using UnityEngine;
using Platformer.Mechanics;
using EerieVillage.Skills;

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 + SpriteRenderer 부착 빈 오브젝트를 반환한다.
        /// PD 지시 2026-05-09 — 시각화: 흰색 원 sprite (Unity 기본 whiteTexture 사용).
        /// </summary>
        private static GameObject LoadProjectilePrefab(ActiveSkillData data)
        {
            var prefab = Resources.Load<GameObject>("Skills/Projectiles/Default");
            if (prefab != null) return prefab;

            // 폴백 — Collider + SpriteRenderer (시각 표시·판정 동시)
            var go = new GameObject($"Projectile_{data.CardId}");
            var col = go.AddComponent<CircleCollider2D>();
            col.isTrigger = true;
            col.radius = 0.2f;

            var sr = go.AddComponent<SpriteRenderer>();
            sr.sprite = GetOrCreateFallbackSprite();
            sr.color = GetColorByAttribute(data.AttributeTags);
            sr.sortingOrder = 50; // Player·Enemy 위
            // 0.4 unit 직경 정도의 작은 원
            go.transform.localScale = new Vector3(0.4f, 0.4f, 1f);

            return go;
        }

        // 캐시: Sprite 매번 생성하지 않도록 정적 보존
        static Sprite _fallbackSprite;

        static Sprite GetOrCreateFallbackSprite()
        {
            if (_fallbackSprite != null) return _fallbackSprite;

            // 16×16 원형 알파 텍스처 (둥근 형태)
            const int size = 16;
            var tex = new Texture2D(size, size, TextureFormat.RGBA32, false);
            tex.wrapMode = TextureWrapMode.Clamp;
            tex.filterMode = FilterMode.Bilinear;
            float r = size * 0.5f;
            for (int y = 0; y < size; y++)
            {
                for (int x = 0; x < size; x++)
                {
                    float dx = x - r + 0.5f;
                    float dy = y - r + 0.5f;
                    float dist = Mathf.Sqrt(dx * dx + dy * dy);
                    float alpha = Mathf.Clamp01(1f - (dist - (r - 1.5f)));
                    tex.SetPixel(x, y, new Color(1f, 1f, 1f, alpha));
                }
            }
            tex.Apply();
            _fallbackSprite = Sprite.Create(tex, new Rect(0, 0, size, size), new Vector2(0.5f, 0.5f), size);
            return _fallbackSprite;
        }

        static Color GetColorByAttribute(AttributeTag attr)
        {
            // 속성별 색상 (시각 구분 영역)
            if ((attr & AttributeTag.Fire) != 0) return new Color(1f, 0.5f, 0.2f);
            if ((attr & AttributeTag.Frost) != 0) return new Color(0.5f, 0.85f, 1f);
            if ((attr & AttributeTag.Dark) != 0) return new Color(0.6f, 0.3f, 0.85f);
            if ((attr & AttributeTag.Lightning) != 0) return new Color(1f, 1f, 0.4f);
            if ((attr & AttributeTag.Physical) != 0) return new Color(0.95f, 0.95f, 0.95f);
            return Color.white;
        }

        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);
        }
    }
}