card-game-engine/RuleEngine/MahjongRoom.cs

namespace RuleEngine;

using RuleEngine.AI;
using RuleEngine.Core;
using RuleEngine.Dsl;
using RuleEngine.Patterns;
using RuleEngine.Phase;
using RuleEngine.Scoring;

public class MahjongRoom
{
    public MahjongGameState State { get; private set; } = new();
    public bool IsFinished { get; private set; }
    private readonly MahjongDslRoot _rules;
    private readonly List<RandomMahjongAI> _ais;
    private readonly HumanMahjongPlayer? _human;
    private readonly MeldsSolver _solver;
    private readonly MahjongPhaseMachine _phaseMachine;
    private readonly MahjongScoreEngine _scoreEngine;
    private readonly bool _autoMode;
    private readonly Random _rng = Random.Shared;
    private readonly PhaseConfig _playPhase;

    public MahjongRoom(MahjongDslRoot rules, string[] playerNames, bool autoMode = false,
        string? humanPlayer = null)
    {
        _rules = rules;
        _autoMode = autoMode;
        _ais = playerNames.Select((n, i) => new RandomMahjongAI(n, new Random(i * 7919))).ToList();

        var fanConfig = BuildFanConfig();
        _solver = new MeldsSolver(fanConfig, State.Wildcards);

        if (humanPlayer != null)
            _human = new HumanMahjongPlayer(humanPlayer, _solver, includeHonors: _rules.Deck.IncludeHonors);

        var phases = BuildPhases();
        _playPhase = phases.FirstOrDefault(p => p.Name == "play") ?? new PhaseConfig();
        var (wc, r258) = GetWinParams();
        _phaseMachine = new MahjongPhaseMachine(phases, _solver, wildcardCount: wc, require258: r258,
            fanConfig: fanConfig,
            jiHuSelfDrawOnly: _rules.WinRule?.JiHuSelfDrawOnly ?? false,
            wildcards: State.Wildcards,
            winMinFan: _rules.WinMinFan);

        _scoreEngine = new MahjongScoreEngine(new ScoringConfig
        {
            Mode = _rules.Scoring.Mode,
            MaxCap = _rules.Scoring.MaxCap,
            FanStacking = _rules.FanStacking,
            PerWildcardBonus = _rules.WildcardRules?.Scoring?.PerWildcardInWin ?? 0,
            JiHuSelfDrawOnly = _rules.WinRule?.JiHuSelfDrawOnly ?? false,
            FlowerNormalScore = _rules.FlowerRules?.Scoring?.Normal ?? 0,
            FlowerMatchScore = _rules.FlowerRules?.Scoring?.Matching?.Value ?? 0,
            FlowerMapping = _rules.FlowerRules?.Scoring?.Matching?.Mapping,
            SelfDrawMultiplier = _rules.Scoring.SelfDrawMultiplier,
            DiscardWinMultiplier = _rules.Scoring.DiscardWinMultiplier,
            DealerMultiplier = _rules.Scoring.DealerMultiplier
        }, _solver, fanConfig);

        // Init state
        State.PlayerOrder = playerNames.ToList();
        State.AlivePlayers = playerNames.ToList();
        State.Dealer = playerNames[0];
        State.CurrentPlayer = playerNames[0];
        State.Phase = "deal";

        foreach (var p in playerNames)
        {
            State.Hands[p] = new List<int>();
            State.Exposed[p] = new List<Meld>();
            State.Scores[p] = 0;
        }
    }

    private Dictionary<string, FanConfig> BuildFanConfig()
    {
        var config = new Dictionary<string, FanConfig>();
        foreach (var f in _rules.FanTypes)
        {
            config[f.Name] = new FanConfig
            {
                Name = f.Name,
                BaseFan = f.BaseFan,
                Level = f.Level,
                Excludes = f.Excludes ?? new(),
                Conflicts = f.Conflicts ?? new(),
                Condition = f.Condition
            };
        }
        return config;
    }

