using System.Collections.Generic;

using UnityEngine;

namespace Colosseum.Player
{
    /// <summary>
    /// 카메라와 타겟 사이의 장애물을 숨기는 컨트롤러
    /// </summary>
    public class ObstacleTransparencyController : MonoBehaviour
    {
        [Header("Occlusion Settings")]
        [Min(0.01f)] [SerializeField] private float checkRadius = 0.3f;

        private Transform cameraTransform;
        private Transform targetTransform;
        private LayerMask occlusionMask;
        private readonly HashSet<Renderer> hiddenRenderers = new();

        public void Initialize(Transform target, LayerMask mask)
        {
            cameraTransform = GetComponent<Camera>().transform;
            targetTransform = target;
            occlusionMask = mask;
        }

        private void LateUpdate()
        {
            if (cameraTransform == null || targetTransform == null) return;

            Vector3 origin = cameraTransform.position;
            Vector3 direction = targetTransform.position - origin;
            float maxDistance = direction.magnitude;

            if (maxDistance < 0.01f) return;

            direction.Normalize();

            HashSet<Renderer> currentHits = CollectHits(origin, direction, maxDistance);

            foreach (Renderer renderer in currentHits)
            {
                if (!hiddenRenderers.Contains(renderer))
                {
                    renderer.enabled = false;
                    hiddenRenderers.Add(renderer);
                }
            }

            List<Renderer> toShow = null;
            foreach (Renderer renderer in hiddenRenderers)
            {
                if (renderer == null || !currentHits.Contains(renderer))
                {
                    if (renderer != null)
                        renderer.enabled = true;
                    (toShow ??= new List<Renderer>()).Add(renderer);
                }
            }

            if (toShow != null)
            {
                foreach (Renderer renderer in toShow)
                    hiddenRenderers.Remove(renderer);
            }
        }

        private HashSet<Renderer> CollectHits(Vector3 origin, Vector3 direction, float maxDistance)
        {
            var hits = new HashSet<Renderer>();
            RaycastHit[] rayHits = Physics.SphereCastAll(origin, checkRadius, direction, maxDistance, occlusionMask, QueryTriggerInteraction.Ignore);

            float targetY = targetTransform.position.y;

            foreach (RaycastHit hit in rayHits)
            {
                if (hit.point.y <= targetY) continue;

                Renderer renderer = hit.collider.GetComponent<Renderer>();
                if (renderer == null) continue;
                if (renderer is ParticleSystemRenderer || renderer is TrailRenderer) continue;

                hits.Add(renderer);
            }

            return hits;
        }

        public void ClearHidden()
        {
            foreach (Renderer renderer in hiddenRenderers)
            {
                if (renderer != null)
                    renderer.enabled = true;
            }

            hiddenRenderers.Clear();
        }

        private void OnDestroy()
        {
            ClearHidden();
        }
    }
}