//#define COSMOSDEBUG
using System;
using System.Collections.Generic;
using System.Drawing;

using Cosmos.HAL.Drivers;

namespace Cosmos.System.Graphics
{
    public class VBECanvas : Canvas
    {
        private static readonly Mode _DefaultMode = new Mode(1024, 768, ColorDepth.ColorDepth32);

        /// <summary>
        /// Driver for Setting vbe modes and ploting/getting pixels
        /// </summary>
        private readonly VBEDriver _VBEDriver;

        private Mode _Mode;

        public VBECanvas() : this(_DefaultMode)
        {
        }

        public VBECanvas(Mode aMode)
        {
            Global.mDebugger.SendInternal($"Creating new VBEScreen() with mode {aMode.Columns}x{aMode.Rows}x{(uint)aMode.ColorDepth}");

            ThrowIfModeIsNotValid(aMode);

            _VBEDriver = new VBEDriver((ushort)aMode.Columns, (ushort)aMode.Rows, (ushort)aMode.ColorDepth);
            Mode = aMode;
        }

        public override void Disable()
        {
            _VBEDriver.DisableDisplay();
        }

        public override Mode Mode
        {
            get => _Mode;
            set
            {
                _Mode = value;
                SetMode(_Mode);
            }
        }

        #region Display

        /// <summary>
        /// All the available screen modes VBE supports, I would like to query the hardware and obtain from it the list but I have
        /// not yet find how to do it! For now I hardcode the most used VESA modes, VBE seems to support until HDTV resolution
        /// without problems that is well... excellent :-)
        /// </summary>
        //public override IReadOnlyList<Mode> AvailableModes { get; } = new List<Mode>
        public override List<Mode> AvailableModes { get; } = new List<Mode>
        {
            new Mode(320, 240, ColorDepth.ColorDepth32),
            new Mode(640, 480, ColorDepth.ColorDepth32),
            new Mode(800, 600, ColorDepth.ColorDepth32),
            new Mode(1024, 768, ColorDepth.ColorDepth32),
            /* The so called HD-Ready resolution */
            new Mode(1280, 720, ColorDepth.ColorDepth32),
            new Mode(1280, 1024, ColorDepth.ColorDepth32),
            /* A lot of HD-Ready screen uses this instead of 1280x720 */
            new Mode(1366, 768, ColorDepth.ColorDepth32),
            new Mode(1680, 1050, ColorDepth.ColorDepth32),
            /* HDTV resolution */
            new Mode(1920, 1080, ColorDepth.ColorDepth32),
            /* HDTV resolution (16:10 AR) */
            new Mode(1920, 1200, ColorDepth.ColorDepth32),
        };

        public override Mode DefaultGraphicMode => _DefaultMode;

        /// <summary>
        /// Use this to setup the screen, this will disable the console.
        /// </summary>
        /// <param name="Mode">The desired Mode resolution</param>
        private void SetMode(Mode aMode)
        {
            ThrowIfModeIsNotValid(aMode);

            ushort xres = (ushort)Mode.Columns;
            ushort yres = (ushort)Mode.Rows;
            ushort bpp = (ushort)Mode.ColorDepth;

            //set the screen
            _VBEDriver.VBESet(xres, yres, bpp);
        }
        #endregion

        #region Drawing

        public override void Clear(Color aColor)
        {
            Global.mDebugger.SendInternal($"Clearing the Screen with Color {aColor}");
            //if (color == null)
            //   throw new ArgumentNullException(nameof(color));

            /*
             * TODO this version of Clear() works only when mode.ColorDepth == ColorDepth.ColorDepth32
             * in the other cases you should before convert color and then call the opportune ClearVRAM() overload
             * (the one that takes ushort for ColorDepth.ColorDepth16 and the one that takes byte for ColorDepth.ColorDepth8)
             * For ColorDepth.ColorDepth24 you should mask the Alpha byte.
             */
            switch (_Mode.ColorDepth)
            {
                case ColorDepth.ColorDepth4:
                    throw new NotImplementedException();
                case ColorDepth.ColorDepth8:
                    throw new NotImplementedException();
                case ColorDepth.ColorDepth16:
                    throw new NotImplementedException();
                case ColorDepth.ColorDepth24:
                    throw new NotImplementedException();
                case ColorDepth.ColorDepth32:
                    _VBEDriver.ClearVRAM((uint)aColor.ToArgb());
                    break;
                default:
                    throw new NotImplementedException();
            }
        }

        /*
         * As DrawPoint() is the basic block of DrawLine() and DrawRect() and in theory of all the future other methods that will
         * be implemented is better to not check the validity of the arguments here or it will repeat the check for any point
         * to be drawn slowing down all.
         */
        public override void DrawPoint(Pen aPen, int aX, int aY)
        {
            Color color = aPen.Color;
            uint offset;

