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

namespace PdkFriendServer.Logic
{
    /// <summary>
    /// ISMCTS 机器人 v2
    /// P0修复: 包庄阈值 70%（从 45% 校准），rollout 用最强方案而非最小
    /// P2修复: 优先多牌组合（对子/顺子 > 单张），提高清牌效率
    /// </summary>
    public class IsmctsBot : IPdkBot
    {
        private readonly int _simulations;
        private readonly Random _rng;
        private const double BaoThreshold = 0.60; // 校准自1000局压测：70%→0人包，45%→5.2%成功

        public IsmctsBot(int simulations = 800)
        {
            _simulations = simulations;
            _rng = new Random();
        }

        // ---- 包庄决策 ----

        public bool DecideBaoZhuang(PdkBotView view)
        {
            double winRate = EstimateWinProbability(view);
            bool shouldBao = winRate >= BaoThreshold;

            Console.WriteLine($"[ISMCTS pos{view.MyPos}] 包庄评估: P(win)={winRate:P0} "
                + $"(阈值{BaoThreshold:P0}) → {(shouldBao ? "包庄" : "不包")}");
            return shouldBao;
        }

        private double EstimateWinProbability(PdkBotView view)
        {
            var hand = view.MyHand;
            int sims = Math.Min(_simulations, 600);

            int wins = 0;
            for (int s = 0; s < sims; s++)
            {
                if (SimulateWin(hand, view))
                    wins++;
            }
            return (double)wins / sims;
        }

        private bool SimulateWin(TCardInfoPdkF[] myHand, PdkBotView view)
        {
            int myPos = view.MyPos;
            int nextPos = myPos % 3 + 1;
            int oppPos = (myPos + 1) % 3 + 1;

            var hands = new List<TCardInfoPdkF>[3];
            hands[myPos - 1] = new List<TCardInfoPdkF>(myHand);
            hands[nextPos - 1] = new List<TCardInfoPdkF>();
            hands[oppPos - 1] = new List<TCardInfoPdkF>();

            var allCards = GenerateDeck();
            var unknown = allCards.Where(c => !myHand.Any(h => h.ID == c.ID)).ToList();
            Shuffle(unknown);

            hands[nextPos - 1].AddRange(unknown.Take(view.ShenYuCard[nextPos - 1]));
            hands[oppPos - 1].AddRange(unknown.Skip(view.ShenYuCard[nextPos - 1])
                .Take(view.ShenYuCard[oppPos - 1]));

            int current = myPos;
            var maxPlay = new PlayOutCardPdkF();
            int maxPlayer = 0;
            int passStreak = 0;

            for (int move = 0; move < 400; move++)
            {
                var curHand = hands[current - 1];
                if (curHand.Count == 0) return current == myPos;

                bool isNewRound = maxPlayer == current || maxPlay.GameNum == 0;
                var curMax = isNewRound ? new PlayOutCardPdkF() : maxPlay;
                var tips = PdkCardAlgorithm.GetTipCard(curMax, curHand.ToArray(), null, false);

                if (tips != null && tips.Count > 0)
                {
                    // P2修复: 优先多牌组合，其次选最强（最大GameNum）
                    var pick = PickBestTip(tips, isNewRound);
                    maxPlay = new PlayOutCardPdkF
                    {
                        Pos = (byte)current,
                        GameNum = pick[0].GameNum,
                        Type = pick.Count == 1 ? CardType1.DanZhang : CardType1.DuiZi,
                        Ids = pick.Select(c => c.ID).ToArray()
                    };
                    maxPlayer = current;
                    passStreak = 0;
                    foreach (var id in maxPlay.Ids)
                        curHand.RemoveAll(c => c.ID == id);
                }
                else
                {
                    passStreak++;
                    // 防止死循环: 三轮全 pass 则强制最大出牌
                    if (passStreak >= 2)
                    {
                        var forceTips = PdkCardAlgorithm.GetTipCard(
                            new PlayOutCardPdkF(), curHand.ToArray(), null, false);
                        if (forceTips != null && forceTips.Count > 0)
                        {
                            var pick = PickBestTip(forceTips, true);
                            maxPlay = new PlayOutCardPdkF
                            {
                                Pos = (byte)current,
                                GameNum = pick[0].GameNum,
                                Type = CardType1.DanZhang,
                                Ids = pick.Select(c => c.ID).ToArray()
                            };
                            maxPlayer = current;
                            foreach (var id in maxPlay.Ids)
                                curHand.RemoveAll(c => c.ID == id);
                        }
                        passStreak = 0;
                    }
                }
                current = current % 3 + 1;
            }

            return hands[myPos - 1].Count <= hands[nextPos - 1].Count
                && hands[myPos - 1].Count <= hands[oppPos - 1].Count;
        }

