using Godot;
using System;
using System.Linq;
using System.Diagnostics;
using Godot.Collections;
using Array = Godot.Collections.Array;
using Vector2 = Godot.Vector2;
using Vector3 = Godot.Vector3;

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

    // constants
    private static readonly Color RockColor = new Color (0.5f, 0.5f, 0.4f, 1f);
    private static readonly Color GrassColor = new Color (0, 0.4f, 0, 1f);
    
    private GenerationState _currentGenerationState = GenerationState.Heightmap;

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

    // public members
    [Export] public int Size = 64;
    public float HeightScale = 2.0f;
    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;
    private Array<Spatial> _rockAssets = new Array<Spatial>();
    private Array<Spatial> _grassAssets = new Array<Spatial>();
    private Spatial _environmentNode;

    // 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));

        GetNode<Spatial>("Assets").Visible = false;
        
        foreach (Spatial asset in GetNode<Node>("Assets/Rocks").GetChildren())
        {
            _rockAssets.Add(asset);
        }

        foreach (Spatial asset in GetNode<Node>("Assets/Grass").GetChildren())
        {
            _grassAssets.Add(asset);
        }

        
        _environmentNode = GetNode<Spatial>("Environment");
        
        Generate(Size);
    }


    public void Generate(int size)
    {
        GD.Print("Triggering generation for size: " + size);
        Size = size;
        _worldOffscreenViewport.Size = new Vector2(size, size);
        _heightmapOffscreenViewport.Size = new Vector2(size, size);

        OnMapGenerationStart();
        
        GenerateNoiseMap();
//        GenerateDebugMap();

        OnHeightMapChanged();
    }

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

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

        Heightmap.Lock();
        Colormap.Lock();
       
        foreach (int coord_x in Enumerable.Range(0, Size))
        {
            foreach (int coord_y in Enumerable.Range(0, Size))
            {
                Colormap.SetPixel(coord_x, coord_y, new Color((float) Mathf.Min(coord_x, coord_y) / Size, (float) 0, 0, 1));
                Heightmap.SetPixel(coord_x, coord_y, new Color((float) Mathf.Min(coord_x, coord_y) / Size, (float) 0, 0, 1));
            }
        }
        
        Colormap.SetPixel(Size - 1, Size -1, new Color(1, 1, 1, 1));
        Colormap.Unlock();
        
        OnMapGenerationComplete();
    }

    
    private void GenerateNoiseMap()
    {
        Heightmap = new Image();
        Heightmap.Create(Size, 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.GetSeamlessImage((int) Size));
        heightmapTexture.Flags = 0;
        _heightmapOffscreenTextureRect.Texture = heightmapTexture;
        Heightmap.CopyFrom(_heightmapOffscreenViewport.GetTexture().GetData());
        
        OnHeightMapChanged();
    }

    private void OnMapGenerationStart()
    {
        foreach (Node child in _environmentNode.GetChildren())
        {
            child.QueueFree();
        }
    }
    
    private void OnHeightMapChanged()
    {
        _currentGenerationState = GenerationState.Heightmap;
    }

    private void OnMapGenerationComplete()
    {
        _currentGenerationState = GenerationState.Done;
        EmitSignal("WorldGenerated");
    }

    Spatial SelectAsset(Vector2 offsetCoord, Array<Spatial> assets, Random randomGenerator, double probability)
    {
        if (randomGenerator.NextDouble() < 1.0 - probability)
        {
            return null;
        }
        
        int assetIndex = randomGenerator.Next(assets.Count);
        Spatial assetInstance = (Spatial) assets[assetIndex].Duplicate();
        Transform assetTransform = Transform.Identity;
        assetTransform.origin = GetTileWorldCenterFromOffset(offsetCoord);
        assetTransform.origin.y += 1.2f;
        assetTransform.basis = assetTransform.basis.Rotated(Vector3.Up, (float)(randomGenerator.NextDouble() * Mathf.Pi * 2));
        assetInstance.Transform = assetTransform;

        return assetInstance;
    }

    bool IsColorEqualApprox(Color colorA, Color colorB)
    {
        Vector3 colorDifference = new Vector3(colorA.r - colorB.r, colorA.g - colorB.g, colorA.b - colorB.b);
        return colorDifference.LengthSquared() < 0.1 * 0.1;
    }
    
    private void PopulateEnvironment()
    {
        Random environmentRandom = new Random(Seed);
        
        Colormap.Lock();
        foreach (int coord_x in Enumerable.Range(0, Size))
        {
            foreach (int coord_y in Enumerable.Range(0, Size))
            {
                Vector2 offsetCoord = new Vector2(coord_x, coord_y);
                Color colorValue = Colormap.GetPixel(coord_x, coord_y);

                if (IsColorEqualApprox(colorValue, RockColor))
                {
                    Spatial rockAsset = SelectAsset(offsetCoord, _rockAssets, environmentRandom, 0.15);
                    if (rockAsset != null)
                    {
                        _environmentNode.AddChild(rockAsset);
                    }
                } else if (IsColorEqualApprox(colorValue, GrassColor))
                {
                    Spatial grassAsset = SelectAsset(offsetCoord, _grassAssets, environmentRandom, 0.35);
                    if (grassAsset != null)
                    {
                        _environmentNode.AddChild(grassAsset);
                    } 
                }
            }
        }
        Colormap.Unlock();
    }

    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(Size, Size, false, Image.Format.Rgb8);
            Colormap.CopyFrom(_worldOffscreenViewport.GetTexture().GetData());
            Heightmap.Lock();

            _currentGenerationState = GenerationState.Objects;
            
            PopulateEnvironment();

            OnMapGenerationComplete();
        }
        
    }

    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))) % (Vector2.One * Size);
        Vector2 mapSize = Vector2.One * Size;
        Vector2 textureCoord = (offsetCoord + mapSize / 2).PosMod(mapSize);
        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);

        float heightmapHeight = Heightmap.GetPixel((int)textureCoord.x, (int)(textureCoord.y)).r;

        if (heightmapHeight > 0.5)
        {
            heightmapHeight = 0.6f;
        }
//        heightmapHeight = Mathf.Floor(heightmapHeight);
//        heightmapHeight = heightmapHeight * 10)
//        heightmapHeight = Mathf.Clamp(heightmapHeight, -1f, 5);

        return heightmapHeight * 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);

        // TODO: coordinates do not match for bigger maps
        return new Vector3(
            tileCenter.x - Size * 0.75f * 0.5f,
            GetHeightAtOffset(offsetCoord),
            tileCenter.y + (Mathf.Sqrt(3) / 2) * Size * 0.5f);
    }
}