PURE AGONY!!

using System;
using System.Collections.Generic;
using UnityEngine;
using Unity.Mathematics;
using Unity.Collections;

public class MeshGenerator : MonoBehaviour
{
    public static Vector3Int chunkDimensions = new Vector3Int(64, 64, 64);

    public Material material;

    public int brushSize;
    public float brushStrength;

    public int LOD;
    public int maxLOD;
    int lod;

    [Header("Noise Settings")]
    public float heightMultiplier;
    public float frequency;
    public float lacunarity;
    public float persistance;
    public int octaves;
    public float density;

    [Header("")]
    public bool autoUpdate;
    public string executionTime;

    float[][] voxelGrid;

    List<Vector3> vertices;
    Dictionary<Vector3, int> vertDictionary;

    List<int> indices;

    int[] caseToNumpolys;
    int[][] triTable;

    public static Vector3Int[] cornerOffsets;

    Camera cam;

    Noise noise;

    public GameObject ChunkObject(Vector2Int position)
    {
        GameObject chunk = new GameObject("Chunk");
        chunk.AddComponent<MeshFilter>().mesh = ChunkMesh(position);
        chunk.AddComponent<MeshRenderer>().material = material;

        return chunk;
    }

    public Mesh ChunkMesh(Vector2Int position)
    {
        //NativeArray<float> noiseMap2D; //= //noise.FractalNoiseMap();
        //NativeArray<float> noiseMap3D; //= new NativeArray<float>()//noise.Fractal3DNoiseMap();

        CreateVoxelGrid();

        for (int z = 0, i = 0; z < chunkDimensions.z; z += lod)
        {
            for (int y = 0; y < chunkDimensions.y; y += lod)
            {
                for (int x = 0; x < chunkDimensions.x; x += lod, i += 3)
                {
                    AddVertices(x, y, z);
                }
            }
        }

        //noiseMap2D.Dispose();
        //noiseMap3D.Dispose();

        Mesh mesh = new Mesh();
        mesh.indexFormat = UnityEngine.Rendering.IndexFormat.UInt32;

        mesh.vertices = vertices.ToArray();
        mesh.triangles = indices.ToArray();

        mesh.RecalculateNormals();

        return mesh;
    }

    public void EditorMesh()
    {
        Initialize();

        float startTime = Time.realtimeSinceStartup;

        Mesh mesh = ChunkMesh(Vector2Int.zero);

        executionTime = ((Time.realtimeSinceStartup - startTime) * 1000f) + "ms";

        if (GameObject.Find("Mesh") == null)
        {
            GameObject obj = new GameObject("Mesh");
            obj.transform.parent = transform;
            obj.AddComponent<MeshFilter>().mesh = mesh;
            obj.AddComponent<MeshRenderer>().material = material;
            obj.AddComponent<MeshCollider>();
        }

        else
        {
            var mf = GameObject.Find("Mesh").GetComponent<MeshFilter>();
            var collider = GameObject.Find("Mesh").GetComponent<MeshCollider>();

            mf.mesh = mesh;
            collider.sharedMesh = null;
            collider.sharedMesh = mesh;
        }
    }

    private void Start()
    {
        Initialize();
    }

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.Space))
        {
            EditorMesh();
        }

        //if (Input.GetMouseButton(1))
        //{
        //    Ray ray = cam.ScreenPointToRay(Input.mousePosition);

        //    if (Physics.Raycast(ray, out RaycastHit hit))
        //    {
        //        ModifyTerrain(new Vector3Int((int)hit.point.x, (int)hit.point.y, (int)hit.point.z), true, hit.collider.gameObject);
        //    }
        //}

        //if (Input.GetMouseButton(0))
        //{
        //    Ray ray = cam.ScreenPointToRay(Input.mousePosition);

        //    if (Physics.Raycast(ray, out RaycastHit hit))
        //    {
        //        ModifyTerrain(new Vector3Int((int)hit.point.x, (int)hit.point.y, (int)hit.point.z), false, hit.collider.gameObject);
        //    }
        //}
    }

    void Initialize()
    {
        caseToNumpolys = Tables.caseToNumPolys;
        triTable = Tables.triTable;

        cam = Camera.main;

        vertices = new();
        vertDictionary = new();

        indices = new();

        lod = LOD == 0 ? 1 : LOD * 2;

        cornerOffsets = new Vector3Int[]
        {
            new Vector3Int(0, 0, 0),
            new Vector3Int(0, 1 * lod, 0),
            new Vector3Int(1 * lod, 1 * lod, 0),
            new Vector3Int(1 * lod, 0, 0),
            new Vector3Int(0, 0, 1 * lod),
            new Vector3Int(0, 1 * lod, 1 * lod),
            new Vector3Int(1 * lod, 1 * lod, 1 * lod),
            new Vector3Int(1 * lod, 0, 1 * lod),

        };

        noise = new Noise(frequency, persistance, lacunarity, octaves, lod);
    }

    void AddVertices(int x, int y, int z)
    {
        int triCase = Utils.CalculateCase(voxelGrid[Utils.VoxelIndex(x/lod, y/lod, z/lod)]);
        int[] edges = triTable[triCase];

        for (int j = 0, i = 0; j < caseToNumpolys[triCase]; j++, i += 3)
        {
            for (int h = 0; h < 3; h++)
            {
                Vector3 vertex = GetEdgePosition(edges[i + (2 - h)], x, y, z);

                if (vertDictionary.ContainsKey(vertex))
                {
                    indices.Add(vertDictionary[vertex]);
                }

                else
                {
                    vertices.Add(vertex);
                    indices.Add(vertices.Count - 1);

                    vertDictionary.Add(vertex, vertices.Count - 1);
                }
            }
        }
    }

