using Godot;
using System;
using System.Linq;
using System.Diagnostics;
using Godot.Collections;
using Namespace;
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);
    private static readonly Color GrassColor = new Color(0, 0.4f, 0);

    private GenerationState _currentGenerationState = GenerationState.Heightmap;

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

    // public members
    public enum MapType
    {
        Noise,
        Debug,
        Flat,
    }

    [ExportFlagsEnum(typeof(MapType))] public MapType GenerationMapType = MapType.Debug;

    [Export] public int Size = 64;
    [Export] public bool DebugMap;

    public float HeightScale = 1.0f;
    public Image HeightmapImage;
    public Image ColormapImage;
    public Image NavigationmapImage;
    public int Seed = 0;
    public Spatial Entities;
    public HexGrid HexGrid;

    // private members
    private int _halfSize;
    private Random _tileTypeRandom;
    private Viewport _worldOffscreenViewport;
    private TextureRect _worldOffscreenTextureRect;
    private Viewport _heightmapOffscreenViewport;
    private TextureRect _heightmapOffscreenTextureRect;
    private Array<Spatial> _rockAssets = new();
    private Array<Spatial> _grassAssets = new();
    private Array<Spatial> _treeAssets = new();
    private PackedScene _chestScene = GD.Load<PackedScene>("res://entities/Chest.tscn");
    private Spatial _environmentNode;
    private bool _resizeTriggered;
    private int _resizeExtraFrameCount = 0;

    // 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);
        }

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

        _chestScene = GD.Load<PackedScene>("res://entities/Chest.tscn");

        _environmentNode = GetNode<Spatial>("Environment");
        Entities = GetNode<Spatial>("Entities");

        ResetWorldImages(Size);
    }

    public void ResetWorldImages(int size)
    {
        GD.Print("Resetting World Images to size " + size);

        Vector2 sizeVector = new Vector2(size, size);

        ColormapImage = new Image();
        ColormapImage.Create(size, size, false, Image.Format.Rgba8);
        ColormapImage.FillRect(new Rect2(0, 0, size, size), Colors.Black);
        _worldOffscreenTextureRect.SetSize(sizeVector);
        _worldOffscreenViewport.Size = sizeVector;

        HeightmapImage = new Image();
        HeightmapImage.Create(size, size, false, Image.Format.Rf);
        HeightmapImage.FillRect(new Rect2(0, 0, size, size), Colors.ForestGreen);
        _heightmapOffscreenTextureRect.SetSize(sizeVector);
        _heightmapOffscreenViewport.Size = sizeVector;

        NavigationmapImage = new Image();
        NavigationmapImage.Create(size, size, false, Image.Format.Rgb8);
        NavigationmapImage.FillRect(new Rect2(0, 0, size, size), new Color(1, 1, 1));
    }


    public void Generate(int size)
    {
        GD.Print("Triggering generation for size: " + size);

        if (Size != size)
        {
            ResetWorldImages(size);
            _resizeTriggered = true;
            _resizeExtraFrameCount = 1;
        }

        Size = size;

        _worldOffscreenViewport.Size = new Vector2(size, size);
        _heightmapOffscreenViewport.Size = new Vector2(size, size);

        _halfSize = Mathf.RoundToInt(size) / 2;
        HexGrid.SetBounds(
            TextureCoordToCell(new Vector2(0, 0)),
            TextureCoordToCell(new Vector2(size, size))
        );

        HexGrid.Obstacles.Clear();
        HexGrid.Barriers.Clear();

        OnMapGenerationStart();

        switch (GenerationMapType)
        {
            case MapType.Debug:
                GenerateDebugMap();
                break;
            case MapType.Flat:
                GenerateFlatMap();
                break;
            case MapType.Noise:
                GenerateNoiseMap();
                break;
        }
    }

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

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

        HeightmapImage.Lock();
        ColormapImage.Lock();

        foreach (int coordX in Enumerable.Range(0, Size))
        {
            foreach (int coordY in Enumerable.Range(0, Size))
            {
                ColormapImage.SetPixel(coordX, coordY,
                    new Color((float)Mathf.Min(coordX, coordY) / Size, 0, 0));
                HeightmapImage.SetPixel(coordX, coordY,
                    new Color((float)Mathf.Min(coordX, coordY) / Size, 0, 0));
            }
        }

