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 v2 — 优化版，静态牌池+数组交换替代对象分配。
    /// 
    /// 性能关键：
    /// - 48张牌静态数组，模拟时只交换索引不创建新对象
    /// - 预生成N份对手手牌分布，分摊 determinization 成本
    /// - 贪心 rollout 直接操作数组切片
    /// </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（同 IsmctsBot.GenerateDeck），只创建一次
        private static readonly TCardInfoPdkF[] FullDeck;
        static SOIsmctsBot()
        {
            FullDeck = new TCardInfoPdkF[52];
            int id = 1;
            foreach (int f in new[] { 1, 2, 3, 4 })
                for (int n = 1; n <= 13; n++)
                    FullDeck[id - 1] = 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 (SimulateToEnd(view.MyHand, view, null)) wins++;

            double wr = (double)wins / 400;
            Console.WriteLine($"[SOv2 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);

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

            // 锁手检测
            if (hand.Length <= 8)
            {
                var lockSeq = LockDetector.FindLockSequence(hand, _tracker, view.MyPos);
                if (lockSeq != null)
                {
                    Console.WriteLine($"[SOv2 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;

            // SO-ISMCTS 主循环：单树 + 预生成手牌
            var root = new SONode(candidates.Count);
            int myPos = view.MyPos;

            // 预生成 N 份对手手牌分布
            int preGen = Math.Min(300, _simBudget);
            var hands1 = new byte[preGen][];
            var hands2 = new byte[preGen][];

            // 建立已知牌ID集合
            var knownIds = new HashSet<byte>();
            foreach (var c in hand) knownIds.Add(c.ID);
            int o1c = view.ShenYuCard[myPos % 3];
            int o2c = view.ShenYuCard[(myPos + 1) % 3];

            var pool = new byte[52 - knownIds.Count];
            int pi = 0;
            foreach (var c in FullDeck)
                if (!knownIds.Contains(c.ID))
                    pool[pi++] = c.ID;

            for (int g = 0; g < preGen; g++)
            {
                Shuffle(pool, _rng);
                hands1[g] = new byte[o1c];
                hands2[g] = new byte[o2c];
                Array.Copy(pool, 0, hands1[g], 0, o1c);
                Array.Copy(pool, o1c, hands2[g], 0, o2c);
            }

            int genIdx = 0;
            int totalSims = 0;

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

                // 取一份预生成手牌
                var o1 = hands1[genIdx % preGen];
                var o2 = hands2[genIdx % preGen];
                genIdx++;

                bool win;
                if (play.play.Type == CardType1.None) // pass
                {
                    win = SimPass(hand, view, o1, o2);
                }
                else
                {
                    var myRem = hand.Where(c => c.GameState == 1 && !play.play.Ids.Contains(c.ID)).ToArray();
                    if (myRem.Length == 0) win = true;
                    else win = SimAfterPlay(myRem, view, o1, o2, play.play.GameNum);
                }

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

                if (totalSims % 150 == 0)
                {
                    int converged = root.BestChild(candidates.Count);
                    if (converged >= 0 && root.VisitCount(converged) > _simBudget / candidates.Count / 2 && root.WinRate(converged) > 0.85)
                        break;
                }
            }

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

            Console.WriteLine($"[SOv2 pos{view.MyPos}] {totalSims}s best={bestIdx} wr={root.WinRate(bestIdx):P0}");
            return candidates[bestIdx].play;
        }

        // ---- 快速模拟（用数组而非对象） ----

        private bool SimPass(TCardInfoPdkF[] myHand, PdkBotView view, byte[] o1Ids, byte[] o2Ids)
        {
            int myPos = view.MyPos;
            var maxPlay = view.MaxPlayCard;
            int maxPlayer = maxPlay.Pos > 0 ? maxPlay.Pos - 1 : myPos - 1;
            int current = myPos % 3;

