using System.Collections.Generic;
using UnityEngine;

namespace BlueWater
{
    public class CharacterHighlighting : MonoBehaviour
    {
        [SerializeField]
        private LayerMask _obstacleLayer;

        [SerializeField, Range(1, 16)]
        private int _maxHitCount = 8;

        private Camera _mainCamera;
        private RaycastHit[] _raycastHits;
        private List<FadeableObject> _currentFadeables;
        private List<FadeableObject> _previousFadeables;

        private void Start()
        {
            _mainCamera = Camera.main;
            _raycastHits = new RaycastHit[_maxHitCount];
            _currentFadeables = new List<FadeableObject>(_maxHitCount);
            _previousFadeables = new List<FadeableObject>(_maxHitCount);
        }

        private void Update()
        {
            _currentFadeables.Clear();
            
            var cameraPosition = _mainCamera.transform.position;
            var direction = transform.position - cameraPosition;
            var distance = direction.magnitude;
            var size = Physics.RaycastNonAlloc(cameraPosition, direction, _raycastHits, distance,
                _obstacleLayer, QueryTriggerInteraction.Collide);

            for (var i = 0; i < size; i++)
            {
                var hitObject = _raycastHits[i].collider.GetComponentInChildren<FadeableObject>();
                if (!hitObject || _currentFadeables.Contains(hitObject)) continue;

                if (hitObject.IsFadeable)
                {
                    hitObject.SetTransparent();
                    _currentFadeables.Add(hitObject);
                }
            }

            foreach (var element in _previousFadeables)
            {
                if (_currentFadeables.Contains(element)) continue;

                element.RestoreOriginal();
            }

            (_previousFadeables, _currentFadeables) = (_currentFadeables, _previousFadeables);
        }
    }
}