    private List<PhaseConfig> BuildPhases()
    {
        return _rules.Phases.Select(p => new PhaseConfig
        {
            Name = p.Name,
            Type = p.Type,
            Action = p.Action ?? "",
            Next = p.Next,
            TurnOrder = p.TurnOrder ?? "counter_clockwise",
            ParallelElimination = p.ParallelElimination,
            OnEliminate = p.OnEliminate,
            SelfActions = p.SubPhases?.SelfAction?.Options?.Select(o => new ActionOption
            {
                Action = o.Action, Priority = o.Priority, Condition = o.Condition
            }).ToList() ?? new(),
            OthersReactions = p.SubPhases?.OthersReaction?.Options?.Select(o => new ActionOption
            {
                Action = o.Action, Priority = o.Priority, Condition = o.Condition
            }).ToList() ?? new(),
            PriorityPolicy = p.SubPhases?.OthersReaction?.PriorityPolicy ?? "highest_wins",
            OnWin = p.SubPhases?.OthersReaction?.OnWin,
            EndConditions = p.EndConditions?.Select(e => new EndCondition
            {
                Type = e.Type, Action = e.Action
            }).ToList() ?? new()
        }).ToList();
    }

    public void Run()
    {
        Deal();
        IsFinished = false;

        while (!IsFinished)
        {
            if (State.Phase == "deal") { State.Phase = "play"; continue; }
            if (State.Phase == "settle" || IsFinished) break;

            StepTurn();
        }
    }

    private void RecordDiscard(string player, int tile)
    {
        State.DiscardPool.Add(tile);
        if (!State.DiscardHistory.ContainsKey(player))
            State.DiscardHistory[player] = new List<int>();
        State.DiscardHistory[player].Add(tile);
    }

    public List<GameEvent> StepTurn()
    {
        State.RecentEvents.Clear();
        var player = State.CurrentPlayer;

        // Phase 1: Check reactions to last discard BEFORE drawing
        if (State.LastDiscard.HasValue && State.LastDiscardPlayer != null)
        {
            bool reacted = HandleDiscardReactions(State.LastDiscard.Value);
            if (reacted)
            {
                AdvancePlayer();
                return State.RecentEvents;
            }
            State.LastDiscard = null;
            State.LastDiscardPlayer = null;
        }

        // Phase 2: Draw card (skip for dealer on first turn — they already have 14)
        bool isDealerFirstTurn = (player == State.Dealer && State.RoundNumber == 0);
        State.IsLastTile = State.Deck.Count == 1;  // 海底: deck has exactly 1 tile left
        if (isDealerFirstTurn)
            State.LastDrawnTile = null;
        else
        {
        if (State.Deck.Count > 0)
        {
            int drawn = State.Deck[^1];
            State.Deck.RemoveAt(State.Deck.Count - 1);
            State.Hands[player].Add(drawn);
            State.LastDrawnTile = drawn;
            State.AddEvent("draw", player, drawn,
                $"摸牌: {MahjongTile.ToString(drawn)}");

            // Check flower — keep replacing until non-flower or deck empty
            if (MahjongTile.IsFlower(drawn))
            {
                State.FlowerReplaced++;
                State.AddEvent("flower_drawn", player, drawn,
                    $"花牌 {MahjongTile.ToString(drawn)} → 补牌");
                if (!State.FlowerPool.ContainsKey(player))
                    State.FlowerPool[player] = new List<int>();
                State.FlowerPool[player].Add(drawn);
                State.Hands[player].Remove(drawn);
                // Keep drawing replacements until we get a non-flower
                int extra = 0;
                while (State.Deck.Count > 0)
                {
                    extra = State.Deck[^1];
                    State.Deck.RemoveAt(State.Deck.Count - 1);
                    if (!MahjongTile.IsFlower(extra))
                    {
                        State.Hands[player].Add(extra);
                        State.AddEvent("draw", player, extra,
                            $"补牌: {MahjongTile.ToString(extra)}");
                        break;
                    }
                    // Replacement is also a flower → add to pool, keep going
                    State.FlowerReplaced++;
                    if (!State.FlowerPool.ContainsKey(player))
                        State.FlowerPool[player] = new List<int>();
                    State.FlowerPool[player].Add(extra);
                    State.AddEvent("flower_drawn", player, extra,
                        $"补花牌 {MahjongTile.ToString(extra)} → 再补");
                }
            }
        }
        else
        {
            State.IsDeckExhausted = true;
            State.AddEvent("deck_exhausted", "", null, "牌墙耗尽");

            if (_playPhase.ParallelElimination)
            {
                CheckHuaZhu();
                CheckTing();
            }
            Settle();
            return State.RecentEvents;
        }
        } // end if (!isDealerFirstTurn)