            // 从 ID 数组构建手牌 GameNum 数组
            var mg = new List<byte>(myHand.Where(c => c.GameState == 1).Select(c => c.GameNum));
            var o1g = new List<byte>(IdsToGameNums(o1Ids));
            var o2g = new List<byte>(IdsToGameNums(o2Ids));

            return FastSim(o1g, o2g, mg, current, maxPlay.GameNum, maxPlay.Type, maxPlayer, 0);
        }

        private bool SimAfterPlay(TCardInfoPdkF[] myRem, PdkBotView view, byte[] o1Ids, byte[] o2Ids, byte myGameNum)
        {
            int myPos = view.MyPos;
            int current = myPos % 3;
            var mg = new List<byte>(myRem.Where(c => c.GameState == 1).Select(c => c.GameNum));
            var o1g = new List<byte>(IdsToGameNums(o1Ids));
            var o2g = new List<byte>(IdsToGameNums(o2Ids));

            return FastSim(o1g, o2g, mg, current, myGameNum, CardType1.DanZhang, myPos - 1, 0);
        }

        // 快速模拟核心：全部用 byte[]。支持单张+对子。
        private bool FastSim(List<byte> h1, List<byte> h2, List<byte> my,
            int current, byte maxGameNum, CardType1 maxType, int maxPlayer, int depth)
        {
            if (depth > 30) return my.Count <= Math.Min(h1.Count, h2.Count);
            if (h1.Count == 0) return false;
            if (h2.Count == 0) return false;
            if (my.Count == 0) return true;

            var cur = current == 0 ? h1 : current == 1 ? h2 : my;
            bool isNewRound = maxPlayer == current || maxGameNum == 0;

            if (isNewRound)
            {
                if (cur.Count == 0) return false;
                // 找对子（贪心：出最大的对子）
                var groups = cur.GroupBy(g => g).Where(g => g.Count() >= 2).OrderByDescending(g => g.Key).ToList();
                if (groups.Count > 0)
                {
                    var pair = groups[0];
                    var toRemove = pair.Take(2).ToList();
                    foreach (var g in toRemove) cur.Remove(g);
                    return FastSim(h1, h2, my, (current + 1) % 3, pair.Key, CardType1.DuiZi, current, depth + 1);
                }
                // 单张
                var sorted = cur.OrderByDescending(g => g).ToList();
                byte play = sorted[0];
                cur.Remove(play);
                return FastSim(h1, h2, my, (current + 1) % 3, play, CardType1.DanZhang, current, depth + 1);
            }
            else
            {
                // 跟牌：找能压制的同类型牌
                var bigger = cur.Where(g => g > maxGameNum).OrderBy(g => g).ToList();
                if (maxType == CardType1.DuiZi)
                {
                    // 对子：找 ≥2 张且大于 maxGameNum
                    var pairGroups = cur.GroupBy(g => g).Where(g => g.Count() >= 2 && g.Key > maxGameNum).OrderBy(g => g.Key).ToList();
                    if (pairGroups.Count > 0)
                    {
                        var pair = pairGroups[0];
                        var toRemove = pair.Take(2).ToList();
                        foreach (var g in toRemove) cur.Remove(g);
                        return FastSim(h1, h2, my, (current + 1) % 3, pair.Key, CardType1.DuiZi, current, depth + 1);
                    }
                }
                if (bigger.Count > 0)
                {
                    byte play = bigger[0];
                    cur.Remove(play);
                    return FastSim(h1, h2, my, (current + 1) % 3, play, CardType1.DanZhang, current, depth + 1);
                }
                // pass
                return FastSim(h1, h2, my, (current + 1) % 3, maxGameNum, maxType, isNewRound ? current : maxPlayer, depth + 1);
            }
        }