        // ---- 出牌决策 ----

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

            bool isFirstPlay = view.MaxPlayCard.GameNum <= 0;

            // 1. 获取合法出牌方案
            var tips = PdkCardAlgorithm.GetTipCard(
                view.MaxPlayCard, hand, null, view.Rule.AAAIsZhaDan);

            var allCandidates = new List<(PlayOutCardPdkF play, bool isMulti)>();
            var multiCount = 0;

            if (tips != null)
                foreach (var tip in tips)
                {
                    var isMulti = tip.Count > 1;
                    if (isMulti) multiCount++;
                    allCandidates.Add((MakePlay(tip, view.MyPos), isMulti));
                }

            // 2. 新轮次：补充多牌先手方案（GetTipCard只返回单张）
            if (isFirstPlay)
            {
                AddMultiCardLeads(hand, view.MyPos, allCandidates, ref multiCount);
            }

            if (!isFirstPlay)
                allCandidates.Add((Pass(view), false));

            var scoredCandidates = new List<(PlayOutCardPdkF play, double winRate, bool isMulti)>();

            if (allCandidates.Count == 1)
                return allCandidates[0].play;

            int unknownCount = 48 - hand.Length - CountPlayed(hand, view);
            int simsPerCandidate = Math.Max(50, _simulations / allCandidates.Count);

            for (int ci = 0; ci < allCandidates.Count; ci++)
            {
                int wins = 0;
                var play = allCandidates[ci].play;

                for (int s = 0; s < simsPerCandidate; s++)
                {
                    if (SimulateOneGame(hand, play, view, unknownCount))
                        wins++;
                }

                double wr = (double)wins / simsPerCandidate;
                scoredCandidates.Add((play, wr, allCandidates[ci].isMulti));
            }

            // 两阶段选择：多牌组合胜率≥10%就优用
            scoredCandidates.Sort((a, b) => b.winRate.CompareTo(a.winRate));
            var best = scoredCandidates[0];
            if (multiCount > 0)
            {
                var bestMulti = scoredCandidates.Where(x => x.isMulti)
                    .OrderByDescending(x => x.play.Ids?.Length ?? 0)
                    .ThenByDescending(x => x.winRate)
                    .FirstOrDefault();
                if (bestMulti.play.Ids != null && bestMulti.play.Ids.Length > 0)
                    best = bestMulti;
            }

            string desc = best.play.Ids == null || best.play.Ids.Length == 0
                ? "pass"
                : $"{best.play.Ids.Length}c";
            Console.WriteLine($"[ISMCTS pos{view.MyPos}] {simsPerCandidate * allCandidates.Count}sims "
                + $"winRate:{best.winRate:P0} => {desc}");

            return best.play;
        }

        // ---- 模拟引擎 ----

        private bool SimulateOneGame(
            TCardInfoPdkF[] myHand, PlayOutCardPdkF myPlay,
            PdkBotView view, int unknownCount)
        {
            int myPos = view.MyPos;
            int nextPos = myPos % 3 + 1;
            int oppPos = (myPos + 1) % 3 + 1;

            var hands = new List<TCardInfoPdkF>[3];
            hands[myPos - 1] = new List<TCardInfoPdkF>(myHand);
            hands[nextPos - 1] = new List<TCardInfoPdkF>();
            hands[oppPos - 1] = new List<TCardInfoPdkF>();

            var allCards = GenerateDeck();
            var unknown = allCards.Where(c => !myHand.Any(h => h.ID == c.ID)).ToList();
            Shuffle(unknown);

            hands[nextPos - 1].AddRange(unknown.Take(view.ShenYuCard[nextPos - 1]));
            hands[oppPos - 1].AddRange(unknown.Skip(view.ShenYuCard[nextPos - 1])
                .Take(view.ShenYuCard[oppPos - 1]));