        // Colormap.SetPixel(Size - 1, Size - 1, new Color(1, 1, 1, 1));
        ColormapImage.Fill(Colors.ForestGreen);
        ColormapImage.Unlock();

        OnMapGenerationComplete();
    }


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

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

        HeightmapImage.Lock();
        ColormapImage.Lock();

        foreach (int coordX in Enumerable.Range(0, Size))
        {
            foreach (int coordY in Enumerable.Range(0, Size))
            {
                HeightmapImage.SetPixel(coordX, coordY,
                    new Color(0.5f, 0.5f, 0.5f));
            }
        }

        ColormapImage.Fill(Colors.ForestGreen);
        ColormapImage.Unlock();

        OnMapGenerationComplete();
    }


    private void GenerateNoiseMap()
    {
        HeightmapImage = new Image();
        HeightmapImage.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(Size));
        heightmapTexture.Flags = 0;
        _heightmapOffscreenTextureRect.Texture = heightmapTexture;

        OnHeightMapChanged();
    }

    private void OnMapGenerationStart()
    {
        foreach (Node child in _environmentNode.GetChildren())
        {
            child.QueueFree();
        }

        foreach (Node child in Entities.GetChildren())
        {
            child.QueueFree();
        }
    }

    private void OnHeightMapChanged()
    {
        GD.Print("Triggering rendering of height map");
        _currentGenerationState = GenerationState.Heightmap;
        _heightmapOffscreenViewport.RenderTargetUpdateMode = Viewport.UpdateMode.Once;
    }

    private void OnMapGenerationComplete()
    {
        _currentGenerationState = GenerationState.Done;
        _worldOffscreenViewport.RenderTargetUpdateMode = Viewport.UpdateMode.Disabled;
        _heightmapOffscreenViewport.RenderTargetUpdateMode = Viewport.UpdateMode.Disabled;
        _resizeTriggered = false;

        HeightmapImage.Lock();
        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 = GetHexCenterFromOffset(offsetCoord);
        assetTransform.origin.y = GetHeightAtOffset(offsetCoord);
        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;
    }

    bool IsColorWater(Color color)
    {
        return (color.r == 0 && color.g == 0 && color.b > 0.01);
    }

    public void MarkCellUnwalkable(HexCell cell)
    {
        HexGrid.AddObstacle(cell);
        NavigationmapImage.Lock();
        NavigationmapImage.SetPixelv(OffsetToTextureCoord(cell.OffsetCoords), Colors.Red);
        NavigationmapImage.Unlock();
    }
    
    private void PopulateEnvironment()
    {
        Random environmentRandom = new Random(Seed);

        ColormapImage.Lock();
        HeightmapImage.Lock();

        foreach (int textureCoordU in Enumerable.Range(0, Size))
        {
            foreach (int textureCoordV in Enumerable.Range(0, Size))
            {
                Color colorValue = ColormapImage.GetPixel(textureCoordU, textureCoordV);
                Vector2 textureCoord = new Vector2(textureCoordU, textureCoordV);
                HexCell cell = TextureCoordToCell(textureCoord);
                Vector2 offsetCoord = cell.OffsetCoords;

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

                    Spatial treeAsset = SelectAsset(offsetCoord, _treeAssets, environmentRandom, 0.10);
                    if (treeAsset != null)
                    {
                        Entities.AddChild(treeAsset);
                        MarkCellUnwalkable(cell);
                    }
                    else if (environmentRandom.NextDouble() < 0.01)
                    {
                        Chest chestAsset = (Chest)_chestScene.Instance();
                        Transform assetTransform = Transform.Identity;
                        assetTransform.origin = GetHexCenterFromOffset(offsetCoord);
                        assetTransform.origin.y = GetHeightAtOffset(offsetCoord);
                        chestAsset.Transform = assetTransform;
                        Entities.AddChild(chestAsset);
                        MarkCellUnwalkable(cell);
                    }
                }
                else if (IsColorWater(colorValue))
                {
                    MarkCellUnwalkable(cell);
                }
            }
        }

