using System;
using System.Collections.Generic;
using System.Linq;
using GameFix.PaoDeKuaiF;
using GameFix.Poker;
using GameMessage;
using GameMessage.PaoDeKuaiF;

namespace PdkFriendServer.Logic
{
    /// <summary>
    /// SO-ISMCTS v4 — 引擎级 rollout，支持全部牌型。
    /// 
    /// 核心改进：用 PdkCardAlgorithm.GetTipCard 替代字节级贪心模拟，
    /// 支持单张/对子/三张/三带二/顺子/连对/飞机/炸弹/四带二/飞机带对。
    /// 
    /// Rollout 策略：优先清牌效率（多牌优先），但保留大牌控制权。
    /// </summary>
    public class SOIsmctsBot : IPdkBot
    {
        private readonly int _simBudget;
        private readonly Random _rng;
        private readonly CardTracker _tracker = new CardTracker();

        // 静态牌池：52张牌，只创建一次，ID→card 快速查找
        private static readonly TCardInfoPdkF[] FullDeck;
        static SOIsmctsBot()
        {
            FullDeck = new TCardInfoPdkF[53]; // 1-indexed
            int id = 1;
            foreach (int f in new[] { 1, 2, 3, 4 })
                for (int n = 1; n <= 13; n++)
                    FullDeck[id] = new TCardInfoPdkF
                    {
                        ID = (byte)id,
                        Flower = (byte)f,
                        GameNum = (byte)(n == 1 ? 14 : n == 2 ? 16 : n),
                        GameState = 1
                    };
        }

        public SOIsmctsBot(int simBudget = 800)
        {
            _simBudget = simBudget;
            _rng = new Random();
        }

        public bool DecideBaoZhuang(PdkBotView view)
        {
            _tracker.Update(view);
            int minPlays = HandOptimizer.MinPlays(view.MyHand);
            if (minPlays >= 7) return false;
            double threshold = minPlays <= 3 ? 0.50 : minPlays <= 4 ? 0.60 : minPlays <= 5 ? 0.65 : 0.70;

            int wins = 0;
            for (int s = 0; s < 400; s++)
                if (Rollout(view.MyHand, view, null)) wins++;

            double wr = (double)wins / 400;
            Console.WriteLine($"[SOv4 pos{view.MyPos}] 包庄: min={minPlays} wr={wr:P0} → {(wr >= threshold ? "包" : "不")}");
            return wr >= threshold;
        }

        public PlayOutCardPdkF DecidePlay(PdkBotView view)
        {
            _tracker.Update(view);
            var hand = view.MyHand;
            if (hand.Length == 0) return Pass(view);

            if (hand.Length <= 5 && _tracker.UnknownCount(hand) <= 15)
            {
                var eg = EndgameSolver.Solve(hand, view, _tracker, _rng);
                if (eg.HasValue) return eg.Value;
            }

            if (hand.Length <= 8)
            {
                var lockSeq = LockDetector.FindLockSequence(hand, _tracker, view.MyPos);
                if (lockSeq != null)
                {
                    Console.WriteLine($"[SOv4 pos{view.MyPos}] LOCK {lockSeq.Count}步");
                    return new PlayOutCardPdkF { Pos = (byte)view.MyPos, GameNum = lockSeq[0].GameNum, Ids = lockSeq[0].Ids, Type = CardType1.None };
                }
            }

            bool isFirstPlay = view.MaxPlayCard.GameNum <= 0;
            var candidates = BuildCandidates(hand, view, isFirstPlay);
            if (candidates.Count == 1) return candidates[0].play;

            var root = new SONode(candidates.Count);
            int myPos = view.MyPos;
            int o1c = view.ShenYuCard[myPos % 3];
            int o2c = view.ShenYuCard[(myPos + 1) % 3];

            // 预生成对手手牌 (TCardInfoPdkF)
            var knownIds = new HashSet<byte>();
            foreach (var c in hand) knownIds.Add(c.ID);
            var poolCards = FullDeck.Where(c => c.ID > 0 && !knownIds.Contains(c.ID)).ToList();

            int preGen = Math.Min(200, _simBudget);
            var preHands1 = new TCardInfoPdkF[preGen][];
            var preHands2 = new TCardInfoPdkF[preGen][];

            for (int g = 0; g < preGen; g++)
            {
                Shuffle(poolCards, _rng);
                preHands1[g] = poolCards.Take(o1c).ToArray();
                preHands2[g] = poolCards.Skip(o1c).Take(o2c).ToArray();
            }

            int genIdx = 0, totalSims = 0;

            for (int iter = 0; iter < _simBudget; iter++)
            {
                int ci = _rng.Next(candidates.Count);
                var (play, isMulti) = candidates[ci];

                // 用预生成的对手手牌
                genIdx = (genIdx + 1) % preGen;
                bool win = Rollout(hand, view, play, preHands1[genIdx], preHands2[genIdx]);

                root.Visit(ci, win);
                totalSims++;
            }

            int bestIdx = root.BestChild(candidates.Count);
            if (bestIdx < 0) bestIdx = 0;