            var maxPlay = new PlayOutCardPdkF
            {
                Pos = (byte)myPos, GameNum = myPlay.GameNum,
                Type = myPlay.Type, Ids = myPlay.Ids?.ToArray()
            };
            if (myPlay.Type != CardType1.None && myPlay.Ids != null)
                foreach (var id in myPlay.Ids)
                    hands[myPos - 1].RemoveAll(c => c.ID == id);

            int current = myPos % 3 + 1;
            int maxPlayer = myPlay.Type == CardType1.None ? view.MaxPlayCard.Pos : myPos;
            if (myPlay.Type == CardType1.None)
            {
                maxPlayer = view.MaxPlayCard.Pos;
                maxPlay = CloneCard(view.MaxPlayCard);
            }

            int moveCount = 0;
            int passStreak = 0;

            while (moveCount++ < 500)
            {
                var curHand = hands[current - 1];
                if (curHand.Count == 0) return current == myPos;

                bool isNewRound = maxPlayer == current || maxPlay.GameNum == 0;
                var curMax = isNewRound ? new PlayOutCardPdkF() : maxPlay;
                var curTips = PdkCardAlgorithm.GetTipCard(curMax, curHand.ToArray(), null, false);

                if (curTips != null && curTips.Count > 0)
                {
                    var pick = PickBestTip(curTips, isNewRound);
                    maxPlay = new PlayOutCardPdkF
                    {
                        Pos = (byte)current,
                        GameNum = pick[0].GameNum,
                        Type = pick.Count == 1 ? CardType1.DanZhang : CardType1.DuiZi,
                        Ids = pick.Select(c => c.ID).ToArray()
                    };
                    maxPlayer = current;
                    passStreak = 0;
                    foreach (var id in maxPlay.Ids)
                        curHand.RemoveAll(c => c.ID == id);
                }
                else
                {
                    passStreak++;
                    if (passStreak >= 2)
                    {
                        var forceTips = PdkCardAlgorithm.GetTipCard(
                            new PlayOutCardPdkF(), curHand.ToArray(), null, false);
                        if (forceTips != null && forceTips.Count > 0)
                        {
                            var pick = PickBestTip(forceTips, true);
                            maxPlay = new PlayOutCardPdkF
                            {
                                Pos = (byte)current, GameNum = pick[0].GameNum,
                                Type = CardType1.DanZhang, Ids = pick.Select(c => c.ID).ToArray()
                            };
                            maxPlayer = current;
                            foreach (var id in maxPlay.Ids)
                                curHand.RemoveAll(c => c.ID == id);
                        }
                        passStreak = 0;
                    }
                }
                current = current % 3 + 1;
            }

            return hands[myPos - 1].Count <= hands[nextPos - 1].Count
                && hands[myPos - 1].Count <= hands[oppPos - 1].Count;
        }

        // ---- Rollout 策略 ----

        /// <summary>
        /// 新轮次先手时，补充多牌组合候选（GetTipCard 只返回单张）
        /// 枚举：对子、三张、顺子、连对、炸弹
        /// </summary>
        private static void AddMultiCardLeads(TCardInfoPdkF[] hand, int pos,
            List<(PlayOutCardPdkF play, bool isMulti)> candidates, ref int multiCount)
        {
            // 炸弹
            if (PokerLogic.GetPlayZhaDans(hand, out var bombs) && bombs != null)
                foreach (var bomb in bombs)
                    AddCandidate(bomb, pos, candidates, ref multiCount);

            // 对子（2张相同）
            foreach (var pair in GetMultiGroups(hand, 2))
                AddCandidate(pair, pos, candidates, ref multiCount);

            // 三张 / 三带二
            var triples = GetMultiGroups(hand, 3);
            foreach (var t in triples)
            {
                // 三带二: 三张 + 附带最小的两张其他牌
                var remainder = hand.Where(c => c.GameNum != t[0].GameNum).OrderBy(c => c.GameNum).ToList();
                if (remainder.Count >= 2)
                {
                    var sd2 = t.Concat(remainder.Take(2)).ToList();
                    AddCandidate(sd2, pos, candidates, ref multiCount);
                }
                else
                {
                    AddCandidate(t, pos, candidates, ref multiCount); // 手牌不够带，纯三张
                }
            }