        // Phase 3: Player decides what to do with their drawn hand
        bool requireWinFan = _rules.WinMinFan > 0;
        var legalActions = _phaseMachine.GetLegalActions(State, player, requireWinFan);
        var (action, tile) = _human != null && player == _human.Name
            ? _human.Decide(legalActions, State)
            : _ais.First(a => a.Name == player).Decide(legalActions, State);

        if (action == "win")
        {
            var (wc, r258) = GetWinParams();
            var fullHand = FullHand(State, player);
            int wildInHand = CountWildcardsInHand(fullHand);
            var result = _solver.CheckWin(fullHand,
                wildcardCount: wildInHand, require258Pair: r258);
            if (result != null)
                result.Fans = _solver.IdentifyFans(result, State);  // event-based fans
            State.HuPlayers.Add(player);
            State.AlivePlayers.Remove(player);
            State.AddEvent("win", player, null,
                $"自摸！番型: {string.Join(" + ", result?.Fans ?? new())}");

            if (_playPhase.ParallelElimination)
            {
                if (State.AlivePlayers.Count <= 1)
                {
                    Settle();
                    return State.RecentEvents;
                }
            }
            else
            {
                _scoreEngine.Settle(State, player, result!, isSelfDraw: true);
                Settle();
                return State.RecentEvents;
            }
        }
        else if (action == "discard" && tile.HasValue)
        {
            State.Hands[player].Remove(tile.Value);
            State.LastDiscard = tile.Value;
            State.LastDiscardPlayer = player;
            RecordDiscard(player, tile.Value);
            // Clear event flags after a normal discard
            State.IsKongDraw = false;
            State.IsRobbedKong = false;
            State.FuFlags[player] = false;  // clear fu_flag on own discard
            if (State.IsFirstTurn && player == State.Dealer)
                State.IsFirstTurn = false;  // dealer's first turn complete
            State.AddEvent("discard", player, tile.Value,
                $"出牌: {MahjongTile.ToString(tile.Value)}");
        }
        else if (action == "an_kong")
        {
            ExecuteAnKong(player);
        }
        else if (action == "bu_kong")
        {
            ExecuteBuKong(player);
        }

        AdvancePlayer();
        return State.RecentEvents;
    }

    /// <summary>Get wildcard count and 258-pair requirement for current rules.</summary>
    private (int wildcardCount, bool require258) GetWinParams()
    {
        int wc = _rules.WildcardRules != null ? _rules.Deck.WildcardCount : 0;
        bool r258 = _rules.WinCondition?.PairMustBe258 ?? false;
        return (wc, r258);
    }

    /// <summary>Count wildcard tiles in a hand (encoding 50-59 + configured).</summary>
    private int CountWildcardsInHand(List<int> hand)
        => State.Wildcards.CountWildcards(hand);

    /// <summary>Combine hand + exposed melds into full virtual hand for CheckWin.</summary>
    private static List<int> FullHand(MahjongGameState state, string player, int? extraTile = null)
    {
        var tiles = new List<int>(state.Hands[player]);
        if (extraTile.HasValue) tiles.Add(extraTile.Value);
        if (state.Exposed.TryGetValue(player, out var melds))
            foreach (var m in melds)
                tiles.AddRange(m.Tiles.Where(t => t != -1));
        return tiles;
    }

    /// <summary>
    /// Let other players react to a discard (pung/kong/win).
    /// Returns true if someone reacted (turn passes to them).
    /// </summary>
    private bool HandleDiscardReactions(int discardTile)
    {
        string discarder = State.LastDiscardPlayer ?? "";
        int startIdx = State.PlayerOrder.IndexOf(discarder);

        // Check in player order (starting after discarder)
        for (int offset = 1; offset < State.PlayerOrder.Count; offset++)
        {
            string p = State.PlayerOrder[(startIdx + offset) % State.PlayerOrder.Count];
            if (!State.AlivePlayers.Contains(p)) continue;
            if (p == discarder) continue;

            int sameCount = State.Hands[p].Count(t => t == discardTile);
            bool canWin = false, canKong = sameCount >= 3, canPung = sameCount >= 2;
            bool canChi = false;

            // Chi: only if DSL allows it + immediate next player + non-honor tile
            if (_phaseMachine.ChiAllowed && offset == 1 && !MahjongTile.IsHonor(discardTile))
                canChi = _phaseMachine.CanChiCheck(State, p, discardTile);

