using System;
using System.Linq;
using System.Windows;
using System.Windows.Media.Imaging;
using Catel.MVVM;

namespace ConvolutionWpf.Commands
{
    public class BlurCommand : Command
    {
        private readonly Func<WriteableBitmap> _imageFactory;

        public BlurCommand(Func<WriteableBitmap> imageFactory)
            : base(() => { })
        {
            _imageFactory = imageFactory;
        }

        public void ExecuteCommand()
        {
            var image = _imageFactory();
            if (image == null)
                return;

            var pixels = new byte[image.PixelHeight * image.BackBufferStride];
            image.CopyPixels(pixels, image.BackBufferStride, 0);

            var resultPixels = new byte[image.PixelHeight * image.BackBufferStride];

            double[] kernel = { 1.0 / 9.0, 1.0 / 9.0, 1.0 / 9.0, 1.0 / 9.0, 1.0 / 9.0, 1.0 / 9.0, 1.0 / 9.0, 1.0 / 9.0, 1.0 / 9.0 };

            var blurPixels = new byte[resultPixels.Length / kernel.Length];

            for (int i = 0; i < image.PixelWidth - 1; ++i)
            {
                for (int j = 0; j < image.PixelHeight - 1; ++j)
                {
                    int index = j * image.BackBufferStride + 4 * i;

                    for (int c = 0; c < 4; ++c)
                    {
                        resultPixels[index + c] = pixels[index + c];
                    }
                }
            }
            for (int i = 0; i < resultPixels.Length; i += 9)
            {
                double[] sum = new double[kernel.Length];
                for (int c = 0; c < kernel.Length; c++)
                {
                    sum[c] = resultPixels[i + c] * kernel[c];
                }
                var result = sum.Sum();
                var index = 0;
                for (; index < blurPixels.Length; index++)
                {
                    blurPixels[index] = (byte)result;
                }
            }

            image.WritePixels(new Int32Rect(0, 0, image.PixelWidth, image.PixelHeight), blurPixels, image.BackBufferStride, 0);
        }


        protected override void Execute(object parameter, bool ignoreCanExecuteCheck)
        {
            ExecuteCommand();
        }
    }
}