FileSliceAndAssemble

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;

//Problem 5.    Slicing File
//Write a program that takes any file and slices it to n parts. Write the following methods:
//•   Slice(string sourceFile, string destinationDirectory, int parts) - slices the given source file into n parts and saves them in destinationDirectory
//•   Assemble(List<string> files, string destinationDirectory) - combines all files into one, in the order they are passed, and saves the result in destinationDirectory.
namespace SplitFile
{
    class SplitInFiles
    {
        static void Assemble(List<string> files, string destinationDir)
        {
             int bufferSize = 4096 * 2;

             string extension = Path.GetExtension(files[0]);

             FileStream outputStream = new FileStream(string.Format("{0}assembled{1}", destinationDir, extension), FileMode.Append);
           using (outputStream)
           {
               int index = 0;
               byte[] buffer = new byte[bufferSize];
               while (index < files.Count)
               {
                   using(var inputStreams = new FileStream (files[index], FileMode.Open))
                   {
                       while (true)
                       {
                           int bytes = inputStreams.Read(buffer, 0, buffer.Length);
                           if (bytes == 0)
                           {
                               break;
                           }
                           outputStream.Write(buffer, 0, bytes);
                       }
                   }
                   index++;
               }
           }


        }
        static void Slice(string sourceFile, string destinationDir, int parts)
        {
            FileStream inputStream = new FileStream(sourceFile, FileMode.Open);
            using (inputStream)
            {
                string extension = Path.GetExtension(sourceFile);
                int bufferSize = 4096 * 2;
                byte[] buffer = new byte[bufferSize];
                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))
                    {
                        long bytesRead = 0;

                        while (bytesRead < partSize)
                        {

                            int bytes = inputStream.Read(buffer, 0, buffer.Length);
                            if (bytes == 0)
                            {
                                break;
                            }
                            outputStream.Write(buffer, 0, bytes);
                            bytesRead += bytes;
                        }
                    }
                    index++;
                }
            }

        }

        static void Main()
        {
            var file = new List<string>() { @"../../Result/part1..mp4", @"../../Result/part2..mp4", @"../../Result/part3..mp4", @"../../Result/part4..mp4" };

            string sourceFile = @"../../Video.mp4";
            string resultDirectory = @"../../Result/";
            //Slice(sourceFile, resultDirectory, 4);
            Assemble(file, resultDirectory);
        }
    }
}