using HexagonSurvive.Constants;
using HexagonSurvive.Containers.ECS;
using HexagonSurvive.Containers.ECS.Models;
using HexagonSurvive.Environment.Aspects;
using HexagonSurvive.Environment.Enums;
using HexagonSurvive.Extensions.ECS;
using HexagonSurvive.Map.Aspects;
using HexagonSurvive.Map.Components;
using HexagonSurvive.Map.Enums;
using HexagonSurvive.Map.Properties;
using Lib;
using Unity.Burst;
using Unity.Collections;
using Unity.Entities;
using Unity.Mathematics;
using Unity.Transforms;
using Random = Unity.Mathematics.Random;

namespace HexagonSurvive.Map.Systems
{
    [UpdateInGroup(typeof(InitializationSystemGroup))]
    public partial struct HexMapInitSystem : ISystem
    {
        private Random _random;
        private HexMapAspect _map;
        private FastNoiseLite _noise;
        private HexMapPrefabs _prefabs;
        private EntityCommandBuffer _ecb;

        private NativeArray<float2> _unitDirections;
        private NativeArray<float2> _chunkDirections;
        private DynamicBuffer<TreePrefabBuffer> _treePrefabs;
        private NativeHashMap<int3, Entity> _coordToUnit;

        private const float Sin60 = 0.8660254f;
        private const float CenterToSide = CenterToVertex * Sin60;
        private const float CenterToVertex = GlobalConstants.HexUnitSideLength;

        [BurstCompile]
        public void OnCreate(ref SystemState state)
        {
            state.RequireForUpdate<EntityContainerData>();
        }

        public void OnUpdate(ref SystemState state)
        {
            state.Enabled = false;
            Generate(ref state);
        }

        [BurstCompile]
        public void OnDestroy(ref SystemState state)
        {
            _coordToUnit.Dispose();
        }

        private void Generate(ref SystemState state)
        {
            foreach (HexMapAspect hexMapAspect in SystemAPI.Query<HexMapAspect>())
            {
                _map = hexMapAspect;
                Initialize(ref state);
                GenerateWaterSurface(ref state);
                GenerateMap(ref state);
                CleanUp();
            }
        }

        private void Initialize(ref SystemState state)
        {
            _ecb = new EntityCommandBuffer(Allocator.Temp);
            _noise = new FastNoiseLite((int)_map.MapData.basicProp.seed);
            _random = new Random(_map.MapData.basicProp.seed);
            _coordToUnit = new NativeHashMap<int3, Entity>();

            EntityContainerData containerData = SystemAPI.GetSingleton<EntityContainerData>();
            _prefabs = containerData.hexMapPrefabs;
            _treePrefabs = SystemAPI.GetBuffer<TreePrefabBuffer>(containerData.container);

            _unitDirections = new NativeArray<float2>(6, Allocator.Temp);
            _unitDirections[0] = new float2(-Sin60, 3 / 2f) * CenterToVertex;
            _unitDirections[1] = new float2(-2 * Sin60, 0) * CenterToVertex;
            _unitDirections[2] = new float2(-Sin60, -3 / 2f) * CenterToVertex;
            _unitDirections[3] = new float2(Sin60, -3 / 2f) * CenterToVertex;
            _unitDirections[4] = new float2(2 * Sin60, 0) * CenterToVertex;
            _unitDirections[5] = new float2(Sin60, 3 / 2f) * CenterToVertex;

            float chunkRadius = _map.MapData.basicProp.chunkRadius;
            _chunkDirections = new NativeArray<float2>(6, Allocator.Temp);
            _chunkDirections[0] = new float2(Sin60 * 3 * chunkRadius - Sin60, 3 / 2f * (chunkRadius - 1)) * CenterToVertex;
            _chunkDirections[1] = new float2(CenterToSide, 3 * CenterToVertex * chunkRadius - 3 / 2f * CenterToVertex);
            _chunkDirections[2] = new float2(2 * CenterToSide - 3 * CenterToSide * chunkRadius, 3 / 2f * CenterToVertex * chunkRadius);
            _chunkDirections[3] = -new float2(Sin60 * 3 * chunkRadius - Sin60, 3 / 2f * (chunkRadius - 1)) * CenterToVertex;
            _chunkDirections[4] = -new float2(CenterToSide, 3 * CenterToVertex * chunkRadius - 3 / 2f * CenterToVertex);
            _chunkDirections[5] = -new float2(2 * CenterToSide - 3 * CenterToSide * chunkRadius, 3 / 2f * CenterToVertex * chunkRadius);
        }