            // Check win
            var fullHand = FullHand(State, p, extraTile: discardTile);
            var (wc, r258) = GetWinParams();
            int wildInHand = CountWildcardsInHand(fullHand);
            var winResult = _solver.CheckWin(fullHand,
                wildcardCount: wildInHand, require258Pair: r258);
            if (winResult != null && winResult.IsWin)
            {
                winResult.Fans = _solver.IdentifyFans(winResult, State);  // event-based fans
                canWin = true;
            }

            // Human player: ask what they want to do
            if (_human != null && p == _human.Name && (canWin || canKong || canPung || canChi))
            {
                Console.WriteLine();
                Console.WriteLine($"=== {p} 可以反应 ===");
                Console.WriteLine($"  对手 {discarder} 出了: {MahjongTile.ToString(discardTile)}");
                Console.WriteLine($"  你的手牌: {string.Join(" ", State.Hands[p].OrderBy(t => t).Select(MahjongTile.ToString))}");
                Console.Write("  操作: ");
                var ops = new List<string>();
                if (canWin) ops.Add("h(胡)");
                if (canKong) ops.Add("k(杠)");
                if (canPung) ops.Add("p(碰)");
                if (canChi) ops.Add("c(吃)");
                ops.Add("Enter(过)");
                Console.WriteLine(string.Join(" ", ops));
                Console.Write("> ");
                string? input = Console.ReadLine()?.Trim().ToLower();

                if (input == "h" && canWin)
                {
                    // Check fu_flag: if player passed a win earlier, block it
                    if (State.FuFlags.GetValueOrDefault(p, false))
                    {
                        Console.WriteLine("  ⚠ 过水——本轮不能胡同一张牌");
                        continue;
                    }
                    State.DiscardPool.Remove(discardTile);
                    State.HuPlayers.Add(p);
                    State.AlivePlayers.Remove(p);
                    State.AddEvent("win", p, discardTile,
                        $"胡！{MahjongTile.ToString(discardTile)}");
                    if (!_playPhase.ParallelElimination)
                    {
                        _scoreEngine.Settle(State, p, winResult!, isSelfDraw: false);
                        IsFinished = true;
                    }
                    return true;
                }

                if ((input == "k" && canKong) || (input == "p" && canPung))
                {
                    string action = input == "k" ? "ming_kong" : "pung";
                    return ExecutePungKongHuman(p, discardTile, action);
                }
                if (input == "c" && canChi)
                {
                    return ExecuteChi(p, discardTile);
                }
                // Human passed — set fu_flag if they could have won
                if (canWin) State.FuFlags[p] = true;
                continue;
            }

            // AI player: auto-decide
            if (canWin) return ExecuteWinClaim(p, discardTile, winResult!);
            if (canKong || canPung) return ExecutePungKong(p, discardTile, canKong ? "ming_kong" : "pung");
            if (canChi) return ExecuteAiChi(p, discardTile);
        }

        return false;
    }

    private bool ExecutePungKongHuman(string p, int discardTile, string action)
    {
        string discarder = State.LastDiscardPlayer ?? "";
        State.DiscardPool.Remove(discardTile);
        int toRemove = action == "ming_kong" ? 3 : 2;
        for (int r = 0; r < toRemove; r++)
            State.Hands[p].Remove(discardTile);
        int meldSize = action == "ming_kong" ? 4 : 3;
        State.Exposed[p].Add(new Meld
        {
            Type = action,
            Tiles = Enumerable.Repeat(discardTile, meldSize).ToList(),
            SourcePlayer = discarder
        });
        State.CurrentPlayer = p;
        State.LastDiscard = null;
        State.LastDiscardPlayer = null;
        State.AddEvent(action, p, discardTile, action == "pung" ? "碰！" : "明杠！");

        var hand = State.Hands[p];
        Console.WriteLine($"  碰/杠后手牌 ({hand.Count}张):");
        var sorted = hand.OrderBy(t => t).ToList();
        for (int i = 0; i < sorted.Count; i++)
            Console.WriteLine($"    [{i + 1}] {MahjongTile.ToString(sorted[i])}");
        Console.Write($"  请出牌 (1-{hand.Count}): ");
        int discardIdx;
        while (!int.TryParse(Console.ReadLine(), out discardIdx) || discardIdx < 1 || discardIdx > sorted.Count)
            Console.Write("  无效，重试: ");
        int tileToDiscard = sorted[discardIdx - 1];
        State.Hands[p].Remove(tileToDiscard);
        State.LastDiscard = tileToDiscard;
        State.LastDiscardPlayer = p;
        RecordDiscard(p, tileToDiscard);
        State.AddEvent("discard", p, tileToDiscard, $"出牌: {MahjongTile.ToString(tileToDiscard)}");
        return true;
    }