    Vector3 GetEdgePosition(int edge, int x, int y, int z)
    {
        float[] voxelData = voxelGrid[Utils.VoxelIndex(x/lod, y/lod, z/lod)];

        switch (edge)
        {
            case 0: return Utils.GetInterpolatedEdgePosition(x, y, z, voxelData[0], voxelData[1], 0, 1, 0);
            case 1: return Utils.GetInterpolatedEdgePosition(x, y + (1 * lod), z, voxelData[1], voxelData[2], 1, 0, 0);
            case 2: return Utils.GetInterpolatedEdgePosition(x + (1 * lod), y, z, voxelData[3], voxelData[2], 0, 1, 0);
            case 3: return Utils.GetInterpolatedEdgePosition(x, y, z, voxelData[0], voxelData[3], 1, 0, 0);

            case 4: return Utils.GetInterpolatedEdgePosition(x, y, z + (1 * lod), voxelData[4], voxelData[5], 0, 1, 0);
            case 5: return Utils.GetInterpolatedEdgePosition(x, y + (1 * lod), z + (1 * lod), voxelData[5], voxelData[6], 1, 0, 0);
            case 6: return Utils.GetInterpolatedEdgePosition(x + (1 * lod), y, z + (1 * lod), voxelData[7], voxelData[6], 0, 1, 0);
            case 7: return Utils.GetInterpolatedEdgePosition(x, y, z + (1 * lod), voxelData[4], voxelData[7], 1, 0, 0);

            case 8: return Utils.GetInterpolatedEdgePosition(x, y, z, voxelData[0], voxelData[4], 0, 0, 1);
            case 9: return Utils.GetInterpolatedEdgePosition(x, y + (1 * lod), z, voxelData[1], voxelData[5], 0, 0, 1);
            case 10: return Utils.GetInterpolatedEdgePosition(x + (1 * lod), y + (1 * lod), z, voxelData[2], voxelData[6], 0, 0, 1);
            case 11: return Utils.GetInterpolatedEdgePosition(x + (1 * lod), y, z, voxelData[3], voxelData[7], 0, 0, 1);

            default: throw new ArgumentOutOfRangeException(nameof(edge), "Invalid edge index: " + edge);
        }
    }

    private void ModifyTerrain(Vector3Int vertex, bool addTerrain, GameObject chunk)
    {
        for (int zOffset = -brushSize; zOffset <= brushSize; zOffset++)
        {
            for (int yOffset = -brushSize; yOffset <= brushSize; yOffset++)
            {
                for (int xOffset = -brushSize; xOffset <= brushSize; xOffset++)
                {
                    bool xOutOfRange = vertex.x + xOffset < 0 || vertex.x + xOffset > chunkDimensions.x - 1;
                    bool yOutOfRange = vertex.y + yOffset < 0 || vertex.y + yOffset > chunkDimensions.y - 1;
                    bool zOutOfRange = vertex.z + zOffset < 0 || vertex.z + zOffset > chunkDimensions.z - 1;

                    if (xOutOfRange || yOutOfRange || zOutOfRange)
                    {
                        continue;
                    }

                    float[] voxel = voxelGrid[Utils.VoxelIndex(vertex.x + xOffset, vertex.y + yOffset, vertex.z + zOffset)];

                    for (int i = 0; i < 8; i++)
                    {
                        int x = vertex.x + xOffset + cornerOffsets[i].x;
                        int y = vertex.y + yOffset + cornerOffsets[i].y;
                        int z = vertex.z + zOffset + cornerOffsets[i].z;

                        float dist = Vector3.Distance(vertex, new Vector3(x, y, z));

                        if (dist < brushSize)
                        {
                            voxel[i] = addTerrain ? voxel[i] + brushStrength : voxel[i] - brushStrength;
                        }
                    }
                }
            }
        }

        chunk.GetComponent<MeshFilter>().mesh = ChunkMesh(new Vector2Int((int)chunk.transform.position.x, (int)chunk.transform.position.z));

    }

    public void CreateVoxelGrid()
    {
        voxelGrid = new float[(chunkDimensions.x * chunkDimensions.y * chunkDimensions.z / (lod * lod * lod))][];

        for (int z = 0, i2D = 0, i3D = 0; z < chunkDimensions.z; z+=lod)
        {
            for (int x = 0; x < chunkDimensions.x; x+=lod, i2D += 8)
            {
                for (int y = 0; y < chunkDimensions.y; y+=lod, i3D+=8)
                {
                    CreateVoxel(new Vector3Int(x, y, z), i2D, i3D);
                }
            }
        }
    }

    public void CreateVoxel(Vector3Int pos, int noise2DIndex, int noise3DIndex)
    {
        Vector3Int index3D = pos / lod;

        if(Utils.VoxelIndex(index3D) - 1 > voxelGrid.Length - 1)
        {
            Debug.Log(Utils.VoxelIndex(index3D));
            Debug.Log(voxelGrid.Length);
        }

        voxelGrid[Utils.VoxelIndex(index3D) - 1] = new float[8];

        for (int i = 0; i < 8; i++)
        {
            Vector3Int cornerPos = pos + cornerOffsets[i];
            voxelGrid[Utils.VoxelIndex(index3D) - 1][i] = -cornerPos.y; //+ noiseMap2D[noise2DIndex + i] * heightMultiplier; //* density + noiseMap3D[noise3DIndex + i];
        }
    }
}