05. Slicing File

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

internal class SlicingFile
{
    private static List<string> files = new List<string>();
    private static MatchCollection matches;
    private static void Main()
    {
        string inputFile = @"../../Rex.avi";
        string folderPath = @"../../";
        int NumberOfParts = 4;

        Slice(inputFile, folderPath, NumberOfParts);

        Assemble(files, folderPath);
    }

    private static void Assemble(List<string> files, string destinationDirectory)
    {
        // creating the file path for the reconstructed file
        string fileOutputPath = destinationDirectory + "assembled" + "." + matches[0].Groups[2];
        var fsSource = new FileStream(fileOutputPath, FileMode.Create);

        fsSource.Close();
        using (fsSource = new FileStream(fileOutputPath, FileMode.Append))
        {
            // reading the file paths of the parts from the files list
            foreach (var filePart in files)
            {
                using (var partSource = new FileStream(filePart, FileMode.Open))
                {
                    // Create a byte array of the content of the current file
                    Byte[] bytePart = new byte[partSource.Length];
                    int readBytes = partSource.Read(bytePart, 0, bytePart.Length);
                    // Write the bytes to the reconstructed file
                    fsSource.Write(bytePart, 0, readBytes);
                }
            }
        }
    }

    private static void Slice(string sourceFile, string destinationDirectory, int parts)
    {
        using (var source = new FileStream(sourceFile, FileMode.Open))
        {
            long partSize = (long) Math.Ceiling((double) source.Length/parts);

            // The offset at which to start reading from the source file
            long fileOffset = 0;
;
            string currPartPath;
            FileStream fsPart;
            long sizeRemaining = source.Length;

            // extracting name and extension of the input file
            string pattern = @"(\w+)(?=\.)\.(?<=\.)(\w+)";
            Regex pairs = new Regex(pattern);
            matches = pairs.Matches(sourceFile);
            for (int i = 0; i < parts; i++)
            {
                currPartPath = destinationDirectory + matches[0].Groups[1] + String.Format(@"-{0}", i) + "." + matches[0].Groups[2];
                files.Add(currPartPath);

                // reading one part size
                using (fsPart = new FileStream(currPartPath, FileMode.Create))
                {
                    byte[] buffer = new byte[partSize];

                    int readBytes = source.Read(buffer, 0, buffer.Length);

                    // creating one part size file
                    fsPart.Write(buffer, 0, readBytes);
                }

                // calculating the remaining file size which iis still too be read
                sizeRemaining = (int) source.Length - (i*partSize);
                if (sizeRemaining < partSize)
                {
                    partSize = sizeRemaining;
                }
                fileOffset += partSize;
            }
        }
    }

    public static Microsoft.Win32.SafeHandles.SafeFileHandle ImagePath { get; set; }
}