    private bool ExecuteChi(string p, int discardTile)
    {
        string discarder = State.LastDiscardPlayer ?? "";
        State.DiscardPool.Remove(discardTile);

        int suit = MahjongTile.Suit(discardTile);
        int rank = MahjongTile.Rank(discardTile);
        var hand = State.Hands[p];

        // Find which two tiles form the chi sequence
        List<int> toRemove = new();
        if (rank >= 3 && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 2)
            && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1))
        {
            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 2));
            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1));
        }
        else if (rank >= 2 && rank <= 8 && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1)
            && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1))
        {
            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1));
            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1));
        }
        else if (rank <= 7 && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1)
            && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 2))
        {
            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1));
            toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 2));
        }
        foreach (var t in toRemove) State.Hands[p].Remove(t);

        var chiTiles = new List<int>(toRemove) { discardTile };
        chiTiles.Sort();
        State.Exposed[p].Add(new Meld
        {
            Type = "chi",
            Tiles = chiTiles,
            SourcePlayer = discarder
        });
        State.CurrentPlayer = p;
        State.LastDiscard = null;
        State.LastDiscardPlayer = null;
        State.AddEvent("chi", p, discardTile, $"吃！{string.Join(",", chiTiles.Select(MahjongTile.ToString))}");

        // Human must discard after chi
        var remainingHand = State.Hands[p];
        Console.WriteLine($"  吃后手牌 ({remainingHand.Count}张):");
        var sorted = remainingHand.OrderBy(t => t).ToList();
        for (int i = 0; i < sorted.Count; i++)
            Console.WriteLine($"    [{i + 1}] {MahjongTile.ToString(sorted[i])}");
        Console.Write($"  请出牌 (1-{remainingHand.Count}): ");
        int discardIdx;
        while (!int.TryParse(Console.ReadLine(), out discardIdx) || discardIdx < 1 || discardIdx > sorted.Count)
            Console.Write("  无效，重试: ");
        int tileToDiscard = sorted[discardIdx - 1];
        State.Hands[p].Remove(tileToDiscard);
        State.LastDiscard = tileToDiscard;
        State.LastDiscardPlayer = p;
        RecordDiscard(p, tileToDiscard);
        State.AddEvent("discard", p, tileToDiscard, $"出牌: {MahjongTile.ToString(tileToDiscard)}");
        return true;
    }

    private bool ExecuteAiChi(string p, int discardTile)
    {
        string discarder = State.LastDiscardPlayer ?? "";
        State.DiscardPool.Remove(discardTile);
        int suit = MahjongTile.Suit(discardTile);
        int rank = MahjongTile.Rank(discardTile);
        var hand = State.Hands[p];

        List<int> toRemove = new();
        if (rank >= 3 && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 2)
            && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1))
        { toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 2));
          toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1)); }
        else if (rank >= 2 && rank <= 8 && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1)
            && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1))
        { toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank - 1));
          toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1)); }
        else if (rank <= 7 && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1)
            && hand.Any(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 2))
        { toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 1));
          toRemove.Add(hand.First(t => MahjongTile.Suit(t) == suit && MahjongTile.Rank(t) == rank + 2)); }
        foreach (var t in toRemove) State.Hands[p].Remove(t);

        var chiTiles = new List<int>(toRemove) { discardTile };
        chiTiles.Sort();
        State.Exposed[p].Add(new Meld { Type = "chi", Tiles = chiTiles, SourcePlayer = discarder });
        State.CurrentPlayer = p;
        State.LastDiscard = null;
        State.LastDiscardPlayer = null;
        State.AddEvent("chi", p, discardTile, $"吃！{string.Join(",", chiTiles.Select(MahjongTile.ToString))}");

        if (hand.Count > 0)
        {
            int tileToDiscard = hand[_rng.Next(hand.Count)];
            State.Hands[p].Remove(tileToDiscard);
            State.LastDiscard = tileToDiscard;
            State.LastDiscardPlayer = p;
            RecordDiscard(p, tileToDiscard);
            State.AddEvent("discard", p, tileToDiscard, $"出牌: {MahjongTile.ToString(tileToDiscard)}");
        }
        return true;
    }

