// See https://aka.ms/new-console-template for more information

using System.Text;
using System.Text.Encodings;

namespace Ray
{
    struct Vec3
    {
        double x, y, z;
    }

    readonly struct Color
    {
        public readonly byte r, g, b;
        
        public Color(byte r, byte g, byte b)
        {
            this.r = r;
            this.g = g;
            this.b = b;
        }
    }

    class BitmapImage
    {
        public readonly UInt16 width, height;
        private Color[,] pixels;


        public BitmapImage(UInt16 width, UInt16 height)
        {
            this.width = width;
            this.height = height;
            this.pixels = new Color[width,height]; 
        }

        public void setPixel(in UInt16 x, in UInt16 y, in Color c)
        {
            this.pixels[x,y] = c;
        }

        public void writeImage(in string path)
        {
            //Rows in BMP images must be divisibly by 4... for some reason.
            int padding = (4 - (width * 3) % 4) % 4;
            //8 bit color depth + 26 bytes for header and BITMAPCORE header
            Int32 bfSize = (width * height * 3) + (padding * this.height) + 26;
            
            using (FileStream fs = new FileStream(path, FileMode.Create))
            using (BinaryWriter bw = new BinaryWriter(fs))
            {
                //File header
                bw.Write('B');
                bw.Write('M');
                bw.Write(bfSize);
                bw.Write((Int32)0); //bfReserved 1 and 2
                bw.Write((Int32)26);
                //DIB header (Bitmap core)
                bw.Write((Int32)12);
                bw.Write(this.width);
                bw.Write(this.height);
                bw.Write((Int16)1);
                bw.Write((Int16)24);

                for (ushort i = 0; i < this.width; i++)
                {
                    for (ushort j = 0; j < this.height; j++)
                    {
                        bw.Write(this.pixels[i, j].b);
                        bw.Write(this.pixels[i, j].g);
                        bw.Write(this.pixels[i, j].r);
                    }
                    for (ushort j = 0; j < padding; j++) //end-of-row padding.
                    {
                        bw.Write((byte)0);
                    }
                }
            }
        }
    }
    class Raytracer
    {
        static void Main()
        {
            var BMP = new BitmapImage(255, 255);
            for (ushort i = 0; i < 255; i++)
            {
                for (ushort j = 0; j < 255; j++)
                {
                    BMP.setPixel(i, j, new Color((byte)i, 0, (byte)j));
                }
            }

            for (ushort i = 200; i < 255; i++)
            {
                for (ushort j = 200; j < 255; j++)
                {
                    BMP.setPixel(i, j, new Color(0, 255, 0));
                }
            }

            BMP.writeImage("C:/Users/Lizzy/test2.bmp");
        }
    }
};