using XericLibrary.Runtime.MacroLibrary;
using XericLibrary.Runtime.Type;

using System.Collections;
using System.Collections.Generic;
using System.Drawing;
using System.Runtime.CompilerServices;

using UnityEngine;
using UnityEngine.UIElements;

namespace XericLibrary.Runtime.MacroLibrary
{
	public class NeighborGrid<T> : WeaklyObject,
	IEnumerable<KeyValuePair<int, List<T>>>
	{
		#region 字段属性

		private Vector3 position;
		private Vector3 cellSize;
		private Vector3Int numCells;
		private int maxNeighbor = 8;


		public Vector3 Position
		{
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			get => position;
		}
		public Vector3 CellSize
		{
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			get => cellSize;
		}
		public Vector3Int NumCells
		{
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			get => numCells;
		}


		internal System.Random random = new System.Random();
		private int NeighborRandomIndex
		{
			get => random.Next(maxNeighbor);
		}

		/// <summary>
		/// 网格系统存储地
		/// </summary>
		private Dictionary<int, List<T>> grid = new Dictionary<int, List<T>>();

		/// <summary>
		/// 网格的总尺寸
		/// </summary>
		public Vector3 Fullsize
		{
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			get => cellSize.Mul(numCells);
		}

		/// <summary>
		/// 此网格系统转为盒体范围
		/// </summary>
		public Bounds GridBounds
		{
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			get => new Bounds(position, Fullsize / 2);
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			set
			{
				position = value.center;
				cellSize = (value.size * 2).Div(numCells);
			}
		}

		#endregion

		#region 构造

		/// <summary>
		/// 临近网格
		/// </summary>
		/// <param name="position">网格原点坐标</param>
		/// <param name="cellSize">网格晶格尺寸</param>
		/// <param name="fullSize">网格总尺寸</param>
		/// <param name="maxNeighbor">单个晶格内最大邻居数量</param>
		public NeighborGrid(Vector3 position, Vector3 cellSize, Vector3 fullSize, int maxNeighbor = 8)
		{
			this.position = position;
			this.cellSize = cellSize;
			this.numCells = fullSize.Div(cellSize).FloorToInt().Max(Vector3Int.one);
			this.maxNeighbor = maxNeighbor;

			Debug.Log($"原点：{position}， 晶格尺寸{cellSize}， 数量：{numCells}");
		}

		#endregion

		#region 类内类

		/// <summary>
		/// 网格索引
		/// </summary>
		public struct NeighborGridIndex
		{
			#region 字段属性

			private NeighborGrid<T> grid;

			private NeighborGridSpace drivenSpace;

			private object drivenIndex;

			#endregion

			#region 构造

			public NeighborGridIndex(NeighborGrid<T> grid)
			{
				this.grid = grid;
				drivenSpace = (NeighborGridSpace)(-1);
				drivenIndex = null;
			}

			#endregion

			#region 方法

			/// <summary>
			/// 获取为 世界空间
			/// </summary>
			/// <param name="world"></param>
			public Vector3 GetDrivenAsWorld()
			{
				DrivenTransformTo(NeighborGridSpace.World);
				return (Vector3)drivenIndex;
			}

			/// <summary>
			/// 获取为 网格系统本地坐标空间
			/// </summary>
			/// <param name="simulation"></param>
			public Vector3 GetDrivenAsSimulation()
			{
				DrivenTransformTo(NeighborGridSpace.Simulation);
				return (Vector3)drivenIndex;
			}

			/// <summary>
			/// 获取为 网格系统本地单位空间
			/// </summary>
			/// <param name="unit"></param>
			public Vector3 GetDrivenAsUnit()
			{
				DrivenTransformTo(NeighborGridSpace.Unit);
				return (Vector3)drivenIndex;
			}

			/// <summary>
			/// 获取为 三维索引
			/// </summary>
			/// <param name="world"></param>
			public Vector3Int GetDrivenAsIndex()
			{
				DrivenTransformTo(NeighborGridSpace.Index);
				return (Vector3Int)drivenIndex;
			}

