using MauMau_Server.Mau.Managers;
using MauMau_Server.Websockets;
using MauMau_Server.Room;
using MauMau_Server.Room.Messages;

namespace MauMau_Server.Mau;

public class Game : RoomType
{
    // Helpers
    private readonly Deck _deck = new();
    private readonly TurnManager _turnManager = new();

    // Game state
    private readonly List<Card> _mauCardBuffer = new();
    private CardType? NextAllowedCardType { get; set; }

    // Variables
    private const int NumberOfFaultcards = 5;
    private const int NumberOfStartCards = 8;

    public Game(Room.Room room, IEnumerable<ConnectionInstance> connections) : base(room)
    {
        // If the current card is a joker, set the next allowed card type to a random card type
        if (_deck.CurrentCard.CardType == CardType.JOKER)
        {
            // In the case the random card type is a joker, try again until it is not
            do
            {
                var cardTypes = Enum.GetValues(typeof(CardType));
                var randomIndex = new Random().Next(cardTypes.Length);
                NextAllowedCardType = (CardType?)cardTypes.GetValue(randomIndex) ?? CardType.SPADES;
            } while (NextAllowedCardType == CardType.JOKER);
        }

        // Convert all the connections to players
        List<Player> players = new();
        foreach (var player in connections.Select(connection => new Player(connection)))
        {
            // Give the new player a hand of cards
            var initialHand = _deck.DrawCards(NumberOfStartCards);
            player.GiveCards(initialHand);
            players.Add(player);
        }

        // Add all the players to the turn manager
        _turnManager.Initialize(players);

        // Broadcast new game state
        SendGameState();
    }

    /**
     * <inheritdoc cref="RoomType.OnMessage"/>
     */
    public override void OnMessage(ConnectionInstance sender, RoomMessage<string> message)
    {
        // If the message type is not a game message, ignore the message
        if (message.Type is not ("CHOOSE" or "DRAW" or "PLAY"))
        {
            return;
        }

        // Get the player that sent the message
        var player = _turnManager.Players.FirstOrDefault(x => x.IsMe(sender.Id));

        // If the player is not the player that is currently playing, ignore the message
        if (_turnManager.CurrentPlayer != player) return;

        // Based on the message intent, handle the message
        switch (message.Type)
        {
            case "CHOOSE":
                Choose(player, message.Data);
                break;
            case "PLAY":
                Play(player, message.Data);
                break;
            default:
                Draw(player);
                break;
        }
    }

    /**
     * <inheritdoc cref="RoomType.OnConnect"/>
     */
    public override void OnConnect(ConnectionInstance connection)
    {
        // Broadcast that a player joined
        var joinMessage = new JoinMessage(_room.Connections, connection);
        _room.BroadCast(new RoomMessage<JoinMessage>("JOIN", joinMessage));

        // Create a new player, give them a new hand and add them to the game
        var player = new Player(connection);
        var initialHand = _deck.DrawCards(8);
        player.GiveCards(initialHand);
        _turnManager.Players.Add(player);

        // Broadcast new game state
        SendGameState();
    }

    /**
     * <inheritdoc cref="RoomType.OnDisconnect"/>
     */
    public override void OnDisconnect(ConnectionInstance connection)
    {
        // Broadcast that the player left
        var leaveMessage = new LeaveMessage(connection);
        _room.BroadCast(new RoomMessage<LeaveMessage>("LEAVE", leaveMessage));

        // Get the player that left
        var player = _turnManager.Players.FirstOrDefault(x => x.IsMe(connection.Id));
        if (player is null) return;

        // Add the player's hand to the used deck
        var playerHand = player.Hand;
        _deck.AddCardsToUsedDeck(playerHand);

        // Change the turn if the player that left was the current player
        if (player == _turnManager.CurrentPlayer)
        {
            _turnManager.ChangeTurnTo();
        }

        // Remove the player from the game
        _turnManager.Players.Remove(player);

