CompressDecompressSplitAndAssemble

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Collections.Generic;
using System.IO.Compression;



namespace SplitFileGzip
{


    class SplitWithGzip
    {
        static void AssembleAndDecompress(List<string> files, string destinationDir, string extension)
        {
            int bufferSize = 4096 * 2;


            FileStream outputStream = new FileStream(string.Format("{0}assembled{1}", destinationDir, extension), FileMode.Append);
            using (outputStream)
            {
                int index = 0;
                while (index < files.Count)
                {
                    using (var inputStreams = new FileStream(files[index], FileMode.Open))
                    {
                        using (var decompressionStream = new GZipStream(inputStreams, CompressionMode.Decompress, false))
                        {
                            byte[] buffer = new byte[bufferSize];
                            while (true)
                            {
                                int bytes = decompressionStream.Read(buffer, 0, buffer.Length);
                                if (bytes == 0)
                                {
                                    break;
                                }
                                outputStream.Write(buffer, 0, bytes);
                            }
                        }
                    }
                    index++;
                }
            }
        }
        static void SliceAndCompress(string sourceFile, string destinationDir, int parts)
        {
            FileStream inputStream = new FileStream(sourceFile, FileMode.Open);
            using (inputStream)
            {
               int bufferSize = 4096 * 2;
                string extension = ".gz";
                int index = 1;
                long partSize = (long)Math.Ceiling((double)inputStream.Length / parts);
                while (inputStream.Position < inputStream.Length)
                {
                    using (var outputStream = new FileStream(string.Format("{0}part{1}{2}", destinationDir, index, extension), FileMode.Create))
                    {
                        using (var compressionStream = new GZipStream(outputStream, CompressionMode.Compress, false))
                        {
                            byte[] buffer = new byte[bufferSize];
                            long bytesRead = 0;
                            while (bytesRead < partSize)
                            {
                                int bytes = inputStream.Read(buffer, 0, buffer.Length);
                                if (bytes == 0)
                                {
                                    break;
                                }
                                compressionStream.Write(buffer, 0, bytes);
                                bytesRead += bytes;
                            }
                        }
                    }
                    index++;
                }
            }
        }

        static void Main()
        {
            string sourceFile = @"../../Video.mp4";
            string resultDirectory = @"../../Result/";
            string extension = Path.GetExtension(sourceFile);
            //Slice(sourceFile, resultDirectory, 3);
            List<string> compressedFiles = Directory.GetFiles(resultDirectory, "*.gz").ToList();
            AssembleAndDecompress(compressedFiles, resultDirectory, extension);

        }
    }
}