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

namespace TKS
{
    /// <summary>슬링샷 한 번의 결과 요약.</summary>
    public class ActionOutcome
    {
        public bool BonusMove;          // 보병: 최종 목표점 명중 → 추가 이동
        public bool Returned;           // 기병: 최종 목표점 명중 → 제자리 복귀
        public bool Overwatch;          // 창병: 최종 목표점 명중 → 대기(견제)
        public bool Crit;               // 궁병: 최종 목표점 명중 → 크리티컬
        public bool MovedOnly;          // 공격 없이 이동만
        public int DamageDealt;
        public int CounterTaken;
        public List<Unit> Attacked = new List<Unit>();
        /// <summary>실제로 지나간 경로(시작 포함). 창병 견제 판정용.</summary>
        public List<Vector2> Path = new List<Vector2>();
    }

    /// <summary>
    /// 슬링샷 벡터(시작점 → 목표점)를 병종 규칙대로 이동·공격으로 해석한다.
    /// ① 보병: 경로 위 첫 적까지 이동 후 공격 · 목표점 명중 시 추가 이동 1회
    /// ② 기병: 경로 위 적을 모두 관통 피해 · 목표점까지 이동 · 목표점 명중 시 제자리 복귀
    /// ③ 창병: 보병과 동일 · 목표점 명중 시 대기 → 반경 안에서 움직이는 적에게 피해
    /// ④ 궁병: 목표 방향에 적이 있으면 사거리까지 이동 후 사격(반격 없음) · 목표점 명중 시 크리티컬
    /// </summary>
    public class ActionResolver
    {
        readonly BalanceConfig cfg;
        readonly BattleManager battle;
        readonly System.Random rng;

        public ActionResolver(BalanceConfig cfg, BattleManager battle, System.Random rng)
        {
            this.cfg = cfg;
            this.battle = battle;
            this.rng = rng;
        }

        public IEnumerator Resolve(Unit u, Vector2 target, bool moveOnly, ActionOutcome o)
        {
            Vector2 origin = u.Position;
            Vector2 delta = target - origin;
            float dist = delta.magnitude;
            o.Path.Add(origin);
            if (dist < 0.001f || !u.IsAlive) yield break;
            Vector2 dir = delta / dist;

            switch (u.Type)
            {
                case UnitType.Infantry:
                case UnitType.Spear:
                    yield return MeleeRoutine(u, origin, dir, dist, target, moveOnly, o);
                    break;
                case UnitType.Cavalry:
                    yield return CavalryRoutine(u, origin, dir, dist, target, moveOnly, o);
                    break;
                case UnitType.Archer:
                    yield return ArcherRoutine(u, origin, dir, dist, target, moveOnly, o);
                    break;
            }
        }

        // ---------- 미리보기(드라이런) ----------

        /// <summary>조작 중 표시용: 이 슬링샷이 공격하게 될 적 목록.</summary>
        public List<Unit> PredictTargets(Unit u, Vector2 target, bool moveOnly)
        {
            var result = new List<Unit>();
            if (moveOnly) return result;
            Vector2 origin = u.Position;
            Vector2 delta = target - origin;
            float dist = delta.magnitude;
            if (dist < 0.001f) return result;
            Vector2 dir = delta / dist;
            float hitDist;
            switch (u.Type)
            {
                case UnitType.Infantry:
                case UnitType.Spear:
                {
                    var first = Combat.FirstEnemyOnPath(u, origin, dir, dist, out hitDist);
                    if (first != null && Combat.FreeTravel(u, origin, dir, hitDist, false) >= hitDist - 0.05f) result.Add(first);
                    break;
                }
                case UnitType.Cavalry:
                {
                    float travel = Combat.FreeTravel(u, origin, dir, dist, false);
                    var dists = new List<float>();
                    result.AddRange(Combat.EnemiesOnPath(u, origin, dir, travel, dists));
                    break;
                }
                case UnitType.Archer:
                {
                    var first = Combat.FirstEnemyOnPath(u, origin, dir, dist + u.AttackRange, out hitDist);
                    if (first != null) result.Add(first);
                    break;
                }
            }
            return result;
        }