        // Broadcast new game state
        SendGameState();
    }

    /**
     * <summary>
     * The player had to choose a new card type
     * </summary>
     * <param name="player">The player that chose a new card type</param>
     * <param name="data">A string that represents a CardType</param>
     */
    private void Choose(Player player, string data)
    {
        // TODO: Validate if choosing a card is allowed
        
        // Convert the data to a CardType, if it fails, ignore the message
        if (!Enum.TryParse(data, out CardType cardType))
        {
            return;
        }

        // Set the next card type that is allowed to be played
        NextAllowedCardType = cardType;

        // Change the turns
        _turnManager.ChangeTurnTo();

        // Broadcast new game state
        SendGameState();
    }

    /**
     * <summary>
     * The player either:
     * <list type="bullet">
     *      <item>Could not play a card and had to draw a card</item>
     *      <item>Chose to draw a card as a strategic move</item>
     * </list>
     * When there are multiple mau cards played, the player has to draw the combined amount of mau cards played.
     * </summary>
     * <param name="player">The player that drew a card</param>
     */
    private void Draw(Player player)
    {
        // If there are cards in the MauCardBuffer, this means there are multiple cards that need to be drawn
        // Otherwise, just draw a single card
        if (_mauCardBuffer.Count > 0)
        {
            // Count the amount of cards that need to be drawn
            var totalCards = CountMauCardBuffer();

            // Draw the cards from the deck
            var drawnCards = _deck.DrawCards(totalCards);

            // Give the cards to the player
            player.GiveCards(drawnCards);

            // Change the turn
            _turnManager.ChangeTurnTo();
        }
        else
        {
            // Draw a card from the deck
            var drawnCard = _deck.DrawCard();

            // Give the card to the player
            player.GiveCard(drawnCard);

            // Change the player if the drawn card cannot be played
            if (!CardCanBePlayed(drawnCard))
            {
                _turnManager.ChangeTurnTo();
            }
        }

        // Broadcast new game state
        SendGameState();
    }

    /**
     * <summary>
     * The player plays a card, this will only be possible if:
     * <list type="bullet">
     *     <item>The player has the correct state</item>
     *     <item>The player has the card in their hand</item>
     *     <item>The card is playable on the current card</item>
     * </list>
     * </summary>
     * <param name="player">The player that played</param>
     * <param name="data">A string that can be serialized to a playcard instance</param>
     */
    private void Play(Player player, string data)
    {
        // Check if the player has the correct state to play a card
        if (player.State != PlayerState.TURN)
        {
            return;
        }

        // Convert the data to a Card instance
        var cardData = JsonSerializer.Deserialize<PlayCard>(data).ToCard();

        // Check if the player indeed has the card they claim to have
        var playerCard = player.TakeCardFromHand(cardData);
        if (playerCard is null)
        {
            return;
        }

        if (!CardCanBePlayed(playerCard)) return;

        // Remove the card from the player's hand
        player.Hand.Remove(playerCard);

        // If the player's last played card is a special card, give the player 5 fault cards
        if (player.Hand.Count < 1 && playerCard.IsSpecialCard())
        {
            var faultCards = _deck.DrawCards(NumberOfFaultcards);
            player.GiveCards(faultCards);
        }

        // Add the card to the used deck
        _deck.AddCardToUsedDeck(playerCard);

        // Reset the allowed card type, so the next player has the normal same type and same value rules
        NextAllowedCardType = null;

        // If the player has no cards left, end the game with player as winner
        if (player.Hand.Count == 0)
        {
            EndGame(player);
            return;
        }

        // Change the turn based on the played card
        HandleNextPlayer(playerCard);