            Console.WriteLine($"[SOv4 pos{view.MyPos}] {totalSims}s best={bestIdx}/{candidates.Count} wr={root.WinRate(bestIdx):P0}");
            return candidates[bestIdx].play;
        }

        // ---- Rollout: 引擎级全牌型模拟 ----

        /// <summary>
        /// Rollout 一局到终局。firstPlay=null 时不改状态直接从当前桌面开始。
        /// </summary>
        private bool Rollout(TCardInfoPdkF[] myHand, PdkBotView view,
            PlayOutCardPdkF? myPlay = null,
            TCardInfoPdkF[] o1Hand = null, TCardInfoPdkF[] o2Hand = null)
        {
            int myPos = view.MyPos;

            var my = myHand.Where(c => c.GameState == 1).ToList();
            if (myPlay.HasValue && myPlay.Value.Type != CardType1.None && myPlay.Value.Ids != null)
            {
                foreach (var id in myPlay.Value.Ids) my.RemoveAll(c => c.ID == id);
                if (my.Count == 0) return true;
            }

            // 构建或取样对手手牌
            List<TCardInfoPdkF> o1, o2;
            if (o1Hand != null)
            {
                o1 = new List<TCardInfoPdkF>(o1Hand);
                o2 = new List<TCardInfoPdkF>(o2Hand);
            }
            else
            {
                var known = new HashSet<byte>();
                foreach (var c in myHand) known.Add(c.ID);
                var pool = FullDeck.Where(c => c.ID > 0 && !known.Contains(c.ID)).ToList();
                Shuffle(pool, _rng);
                int o1c = view.ShenYuCard[myPos % 3];
                o1 = pool.Take(o1c).ToList();
                o2 = pool.Skip(o1c).Take(view.ShenYuCard[(myPos + 1) % 3]).ToList();
            }

            // 初始状态
            PlayOutCardPdkF maxPlay;
            int maxPlayer, current;

            if (myPlay.HasValue && myPlay.Value.Type != CardType1.None)
            {
                maxPlay = ClonePlay(myPlay.Value);
                maxPlayer = myPos - 1;
                current = myPos % 3;
            }
            else
            {
                maxPlay = ClonePlay(view.MaxPlayCard);
                maxPlayer = maxPlay.Pos > 0 ? maxPlay.Pos - 1 : myPos - 1;
                current = myPos % 3;
            }

            return SimLoop(my, o1, o2, current, maxPlay, maxPlayer, 0);
        }

        private bool SimLoop(List<TCardInfoPdkF> my, List<TCardInfoPdkF> o1, List<TCardInfoPdkF> o2,
            int current, PlayOutCardPdkF maxPlay, int maxPlayer, int depth)
        {
            if (depth > 50) return my.Count <= Math.Min(o1.Count, o2.Count);
            if (o1.Count == 0) return false;
            if (o2.Count == 0) return false;
            if (my.Count == 0) return true;

            var cur = current == 0 ? o1 : current == 1 ? o2 : my;
            bool isNewRound = maxPlayer == current || maxPlay.GameNum <= 0;
            int next = (current + 1) % 3;

            // 用引擎获取合法出牌
            var tips = PdkCardAlgorithm.GetTipCard(
                isNewRound ? new PlayOutCardPdkF() : maxPlay,
                cur.ToArray(), null, false);

            if (tips != null && tips.Count > 0)
            {
                // Rollout 策略：多牌优先 + 最小 rank 保留大牌
                // isNewRound 时 GetTipCard 只返回单张 → 需要补充多牌先手
                List<List<TCardInfoPdkF>> allPlays = new List<List<TCardInfoPdkF>>(tips);
                if (isNewRound)
                {
                    var arr = cur.ToArray();
                    // 对子 (2张同rank)
                    foreach (var g in arr.GroupBy(c => c.GameNum).Where(g => g.Count() >= 2))
                        allPlays.Add(g.Take(2).ToList());
                    // 三张
                    foreach (var g in arr.GroupBy(c => c.GameNum).Where(g => g.Count() >= 3))
                        allPlays.Add(g.Take(3).ToList());
                    // 顺子 (≥5张连续rank)
                    var ranks = arr.Select(c => (int)c.GameNum).Where(r => r >= 3 && r <= 14).Distinct().OrderBy(r => r).ToList();
                    for (int len = Math.Min(ranks.Count, 12); len >= 5; len--)
                        for (int si = 0; si <= ranks.Count - len; si++)
                        {
                            bool isConsecutive = true;
                            for (int i = 1; i < len; i++)
                                if (ranks[si + i] != ranks[si + i - 1] + 1)
                                { isConsecutive = false; break; }
                            if (!isConsecutive) continue;
                            var strCards = ranks.Skip(si).Take(len)
                                .SelectMany(r => arr.Where(c => c.GameNum == r).Take(1)).ToList();
                            if (strCards.Count == len) allPlays.Add(strCards);
                        }
                }

