card-game-engine/RuleEngine/Scoring/ScoreEngine.cs

namespace RuleEngine.Scoring;

using RuleEngine.Core;
using RuleEngine.Patterns;

public class ScoringConfig
{
    public string Mode { get; set; } = "fan_table";
    public int MaxCap { get; set; } = int.MaxValue;
}

public class MahjongScoreEngine
{
    private readonly ScoringConfig _config;
    private readonly MeldsSolver _solver;

    public MahjongScoreEngine(ScoringConfig config, MeldsSolver solver)
    {
        _config = config;
        _solver = solver;
    }

    public void Settle(MahjongGameState state, string winner, MeldsResult result, bool isSelfDraw)
    {
        int baseFan = result.Fans.Sum(f => FanValue(f));
        baseFan = Math.Min(baseFan, _config.MaxCap);

        if (isSelfDraw)
        {
            // Self-draw: all losers pay winner
            int perPlayer = baseFan * (state.HuPlayers.Contains(winner) ? 1 : 1);
            foreach (var p in state.AlivePlayers)
            {
                if (p == winner) continue;
                state.Scores[p] = (state.Scores.GetValueOrDefault(p) - baseFan);
                state.Scores[winner] = (state.Scores.GetValueOrDefault(winner) + baseFan);
            }
        }
        else
        {
            // Discard win: discarder pays
            if (state.LastDiscardPlayer != null && state.LastDiscardPlayer != winner)
            {
                state.Scores[state.LastDiscardPlayer] = (state.Scores.GetValueOrDefault(state.LastDiscardPlayer) - baseFan * 3);
                state.Scores[winner] = (state.Scores.GetValueOrDefault(winner) + baseFan * 3);
            }
        }
    }

    public void CheckFinish(MahjongGameState state, MeldsSolver solver,
        bool require258Pair, int wildcardCount)
    {
        // Check each alive player for ting
        foreach (var p in state.AlivePlayers)
        {
            var hand = state.Hands[p];
            if (hand.Count <= 14)
            {
                // Simple: check if removing any one tile leads to win
                bool hasTing = false;
                foreach (var t in hand)
                {
                    var testHand = new List<int>(hand);
                    testHand.Remove(t);
                    var r = solver.CheckWin(testHand, wildcardCount: wildcardCount, require258Pair: require258Pair);
                    if (r != null && r.IsWin)
                    {
                        hasTing = true;
                        break;
                    }
                }
                if (hasTing)
                    state.AddEvent("ting_checked", p, null, "听牌");
                else
                    state.AddEvent("ting_failed", p, null, "不听牌 — 罚分");
            }
        }
    }

    private int FanValue(string fan) => fan switch
    {
        "清一色" => 4,
        "对对胡" => 2,
        "暗七对" => 4,
        "带幺九" => 2,
        "十三幺" => 88,
        _ => 1
    };
}