            /*
             * For now we can Draw only if the ColorDepth is 32 bit, we will throw otherwise.
             *
             * How to support other ColorDepth? The offset calculation should be the same (and so could be done out of the switch)
             * ColorDepth.ColorDepth16 and ColorDepth.ColorDepth8 need a conversion from color (an ARGB32 color) to the RGB16 and RGB8
             * how to do this conversion faster maybe using pre-computed tables? What happens if the color cannot be converted? We will throw?
             */
            switch (Mode.ColorDepth)
            {
                case ColorDepth.ColorDepth32:
                    offset = (uint)GetPointOffset(aX, aY);

                    Global.mDebugger.SendInternal($"Drawing Point of color {color} at offset {offset}");

                    _VBEDriver.SetVRAM(offset, (uint)color.ToArgb());

                    Global.mDebugger.SendInternal("Point drawn");
                    break;
                case ColorDepth.ColorDepth24:

                    offset = (uint)GetPointOffset(aX, aY);
                    Global.mDebugger.SendInternal($"Drawing Point of color {color} at offset {offset}");
                    _VBEDriver.SetVRAM(offset, color.B);
                    _VBEDriver.SetVRAM(offset + 1, color.G);
                    _VBEDriver.SetVRAM(offset + 2, color.R);

                    Global.mDebugger.SendInternal("Point drawn");
                    break;
                default:
                    string errorMsg = "DrawPoint() with ColorDepth " + (int)Mode.ColorDepth + " not yet supported";
                    throw new NotImplementedException(errorMsg);
            }
        }

        public override void DrawPoint(Pen aPen, float aX, float aY)
        {
            throw new NotImplementedException();
        }

        /* This is just temp */
        public override void DrawArray(Color[] aColors, int aX, int aY, int aWidth, int aHeight)
        {
            ThrowIfCoordNotValid(aX, aY);

            ThrowIfCoordNotValid(aX + aWidth, aY + aHeight);

            for (int i = 0; i < aX; i++)
            {

                for (int ii = 0; ii < aY; ii++)
                {

                    DrawPoint(new Pen(aColors[i + (ii * aWidth)]), i, ii);

                }
            }
        }

        private int GetPointOffset(int aX, int aY)
        {
            Global.mDebugger.SendInternal($"Computing offset for coordinates {aX},{aY}");
            int xBytePerPixel = (int)Mode.ColorDepth / 8;
            int stride = (int)Mode.ColorDepth / 8;
            int pitch = Mode.Columns * xBytePerPixel;

            return (aX * stride) + (aY * pitch);
        }

        public override void DrawFilledRectangle(Pen aPen, int aX, int aY, int aWidth, int aHeight)
        {
            int xOffset = GetPointOffset(aX, aY);
            int xScreenWidthInPixel = Mode.Columns * ((int)Mode.ColorDepth / 8);

            for (int i = 0; i < aHeight; i++)
            {
                _VBEDriver.ClearVRAM((i * xScreenWidthInPixel) + xOffset, aWidth, aPen.Color.ToArgb());
            }
        }

        public override void DrawImage(Image aImage, int aX, int aY)
        {
            var xBitmap = aImage.rawData;
            var xWidht = (int)aImage.Width;
            var xHeight = (int)aImage.Height;

            int xOffset = GetPointOffset(aX, aY);
            int xScreenWidthInPixel = Mode.Columns * ((int)Mode.ColorDepth / 8);

            Global.mDebugger.SendInternal($"Drawing image of size {aImage.Width}x{aImage.Height} array size {aImage.rawData.Length}");
            for (int i = 0; i < xHeight; i++)
            {
                _VBEDriver.CopyVRAM((i * xScreenWidthInPixel) + xOffset, xBitmap, (i * xWidht), xWidht);
            }
            Global.mDebugger.SendInternal("Done");
        }

        #endregion

        #region Reading

        public override Color GetPointColor(int aX, int aY)
        {
            uint pitch;
            uint stride;
            uint offset;
            uint ColorDepthInBytes = (uint)Mode.ColorDepth / 8;

            Global.mDebugger.SendInternal("Computing offset...");
            pitch = (uint)Mode.Columns * ColorDepthInBytes;
            stride = ColorDepthInBytes;
            //offset = ((uint)x * pitch) + ((uint)y * stride);
            offset = ((uint)aX * stride) + ((uint)aY * pitch);

            Global.mDebugger.SendInternal($"Getting color from point at offset {offset}");
            return Color.FromArgb(_VBEDriver.GetVRAM(offset));
        }

        #endregion

    }
}