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;

    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);

        if (humanPlayer != null)
            _human = new HumanMahjongPlayer(humanPlayer, _solver);

        var phases = BuildPhases();
        var (wc, r258) = GetWinParams();
        _phaseMachine = new MahjongPhaseMachine(phases, _solver, wildcardCount: wc, require258: r258);

        _scoreEngine = new MahjongScoreEngine(new ScoringConfig
        {
            Mode = _rules.Scoring.Mode,
            MaxCap = _rules.Scoring.MaxCap
        }, _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 = "counter_clockwise",
            ParallelElimination = p.ParallelElimination,
            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
        }).ToList();
    }

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

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

            StepTurn();
        }

        if (!IsFinished)
            Settle();
    }

    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);
        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
            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);
                if (State.Deck.Count > 0)
                {
                    int extra = State.Deck[^1];
                    State.Deck.RemoveAt(State.Deck.Count - 1);
                    State.Hands[player].Add(extra);
                    State.AddEvent("draw", player, extra,
                        $"补牌: {MahjongTile.ToString(extra)}");
                }
            }
        }
        else
        {
            State.IsDeckExhausted = true;
            State.AddEvent("deck_exhausted", "", null, "牌墙耗尽");

            if (_rules.Phases.Any(p => p.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();
            int wildInHand = CountWildcardsInHand(State.Hands[player]);
            var result = _solver.CheckWin(State.Hands[player],
                wildcardCount: wildInHand, require258Pair: r258);
            State.HuPlayers.Add(player);
            State.AlivePlayers.Remove(player);
            State.AddEvent("win", player, null,
                $"自摸！番型: {string.Join(" + ", result?.Fans ?? new())}");

            if (_rules.Phases.Any(p => p.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;
            State.DiscardPool.Add(tile.Value);
            State.AddEvent("discard", player, tile.Value,
                $"出牌: {MahjongTile.ToString(tile.Value)}");
        }

        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).</summary>
    private static int CountWildcardsInHand(List<int> hand)
        => hand.Count(MahjongTile.IsWildcard);

    /// <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;

            // Check win
            var handWithTile = new List<int>(State.Hands[p]) { discardTile };
            var (wc, r258) = GetWinParams();
            int wildInHand = CountWildcardsInHand(handWithTile);
            var winResult = _solver.CheckWin(handWithTile,
                wildcardCount: wildInHand, require258Pair: r258);
            if (winResult != null && winResult.IsWin)
                canWin = true;

            // Human player: ask what they want to do
            if (_human != null && p == _human.Name && (canWin || canKong || canPung))
            {
                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)");
                ops.Add("Enter(过)");
                Console.WriteLine(string.Join(" ", ops));
                Console.Write("> ");
                string? input = Console.ReadLine()?.Trim().ToLower();

                if (input == "h" && canWin)
                {
                    State.DiscardPool.Remove(discardTile);
                    State.HuPlayers.Add(p);
                    State.AlivePlayers.Remove(p);
                    State.AddEvent("win", p, discardTile,
                        $"胡！{MahjongTile.ToString(discardTile)}");
                    if (!_rules.Phases.Any(ph => ph.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";
                    int toRemove = action == "ming_kong" ? 3 : 2;
                    for (int r = 0; r < toRemove; r++)
                        State.Hands[p].Remove(discardTile);

                    State.DiscardPool.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！");

                    // Human must discard after pung/kong
                    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-{0}): ".Replace("{0}", hand.Count.ToString()), 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;
                    State.DiscardPool.Add(tileToDiscard);
                    State.AddEvent("discard", p, tileToDiscard,
                        $"出牌: {MahjongTile.ToString(tileToDiscard)}");
                    return true;
                }
                // Human passed — continue to next player
                continue;
            }

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

        return false;
    }

    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 (!_rules.Phases.Any(ph => ph.ParallelElimination))
        {
            _scoreEngine.Settle(State, player, winResult, isSelfDraw: false);
            IsFinished = true;
        }
        return true;
    }

    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[Random.Shared.Next(hand.Count)];
            State.Hands[player].Remove(tileToDiscard);
            State.LastDiscard = tileToDiscard;
            State.LastDiscardPlayer = player;
            State.DiscardPool.Add(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;
        int wildcardCount = _rules.WildcardRules != null ? _rules.Deck.WildcardCount : 0;

        var deck = new MahjongDeck(includeHonors, includeFlowers, wildcardCount);
        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");
    }

    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 hasWildcard = _rules.WildcardRules != null;
        int wildcardCount = hasWildcard ? _rules.Deck.WildcardCount : 0;
        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 r = _solver.CheckWin(hand, newTile: tile,
                    wildcardCount: wildcardCount, 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");
    }
}