using System.Collections;
using System.Collections.Generic;
using UnityEngine;

namespace TKS
{
    /// <summary>
    /// 가상 실행(dry-run · PD #1098 적 AI 예측 시뮬레이션): Active 동안 ActionResolver 가 연출 없이 한 프레임 안에 끝난다 —
    /// Fx 이동·대기·투사체 = 즉시 · 팝업·광역 터짐 = 없음 · 유닛 표시(UnitView) 갱신 없음 · 피해 난수 = 분산 0 · 전투 이벤트 카운터 없음.
    /// 상태는 Snapshot 으로 떠 두고 Restore 로 되돌린다(유닛 · 스킬 상태 · 기믹 레이어).
    /// </summary>
    public static class Sim
    {
        public static bool Active;

        /// <summary>코루틴을 이 프레임 안에서 끝까지 돌린다(중첩 IEnumerator 포함 · null/기타 yield = 즉시 진행).</summary>
        public static void Run(IEnumerator routine)
        {
            if (routine == null) return;
            var stack = new Stack<IEnumerator>();
            stack.Push(routine);
            int guard = 0;
            while (stack.Count > 0)
            {
                if (++guard > 200000)
                {
                    Debug.LogError("[TKS] 가상 실행 루프 상한 초과 — 중단");
                    return;
                }
                var top = stack.Peek();
                if (!top.MoveNext())
                {
                    stack.Pop();
                    continue;
                }
                var cur = top.Current as IEnumerator;
                if (cur != null) stack.Push(cur);
            }
        }

        public class UnitSnap
        {
            public Unit U;
            public Vector2 Pos;
            public int Hp, MaxHp, Atk, Def;
            public bool Acted, Bonus, Overwatch, Collider, Active;
        }

        public class SkillSnap
        {
            public UnitSkills S;
            public int ReadyTurn, BonusMovesLeft, PierceHits;
            public bool Reserved, Armed, BonusAttack, OwUnlimited;
            public float OwMult, OwAdd;
        }

        public class Snapshot
        {
            public readonly List<UnitSnap> Units = new List<UnitSnap>();
            public readonly List<SkillSnap> Skills = new List<SkillSnap>();
            public List<SkillSystem.Timed> Timed;
            public int LogCount;
            public GimmickLayer.Snapshot Gimmicks;
            public string Message;
        }

        public static Snapshot Take(BattleManager bm)
        {
            var s = new Snapshot { Message = bm.LastMessage };
            foreach (var u in bm.Units)
            {
                if (u == null) continue;
                s.Units.Add(new UnitSnap
                {
                    U = u, Pos = u.Position, Hp = u.Hp, MaxHp = u.MaxHp, Atk = u.Atk, Def = u.Def, Acted = u.ActedThisTurn, Bonus = u.BonusMoveAvailable,
                    Overwatch = u.Overwatch, Collider = u.Collider != null && u.Collider.enabled, Active = u.gameObject.activeSelf
                });
            }
            var sys = bm.Skills;
            if (sys != null)
            {
                foreach (var e in sys.Entries)
                {
                    s.Skills.Add(new SkillSnap
                    {
                        S = e, ReadyTurn = e.ReadyTurn, BonusMovesLeft = e.BonusMovesLeft, PierceHits = e.PierceHits, Reserved = e.Reserved, Armed = e.Armed,
                        BonusAttack = e.BonusAttack, OwUnlimited = e.OwUnlimited, OwMult = e.OwMult, OwAdd = e.OwAdd
                    });
                }
                s.Timed = new List<SkillSystem.Timed>(sys.TimedEffects);
                s.LogCount = sys.Log.Count;
            }
            if (GimmickLayer.Current != null) s.Gimmicks = GimmickLayer.Current.Take();
            return s;
        }

        public static void Restore(BattleManager bm, Snapshot s)
        {
            foreach (var x in s.Units)
            {
                var u = x.U;
                if (u == null) continue;
                u.Position = x.Pos;
                u.Hp = x.Hp;
                u.MaxHp = x.MaxHp;
                u.Atk = x.Atk;
                u.Def = x.Def;
                u.ActedThisTurn = x.Acted;
                u.BonusMoveAvailable = x.Bonus;
                u.Overwatch = x.Overwatch;
                if (u.Collider != null) u.Collider.enabled = x.Collider;
                if (u.gameObject.activeSelf != x.Active) u.gameObject.SetActive(x.Active);
            }
            var sys = bm.Skills;
            if (sys != null)
            {
                foreach (var k in s.Skills)
                {
                    var e = k.S;
                    e.ReadyTurn = k.ReadyTurn;
                    e.BonusMovesLeft = k.BonusMovesLeft;
                    e.PierceHits = k.PierceHits;
                    e.Reserved = k.Reserved;
                    e.Armed = k.Armed;
                    e.BonusAttack = k.BonusAttack;
                    e.OwUnlimited = k.OwUnlimited;
                    e.OwMult = k.OwMult;
                    e.OwAdd = k.OwAdd;
                }
                if (s.Timed != null)
                {
                    sys.TimedEffects.Clear();
                    sys.TimedEffects.AddRange(s.Timed);
                }
                if (sys.Log.Count > s.LogCount) sys.Log.RemoveRange(s.LogCount, sys.Log.Count - s.LogCount);
            }
            if (GimmickLayer.Current != null && s.Gimmicks != null) GimmickLayer.Current.Restore(s.Gimmicks);
            bm.LastMessage = s.Message;
            Physics2D.SyncTransforms();
        }
    }
}