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);
		private QuadtreeRoot<IWorldChunkObject, Node<IWorldChunkObject>> _quadtree;

		[SerializeReference, SubclassSelector] private ITicker ticker;
		[SerializeField, ReadOnly] private int count;
		[SerializeField, Range(0, 128)] private int[] lodDistances;
		[SerializeField] private Vector3 size;
		private Camera _camera;
		private readonly HashSet<int> cacheList = new();

		private void Awake()
		{
			Singleton = (T) this;
		}

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

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