        // Broadcast new game state
        SendGameState();
    }

    /**
     * <summary>
     * Based on the played card, change the turn to the next player.
     * </summary>
     * <param name="card">The card that was played</param>
     */
    private void HandleNextPlayer(Card card)
    {
        switch (card.CardValue)
        {
            case CardValue.RED:
            case CardValue.BLACK:
            {
                _mauCardBuffer.Add(card);
                _turnManager.CurrentPlayer.State = PlayerState.CHOOSE;
                break;
            }
            case CardValue.TWO:
            {
                _mauCardBuffer.Add(card);
                _turnManager.ChangeTurnTo();
                break;
            }
            case CardValue.SEVEN:
            case CardValue.KING:
                break;
            case CardValue.EIGHT:
                _turnManager.ChangeTurnTo(_turnManager.GetNextPlayer(2));
                break;
            case CardValue.ACE:
                if (_turnManager.Players.Count > 2)
                {
                    _turnManager.ChangeDirection();
                    _turnManager.ChangeTurnTo();
                }

                break;
            case CardValue.JACK:
                _turnManager.CurrentPlayer.State = PlayerState.CHOOSE;
                break;
            case CardValue.THREE:
            case CardValue.FOUR:
            case CardValue.FIVE:
            case CardValue.SIX:
            case CardValue.NINE:
            case CardValue.TEN:
            case CardValue.QUEEN:
            default:
                _turnManager.ChangeTurnTo();
                break;
        }
    }

    /**
     * <summary>
     * Check if the card can be played with the current game state.
     * <list type="bullet">
     * <item>The player can only play a mau card if there are pending mau cards (or draw)</item>
     * <item>If there is a next allowed card type, the player can only play that card type, a joker or a card with the same value as the current card</item>
     * <item>Otherwise, the player can play a card that has the same type, same value or is a joker</item>
     * </list>
     * </summary>
     * <returns>True if the given card could be played</returns>
     */
    private bool CardCanBePlayed(Card card)
    {
        // Check if there are pending mau cards played
        if (_mauCardBuffer.Count > 0)
        {
            // If so, the card must be a mau card
            return card.IsMauCard();
        }

        // Check if there is a next allowed card type
        if (NextAllowedCardType != null)
        {
            // If so, the card must be the allowed card type, a joker or the same value as the current card
            return card.CardType == NextAllowedCardType || card.CardType == CardType.JOKER ||
                   card.CardValue == _deck.CurrentCard.CardValue;
        }

        // Otherwise, use the normal rules
        return card.CanBePlayedOn(_deck.CurrentCard);
    }

    /**
     * <summary>
     * Count the amount of cards that need to be drawn from the MauCardBuffer. This method also clears the buffer.
     * </summary>
     * <returns>The amount of cards that need to be drawn</returns>
     */
    private int CountMauCardBuffer()
    {
        var totalCards = 0;
        foreach (var card in _mauCardBuffer)
        {
            if (card.CardType == CardType.JOKER)
            {
                totalCards += 5;
            }
            else if (card.CardValue == CardValue.TWO)
            {
                totalCards += 2;
            }
        }

        _mauCardBuffer.Clear();
        return totalCards;
    }

    /**
     * <summary>
     * Create a game state for each player and send it to them.
     * By making a unique game state for each player we can hide information (like other player's hands).
     * </summary>
     */
    private void SendGameState()
    {
        foreach (var player in _turnManager.Players)
        {
            var gameState = new GameState(player, _deck.CurrentCard, NextAllowedCardType, _turnManager.CurrentPlayer,
                _turnManager.Players);
            player.Connection.SendMessageAsync(
                JsonSerializer.Serialize(new RoomMessage<GameState>("GAME", gameState)));
        }
    }

    /**
     * <summary>
     * Broadcast the winner of the game and change the room's type to a lobby.
     * </summary>
     * <param name="winner">The player that won the game</param>
     */
    private void EndGame(Player winner)
    {
        var winMessage = new EndMessage(winner.Connection);
        _room.BroadCast(new RoomMessage<EndMessage>("END", winMessage));
        _room.RoomType = new Lobby(_room);
    }
}