			/// <summary>
			/// 获取为 线性索引
			/// </summary>
			/// <param name="world"></param>
			public int GetDrivenAsLinear()
			{
				DrivenTransformTo(NeighborGridSpace.Linear);
				return (int)drivenIndex;
			}


			/// <summary>
			/// 设置为 世界空间
			/// </summary>
			/// <param name="world"></param>
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			public NeighborGridIndex SetDrivenAsWorld(Vector3 world)
			{
				drivenIndex = world;
				drivenSpace = NeighborGridSpace.World;
				return this;
			}

			/// <summary>
			/// 设置为 网格系统本地坐标空间
			/// </summary>
			/// <param name="simulation"></param>
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			public NeighborGridIndex SetDrivenAsSimulation(Vector3 simulation)
			{
				drivenIndex = simulation;
				drivenSpace = NeighborGridSpace.Simulation;
				return this;
			}

			/// <summary>
			/// 设置为 网格系统本地单位空间
			/// </summary>
			/// <param name="unit"></param>
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			public NeighborGridIndex SetDrivenAsUnit(Vector3 unit)
			{
				drivenIndex = unit;
				drivenSpace = NeighborGridSpace.Unit;
				return this;
			}

			/// <summary>
			/// 设置为 三维索引
			/// </summary>
			/// <param name="world"></param>
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			public NeighborGridIndex SetDrivenAsIndex(Vector3Int index)
			{
				drivenIndex = index;
				drivenSpace = NeighborGridSpace.Index;
				return this;
			}

			/// <summary>
			/// 设置为 线性索引
			/// </summary>
			/// <param name="world"></param>
			[MethodImpl(MethodImplOptions.AggressiveInlining)]
			public NeighborGridIndex SetDrivenAsLinear(int linear)
			{
				drivenIndex = linear;
				drivenSpace = NeighborGridSpace.Linear;
				return this;
			}


			/// <summary>
			/// 转换当前索引到目标空间
			/// </summary>
			/// <param name="targetSpace"></param>
			public NeighborGridIndex DrivenTransformTo(NeighborGridSpace targetSpace)
			{
				switch(targetSpace)
				{
					case NeighborGridSpace.World:
					TransformToWorld();
					break;

					case NeighborGridSpace.Simulation:
					TransformToSimulation();
					break;

					case NeighborGridSpace.Unit:
					TransformToUnit();
					break;

					case NeighborGridSpace.Index:
					TransformToIndex();
					break;

					case NeighborGridSpace.Linear:
					TransformToLiear();
					break;

					default:
					throw new System.Exception("转换空间是无效的");
				}
				return this;
			}


			/// <summary>
			/// 将当前的目标转换到世界空间
			/// </summary>
			private void TransformToWorld()
			{
				switch(drivenSpace)
				{
					case NeighborGridSpace.World:
					drivenSpace = NeighborGridSpace.World;
					break;

					case NeighborGridSpace.Simulation:
					drivenIndex = grid.SimulationToWorld((Vector3)drivenIndex);
					goto case NeighborGridSpace.World;

					case NeighborGridSpace.Unit:
					drivenIndex = grid.UnitToSimulation((Vector3)drivenIndex);
					goto case NeighborGridSpace.Simulation;

					case NeighborGridSpace.Index:
					drivenIndex = grid.IndexToUnit((Vector3Int)drivenIndex);
					goto case NeighborGridSpace.Unit;

					case NeighborGridSpace.Linear:
					drivenIndex = grid.LinearToIndex((int)drivenIndex);
					goto case NeighborGridSpace.Index;

					default:
					throw new System.Exception("转换空间是无效的");
				}
			}

			/// <summary>
			/// 将当前的目标转换到本地空间
			/// </summary>
			private void TransformToSimulation()
			{
				switch(drivenSpace)
				{
					case NeighborGridSpace.World:
					drivenIndex = grid.WorldToSimulation((Vector3)drivenIndex);
					goto case NeighborGridSpace.Simulation;

