Randomize File Lines 100%

    Private Shared ReadOnly Rnd As New Random(Now.Millisecond)

    Public Shared Sub RandomizeLines(targetFile As String, Optional randomizeRate As Integer = 10, Optional keepFile As Boolean = False)
        randomizeRate = Math.Max(randomizeRate, 2)

        Dim currPath As String = Path.GetDirectoryName(targetFile)
        Dim currFile As String = Path.Combine(currPath, Path.GetFileNameWithoutExtension(targetFile) & " (Randomized)" & Path.GetExtension(targetFile))
        Dim currWriter As String

        Dim writers() As StreamWriter = {}
        Array.Resize(writers, randomizeRate)
        For i As Integer = 0 To randomizeRate - 1
            writers(i) = New StreamWriter(Path.Combine(currPath, "temp" & i.ToString & ".txt")) 'With {.AutoFlush = True}
        Next

        Dim o As Integer
        Dim lastIndex As Integer
        Using fs As FileStream = File.OpenRead(targetFile)
            Using sr As New StreamReader(fs)
                While Not sr.EndOfStream
                    o = Rnd.Next(randomizeRate)
                    While o = lastIndex
                        o = Rnd.Next(randomizeRate)
                        If o = lastIndex Then
                            o = Math.Min(o + 1, randomizeRate - 1)
                        End If
                    End While
                    lastIndex = o

                    writers(o).WriteLine(sr.ReadLine())
                End While
            End Using
        End Using

        Using sw As New StreamWriter(currFile) 'With {.AutoFlush = True}
            For i As Integer = 0 To randomizeRate - 1
                writers(i).Dispose()
                currWriter = Path.Combine(currPath, "temp" & i.ToString & ".txt")
                Using reader As New StreamReader(currWriter)
                    While Not reader.EndOfStream
                        sw.WriteLine(reader.ReadLine)
                    End While
                End Using
                File.Delete(currWriter)
            Next
        End Using

        If keepFile Then
            Try
                File.Delete(targetFile)
                Rename(currFile, targetFile)
            Catch ex As Exception

            End Try
        End If
    End Sub