    private bool ExecuteWinClaim(string player, int discardTile, MeldsResult winResult)
    {
        State.DiscardPool.Remove(discardTile);
        State.HuPlayers.Add(player);
        State.AlivePlayers.Remove(player);
        State.AddEvent("win", player, discardTile, $"胡！{MahjongTile.ToString(discardTile)}");
        if (!_playPhase.ParallelElimination)
        {
            _scoreEngine.Settle(State, player, winResult, isSelfDraw: false);
            Settle();
        }
        return true;
    }

    private void ExecuteAnKong(string player)
    {
        var hand = State.Hands[player];
        var group = hand.GroupBy(t => t)
            .FirstOrDefault(g => g.Count() >= 4 && !State.Wildcards.IsWildcard(g.Key));
        if (group == null) return; // defensive: PhaseMachine should prevent this
        int tile = group.Key;
        for (int i = 0; i < 4; i++) State.Hands[player].Remove(tile);
        State.Exposed[player].Add(new Meld
        {
            Type = "kong_an",
            Tiles = Enumerable.Repeat(tile, 4).ToList(),
            IsConcealed = true
        });
        State.AddEvent("an_kong", player, tile, $"暗杠！{MahjongTile.ToString(tile)}");

        // Kong draw
        if (State.Deck.Count > 0)
        {
            int drawn = State.Deck[^1];
            State.Deck.RemoveAt(State.Deck.Count - 1);
            State.Hands[player].Add(drawn);
            State.LastDrawnTile = drawn;
            State.IsKongDraw = true;  // 杠后摸牌标志
            State.AddEvent("draw", player, drawn, $"杠补: {MahjongTile.ToString(drawn)}");
        }

        // Discard one tile after kong
        if (State.Hands[player].Count > 0)
        {
            int tileToDiscard = _human != null && player == _human.Name
                ? HumanPickDiscard(player)
                : State.Hands[player][_rng.Next(State.Hands[player].Count)];
            State.Hands[player].Remove(tileToDiscard);
            State.LastDiscard = tileToDiscard;
            State.LastDiscardPlayer = player;
            RecordDiscard(player, tileToDiscard);
            State.AddEvent("discard", player, tileToDiscard, $"出牌: {MahjongTile.ToString(tileToDiscard)}");
        }
    }

    private void ExecuteBuKong(string player)
    {
        var exposed = State.Exposed[player];
        var pung = exposed.FirstOrDefault(m => m.Type == "pung" && State.Hands[player].Contains(m.Tiles[0]));
        if (pung == null) return; // defensive: PhaseMachine should prevent this
        int tile = pung.Tiles[0];
        State.Hands[player].Remove(tile);
        pung.Type = "kong_bu";
        pung.Tiles.Add(tile);
        State.AddEvent("bu_kong", player, tile, $"加杠！{MahjongTile.ToString(tile)}");
        State.IsRobbedKong = true;  // 抢杠标志

        if (State.Deck.Count > 0)
        {
            int drawn = State.Deck[^1];
            State.Deck.RemoveAt(State.Deck.Count - 1);
            State.Hands[player].Add(drawn);
            State.LastDrawnTile = drawn;
            State.IsKongDraw = true;
            State.AddEvent("draw", player, drawn, $"杠补: {MahjongTile.ToString(drawn)}");
        }

        // Discard after kong
        if (State.Hands[player].Count > 0)
        {
            int tileToDiscard = _human != null && player == _human.Name
                ? HumanPickDiscard(player)
                : State.Hands[player][_rng.Next(State.Hands[player].Count)];
            State.Hands[player].Remove(tileToDiscard);
            State.LastDiscard = tileToDiscard;
            State.LastDiscardPlayer = player;
            RecordDiscard(player, tileToDiscard);
            State.AddEvent("discard", player, tileToDiscard, $"出牌: {MahjongTile.ToString(tileToDiscard)}");
        }
    }

