using System.Collections.Generic;

using UnityEngine;

using Colosseum.Enemy;
using Colosseum.Passives;
using Colosseum.Skills;

namespace Colosseum.Combat
{
    /// <summary>
    /// 힐, 보호막, 버프 등 비공격 스킬에서 위협을 생성할 때 사용하는 공통 유틸리티입니다.
    /// 시전자 주변의 적을 탐색하고, 위협 배율 체인을 적용하여 위협을 누적합니다.
    /// </summary>
    public static class ThreatUtility
    {
        private const float DefaultThreatRadius = 50f;

        private static readonly Collider[] overlapBuffer = new Collider[256];
        private static readonly HashSet<EnemyBase> processedEnemies = new HashSet<EnemyBase>();

        /// <summary>
        /// 시전자 주변의 적들에게 위협을 분배합니다.
        /// 위협 공식: baseThreat × (Gem 배율 × ThreatController 배율 × Passive 배율)
        /// </summary>
        /// <param name="caster">시전자 (위협을 얻을 주체)</param>
        /// <param name="baseThreat">배율 적용 전 기본 위협 수치</param>
        /// <param name="radius">위협을 생성할 반경 (기본 50m)</param>
        public static void GenerateThreatOnNearbyEnemies(GameObject caster, float baseThreat, float radius = DefaultThreatRadius)
        {
            if (caster == null || baseThreat <= 0f)
                return;

            float multiplier = ResolveThreatMultiplier(caster);
            float finalThreat = baseThreat * multiplier;

            processedEnemies.Clear();
            int hitCount = Physics.OverlapSphereNonAlloc(
                caster.transform.position,
                Mathf.Max(radius, 1f),
                overlapBuffer);

            for (int i = 0; i < hitCount; i++)
            {
                Collider hit = overlapBuffer[i];
                if (hit == null)
                    continue;

                EnemyBase enemy = hit.GetComponentInParent<EnemyBase>();
                if (enemy == null || processedEnemies.Contains(enemy))
                    continue;

                if (!enemy.UseThreatSystem || enemy.IsDead)
                    continue;

                // 같은 팀(적이 아님)은 제외
                if (Colosseum.Team.IsSameTeam(caster, enemy.gameObject))
                    continue;

                processedEnemies.Add(enemy);
                enemy.AddThreat(caster, finalThreat);
            }

            if (processedEnemies.Count > 0)
            {
                CombatBalanceTracker.RecordThreat(caster, finalThreat);
            }
        }

        /// <summary>
        /// 시전자의 전체 위협 배율을 계산합니다.
        /// 체인: SkillGem 배율 × ThreatController 배율 × Passive 배율
        /// </summary>
        public static float ResolveThreatMultiplier(GameObject source)
        {
            if (source == null)
                return 1f;

            float gemMultiplier = SkillRuntimeModifierUtility.GetThreatMultiplier(source);

            ThreatController threatController = source.GetComponent<ThreatController>();
            float runtimeMultiplier = threatController != null
                ? Mathf.Max(0f, threatController.CurrentThreatMultiplier)
                : 1f;

            float passiveMultiplier = PassiveRuntimeModifierUtility.GetThreatGeneratedMultiplier(source);

            return gemMultiplier * runtimeMultiplier * passiveMultiplier;
        }
    }
}