using UnityEngine;
using Platformer.Mechanics;

namespace EerieVillage.Skills.Effectors
{
    /// <summary>
    /// 투사체 생성기. IEffector 구현체.
    /// SkillFireEvent.Execute 에서 ActiveCategory.Projectile 분기 시 호출.
    /// BT12-Dev Phase 2-B §4-4.
    ///
    /// 다중 발사: PlayerStats.ExtraProjectiles 반영 (P08 투사체증폭).
    /// 궤적 분기: ActiveSkillData.Trajectory — Line → Projectile, Homing → HomingProjectile.
    /// </summary>
    public class ProjectileSpawner : IEffector
    {
        public void Trigger(ActiveSkillRuntime runtime, PlayerSkillInventory inventory)
        {
            var data = runtime.ActiveData;

            // 플레이어 위치·방향 취득
            Transform playerTransform = inventory.transform;
            Vector2 spawnPos = playerTransform.position;

            // PlayerController.Facing 참조
            Vector2 facing = Vector2.right;
            var pc = inventory.GetComponent<PlayerController>();
            if (pc != null) facing = pc.Facing;

            // 프리팹 로드
            GameObject prefab = LoadProjectilePrefab(data);
            if (prefab == null)
            {
                Debug.LogWarning($"[ProjectileSpawner] 투사체 프리팹 로드 실패 (data.id={data.CardId})");
                return;
            }

            // 다중 발사 수 (기본 1 + ExtraProjectiles)
            int count = 1 + Mathf.Max(0, inventory.Stats.ExtraProjectiles);
            float angleStep = count > 1 ? 10f : 0f;
            float startAngle = -angleStep * (count - 1) * 0.5f;

            for (int i = 0; i < count; i++)
            {
                float angle = startAngle + angleStep * i;
                Vector2 dir = RotateVector(facing, angle);

                var go = Object.Instantiate(prefab, (Vector3)spawnPos, Quaternion.identity);

                Projectile proj;
                if (data.Trajectory == ProjectileTrajectory.Homing)
                    proj = go.GetComponent<HomingProjectile>() ?? go.AddComponent<HomingProjectile>();
                else
                    proj = go.GetComponent<Projectile>() ?? go.AddComponent<Projectile>();

                proj.Initialize(runtime, inventory, dir);
            }
        }

        /// <summary>
        /// 투사체 프리팹 로드.
        /// Phase 2-C 에서 data.projectilePrefab 필드를 추가하면 해당 경로 우선 사용.
        /// 현재는 Resources/Skills/Projectiles/Default 폴백.
        /// 폴백 실패 시 Collider2D 부착 빈 오브젝트를 반환한다.
        /// </summary>
        private static GameObject LoadProjectilePrefab(ActiveSkillData data)
        {
            var prefab = Resources.Load<GameObject>("Skills/Projectiles/Default");
            if (prefab != null) return prefab;

            // 폴백 — 빈 오브젝트 + CircleCollider2D (시각 없음, 판정만)
            var go = new GameObject($"Projectile_{data.CardId}");
            var col = go.AddComponent<CircleCollider2D>();
            col.isTrigger = true;
            col.radius = 0.2f;
            return go;
        }

        private static Vector2 RotateVector(Vector2 v, float degrees)
        {
            float rad = degrees * Mathf.Deg2Rad;
            float cos = Mathf.Cos(rad);
            float sin = Mathf.Sin(rad);
            return new Vector2(v.x * cos - v.y * sin, v.x * sin + v.y * cos);
        }
    }
}