using UnityEngine;
using Unity.Jobs;
using Unity.Collections;
using Unity.Burst;

namespace Voxels {
    [BurstCompile]
    public struct HeightGenJob : IJobParallelFor {
        public int SizeX;
        public int SizeY;
        public int OffsetX;
        public int OffsetY;
        public int Seed;
        public float BaseScale;

        [WriteOnly]
        public NativeArray<byte> Height;

        public void Execute(int index) {
            var x = OffsetX + ( index / SizeX);
            var y = OffsetY + (index % SizeY);

            var noise =  Mathf.PerlinNoise(x / (float) 32 + Seed, y / (float) 32 + Seed) * BaseScale * 0.5f;
            noise += Mathf.PerlinNoise(x / (float)64 + Seed - 3, y / (float)64 + Seed - 3) * BaseScale;
            noise += Mathf.PerlinNoise(x / (float)128 + Seed + 5, y / (float)128 + Seed + 5) * BaseScale * 2;
            noise += Mathf.PerlinNoise(x / (float)16 + Seed - 4, y / (float)16 + Seed - 8) * BaseScale * 0.25f;
            Height[index] = System.Convert.ToByte(noise);
        }
    }

    [BurstCompile]
    public struct ChunkGenJob  : IJobParallelFor {
        public int SizeH;
        public int SizeY;
        public int Seed;
        public int SeaLevel;
        public Unity.Mathematics.Random Random;

        [ReadOnly]
        public NativeArray<byte> HeightMap;

        [WriteOnly]
        public NativeArray<BlockData> Blocks;
        public void Execute(int index) {
            var dh = SizeH * SizeH;
            var y = index / dh;
            var h = index % dh;
            var x = h % SizeH;
            var z = h / SizeH;
            var height = HeightMap[(x) * SizeH + z];
            var stoneHeight = (int)(height * 0.8f);

            var rnd8pct = Random.NextUInt(0, 12) < 1 ? true : false;
            var rnd3pct = Random.NextUInt(0, 30) < 1 ? true : false;

            if ( y == 0 ) {
                Blocks[y * dh + z * SizeH + x] = new BlockData(BlockType.Bedrock, 0);
                return;
            }
            if ( y < stoneHeight ) {
                Blocks[y * dh + z * SizeH + x] = new BlockData(BlockType.Stone, 0);
            } else if ( y < height ){
                Blocks[y * dh + z * SizeH + x] = new BlockData(BlockType.Dirt, 0);
                return;
            } else if ( y == height ) {
                if ( y > SeaLevel ) {
                    Blocks[y * dh + z * SizeH + x] = new BlockData(BlockType.Grass, 0);
                } else {
                    Blocks[y * dh + z * SizeH + x] = new BlockData(BlockType.Sand, 0);
                }

            } else if ( y > height && y < SeaLevel ) {
                Blocks[y * dh + z * SizeH + x] = new BlockData() {
                    Type = BlockType.WaterStill,
                    SunLevel = (byte) (225 - (SeaLevel - y) * 10),
                    AddColor = 65535,
                };
            } else if (y == height + 1 && rnd8pct && y > SeaLevel ) {
                Blocks[y * dh + z * SizeH + x] = new BlockData() {
                    Type = BlockType.Weed,
                    SunLevel = 255,
                    AddColor = 65535,
                };
            } else if ( y == height + 1 && rnd3pct && y > SeaLevel ) {
                Blocks[y * dh + z * SizeH + x] = new BlockData() {
                    Type = BlockType.Shrub,
                    Subtype  = (byte) Random.NextInt(0, 3),
                    SunLevel = 255,
                    AddColor = 65535,
                };
            } else if ( y > height  || (!rnd8pct && y > height)) {
                Blocks[y * dh + z * SizeH + x] = new BlockData() {
                    SunLevel = 255
                };
            }
        }
    }
}