using OpenMacroBoard.SDK.Internals;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.PixelFormats;
using SixLabors.ImageSharp.Processing;
using System;

namespace OpenMacroBoard.SDK
{
    /// <summary>
    /// Extension method to generate fullscreen images on <see cref="IMacroBoard"/>s.
    /// </summary>
    public static class DrawFullScreenExtensions
    {
        /// <summary>
        /// Draw a given image as fullscreen (spanning over all keys)
        /// </summary>
        /// <param name="board">The board the image should be drawn to.</param>
        /// <param name="image">The image that should be drawn.</param>
        /// <param name="resizeMode">The resize mode that should be used to fit the image.</param>
        /// <exception cref="ArgumentNullException">The provided board or bitmap is null.</exception>
        public static void DrawFullScreenBitmap
        (
            this IMacroBoard board,
            Image image,
            ResizeMode resizeMode = ResizeMode.BoxPad
        )
        {
            if (board is null)
            {
                throw new ArgumentNullException(nameof(board));
            }

            if (image is null)
            {
                throw new ArgumentNullException(nameof(image));
            }

            byte[] imgData = null;

            using (var ctx = ResizeToFullStreamDeckImage(image, board.Keys.Area.Size, resizeMode))
            {
                imgData = ctx.Item.ToBgr24PixelArray();
            }

            for (var i = 0; i < board.Keys.Count; i++)
            {
                var img = GetKeyImageFromFull(board.Keys[i], imgData, board.Keys.Area.Size);
                board.SetButtonImage(i, img);
            }
        }

        private static ConditionalDisposable<Image<Bgr24>> ResizeToFullStreamDeckImage
        (
            Image image,
            OmbSize newSize,
            ResizeMode resizeMode
        )
        {
            return ConstrainedContext.For(
                image,
                x =>
                {
                    if (x is not Image<Bgr24> bgr24)
                    {
                        return null;
                    }

                    if (x.Width != newSize.Width || x.Height != newSize.Height)
                    {
                        return null;
                    }

                    return bgr24;
                },
                _ =>
                {
                    var scaled = new Image<Bgr24>(image.Width, image.Height);

                    var resizeOptions = new ResizeOptions()
                    {
                        Mode = resizeMode,
                        Size = new(newSize.Width, newSize.Height),
                        Sampler = KnownResamplers.Welch,
                    };

                    scaled.Mutate(x =>
                    {
                        x.DrawImage(image, 1);
                        x.Resize(resizeOptions);
                    });

                    return scaled;
                }
            );
        }

        private static KeyBitmap GetKeyImageFromFull
        (
            OmbRectangle keyPos,
            byte[] fullImageData,
            OmbSize fullImageSize
        )
        {
            var keyImgData = new byte[keyPos.Width * keyPos.Height * 3];
            var stride = 3 * fullImageSize.Width;

            for (var y = 0; y < keyPos.Height; y++)
            {
                for (var x = 0; x < keyPos.Width; x++)
                {
                    var p = (keyPos.Top + y) * stride + (keyPos.Left + x) * 3;
                    var kPos = (y * keyPos.Width + x) * 3;

                    keyImgData[kPos + 0] = fullImageData[p + 0];
                    keyImgData[kPos + 1] = fullImageData[p + 1];
                    keyImgData[kPos + 2] = fullImageData[p + 2];
                }
            }

            return KeyBitmap.Create.FromBgr24Array(keyPos.Width, keyPos.Height, keyImgData);
        }
    }
}