BITKit/Src/Unity/Scripts/WorldChunk/WorldChunkService.cs

using System;
using System.Collections;
using System.Collections.Concurrent;
using System.Collections.Generic;
using Quadtree;
using UnityEngine;


namespace BITKit.OpenWorld
{
	public class WorldChunkService<T> : MonoBehaviour
		where T : WorldChunkService<T>
	{
		
		public static T Singleton { get; private set; }
		private readonly ConcurrentQueue<IWorldChunkObject> _registerQueue = new();
		private readonly ConcurrentQueue<IWorldChunkObject> _unregisterQueue = new();
		public void Register(IWorldChunkObject obj) => _registerQueue.Enqueue(obj);
		public void Unregister(IWorldChunkObject obj) => _unregisterQueue.Enqueue(obj);
		protected QuadtreeRoot<IWorldChunkObject, Node<IWorldChunkObject>> _quadtree;
		private readonly ConcurrentDictionary<int, IWorldChunkObject> dictionary=new();

		[SerializeReference, SubclassSelector] private ITicker ticker;
		[SerializeField, ReadOnly] private int count;
		[SerializeField] private bool drawBounds;
		[SerializeField, Range(0, 1024)] private int[] lodDistances;
		[SerializeField] private Vector3 size;
		private Camera _camera;
		private readonly HashSet<int> cacheList = new();

		protected virtual void Awake()
		{
			Singleton = (T) this;
		}

		protected virtual void Start()
		{
			ticker.Add(OnTick);
			destroyCancellationToken.Register(Dispose);
			_quadtree = new QuadtreeRoot<IWorldChunkObject, Node<IWorldChunkObject>>(transform.position, size);
			_camera = Camera.main;
		}
		private void Dispose()
		{
			ticker.Remove(OnTick);
			_registerQueue.Clear();
			_unregisterQueue.Clear();
		}
		protected virtual void OnTick(float deltaTime)
		{
			while (_unregisterQueue.TryDequeue(out var obj))
			{
				_quadtree.Remove(obj);
				dictionary.Remove(obj.Id, out _);
			}

			while (_registerQueue.TryDequeue(out var obj))
			{
				obj.Id = count++;
				_quadtree.Insert(obj);
				dictionary.TryAdd(obj.Id, obj);
			}

			var cameraPosition = _camera.transform.position;

			for (var index = 0; index < lodDistances.Length; index++)
			{
				var distance = lodDistances[index];
				foreach (var chunkObject in _quadtree.Find(new Bounds(cameraPosition, Vector3.one * distance)))
				{
					if (cacheList.Contains(chunkObject.Id)) continue;
					cacheList.Add(chunkObject.Id);

					 var lod = chunkObject.Lod;
					 if (lod == index) continue;
					 try
					 {
					 	chunkObject.Lod = index;
					 }
					 catch (Exception e)
					 {
					 	BIT4Log.LogException(e);
					 }
				}
			}
			
			cacheList.Clear();
		}
		private void OnDrawGizmosSelected()
		{
			var pos = transform.position;
			Gizmos.DrawWireCube(pos,transform.rotation * size);
			
			if(drawBounds)
				_quadtree.CurrentRootNode.DrawBounds(true);
			
			if(!_camera)return;
			
			var cameraPosition = _camera.transform.position;

			foreach (var VARIABLE in lodDistances)
			{
				Gizmos.DrawWireSphere(cameraPosition, VARIABLE);
			}
		}
	}
}