using OECS;

namespace Game.Blackjack;

/// <summary>
/// Dealer draws cards until reaching 17 or higher,
/// then resolves the round result.
/// </summary>
public class DealerSystem : ISystem
{
    public void Run(World world)
    {
        var state = world.ReadSingleton<GameState>();
        if (state.Phase != GamePhase.DealerTurn)
            return;

        ref var mutableState = ref world.GetSingleton<GameState>();

        // Dealer must hit on 16 and below, stand on 17+.
        int dealerTotal = HandUtil.CalculateHand(world, DealerHandTag.Instance);
        while (dealerTotal < 17)
        {
            HitCommand.DrawCard<DealerHand>(world);
            dealerTotal = HandUtil.CalculateHand(world, DealerHandTag.Instance);
        }

        int playerTotal = HandUtil.CalculateHand(world, PlayerHandTag.Instance);

        mutableState.Phase = GamePhase.RoundOver;

        if (dealerTotal > 21)
        {
            mutableState.Result = RoundResult.DealerBust;
            mutableState.Chips += mutableState.CurrentBet * 2;
        }
        else if (playerTotal > dealerTotal)
        {
            mutableState.Result = RoundResult.PlayerWin;
            mutableState.Chips += mutableState.CurrentBet * 2;
        }
        else if (dealerTotal > playerTotal)
        {
            mutableState.Result = RoundResult.DealerWin;
        }
        else
        {
            // Push: return the bet.
            mutableState.Result = RoundResult.Push;
            mutableState.Chips += mutableState.CurrentBet;
        }

        world.MarkModified<GameState>(World.SingletonEntity);
    }
}