        // ---------- 보병 · 창병 ----------

        IEnumerator MeleeRoutine(Unit u, Vector2 origin, Vector2 dir, float dist, Vector2 target, bool moveOnly, ActionOutcome o)
        {
            float hitDist = 0f;
            Unit first = moveOnly ? null : Combat.FirstEnemyOnPath(u, origin, dir, dist, out hitDist);
            if (first == null)
            {
                float free = Combat.FreeTravel(u, origin, dir, dist, true);
                yield return Move(u, origin + dir * free, o);
                o.MovedOnly = true;
                yield break;
            }

            float freeToEnemy = Combat.FreeTravel(u, origin, dir, hitDist, false);
            if (freeToEnemy < hitDist - 0.05f)
            {
                // 아군·벽이 먼저 막는다 → 거기까지만 이동
                yield return Move(u, origin + dir * freeToEnemy, o);
                o.MovedOnly = true;
                yield break;
            }

            yield return Move(u, origin + dir * hitDist, o);
            Unit finalHit = Combat.EnemyAtPoint(u, target, cfg.finalHitTolerance);
            bool isFinal = finalHit == first;
            yield return Attack(u, first, false, false, o);
            if (!u.IsAlive) yield break;

            if (u.Type == UnitType.Infantry && isFinal) o.BonusMove = true;
            if (u.Type == UnitType.Spear && isFinal)
            {
                u.SetOverwatch(true);
                o.Overwatch = true;
            }
        }

        // ---------- 기병 ----------

        IEnumerator CavalryRoutine(Unit u, Vector2 origin, Vector2 dir, float dist, Vector2 target, bool moveOnly, ActionOutcome o)
        {
            float travel = Combat.FreeTravel(u, origin, dir, dist, false);
            var dists = new List<float>();
            var enemies = moveOnly ? new List<Unit>() : Combat.EnemiesOnPath(u, origin, dir, travel, dists);
            Unit finalHit = moveOnly ? null : Combat.EnemyAtPoint(u, target, cfg.finalHitTolerance);
            bool willReturn = finalHit != null && enemies.Contains(finalHit);

            Vector2 end = origin + dir * travel;
            if (!willReturn) end = BackOffFromEnemies(u, origin, dir, travel);

            if (enemies.Count == 0)
            {
                yield return Move(u, end, o);
                o.MovedOnly = true;
                yield break;
            }

            int idx = 0;
            var hit = new List<Unit>();
            yield return Fx.MoveAlong(u.transform, origin, end, cfg.moveSpeed, travelled =>
            {
                while (idx < enemies.Count && travelled >= dists[idx] - 0.01f)
                {
                    PierceHit(u, enemies[idx], dir, o);
                    hit.Add(enemies[idx]);
                    idx++;
                }
            });
            u.Position = end;
            o.Path.Add(end);
            for (; idx < enemies.Count; idx++)
            {
                if (dists[idx] <= travel + 0.01f)
                {
                    PierceHit(u, enemies[idx], dir, o);
                    hit.Add(enemies[idx]);
                }
            }
            yield return Fx.Wait(0.15f);

            // 살아남은 근접 적의 반격
            foreach (var e in hit)
            {
                if (!u.IsAlive) break;
                if (!e.IsAlive || !UnitTypeInfo.IsMelee(e.Type)) continue;
                int c = Combat.CounterDamage(cfg, e, u, rng);
                u.TakeDamage(c);
                o.CounterTaken += c;
                Fx.Popup(u.Position, c.ToString(), new Color(1f, 0.45f, 0.45f));
                battle.NotifyChanged();
                yield return Fx.Wait(0.12f);
            }

            if (willReturn && u.IsAlive)
            {
                yield return Fx.Wait(0.1f);
                yield return Move(u, origin, o);
                o.Returned = true;
            }
        }