        HeightmapImage.Unlock();
        ColormapImage.Unlock();
    }

    public override void _Process(float delta)
    {
        if (_resizeTriggered && _resizeExtraFrameCount > 0)
        {
            _resizeExtraFrameCount--;
            return;
        }

        if (_currentGenerationState == GenerationState.Heightmap)
        {
            HeightmapImage.CopyFrom(_heightmapOffscreenViewport.GetTexture().GetData());

            _currentGenerationState = GenerationState.Color;
            ImageTexture imageTexture = new ImageTexture();
            imageTexture.CreateFromImage(HeightmapImage);
            imageTexture.Flags = 0;
            _worldOffscreenTextureRect.Texture = imageTexture;

            GD.Print("Triggering rendering of color map");

            _worldOffscreenViewport.RenderTargetUpdateMode = Viewport.UpdateMode.Once;
            _resizeExtraFrameCount = 1;
        }
        else if (_currentGenerationState == GenerationState.Color)
        {
            ColormapImage = new Image();
            ColormapImage.Create(Size, Size, false, Image.Format.Rgb8);
            ColormapImage.CopyFrom(_worldOffscreenViewport.GetTexture().GetData());

            _currentGenerationState = GenerationState.Objects;

            PopulateEnvironment();
        }
        else if (_currentGenerationState == GenerationState.Objects)
        {
            OnMapGenerationComplete();
        }
    }

    public bool IsOffsetCoordValid(Vector2 offsetCoord)
    {
        return ((int)Math.Clamp(offsetCoord.x, -(float)Size / 2, (float)Size / 2 - 1) == (int)offsetCoord.x
                && (int)Math.Clamp(offsetCoord.y, -(float)Size / 2, (float)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 mapSize = Vector2.One * Size;
        Vector2 textureCoord = (offsetCoord + mapSize / 2).PosMod(mapSize);
        return textureCoord;
    }

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

        HeightmapImage.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 = (HeightmapImage.GetPixel((int)textureCoord.x, (int)(textureCoord.y)).r - 0.5f) * HeightScale;

        if (heightmapHeight <= 0)
        {
            heightmapHeight -= 0.03f;
        }
        else
        {
            heightmapHeight = 0f;
        }

        return heightmapHeight;
    }


    public void SetTileColorAtOffset(Vector2 offsetCoord, Color color)
    {
        Vector2 textureCoord = OffsetToTextureCoord(offsetCoord);

        ColormapImage.Lock();
        ColormapImage.SetPixel((int)textureCoord.x, (int)textureCoord.y, color);
        ColormapImage.Unlock();
    }

    public Vector2 WorldToOffsetCoords(Vector3 worldCoord)
    {
        return HexGrid.GetHexAt(new Vector2(worldCoord.x, worldCoord.z)).OffsetCoords +
               Vector2.One * Mathf.Round(Size / 2f);
    }

    public Vector3 GetTileWorldCenterFromOffset(Vector2 offsetCoord)
    {
        Vector2 tileCenter = HexGrid.GetHexCenterFromOffset(offsetCoord - Vector2.One * Mathf.Round(Size / 2f));
        return new Vector3(tileCenter.x, GetHeightAtOffset(offsetCoord), tileCenter.y);
    }


    public Vector3 GetHexCenterFromOffset(Vector2 offsetCoord)
    {
        Vector2 tileCenter = HexGrid.GetHexCenterFromOffset(offsetCoord);
        return new Vector3(tileCenter.x, GetHeightAtOffset(offsetCoord), tileCenter.y);
    }

    public HexCell TextureCoordToCell(Vector2 textureCoord)
    {
        return HexCell.FromOffsetCoords(textureCoord - Vector2.One * _halfSize);
    }

    public Vector2 TextureCoordToOffsetCoord(Vector2 textureCoord)
    {
        return TextureCoordToCell(textureCoord).OffsetCoords;
    }
}