using System;
using UnityEngine;

// ReSharper disable once CheckNamespace
namespace BlueWaterProject
{
    public class FieldOfView : MonoBehaviour
    {
        #region Property and variable

        [Header("타겟 및 시야 설정")]
        [SerializeField] private bool drawGizmo = true;
        
        [SerializeField] private LayerMask targetLayer;
        
        [Tooltip("시야 각도\n상대를 감지하는 0~360도 사이의 시야각")]
        [Range(0f, 360f)]
        [SerializeField] private float viewAngle = 360f;
        
        [Tooltip("시야 길이\n상대를 감지하는 최대 길이, 부채꼴 혹은 원의 반지름 길이")]
        [Range(0f, 50f)]
        [SerializeField] private float viewRadius;
        
        [Header("시야 내 타겟 정보")]
        [SerializeField] private Collider[] colliderWithinRange = new Collider[TARGET_MAX_SIZE];
        [SerializeField] private Transform targetTransform;

        private const int TARGET_MAX_SIZE = 20;

        #endregion

        #region Unity built-in Function

#if UNITY_EDITOR
        public void OnDrawGizmosSelected()
        {
            if (!drawGizmo) return;

            var myPos = transform.position;

            Gizmos.color = Color.green;
            Gizmos.DrawWireSphere(myPos, viewRadius);

            if (targetTransform == null) return;
            
            Debug.DrawLine(myPos, targetTransform.position, Color.red);
        }
#endif  

        private void LateUpdate()
        {
            Array.Clear(colliderWithinRange, 0, TARGET_MAX_SIZE);
            
            var myPos = transform.position;
            var maxColliderCount = Physics.OverlapSphereNonAlloc(myPos, viewRadius, colliderWithinRange, 
                targetLayer, QueryTriggerInteraction.Collide);

            if (maxColliderCount <= 0)
            {
                targetTransform = null;
                return;
            }

            var nearestDistance = Vector3.Distance(colliderWithinRange[0].transform.position, myPos);
            var nearestTargetTransform = colliderWithinRange[0].transform;

            for (var i = 1; i < maxColliderCount; i++)
            {
                var distance = Vector3.Distance(colliderWithinRange[i].transform.position, myPos);

                if (nearestDistance < distance) continue;

                nearestDistance = distance;
                nearestTargetTransform = colliderWithinRange[i].transform;
            }

            targetTransform = nearestTargetTransform;
            
            if (!targetTransform) return;

            var targetPos = targetTransform.position;
            targetPos.y = transform.position.y;
            transform.LookAt(targetPos);
        }

        #endregion

        #region Custom Function

        public int GetTargetLayer() => targetLayer;
        public Transform GetTargetTransform() => targetTransform;

        #endregion
    }
}