using Godot;
using System;
using System.Linq;
using System.Numerics;
using System.Diagnostics;
using GoDotLog;
using Vector2 = Godot.Vector2;
using Vector3 = Godot.Vector3;

public class TileWorld : Spatial
{
    private enum GenerationState
    {
        Heightmap,
        Color,
        Done
    }

    private GenerationState CurrentGenerationState = GenerationState.Heightmap;

    // signals
    [Signal]
    delegate void WorldGenerated();

    // public members
    public float Size = 100;
    public float HeightScale = 10.0f;
    public Image Heightmap;
    public Image Colormap;
    public int Seed = 0;

    // private members
    private HexGrid _hexGrid;
    private Random _tileTypeRandom;
    private Viewport _worldOffscreenViewport;
    private TextureRect _worldOffscreenTextureRect;
    private Viewport _heightmapOffscreenViewport;
    private TextureRect _heightmapOffscreenTextureRect;


    // Called when the node enters the scene tree for the first time.
    public override void _Ready()
    {
        _hexGrid = new HexGrid();
        _tileTypeRandom = new Random();

        _worldOffscreenViewport = (Viewport)GetNode("WorldOffscreenViewport");
        Debug.Assert(_worldOffscreenViewport != null);
        _worldOffscreenViewport.Size = new Vector2(Size, Size);
        _worldOffscreenTextureRect = (TextureRect)GetNode("WorldOffscreenViewport/TextureRect");
        Debug.Assert(_worldOffscreenTextureRect != null);
        _worldOffscreenTextureRect.SetSize(new Vector2(Size, Size));

        _heightmapOffscreenViewport = (Viewport)GetNode("HeightmapOffscreenViewport");
        Debug.Assert(_heightmapOffscreenViewport != null);
        _heightmapOffscreenViewport.Size = new Vector2(Size, Size);
        _heightmapOffscreenTextureRect = (TextureRect)GetNode("HeightmapOffscreenViewport/TextureRect");
        Debug.Assert(_heightmapOffscreenTextureRect != null);
        _heightmapOffscreenTextureRect.SetSize(new Vector2(Size, Size));

        Generate();
    }


    public void Generate()
    {
        GenerateNoiseMap();
        //GenerateDebugMap();
    }

    private void GenerateDebugMap()
    {
        Colormap = new Image();
        Colormap.Create((int)Size, (int)Size, false, Image.Format.Rgba8);

        Heightmap = new Image();
        Heightmap.Create((int)Size, (int)Size, false, Image.Format.Rf);

        Heightmap.Lock();
        Colormap.Lock();
        foreach (int coord_x in Enumerable.Range(0, (int)Size))
        {
            foreach (int coord_y in Enumerable.Range(0, (int)Size))
            {
//                Colormap.SetPixel(coord_x, coord_y, new Color((float) coord_x, (float) coord_y, 0, 1));
                float coord_to_height =
                    (float)coord_y / Size * 0f;

                if (coord_x == 1 && coord_y == 4)
                {
                    coord_to_height = 1;
                }

                SetHeightAtOffset(new Vector2(coord_x, coord_y), coord_to_height);
            }
        }

        Colormap.Unlock();

        ImageTexture imageTexture = new ImageTexture();
        imageTexture.CreateFromImage(Heightmap);
        imageTexture.Flags = 0;
        _worldOffscreenTextureRect.Texture = imageTexture;
        Colormap.CopyFrom(imageTexture.GetData());
    }

    private void GenerateSimpleMap()
    {
        Heightmap = new Image();
        Heightmap.Create((int)Size, (int)Size, false, Image.Format.Rf);
        Heightmap.Lock();

        foreach (int coord_x in Enumerable.Range(-(int)Size / 2, (int)Size))
        {
            foreach (int coord_y in Enumerable.Range(-(int)Size / 2, (int)Size))
            {
                SetHeightAtOffset(new Vector2(coord_x, coord_y), 5f);
            }
        }
    }


    private void GenerateNoiseMap()
    {
        Heightmap = new Image();
        Heightmap.Create((int)Size, (int)Size, false, Image.Format.Rgba8);

        OpenSimplexNoise noiseGenerator = new OpenSimplexNoise();

        noiseGenerator.Seed = Seed;
        noiseGenerator.Octaves = 4;
        noiseGenerator.Period = 20;
        noiseGenerator.Persistence = 0.2f;
        noiseGenerator.Lacunarity = 4;

