[ZUGFeRD] fix versioning of files

Filesystem/File.vb

@@ -31,6 +31,76 @@ Public Class File
         _logger = LogConfig.GetLogger()
     End Sub
 
+    ''' <summary>
+    ''' Adds fileversions to given filename `Destination` if that file already exists.
+    ''' </summary>
+    ''' <param name="Destination"></param>
+    ''' <returns></returns>
+    Public Function GetVersionedFilename(Destination As String) As String
+        Try
+            Dim oFileName As String = Destination
+            Dim oFinalFileName = oFileName
+
+            Dim oDestinationDir = Path.GetDirectoryName(oFileName)
+            Dim oExtension = Path.GetExtension(oFileName)
+
+            Dim oVersionSeparator As Char = "~"c
+            Dim oFileVersion As Integer = Nothing
+
+            ' Split Filename without extension at version separator to:
+            ' - Check if file is already versioned
+            ' - Get the file version of an already versioned file
+            ' 
+            ' Example: 
+            ' test1.pdf         --> test1           --> ['test1']               --> no fileversion
+            ' test1~2.pdf       --> test1~2         --> ['test1', '2']          --> version 2
+            ' test1~12345~2.pdf --> test1~12345~2   --> ['test1', '12345', '2'] --> still version 2
+            Dim oFileNameWithoutExtension = Path.GetFileNameWithoutExtension(oFileName)
+            Dim oSplitFilename = oFileNameWithoutExtension.Split(oVersionSeparator).ToList()
+
+            ' if file is already versioned, extract file version
+            ' else just use the filename and set version to 1
+            If oSplitFilename.Count > 1 Then
+                Dim oVersion As Integer = 1
+                Try
+                    oVersion = Integer.Parse(oSplitFilename.Last())
+                Catch ex As Exception
+                    ' oFilenameWithoutExtension does NOT change
+                    oFileNameWithoutExtension = oFileNameWithoutExtension
+                Finally
+                    oFileVersion = oVersion
+                End Try
+            Else
+                oFileVersion = 1
+                oFileNameWithoutExtension = String.Join(String.Empty, oSplitFilename.Take(oSplitFilename.Count - 1))
+            End If
+
+            ' while file exists, increment version    
+            Do
+                oFinalFileName = Path.Combine(oDestinationDir, GetFilenameWithVersion(oFileNameWithoutExtension, oVersionSeparator, oFileVersion, oExtension))
+                _logger.Debug("Intermediate Filename is {0}", oFinalFileName)
+                _logger.Debug("File version: {0}", oFileVersion)
+                oFileVersion += 1
+            Loop While (IO.File.Exists(oFinalFileName))
+
+            _logger.Debug("Final Filename is {0}", oFinalFileName)
+
+            Return oFinalFileName
+        Catch ex As Exception
+            _logger.Warn("Filename {0} could not be versioned. Original filename will be returned!", Destination)
+            _logger.Error(ex)
+            Return Destination
+        End Try
+    End Function
+
+    Private Function GetFilenameWithVersion(FileNameWithoutExtension As String, VersionSeparator As Char, FileVersion As Integer, Extension As String) As String
+        If FileVersion <= 1 Then
+            Return $"{FileNameWithoutExtension}{Extension}"
+        Else
+            Return $"{FileNameWithoutExtension}{VersionSeparator}{FileVersion}{Extension}"
+        End If
+    End Function
+
     ''' <summary>
     ''' Removes files in a directory filtered by filename, extension and last write date
     ''' </summary>