                // 选择：优先多牌(×10权重)，同长度选最小rank
                var best = allPlays
                    .OrderByDescending(t => t.Count * 10)
                    .ThenBy(t => t[0].GameNum)
                    .First();

                foreach (var c in best) cur.RemoveAll(x => x.ID == c.ID);

                var newMax = new PlayOutCardPdkF
                {
                    GameNum = best[0].GameNum,
                    Type = InferType(best),
                    Ids = best.Select(c => c.ID).ToArray()
                };

                return SimLoop(my, o1, o2, next, newMax, current, depth + 1);
            }

            // pass
            int newMaxPlayer = isNewRound ? current : maxPlayer;
            return SimLoop(my, o1, o2, next, maxPlay, newMaxPlayer, depth + 1);
        }

        // ---- 候选构建 ----

        private List<(PlayOutCardPdkF play, bool isMulti)> BuildCandidates(
            TCardInfoPdkF[] hand, PdkBotView view, bool isFirstPlay)
        {
            var tips = PdkCardAlgorithm.GetTipCard(view.MaxPlayCard, hand, null, view.Rule.AAAIsZhaDan);
            var candidates = new List<(PlayOutCardPdkF, bool)>();
            if (tips != null)
                foreach (var t in tips)
                    candidates.Add((new PlayOutCardPdkF { Pos = (byte)view.MyPos, GameNum = t[0].GameNum, Ids = t.Select(c => c.ID).ToArray(), Type = InferType(t) }, t.Count > 1));
            if (isFirstPlay)
                AddMultiCardLeads(hand, view.MyPos, candidates);
            if (!isFirstPlay)
                candidates.Add((Pass(view), false));
            return candidates;
        }

        private static void AddMultiCardLeads(TCardInfoPdkF[] hand, int pos,
            List<(PlayOutCardPdkF, bool)> candidates)
        {
            void add(List<TCardInfoPdkF> cards) => candidates.Add((
                new PlayOutCardPdkF { Pos = (byte)pos, GameNum = cards[0].GameNum, Ids = cards.Select(c => c.ID).ToArray(), Type = InferType(cards) }, true));

            if (PokerLogic.GetPlayZhaDans(hand, out var bombs) && bombs != null)
                foreach (var b in bombs) add(b);
            foreach (var g in hand.GroupBy(c => c.GameNum).Where(g => g.Count() >= 2))
                add(g.Take(2).ToList());
            foreach (var g in hand.GroupBy(c => c.GameNum).Where(g => g.Count() >= 3))
            {
                var t = g.Take(3).ToList();
                var rest = hand.Where(c => c.GameNum != g.Key).Take(2).ToList();
                add(rest.Count == 2 ? t.Concat(rest).ToList() : t);
            }
            var straights = PokerLogic.GetShunZi(hand);
            if (straights != null) foreach (var s in straights) add(s);
        }

        // ---- 辅助 ----

        private static CardType1 InferType(List<TCardInfoPdkF> cards)
        {
            int n = cards.Count;
            if (n == 1) return CardType1.DanZhang;
            if (n == 2) return CardType1.DuiZi;
            var cnts = cards.GroupBy(c => c.GameNum).Select(g => g.Count()).OrderByDescending(x => x).ToList();
            if (cnts[0] == 4) { if (n == 4) return CardType1.ZhaDan; if (n == 6) return CardType1.SiDai2; if (n == 7) return CardType1.SiDai3; }
            if (cnts[0] >= 3) return n == 3 ? CardType1.SanZhang : CardType1.SanDai2;
            if (cnts[0] == 2 && n % 2 == 0) return n == 4 ? CardType1.LianDui : CardType1.LianDui;
            return n >= 5 ? CardType1.ShunZi : CardType1.DanZhang;
        }

        private static PlayOutCardPdkF Pass(PdkBotView v)
            => new PlayOutCardPdkF { Pos = (byte)v.MyPos, Type = CardType1.None };

        private static PlayOutCardPdkF ClonePlay(PlayOutCardPdkF s)
            => new PlayOutCardPdkF { Pos = s.Pos, GameNum = s.GameNum, Type = s.Type, Ids = s.Ids?.ToArray() };

        private static void Shuffle<T>(List<T> list, Random rng)
        {
            for (int i = list.Count - 1; i > 0; i--)
            { int j = rng.Next(i + 1); (list[i], list[j]) = (list[j], list[i]); }
        }
    }

    internal class SONode
    {
        private readonly int[] _wins, _visits;
        public SONode(int n) { _wins = new int[n]; _visits = new int[n]; }
        public void Visit(int i, bool w) { if (i >= 0 && i < _visits.Length) { _visits[i]++; if (w) _wins[i]++; } }
        public double WinRate(int i) => i >= 0 && i < _visits.Length && _visits[i] > 0 ? (double)_wins[i] / _visits[i] : 0;
        public int VisitCount(int i) => i >= 0 && i < _visits.Length ? _visits[i] : 0;
        public int BestChild(int n)
        {
            int best = -1; double bestRate = -1;
            for (int i = 0; i < Math.Min(n, _visits.Length); i++)
            { double r = WinRate(i); if (r > bestRate) { bestRate = r; best = i; } }
            return best;
        }
    }
}