using Godot;
using Godot.NativeInterop;
using System;
using System.Collections.Generic;

public partial class Chunk : MeshInstance3D
{
    ArrayMesh mesh;
    int[][][] voxels;
    public override void _Ready()
    {
        base._Ready();
        voxels = GenerateVoxels();
        GenerateMesh(voxels);
    }
    static int[][][] GenerateVoxels()
    {
        int[][][] array = new int[16][][];
        for (int x = 0; x < 16; x++)
        {
            array[x] = new int[16][];
            for (int y = 0; y < 16; y++)
            {
                array[x][y] = new int[16];
                for (int z = 0; z < 16; z++) array[x][y][z] = 1;
            }
        }
        return array;
    }
    public void GenerateMesh(int[][][] vxls)
    {
        Vector2[] tempUVs = [
            new(0,0),
            new(1,0),
            new(1,1),
            new(0,1)
        ];
        var faces = new List<Dictionary<string, Godot.Collections.Array>>();
        for (int x = 0; x < 16; x++)
        {
            for (int y = 0; y < 16; y++)
            {
                for (int z = 0; z < 16; z++)
                {
                    if (vxls[x][y][z] == 1)
                    {
                        Vector3 pos = new(x, y, z);
                        faces.Add(CreateFace(Vector3.Left, pos, tempUVs));
                        faces.Add(CreateFace(Vector3.Right, pos, tempUVs));
                        faces.Add(CreateFace(Vector3.Up, pos, tempUVs));
                        faces.Add(CreateFace(Vector3.Down, pos, tempUVs));
                        faces.Add(CreateFace(Vector3.Forward, pos, tempUVs));
                        faces.Add(CreateFace(Vector3.Back, pos, tempUVs));
                    }
                }
            }
        }
        var verts = new Godot.Collections.Array();
        var norms = new Godot.Collections.Array();
        var uvs = new Godot.Collections.Array();
        foreach (var face in faces)
        {
            verts.Add(face["verts"]);
            verts.Add(face["verts"]);
            uvs.Add(face["uvs"]);
        }
        var arrays = new Godot.Collections.Array();
        arrays.Resize((int)Mesh.ArrayType.Max);
        arrays[(int)Mesh.ArrayType.Vertex] = verts;
        arrays[(int)Mesh.ArrayType.Normal] = norms;
        arrays[(int)Mesh.ArrayType.TexUV] = uvs;
        mesh = new ArrayMesh();
        mesh.AddSurfaceFromArrays(Mesh.PrimitiveType.Triangles, arrays);
        Mesh = mesh;
    }
    public Dictionary<string, Godot.Collections.Array> CreateFace(Vector3 dir, Vector3 pos, Vector2[] uvs)
    {
        Vector3[] verts = new Vector3[4];
        Vector3[] norms = [dir, dir, dir, dir];
        if (dir == Vector3.Up)
            verts = [
                pos + new Vector3(-.5f, .5f, -.5f),
                pos + new Vector3(.5f, .5f, -.5f),
                pos + new Vector3(.5f, .5f, .5f),
                pos + new Vector3(-.5f, .5f, .5f)
            ];
        else if (dir == Vector3.Down)
            verts = [
                pos + new Vector3(-.5f, -.5f, .5f),
                pos + new Vector3(.5f, -.5f, .5f),
                pos + new Vector3(.5f, -.5f, -.5f),
                pos + new Vector3(-.5f, -.5f, -.5f)
            ];
        else if (dir == Vector3.Left)
            verts = [
                pos + new Vector3(-.5f, -.5f, -.5f),
                pos + new Vector3(-.5f, .5f, -.5f),
                pos + new Vector3(-.5f, .5f, .5f),
                pos + new Vector3(-.5f, -.5f, .5f)
            ];
        else if (dir == Vector3.Right)
            verts = [
                pos + new Vector3(.5f, -.5f, .5f),
                pos + new Vector3(.5f, .5f, .5f),
                pos + new Vector3(.5f, .5f, -.5f),
                pos + new Vector3(.5f, -.5f, -.5f)
            ];
        else if (dir == Vector3.Forward)
            verts = [
                pos + new Vector3(-.5f, -.5f, -.5f),
                pos + new Vector3(.5f, -.5f, -.5f),
                pos + new Vector3(.5f, .5f, -.5f),
                pos + new Vector3(-.5f, .5f, -.5f)
            ];
        else if (dir == Vector3.Back)
            verts = [
                pos + new Vector3(-.5f, .5f, .5f),
                pos + new Vector3(.5f, .5f, .5f),
                pos + new Vector3(.5f, -.5f, .5f),
                pos + new Vector3(-.5f, -.5f, .5f)
            ];
        return new Dictionary<string, Godot.Collections.Array>
        {
            ["verts"] = [
                verts[0], verts[1], verts[2],
                verts[0], verts[2], verts[3]
            ],
            ["norms"] = [
                norms[0], norms[1], norms[2],
                norms[0], norms[2], norms[3]
            ],
            ["uvs"] = [
                uvs[0], uvs[1], uvs[2],
                uvs[0], uvs[2], uvs[3]
            ]
        };
    }
}