    private int HumanPickDiscard(string player)
    {
        var hand = State.Hands[player];
        var sorted = hand.OrderBy(t => t).ToList();
        Console.WriteLine($"  杠后手牌 ({hand.Count}张):");
        for (int i = 0; i < sorted.Count; i++)
            Console.WriteLine($"    [{i + 1}] {MahjongTile.ToString(sorted[i])}");
        Console.Write($"  请出牌 (1-{hand.Count}): ");
        int idx;
        while (!int.TryParse(Console.ReadLine(), out idx) || idx < 1 || idx > sorted.Count)
            Console.Write("  无效，重试: ");
        return sorted[idx - 1];
    }

    private bool ExecutePungKong(string player, int discardTile, string action)
    {
        State.DiscardPool.Remove(discardTile);
        int toRemove = action == "ming_kong" ? 3 : 2;
        for (int r = 0; r < toRemove; r++)
            State.Hands[player].Remove(discardTile);

        int meldSize = action == "ming_kong" ? 4 : 3;
        State.Exposed[player].Add(new Meld
        {
            Type = action,
            Tiles = Enumerable.Repeat(discardTile, meldSize).ToList(),
            SourcePlayer = State.LastDiscardPlayer ?? ""
        });
        State.CurrentPlayer = player;
        State.LastDiscard = null;
        State.LastDiscardPlayer = null;
        State.AddEvent(action, player, discardTile,
            action == "pung" ? "碰！" : "明杠！");

        // AI discards after pung/kong
        var hand = State.Hands[player];
        if (hand.Count > 0)
        {
            int tileToDiscard = hand[_rng.Next(hand.Count)];
            State.Hands[player].Remove(tileToDiscard);
            State.LastDiscard = tileToDiscard;
            State.LastDiscardPlayer = player;
            RecordDiscard(player, tileToDiscard);
            State.AddEvent("discard", player, tileToDiscard,
                $"出牌: {MahjongTile.ToString(tileToDiscard)}");
        }
        return true;
    }

    private void AdvancePlayer()
    {
        int idx = State.PlayerOrder.IndexOf(State.CurrentPlayer);
        for (int i = 0; i < State.PlayerOrder.Count; i++)
        {
            int next = (idx + 1 + i) % State.PlayerOrder.Count;
            if (State.AlivePlayers.Contains(State.PlayerOrder[next]))
            {
                State.CurrentPlayer = State.PlayerOrder[next];
                State.RoundNumber++;
                return;
            }
        }
        // No alive players
        IsFinished = true;
    }

    public void Deal()
    {
        int perPlayer = _rules.Deal.CardsPerPlayer;
        bool includeFlowers = _rules.Deck.IncludeFlowers;
        bool includeHonors = _rules.Deck.IncludeHonors;

        // Reset wildcards — always clear to avoid test state leak
        State.Wildcards.Clear();
        int wildcardBase = _rules.WildcardRules?.WildcardEncoding ?? 50;
        State.Wildcards.WildcardBase = wildcardBase;
        int wildcardCount = 0;
        if (_rules.WildcardRules != null)
        {
            if (_rules.WildcardRules.Type == "fixed" && _rules.WildcardRules.Tiles != null)
            {
                // Fixed wildcards: specified tiles ARE the wildcards, not extra tiles
                var wcTiles = _rules.WildcardRules.Tiles
                    .Select(t => WildcardRegistry.NameToEncoding(t) ?? -1)
                    .Where(t => t > 0).ToArray();
                State.Wildcards.AddRange(wcTiles);
                wildcardCount = 0; // No extra tiles
            }
            else
            {
                wildcardCount = _rules.Deck.WildcardCount;
            }
        }

        var deck = new MahjongDeck(includeHonors, includeFlowers, wildcardCount,
            expectedTotal: _rules.Deck.Total, wildcardBase: wildcardBase);
        deck.Shuffle(_rng);

        State.Deck = deck.Tiles;
        State.AddEvent("deal_start", "", null,
            $"发牌 — {deck.Count}张牌({(includeHonors ? "+字" : "")}{(includeFlowers ? "+花" : "")}{(wildcardCount > 0 ? "+癞子" : "")})");

        foreach (var p in State.PlayerOrder)
        {
            int count = p == State.Dealer ? perPlayer + _rules.Deal.DealerExtra : perPlayer;
            for (int i = 0; i < count; i++)
            {
                int tile = State.Deck[^1];
                State.Deck.RemoveAt(State.Deck.Count - 1);
                State.Hands[p].Add(tile);
            }
        }

        State.AddEvent("deal_done", "", null, "发牌完成");