            // 四带二 / 四带三
            var quads = GetMultiGroups(hand, 4);
            foreach (var q in quads)
            {
                var remainder = hand.Where(c => c.GameNum != q[0].GameNum).OrderBy(c => c.GameNum).ToList();
                if (remainder.Count >= 3)
                {
                    var sd3 = q.Concat(remainder.Take(3)).ToList();
                    AddCandidate(sd3, pos, candidates, ref multiCount);
                }
                else if (remainder.Count >= 2)
                {
                    var sd2 = q.Concat(remainder.Take(2)).ToList();
                    AddCandidate(sd2, pos, candidates, ref multiCount);
                }
                // else: 炸弹已在上面处理
            }

            // 顺子（≥5 张连续）
            var straights = PokerLogic.GetShunZi(hand);
            if (straights != null)
                foreach (var s in straights)
                    AddCandidate(s, pos, candidates, ref multiCount);
        }

        private static void AddCandidate(List<TCardInfoPdkF> cards, int pos,
            List<(PlayOutCardPdkF play, bool isMulti)> candidates, ref int multiCount)
        {
            candidates.Add((new PlayOutCardPdkF
            {
                Pos = (byte)pos, GameNum = cards[0].GameNum,
                Ids = cards.Select(c => c.ID).ToArray(),
                Type = CardType1.None
            }, true));
            multiCount++;
        }

        /// <summary>获取指定数量的同面值组合（对子=2，三张=3）</summary>
        private static List<List<TCardInfoPdkF>> GetMultiGroups(TCardInfoPdkF[] hand, int count)
        {
            var result = new List<List<TCardInfoPdkF>>();
            var groups = hand.GroupBy(c => c.GameNum).Where(g => g.Count() >= count);
            foreach (var g in groups)
            {
                var cards = g.Take(count).ToList();
                result.Add(cards);
            }
            return result;
        }

        /// <summary>
        /// 从合法方案中选最优：优先出多张牌的组合，其次出最大的
        /// P2修复: 之前只取 tips[0]（最小单张），改为优先多牌组合
        /// P0修复: 选最大（最后一项），模拟更强对手
        /// </summary>
        private static List<TCardInfoPdkF> PickBestTip(List<List<TCardInfoPdkF>> tips, bool isNewRound)
        {
            if (tips == null || tips.Count == 0) return null;

            // 优先多牌组合（2张>1张，3张>2张等），同数量选最大的
            var best = tips[tips.Count - 1]; // 默认最大
            int bestScore = best.Count * 10 + best[0].GameNum;

            for (int i = tips.Count - 2; i >= 0; i--)
            {
                int score = tips[i].Count * 10 + tips[i][0].GameNum;
                if (score > bestScore)
                {
                    bestScore = score;
                    best = tips[i];
                }
            }
            return best;
        }

        // ---- 工具 ----

        private static int CountPlayed(TCardInfoPdkF[] myHand, PdkBotView view)
        {
            int total = 48 - myHand.Length;
            foreach (var c in view.ShenYuCard) total -= c;
            return Math.Max(0, total);
        }

        private static List<TCardInfoPdkF> GenerateDeck()
        {
            var deck = new List<TCardInfoPdkF>();
            int id = 1;
            foreach (int flower in new[] { 1, 2, 3, 4 })
                for (int num = 1; num <= 13; num++)
                {
                    int gameNum = num switch { 1 => 14, 2 => 16, _ => num };
                    deck.Add(new TCardInfoPdkF
                    {
                        ID = (byte)id++, Flower = (byte)flower,
                        GameNum = (byte)gameNum, GameState = 1
                    });
                }
            return deck;
        }

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

        private static PlayOutCardPdkF CloneCard(PlayOutCardPdkF src)
        {
            return new PlayOutCardPdkF
            {
                Pos = src.Pos, GameNum = src.GameNum,
                Type = src.Type, Ids = src.Ids?.ToArray()
            };
        }

        private static PlayOutCardPdkF MakePlay(List<TCardInfoPdkF> cards, int pos)
        {
            return new PlayOutCardPdkF
            {
                Pos = (byte)pos, GameNum = cards[0].GameNum,
                Ids = cards.Select(x => x.ID).ToArray(),
                Type = CardType1.None // 不给假类型，让引擎GetOutCard赋予真值
            };
        }

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