        void PierceHit(Unit cav, Unit e, Vector2 dir, ActionOutcome o)
        {
            if (!e.IsAlive) return;
            int dmg = Combat.Damage(cfg, cav, e, false, rng);
            e.TakeDamage(dmg);
            o.Attacked.Add(e);
            o.DamageDealt += dmg;
            Fx.Popup(e.Position, dmg.ToString(), Color.white);
            // 옆으로 밀어내기
            Vector2 side = new Vector2(-dir.y, dir.x);
            float sign = Vector2.Dot(e.Position - cav.Position, side) >= 0f ? 1f : -1f;
            if (e.IsAlive)
            {
                Vector2 to = battle.Board.ClampInside(e.Position + side * sign * cfg.cavalryKnockback, e.Radius);
                Fx.Run(Fx.MoveAlong(e.transform, e.Position, to, cfg.moveSpeed * 0.6f, null));
            }
            battle.NotifyChanged();
        }

        /// <summary>종착점이 적과 겹치면 경로를 되짚어 겹치지 않는 지점까지 물러선다.</summary>
        Vector2 BackOffFromEnemies(Unit u, Vector2 origin, Vector2 dir, float travel)
        {
            float t = travel;
            for (int i = 0; i < 40 && t > 0f; i++)
            {
                Vector2 p = origin + dir * t;
                bool overlap = false;
                foreach (var e in battle.AliveUnits(u.Faction == Faction.Player ? Faction.Enemy : Faction.Player))
                {
                    if (Vector2.Distance(p, e.Position) < u.Radius + e.Radius - 0.01f)
                    {
                        overlap = true;
                        break;
                    }
                }
                if (!overlap) return p;
                t -= 0.1f;
            }
            return origin;
        }

        // ---------- 궁병 ----------

        IEnumerator ArcherRoutine(Unit u, Vector2 origin, Vector2 dir, float dist, Vector2 target, bool moveOnly, ActionOutcome o)
        {
            float hitDist;
            Unit first = moveOnly ? null : Combat.FirstEnemyOnPath(u, origin, dir, dist + u.AttackRange, out hitDist);
            if (first == null)
            {
                float free = Combat.FreeTravel(u, origin, dir, dist, true);
                yield return Move(u, origin + dir * free, o);
                o.MovedOnly = true;
                yield break;
            }

            float centerDist = Vector2.Distance(origin, first.Position);
            float need = Mathf.Clamp(centerDist - u.AttackRange, 0f, dist);
            float freeMove = Combat.FreeTravel(u, origin, dir, need, true);
            if (freeMove > 0.01f) yield return Move(u, origin + dir * freeMove, o);

            if (Vector2.Distance(u.Position, first.Position) <= u.AttackRange + 0.05f)
            {
                bool crit = Combat.EnemyAtPoint(u, target, cfg.finalHitTolerance) == first;
                yield return Attack(u, first, true, crit, o);
            }
            else
            {
                o.MovedOnly = true;
            }
        }

        // ---------- 공통 ----------

        IEnumerator Move(Unit u, Vector2 to, ActionOutcome o)
        {
            yield return Fx.MoveAlong(u.transform, u.Position, to, cfg.moveSpeed, null);
            u.Position = to;
            o.Path.Add(to);
        }

        IEnumerator Attack(Unit a, Unit d, bool ranged, bool crit, ActionOutcome o)
        {
            if (ranged) yield return Fx.Arrow(a.Position, d.Position);
            else yield return Fx.Lunge(a, d.Position);

            int dmg = Combat.Damage(cfg, a, d, crit, rng);
            d.TakeDamage(dmg);
            o.Attacked.Add(d);
            o.DamageDealt += dmg;
            o.Crit |= crit;
            Fx.Popup(d.Position, crit ? dmg + "!" : dmg.ToString(), crit ? new Color(1f, 0.7f, 0.2f) : Color.white);
            battle.NotifyChanged();
            yield return Fx.Wait(0.2f);

            if (!ranged && d.IsAlive && a.IsAlive)
            {
                int c = Combat.CounterDamage(cfg, d, a, rng);
                yield return Fx.Lunge(d, a.Position);
                a.TakeDamage(c);
                o.CounterTaken += c;
                Fx.Popup(a.Position, c.ToString(), new Color(1f, 0.45f, 0.45f));
                battle.NotifyChanged();
                yield return Fx.Wait(0.2f);
            }
        }
    }
}