					case NeighborGridSpace.Simulation:
					drivenSpace = NeighborGridSpace.Simulation;
					break;

					case NeighborGridSpace.Unit:
					drivenIndex = grid.UnitToSimulation((Vector3)drivenIndex);
					goto case NeighborGridSpace.Simulation;

					case NeighborGridSpace.Index:
					drivenIndex = grid.IndexToUnit((Vector3Int)drivenIndex);
					goto case NeighborGridSpace.Unit;

					case NeighborGridSpace.Linear:
					drivenIndex = grid.LinearToIndex((int)drivenIndex);
					goto case NeighborGridSpace.Index;

					default:
					throw new System.Exception("转换空间是无效的");
				}
			}

			/// <summary>
			/// 将当前的目标转换到单位空间
			/// </summary>
			private void TransformToUnit()
			{
				switch(drivenSpace)
				{
					case NeighborGridSpace.World:
					drivenIndex = grid.WorldToSimulation((Vector3)drivenIndex);
					goto case NeighborGridSpace.Simulation;

					case NeighborGridSpace.Simulation:
					drivenIndex = grid.SimulationToUnit((Vector3)drivenIndex);
					goto case NeighborGridSpace.Unit;

					case NeighborGridSpace.Unit:
					drivenSpace = NeighborGridSpace.Unit;
					break;

					case NeighborGridSpace.Index:
					drivenIndex = grid.IndexToUnit((Vector3Int)drivenIndex);
					goto case NeighborGridSpace.Unit;

					case NeighborGridSpace.Linear:
					drivenIndex = grid.LinearToIndex((int)drivenIndex);
					goto case NeighborGridSpace.Index;

					default:
					throw new System.Exception("转换空间是无效的");
				}
			}

			/// <summary>
			/// 将当前的目标转换到三维索引
			/// </summary>
			private void TransformToIndex()
			{
				switch(drivenSpace)
				{
					case NeighborGridSpace.World:
					drivenIndex = grid.WorldToSimulation((Vector3)drivenIndex);
					goto case NeighborGridSpace.Simulation;

					case NeighborGridSpace.Simulation:
					drivenIndex = grid.SimulationToUnit((Vector3)drivenIndex);
					goto case NeighborGridSpace.Unit;

					case NeighborGridSpace.Unit:
					drivenIndex = grid.UnitToIndex((Vector3)drivenIndex);
					goto case NeighborGridSpace.Index;

					case NeighborGridSpace.Index:
					drivenSpace = NeighborGridSpace.Index;
					break;

					case NeighborGridSpace.Linear:
					drivenIndex = grid.LinearToIndex((int)drivenIndex);
					goto case NeighborGridSpace.Index;

					default:
					throw new System.Exception("转换空间是无效的");
				}
			}

			/// <summary>
			/// 将当前的目标转换到线性索引
			/// </summary>
			private void TransformToLiear()
			{
				switch(drivenSpace)
				{
					case NeighborGridSpace.World:
					drivenIndex = grid.WorldToSimulation((Vector3)drivenIndex);
					goto case NeighborGridSpace.Simulation;

					case NeighborGridSpace.Simulation:
					drivenIndex = grid.SimulationToUnit((Vector3)drivenIndex);
					goto case NeighborGridSpace.Unit;

					case NeighborGridSpace.Unit:
					drivenIndex = grid.UnitToIndex((Vector3)drivenIndex);
					goto case NeighborGridSpace.Index;

					case NeighborGridSpace.Index:
					drivenIndex = grid.IndexToLinear((Vector3Int)drivenIndex);
					break;

					case NeighborGridSpace.Linear:
					drivenSpace = NeighborGridSpace.Linear;
					break;

					default:
					throw new System.Exception("转换空间是无效的");
				}

			}

			#endregion

		}

		/// <summary>
		/// 临近网络空间枚举
		/// </summary>
		public enum NeighborGridSpace
		{
			World,
			Simulation,
			Unit,
			Index,
			Linear
		}