        // Random wildcard (骰子翻牌定精): flip one tile from remaining deck to determine 精
        if (_rules.WildcardRules?.Type == "random" && State.Deck.Count > 0)
        {
            int revealed = State.Deck[^1];
            State.Deck.RemoveAt(State.Deck.Count - 1);
            int count = _rules.WildcardRules.RandomCount > 0 ? _rules.WildcardRules.RandomCount : 2;
            var wildcardTiles = WildcardRegistry.ComputeNextTiles(revealed, count);
            State.Wildcards.AddRange(wildcardTiles);
            State.Wildcards.RevealedTile = revealed;
            State.AddEvent("reveal_wildcard", "", revealed,
                $"翻牌定精: {MahjongTile.ToString(revealed)} → 精: {string.Join(", ", wildcardTiles.Select(t => MahjongTile.ToString(t, State.Wildcards)))}");
        }

        // Set first-turn flags for event-based fans
        State.IsFirstTurn = true;
        State.DealerOnFirstTurn = State.Dealer;

        // Replace flowers in initial hands BEFORE game starts.
        // Triggers for: Guangdong (replace_tiles: BEFORE_GAME_START),
        // Guobiao (deal action: deal_cards_with_flowers), or any variant with flowers.
        bool replaceInitialFlowers = _rules.FlowerRules != null && includeFlowers
            && (string.Equals(_rules.FlowerRules.ReplaceTiles, "BEFORE_GAME_START", StringComparison.OrdinalIgnoreCase)
                || string.Equals(_playPhase.Action, "deal_cards_with_flowers", StringComparison.OrdinalIgnoreCase));
        if (replaceInitialFlowers)
        {
            int replaced = 0;
            foreach (var p in State.PlayerOrder)
            {
                var hand = State.Hands[p];
                while (true)
                {
                    var flower = hand.FirstOrDefault(MahjongTile.IsFlower);
                    if (flower == 0) break; // no more flowers
                    hand.Remove(flower);
                    if (!State.FlowerPool.ContainsKey(p))
                        State.FlowerPool[p] = new List<int>();
                    State.FlowerPool[p].Add(flower);
                    if (State.Deck.Count > 0)
                    {
                        int extra = State.Deck[^1];
                        State.Deck.RemoveAt(State.Deck.Count - 1);
                        hand.Add(extra);
                        replaced++;
                    }
                    else break; // deck empty, stop
                }
            }
            if (replaced > 0)
                State.AddEvent("flower_replace", "", null, $"开局换花牌: {replaced}张");
        }
    }

    private void CheckHuaZhu()
    {
        foreach (var p in State.AlivePlayers)
        {
            var suits = State.Hands[p]
                .Where(t => MahjongTile.IsNumbered(t))
                .Select(MahjongTile.Suit)
                .Distinct()
                .Count();
            if (suits == 3)
                State.AddEvent("hua_zhu", p, null, "花猪！三色齐全");
            else
                State.AddEvent("hua_zhu_ok", p, null, $"✓ {suits}种花色");
        }
    }

    private void CheckTing()
    {
        bool require258 = _rules.WinCondition?.PairMustBe258 ?? false;

        // All possible tiles that could be drawn (numbered 1-9 across 3 suits + 7 honors)
        var allPossibleTiles = MahjongTile.AllTiles(
            includeHonors: _rules.Deck.IncludeHonors,
            includeFlowers: false);

        foreach (var p in State.AlivePlayers)
        {
            bool ting = false;
            var hand = State.Hands[p];

            // For each possible tile we could draw, check if hand + tile is a win
            foreach (var tile in allPossibleTiles)
            {
                // Count how many of this tile exist (4 max per tile type)
                int alreadyHave = hand.Count(t => t == tile);
                if (alreadyHave >= 4) continue; // can't draw more of this tile

                var handWithTile = new List<int>(hand) { tile };
                int wc = CountWildcardsInHand(handWithTile);
                var r = _solver.CheckWin(hand, newTile: tile,
                    wildcardCount: wc, require258Pair: require258);
                if (r != null && r.IsWin) { ting = true; break; }
            }

            if (ting)
                State.AddEvent("ting_checked", p, null, "✓ 听牌");
            else
                State.AddEvent("ting_failed", p, null, "❌ 未听牌");
        }
    }

    private void Settle()
    {
        IsFinished = true;
        State.Phase = "settle";
        State.AddEvent("settle", "", null, "结算");
    }
}