        // ---- 旧的 SimulateToEnd (保留兼容) ----

        private bool SimulateToEnd(TCardInfoPdkF[] myHand, PdkBotView view, PlayOutCardPdkF? fp)
        {
            int myPos = view.MyPos;
            var myList = myHand.Where(c => c.GameState == 1).Select(c => c.GameNum).ToList();
            int o1c = view.ShenYuCard[myPos % 3];
            int o2c = view.ShenYuCard[(myPos + 1) % 3];

            var knownIds = new HashSet<byte>();
            foreach (var c in myHand) knownIds.Add(c.ID);

            var pool = FullDeck.Where(c => !knownIds.Contains(c.ID)).Select(c => c.GameNum).ToList();
            Shuffle(pool, _rng);
            var o1 = pool.Take(o1c).ToList();
            var o2 = pool.Skip(o1c).Take(o2c).ToList();

            byte maxGn = 0;
            int maxP = 0;
            int cur = myPos % 3;

            if (fp.HasValue && fp.Value.Type != CardType1.None)
            {
                maxGn = fp.Value.GameNum;
                maxP = myPos - 1;
                foreach (var id in fp.Value.Ids ?? Array.Empty<byte>())
                    myList.RemoveAll(g => g == GameNumOf(id));
            }
            else if (fp.HasValue) // pass
            {
                maxGn = view.MaxPlayCard.GameNum;
                maxP = view.MaxPlayCard.Pos > 0 ? view.MaxPlayCard.Pos - 1 : myPos - 1;
            }

            return FastSim(o1, o2, myList, cur, maxGn, CardType1.DanZhang, maxP, 0);
        }

        // ---- 辅助 ----

        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((MakePlay(t, view.MyPos), t.Count > 1));
            if (isFirstPlay)
                AddMultiCardLeads(hand, view.MyPos, candidates);
            if (!isFirstPlay)
                candidates.Add((Pass(view), false));
            return candidates;
        }

        // 复用 IsmctsBot 的多牌枚举（对子/三张/顺子/飞机/炸弹/连对）
        private static void AddMultiCardLeads(TCardInfoPdkF[] hand, int pos,
            List<(PlayOutCardPdkF, bool)> candidates)
        {
            var make = (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) make(b);
            foreach (var g in hand.GroupBy(c => c.GameNum).Where(g => g.Count() >= 2))
                make(g.Take(2).ToList());
            foreach (var g in hand.GroupBy(c => c.GameNum).Where(g => g.Count() >= 3))
                make(g.Take(3).ToList());
            var straights = PokerLogic.GetShunZi(hand);
            if (straights != null) foreach (var s in straights) make(s);
        }

        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 CardType1.SanZhang;
            if (cnts[0] == 2 && n % 2 == 0) return CardType1.LianDui;
            return CardType1.ShunZi;
        }

        private static PlayOutCardPdkF MakePlay(List<TCardInfoPdkF> cards, int pos)
            => new PlayOutCardPdkF { Pos = (byte)pos, GameNum = cards[0].GameNum, Ids = cards.Select(x => x.ID).ToArray(), Type = CardType1.DanZhang };

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

        private static List<byte> IdsToGameNums(byte[] ids)
        {
            var result = new List<byte>();
            foreach (var id in ids)
            {
                var card = FullDeck.FirstOrDefault(c => c.ID == id);
                if (card.GameNum > 0) result.Add(card.GameNum);
            }
            return result;
        }

        private static byte GameNumOf(byte id)
        {
            var card = FullDeck.FirstOrDefault(c => c.ID == id);
            return card.GameNum;
        }

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

        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;
        private readonly int[] _visits;

        public SONode(int numChildren)
        {
            _wins = new int[numChildren];
            _visits = new int[numChildren];
        }

        public void Visit(int idx, bool win)
        {
            if (idx < 0 || idx >= _visits.Length) return;
            _visits[idx]++;
            if (win) _wins[idx]++;
        }

        public double WinRate(int idx)
            => idx >= 0 && idx < _visits.Length && _visits[idx] > 0 ? (double)_wins[idx] / _visits[idx] : 0;

        public int VisitCount(int idx)
            => idx >= 0 && idx < _visits.Length ? _visits[idx] : 0;

        public int BestChild(int n)
        {
            int best = -1;
            double bestRate = -1;
            for (int i = 0; i < Math.Min(n, _visits.Length); i++)
            {
                double rate = WinRate(i);
                if (rate > bestRate) { bestRate = rate; best = i; }
            }
            return best;
        }
    }
}