		#endregion

		#region 索引变换

		/// <summary>
		/// 世界空间 变换为 网格系统本地坐标空间
		/// </summary>
		/// <param name="world">项目的世界空间坐标</param>
		/// <returns></returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public Vector3 WorldToSimulation(Vector3 world)
			=> world - position - (-Fullsize / 2);

		/// <summary>
		/// 网格系统本地坐标空间 变换为 世界空间
		/// </summary>
		/// <param name="world">项目的世界空间坐标</param>
		/// <returns></returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public Vector3 SimulationToWorld(Vector3 simulation)
			=> simulation + position + (-Fullsize / 2);


		/// <summary>
		/// 网格系统本地坐标空间 变换为 网格系统本地单位空间
		/// </summary>
		/// <param name="simulation">网格系统本地坐标空间</param>
		/// <returns></returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public Vector3 SimulationToUnit(Vector3 simulation)
			=> simulation.Div(Fullsize);

		/// <summary>
		/// 网格系统本地坐标空间 变换为 网格系统本地单位空间
		/// </summary>
		/// <param name="simulation">网格系统本地坐标空间</param>
		/// <returns></returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public Vector3 UnitToSimulation(Vector3 unit)
			=> unit.Mul(Fullsize);


		/// <summary>
		/// 网格系统本地单位空间 变换为 三维索引
		/// </summary>
		/// <param name="unit">网格系统本地单位空间</param>
		/// <returns></returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public Vector3Int UnitToIndex(Vector3 unit)
			=> unit.IsInUnit() ? unit.Mul(numCells).FloorToInt() : MacroMath.Vector3Int_Negate;

		/// <summary>
		/// 三维索引 变换为 网格系统本地单位空间
		/// </summary>
		/// <param name="index">三维索引</param>
		/// <returns></returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public Vector3 IndexToUnit(Vector3Int index)
		{
			if(index.IsValid())
			{
				Vector3 unit = ((Vector3)index).Div(numCells);
				unit.x = numCells.x == 1 && unit.x <= 0 ? .5f : unit.x;
				unit.y = numCells.y == 1 && unit.y <= 0 ? .5f : unit.y;
				unit.z = numCells.z == 1 && unit.z <= 0 ? .5f : unit.z;
				return unit;
			}
			return MacroMath.Vector3Int_Negate;
		}


		/// <summary>
		/// 网格系统本地单位空间 变换为 线性索引
		/// </summary>
		/// <param name="unit">网格系统本地坐标空间</param>
		/// <returns></returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public int UnitToLinear(Vector3 unit)
		{
			if(unit.IsInUnit())
			{
				return IndexToLinear(UnitToIndex(unit));
			}
			return -1;
		}

		/// <summary>
		/// 三维索引 变换为 线性索引
		/// </summary>
		/// <param name="index">三维索引</param>
		/// <returns></returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public int IndexToLinear(Vector3Int index)
		{
			if(index.IsValid() && index.IsInIndexRange(numCells))
			{
				return (int)(index.x +
				(index.y * numCells.x) +
				(index.z * numCells.y * numCells.x));
			}
			return -1;
		}

		/// <summary>
		/// 根据线性索引获取网格中索引偏移量
		/// </summary>
		/// <param name="linear">线性索引</param>
		/// <param name="side">边长</param>
		/// <returns></returns>
		public Vector3Int LinearToGridIndex(int linear, int side)
		{
			return new Vector3Int(linear % side, linear / side, linear / side.Quad());
		}

		/// <summary>
		/// 线性索引 变换为 三维索引
		/// </summary>
		/// <param name="linear">线性索引</param>
		/// <returns></returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public Vector3Int LinearToIndex(int linear)
		{
			int z = linear / (numCells.x * numCells.y);
			int y = (linear - (z * numCells.x * numCells.y)) / numCells.x;
			int x = linear - (z * numCells.x * numCells.y) - (y * numCells.x);

			return new Vector3Int(x, y, z);
		}

		/// <summary>
		/// 线性索引 变换为 网格系统本地单位空间
		/// </summary>
		/// <param name="linear">线性索引</param>
		/// <returns></returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public Vector3 LinearToUnit(int linear)
		{
			Debug.Log($"线性转索引空间{LinearToIndex(linear)}，再转单位");
			return IndexToUnit(LinearToIndex(linear));
		}

