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

namespace Skill_V2
{
    [CreateAssetMenu(fileName = "SpawnAttatchBullet", menuName = "ScriptableObject/Skill/SkillSequence/SpawnAttatchBullet")]
    public class SpawnAttatchBullet : SkillSequence
    {
        class BulletElement
        {
            public IBattleEntity target;
            public AttatchBullet bullet;
            public float prevDamagedTime;
        }

        [SerializeField] AttatchBullet attatchBulletPrefab;
        [SerializeField] int spawnCount;
        [SerializeField] float damageInterval = 0.5f;
        [SerializeField] bool resetBulletLifeTimeIfFindNewTarget;

        List<BulletElement> bulletElements;
        BigInteger skillDmg;

        public override void Enter()
        {
#if UNITY_EDITOR
            if (attatchBulletPrefab == null)
            {
                Logger.LogError(Owner.gameObject.name + " prefab is null");
                IsDone = true;
                return;
            }
#endif
            if(bulletElements is null)
                bulletElements = new List<BulletElement>();

            var nearestTarget = TargetFinder.GetNears(Owner.transform.position, Owner.TargetTags, spawnCount);
            for (int i = 0; i < nearestTarget.Count; i++)
            {
                BulletElement bulletElm = new BulletElement();
                bulletElm.target = nearestTarget[i];

                var bullet = Instantiate(attatchBulletPrefab, Owner.Caster.CenterPivot, UnityEngine.Quaternion.identity);
                bullet.ChangeLookDirection(Owner.LookDirection);
                bullet.OnAttatching += () => OnAttatching(bulletElm);
                bullet.OnBeforeDestroy += (bullet) => bulletElements.Remove(bulletElm);
                bulletElm.bullet = bullet;

                bullet.Fire((nearestTarget[i] as Entity).CenterPivotTransform);
            }

            skillDmg = Owner.GetSkillDamage();

            IsDone = true;
        }

        public override void Stop()
        {
            for (int i = 0; i < bulletElements.Count; i++)
            {
                var targetObj = bulletElements[i];
                Destroy(targetObj.bullet.gameObject);
            }

            bulletElements.Clear();
        }

        private void OnAttatching(BulletElement bulletElm)
        {
            if (!bulletElm.target.IsBattleAvail())
            {
                if (TargetFinder.TryFindNearest(bulletElm.bullet.CenterPivot, Owner.TargetTags, out var target, GetTargets()))
                {
                    bulletElm.target = target;
                    bulletElm.bullet.Fire((target as Entity).transform, resetBulletLifeTimeIfFindNewTarget);
                }
                else
                {
                    bulletElements.Remove(bulletElm);
                    Destroy(bulletElm.bullet.gameObject);
                }
            }
            else if(Time.time - bulletElm.prevDamagedTime > damageInterval)
            {
                bulletElm.prevDamagedTime = Time.time;
                BattleMgr.Instance.SendDamage(bulletElm.target, skillDmg, 0, 0);
            }
        }

        private HashSet<IBattleEntity> GetTargets()
        {
            var targets = new HashSet<IBattleEntity>();
            for (int i = 0; i < bulletElements.Count; i++)
            {
                targets.Add(bulletElements[i].target);
            }

            return targets;
        }
    }
}