using System.Diagnostics;
using System.Numerics;
using System.Runtime.InteropServices;
using Raylib_cs;


public class RenderDevice
{
    public int width { get; private set; }
    public int height { get; private set; }
    
    private int screenWidth, screenHeight;
    
    private Texture2D renderTarget;
    private IntPtr pixelPtr;
    private byte[] pixelData;

    private int frame = 1;
    public RenderDevice(int width, int height, int screenWidth, int screenHeight)
    {
        this.width = width;
        this.height = height;
        this.screenWidth = screenWidth;
        this.screenHeight = screenHeight;
        
        Image image = Raylib.GenImageColor(width, height, Color.Black);
        renderTarget = Raylib.LoadTextureFromImage(image);
        Raylib.UnloadImage(image); 
        
        pixelData = new byte[width * height * 4];
        pixelPtr = Marshal.AllocHGlobal(pixelData.Length);

    }

    public void render()
    {
        Marshal.Copy(pixelData, 0, pixelPtr, pixelData.Length);
        unsafe
        {
            Raylib.UpdateTexture(renderTarget, (void*)pixelPtr);
        }
        
        Raylib.DrawTexturePro(renderTarget, new Rectangle(0,0, width, height), new Rectangle(0, 0, screenWidth, screenHeight), Vector2.Zero, 0f, Color.White);

        frame++;
    }
    
    public void SetPixel(int x, int y, float3 color)
    {
        if (x < 0 || x >= width || y < 0 || y >= height) return;
        int idx = (y * width + x) * 4;
        pixelData[idx] = (byte)(Math.Clamp(color.r * 255, 0, 255));
        pixelData[idx + 1] = (byte)(Math.Clamp(color.g * 255, 0, 255));
        pixelData[idx + 2] = (byte)(Math.Clamp(color.b * 255, 0, 255));
        pixelData[idx + 3] = 0xFF;
    }

    public void Clear()
    {
        for (int i = 0; i < pixelData.Length; i++) pixelData[i] = 0;
    }
    
    public void DrawTriangle(float2 v0, float2 v1, float2 v2, IPixelShader pixelShader)
    {
        v0 = MathHelpers.NDCToScreen(v0, width, height);
        v1 = MathHelpers.NDCToScreen(v1, width, height);
        v2 = MathHelpers.NDCToScreen(v2, width, height);
        
        Debug.WriteLine(v0.x);
        
        int minX = (int)MathF.Floor(MathF.Min(v0.x, MathF.Min(v1.x, v2.x)));
        int maxX = (int)MathF.Ceiling(MathF.Max(v0.x, MathF.Max(v1.x, v2.x)));
        int minY = (int)MathF.Floor(MathF.Min(v0.y, MathF.Min(v1.y, v2.y)));
        int maxY = (int)MathF.Ceiling(MathF.Max(v0.y, MathF.Max(v1.y, v2.y)));
        
        float area = MathHelpers.Edge(v0, v1, v2);
        if (area == 0f) return; // Degenerate

        for (int y = minY; y <= maxY; y++)
        {
            for (int x = minX; x <= maxX; x++)
            {
                float2 p = new float2(x + 0.5f, y + 0.5f);
                
                float w0 = MathHelpers.Edge(v1, v2, p);
                float w1 = MathHelpers.Edge(v2, v0, p);
                float w2 = MathHelpers.Edge(v0, v1, p);

                
                
                if (w0 <= 0 && w1 <= 0 && w2 <= 0)
                {
                                    
                    w0 /= area;
                    w1 /= area;
                    w2 /= area;
                    float3 bary = new float3(w0, w1, w2);

                    // Inside triangle
                    SetPixel(x, y, pixelShader.GetColor(bary, x, y, frame)); 
                }
            }
        }

    }

    public void cleanup()
    {
        Raylib.UnloadTexture(renderTarget);
        Marshal.FreeHGlobal(pixelPtr); // always free after upload
    }
}