		#endregion

		#region 增删查

		/// <summary>
		/// 清空网格
		/// </summary>
		public void Clean()
		{
			grid.Clear();
		}

		/// <summary>
		/// 在给定索引处添加一个项目
		/// </summary>
		/// <param name="linear">索引</param>
		/// <returns>返回是否添加成功</returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public bool Insert(int linear, T obj)
		{
			if(linear < 0)
				return false;
			if(grid.ContainsKey(linear))
			{
				int index = grid[linear].IndexOf(obj);
				if(index < 0)
				{
					grid[linear].Add(obj);
					return true;
				}
				return false;
			}
			else
			{
				grid.Add(linear, new List<T> { obj });
				return true;
			}
		}

		/// <summary>
		/// 移除给定索引处的项目
		/// </summary>
		/// <param name="linear">索引</param>
		/// <param name="obj">项目</param>
		/// <returns>返回是否移除成功</returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public bool Remove(int linear, T obj)
		{
			if(grid.ContainsKey(linear))
			{
				bool resualt = grid[linear].Remove(obj);
				if(grid[linear].Count <= 0)
					grid.Remove(linear);
				return resualt;
			}
			return false;
		}
		/// <summary>
		/// 移除给定索引下所有项目
		/// </summary>
		/// <param name="linear">索引</param>
		/// <returns>返回是否移除成功</returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public void Remove(int linear)
		{
			if(grid[linear] is not null)
			{
				grid[linear].Clear();
			}
		}

		/// <summary>
		/// 查询给定索引处是否存在项目
		/// </summary>
		/// <param name="linear">索引</param>
		/// <param name="obj">项目</param>
		/// <returns>返回项目是否存在</returns>
		[MethodImpl(MethodImplOptions.AggressiveInlining)]
		public bool Contains(int linear, T obj)
		{
			if(grid[linear] is not null)
			{
				return grid[linear].Contains(obj);
			}
			return false;
		}

		/// <summary>
		/// 忽略限制获取所有的邻居
		/// <code>
		/// 警告：潜在的高性能开销
		/// </code>
		/// </summary>
		/// <param name="linear"></param>
		/// <returns></returns>
		public bool GetAllNeighbor(int linear, out List<T> values)
		{
			return grid.TryGetValue(linear, out values);
		}

		/// <summary>
		/// 获取允许范围内的邻居
		/// </summary>
		/// <param name="linear">所在位置的索引</param>
		/// <returns></returns>
		public IEnumerable<T> GetNeighbor(int linear)
		{
			int startIndex = NeighborRandomIndex;
			int count = grid[linear].Count;
			for(int i = 0; i < maxNeighbor; i++)
			{
				yield return grid[linear][(startIndex + i) % count];
			}
		}

		/// <summary>
		/// 获取半径内所有允许的邻居
		/// </summary>
		/// <param name="linear">所在位置的索引</param>
		/// <param name="range">检查的范围</param>
		/// <returns></returns>
		public IEnumerable<T> GetNeighbor(int linear, int radius)
		{
			int side = radius * 2 + 1;
			int length = side.Cubic();
			Vector3Int index = LinearToIndex(linear);
			index = index.Sub(radius);

			for(int i = 0; i < length; i++)
			{
				var neighbor = GetNeighbor(IndexToLinear(index +
					LinearToGridIndex(i, side)))
						.GetEnumerator();
				while(neighbor.MoveNext())
				{
					yield return neighbor.Current;
				}
			}
		}

		#endregion

		#region 实现

		public IEnumerator<KeyValuePair<int, List<T>>> GetEnumerator()
		{
			foreach(var list in grid)
			{
				yield return list;
			}
		}

		IEnumerator IEnumerable.GetEnumerator()
		{
			return GetEnumerator();
		}

		#endregion
	}
}