FileSplitAndJoin.cs

////////////////////////////////////////////////
// © https://github.com/badhitman - @fakegov 
////////////////////////////////////////////////

using System.Globalization;

namespace TextFileScannerLib;

/// <summary>
/// File split-and-join
/// </summary>
public class FileSplitAndJoin : AdapterFileWriter
{
    /// <summary>
    /// Из исходного файла создаёт новый(е) (не изменяя исходный) "нарезая" на указанные размеры файл(ы).
    /// </summary>
    public void SplitFile(string DestinationFolder, long size, int DimensionGroup = 1)
    {
        if (size < 1 || Length < size)
            return;

        int part_file = 0;
        long StartPosition = 0;
        long EndPosition = FileFilteredReadStream.Length;
        string tmpl_new_file_names = Path.GetFileName(FileFilteredReadStream.Name);
        while (StartPosition + size * DimensionGroup < EndPosition)
        {
            part_file++;
            CopyData(StartPosition, StartPosition + size * DimensionGroup, Path.Combine(DestinationFolder, tmpl_new_file_names + ".part_" + part_file.ToString(CultureInfo.CurrentCulture)));
            StartPosition += size * DimensionGroup;
        }

        if (StartPosition < EndPosition)
            CopyData(StartPosition, EndPosition, Path.Combine(DestinationFolder, tmpl_new_file_names + ".part_" + (part_file + 1).ToString(CultureInfo.CurrentCulture)));
    }

    /// <summary>
    /// Нарезка
    /// </summary>
    public void SplitFile(string DestinationFolder, int DimensionGroup = 1)
    {
        long[] entry_points = FindDataAll(0);
        if (entry_points.Length == 0 || (entry_points.Length == 1 && entry_points[0] == 0))
            return;

        if (DimensionGroup <= 0)
            DimensionGroup = 1;

        string tmpl_new_file_names = Path.GetFileName(FileFilteredReadStream.Name) + ".split.part_";

        if (entry_points[0] > 0)
            CopyData(0, entry_points[0], tmpl_new_file_names + "0");

        int operative_dimension_group = 0;
        int part_file = 1;

        long start_position_copy_data = -1;
        foreach (long point in entry_points)
        {
            if (operative_dimension_group <= 1)
            {
                start_position_copy_data = start_position_copy_data < 0 ? point : start_position_copy_data;
            }

            if (operative_dimension_group == DimensionGroup)
            {
                CopyData(start_position_copy_data, point, Path.Combine(DestinationFolder, tmpl_new_file_names + part_file.ToString(CultureInfo.CurrentCulture)));
                start_position_copy_data = point;

                operative_dimension_group = 0;
                part_file++;
            }

            operative_dimension_group++;
        }

        CopyData(start_position_copy_data, Length, Path.Combine(DestinationFolder, tmpl_new_file_names + part_file.ToString(CultureInfo.CurrentCulture)));
    }
}