oecs-sharp/Game.Blackjack/Systems/PlayerBustCheckSystem.cs

using OECS;

namespace Game.Blackjack;

/// <summary>
/// Evaluates the player's hand total after each hit.
/// Busts the player if they exceed 21.
/// </summary>
public class PlayerBustCheckSystem : ISystem
{
    public void Run(World world)
    {
        var state = world.ReadSingleton<GameState>();
        if (state.Phase != GamePhase.PlayerTurn)
            return;

        var total = HandUtil.CalculateHand(world, PlayerHandTag.Instance);
        if (total <= 21)
            return;

        ref var mutableState = ref world.GetSingleton<GameState>();
        mutableState.Phase = GamePhase.RoundOver;
        mutableState.Result = RoundResult.PlayerBust;
        world.MarkModified<GameState>(World.SingletonEntity);
    }
}