        ImageTexture heightmapTexture = new ImageTexture();
        // heightmapTexture.CreateFromImage(noiseGenerator.GetImage((int)Size, (int)Size));
        heightmapTexture.CreateFromImage(noiseGenerator.GetSeamlessImage((int) Size));
        heightmapTexture.Flags = 0;
        _heightmapOffscreenTextureRect.Texture = heightmapTexture;
        Heightmap.CopyFrom(_heightmapOffscreenViewport.GetTexture().GetData());

        CurrentGenerationState = GenerationState.Heightmap;
    }


    public override void _Process(float delta)
    {
        if (CurrentGenerationState == GenerationState.Heightmap)
        {
            CurrentGenerationState = GenerationState.Color;
            ImageTexture imageTexture = new ImageTexture();
            imageTexture.CreateFromImage(Heightmap);
            imageTexture.Flags = 0;
            _worldOffscreenTextureRect.Texture = imageTexture;
        }
        else if (CurrentGenerationState == GenerationState.Color)
        {
            Colormap = new Image();
            Colormap.Create((int)Size, (int)Size, false, Image.Format.Rgba8);

            Colormap.CopyFrom(_worldOffscreenViewport.GetTexture().GetData());
            Heightmap.Lock();

            CurrentGenerationState = GenerationState.Done;

            EmitSignal("WorldGenerated");
        }
    }

    public void ApplyHeightmap(Image heightmap)
    {
        foreach (int coord_x in Enumerable.Range(-(int)Size / 2, (int)Size))
        {
            foreach (int coord_y in Enumerable.Range(-(int)Size / 2, (int)Size))
            {
                Vector2 textureCoord = OffsetToTextureCoord(new Vector2(coord_x, coord_y));
                float height = heightmap.GetPixel((int)textureCoord.x, (int)textureCoord.y).r;
                SetHeightAtOffset(new Vector2(coord_x, coord_y), height);
            }
        }
    }


    public bool IsOffsetCoordValid(Vector2 offsetCoord)
    {
        return ((int)Math.Clamp(offsetCoord.x, -Size / 2, Size / 2 - 1) == (int)offsetCoord.x
                && (int)Math.Clamp(offsetCoord.y, -Size / 2, Size / 2 - 1) == (int)offsetCoord.y);
    }


    public HexTile3D.TileType GetTileTypeAtOffset(Vector2 offsetCoord)
    {
        if (!IsOffsetCoordValid(offsetCoord))
        {
            return HexTile3D.TileType.Undefined;
        }

        return HexTile3D.ValidTileTypes[_tileTypeRandom.Next(HexTile3D.ValidTileTypes.Length)];
    }


    public Vector2 OffsetToTextureCoord(Vector2 offsetCoord)
    {
        Vector2 textureCoord = (offsetCoord - Vector2.One * (Mathf.Floor(Size / 2) + 1)) % (Vector2.One * Size);
        if (textureCoord[0] < 0)
        {
            textureCoord[0] += Size;
        }

        if (textureCoord[1] < 0)
        {
            textureCoord[1] += Size;
        }

        return textureCoord;
    }

    public void SetHeightAtOffset(Vector2 offsetCoord, float height)
    {
        Vector2 textureCoord = OffsetToTextureCoord(offsetCoord);

        Heightmap.SetPixel((int)textureCoord.x, (int)textureCoord.y, new Color(height, 0f, 0f));
    }

    public float GetHeightAtOffset(Vector2 offsetCoord)
    {
        if (CurrentGenerationState != GenerationState.Done)
        {
            return 0f;
        }
        
        Vector2 textureCoord = OffsetToTextureCoord(offsetCoord);

        return Heightmap.GetPixel((int)textureCoord.x, (int)(textureCoord.y)).r * HeightScale;
    }


    public Vector2 WorldToOffsetCoords(Vector3 worldCoord)
    {
        return _hexGrid.GetHexAt(new Vector2(worldCoord.x, worldCoord.z)).OffsetCoords;
    }


    public Vector3 GetTileWorldCenterFromOffset(Vector2 offsetCoord)
    {
        Vector2 tileCenter = _hexGrid.GetHexCenterFromOffset(offsetCoord);

        return new Vector3(
            tileCenter.x,
            GetHeightAtOffset(offsetCoord),
            tileCenter.y);
    }
}