        /// <summary>
        /// 生成区块拼接成为地图
        /// </summary>
        private void GenerateMap(ref SystemState state)
        {
            float2 mapCenter = new float2(_map.Position.x, _map.Position.z);
            GenerateChunk(ref state, float2.zero);

            for (int r = 1; r < _map.MapData.basicProp.mapRadius; r++)
            {
                float2 curCenter = mapCenter + _chunkDirections[4] * r;

                foreach (float2 dir in _chunkDirections)
                {
                    for (int hex = 0; hex < r; hex++)
                    {
                        GenerateChunk(ref state, curCenter);
                        curCenter += dir;
                    }
                }
            }
        }

        /// <summary>
        /// 生成六边形单元生成区块
        /// </summary>
        /// <param name="state">ECS SystemState</param>
        /// <param name="center">区块中心,即中心六边形的中心</param>
        /// <returns></returns>
        private void GenerateChunk(ref SystemState state, float2 center)
        {
            InstantiateUnit(ref state, center);

            for (int r = 1; r < _map.MapData.basicProp.chunkRadius; r++)
            {
                float2 curCenter = new float2(center.x + r * CenterToSide * 2, center.y);

                foreach (float2 dir in _unitDirections)
                {
                    for (int hex = 0; hex < r; hex++)
                    {
                        InstantiateUnit(ref state, curCenter);
                        curCenter += dir;
                    }
                }
            }
        }

        /// <summary>
        /// 生成六边形单元
        /// </summary>
        /// <param name="state">ECS SystemState</param>
        /// <param name="pos">生成位置</param>
        /// <returns></returns>
        private void InstantiateUnit(ref SystemState state, float2 pos)
        {
            Entity hexUnit = state.EntityManager.Instantiate(_prefabs.hexUnit);
            HexUnitAspect unitAspect = SystemAPI.GetAspect<HexUnitAspect>(hexUnit);

            float height = GetUnitHeight(pos);
            int altitude = StepAltitude(height);
            TerrainNoiseProperties settings = _map.MapData.tnProp;
            float unitHeight = altitude * settings.stepHeight + settings.baseHeight;
            Biome biome = height > settings.seaLevel
                ? GetBiomeLand(unitAspect, pos, unitHeight)
                : GetBiomeWater(unitAspect, pos, unitHeight);

            unitAspect.AdjustData
            (
                altitude,
                unitHeight / 2,
                unitHeight > _map.MapData.tnProp.seaLevel,
                biome
            );
            unitAspect.Position = new float3(pos.x, unitHeight / 4, pos.y);
            unitAspect.NonUniformScale = new float3(1, unitHeight / 2, 1);

            CalculateCoordinates(unitAspect);
            GenerateVegetation(ref state, unitAspect);
        }

        private void CalculateCoordinates(HexUnitAspect unit)
        {
            float3 p = unit.Position;
            int x = Round(p.x / MathConstants.Sqrt3 / GlobalConstants.HexUnitSideLength * 2);
            int z = Round(p.z / 1.5f / GlobalConstants.HexUnitSideLength);
            unit.Coordinate = new int3((x - z) / 2, z, (-x - z) / 2);
            _coordToUnit.Add(unit.Coordinate, unit.self);
        }

        private int Round(float x) =>
            math.frac(x) > 0.5 ? (int)x + 1 : (int)x;

        /// <summary>
        /// 使海拔数值阶梯化
        /// </summary>
        /// <param name="altitude">原始海拔</param>
        /// <returns>阶梯化后的海拔等级</returns>
        private int StepAltitude(float altitude)
        {
            TerrainNoiseProperties settings = _map.MapData.tnProp;
            float refAltitude = altitude - settings.baseHeight;

            for (int i = 0; i < settings.terrainSteps; i++)
            {
                if (refAltitude < i * settings.altitudePerStep)
                    return i;
            }

            return settings.terrainSteps;
        }

        /// <summary>
        /// 生成陆地气候
        /// </summary>
        /// <param name="unitAspect">目标六边形</param>
        /// <param name="pos">六边形位置</param>
        /// <param name="altitude">六边形海拔,即噪声值</param>
        /// <returns>六边形高度</returns>
        private Biome GetBiomeLand(HexUnitAspect unitAspect, float2 pos, float altitude)
        {
            return Biome.Plains;
        }

        /// <summary>
        /// 生成水面气候,并重新调整六边形单元的高度
        /// </summary>
        /// <param name="unitAspect">目标六边形</param>
        /// <param name="pos">六边形位置</param>
        /// <param name="altitude">六边形海拔,即噪声值</param>
        /// <returns>六边形高度</returns>
        private Biome GetBiomeWater(HexUnitAspect unitAspect, float2 pos, float altitude)
        {
            return Biome.River;
        }

        // /// <summary>
        // /// 获取当前位置的生物群系噪声值
        // /// </summary>
        // /// <param name="pos">六边形位置</param>
        // /// <param name="altitude">海拔</param>
        // /// <returns>0: 温度(现实温度) 1: 降水(0-1) 2: 特别程度(0-1)</returns>
        // private float[] GetBiomeNoiseValue(Vector2 pos, float altitude)
        // {
        //     _noise.SetNoiseType(FastNoiseLite.NoiseType.OpenSimplex2S);
        //     BiomeNoiseSettings settings = _map.Data.biomeSettings;
        //
        //     _noise.SetSeed((int)_mapMono.seed + _random.Int(0, int.MaxValue));
        //     Vector2 tempNoisePos = pos * settings.temperatureFrequency + settings.temperatureOffset;
        //     float tempNoise = (_noise.GetNoise(tempNoisePos.x, tempNoisePos.y) + 1) / 2;
        //     tempNoise = Mathf.Pow(tempNoise, settings.temperaturePower);
        //
        //     _noise.SetSeed((int)_mapMono.seed + _random.Int(0, int.MaxValue));
        //     Vector2 precipNoisePos = pos * settings.precipitationFrequency + settings.precipitationOffset;
        //     float precipNoise = (_noise.GetNoise(precipNoisePos.x, precipNoisePos.y) + 1) / 2;
        //     precipNoise = Mathf.Pow(precipNoise, settings.precipitationPower);
        //
        //     _noise.SetSeed((int)_mapMono.seed + _random.Int(0, int.MaxValue));
        //     Vector2 peculiarityPos = pos * settings.peculiarityFrequency + settings.peculiarityOffset;
        //     float peculiarity = (_noise.GetNoise(peculiarityPos.x, peculiarityPos.y) + 1) / 2;
        //     peculiarity = Mathf.Pow(peculiarity, settings.peculiarityPower);
        //
        //     _noise.SetSeed((int)_mapMono.seed);
        //     float latitude = Mathf.Abs(pos.y / _mapMono.mapRadius / _mapMono.chunkRadius / GlobalConstants.HexUnitSideLength / 2 * 90);
        //     latitude = Mathf.Clamp(latitude, 0, 90);
        //
        //     float temp = Mathf.Cos(latitude / 180 * Mathf.PI) * 53.595f - 20.055f - altitude * 0.6f + tempNoise * 5;
        //     return new[] { temp, precipNoise, peculiarity };
        // }

        /// <summary>
        /// 使用噪声生成地形
        /// </summary>
        /// <param name="pos">六边形的位置</param>
        /// <returns>六边形高度</returns>
        private float GetUnitHeight(float2 pos)
        {
            float baseNoise = _map.MapData.tnProp.baseTerrain.GetNoise(_noise, pos);
            float ridgeNoise = _map.MapData.tnProp.ridged.GetNoise(_noise, pos);
            float riverNoise = _map.MapData.tnProp.river.GetNoise(_noise, pos);
            return (baseNoise + ridgeNoise - riverNoise) * _map.MapData.tnProp.altitudeMultiplier + _map.MapData.tnProp.baseHeight;
        }

        /// <summary>
        /// 生成树
        /// </summary>
        /// <param name="state">ECS SystemState</param>
        /// <param name="targetUnit">目标六边形</param>
        private void GenerateVegetation(ref SystemState state, HexUnitAspect targetUnit)
        {
            if (targetUnit.Data.height <= _map.MapData.tnProp.seaLevel)
                return;

            float2 pos = new float2(targetUnit.Position.x, targetUnit.Position.z);
            if (_map.MapData.bnProp.treeNoise.GetNoise(_noise, pos) < _map.MapData.bnProp.treeSpawnThreshold
                || _random.NextFloat() > _map.MapData.bnProp.treeDensity)
                return;

            Entity tree = state.EntityManager.Instantiate(_random.Sample(ref _treePrefabs).entity);
            NaturalEntityAspect naturalEntityAspect = SystemAPI.GetAspect<NaturalEntityAspect>(tree);
            naturalEntityAspect.Init
            (
                NatualEntityType.Tree,
                new float3(targetUnit.Position.x, targetUnit.Data.height, targetUnit.Position.z),
                _random.NextFloat() * 360,
                targetUnit.self
            );
            targetUnit.NaturalEntity = tree;
        }

        private void GenerateWaterSurface(ref SystemState state)
        {
            Entity water = state.EntityManager.Instantiate(_prefabs.waterSurface);
            SystemAPI.GetComponentRW<LocalToWorld>(water).ValueRW.Value =
                float4x4.Translate(new float3
                (
                    -_map.EnvData.planeMeshSize.x / 2f,
                    _map.MapData.tnProp.seaLevel,
                    -_map.EnvData.planeMeshSize.y / 2f
                ));
        }

        private void CleanUp()
        {
            _ecb.Dispose();
            _unitDirections.Dispose();
            _chunkDirections.Dispose();
        }
    }
}