ZUGFeRDService: Rework MD5 Checksum checking to allow for configuration of rejected state

Modules.Jobs/EDMI/ZUGFeRD/ImportZUGFeRDFiles.vb

@@ -240,32 +240,8 @@ Public Class ImportZUGFeRDFiles
                                     oEmbeddedAttachmentFiles.AddRange(oAttachments)
                                 End If
 
-                                oMD5CheckSum = CreateMD5(oFile.FullName)
+                                ' TODO MD5
-                                If oMD5CheckSum <> String.Empty Then
+                                oMD5CheckSum = Check_MD5Sum(oFile.FullName)
-                                    Dim oCheckCommand = $"SELECT * FROM TBEDM_ZUGFERD_HISTORY_IN WHERE GUID = (SELECT MAX(GUID) FROM TBEDM_ZUGFERD_HISTORY_IN WHERE UPPER(MD5HASH) = UPPER('{oMD5CheckSum}'))"
-                                    Dim oMD5DT As DataTable = _firebird.GetDatatable(oCheckCommand, Firebird.TransactionMode.NoTransaction)
-                                    If Not IsNothing(oMD5DT) Then
-                                        If oMD5DT.Rows.Count = 1 Then
-                                            Dim oRejected As Boolean
-                                            Try
-                                                oRejected = CBool(oMD5DT.Rows(0).Item("REJECTED"))
-                                            Catch ex As Exception
-                                                _logger.Warn("Error while converting REJECTED: " & ex.Message)
-                                                oRejected = False
-                                            End Try
-                                            If oRejected = False Then
-                                                Dim oHistoryId = oMD5DT.Rows(0).Item("GUID")
-                                                Throw New MD5HashException($"There is already an identical invoice! - HistoryID [{oHistoryId}]")
-                                            Else
-                                                _logger.Info("ZuGFeRDFile already has been worked, but formerly obviously was rejected!")
-                                            End If
-                                        End If
-                                    Else
-                                        _logger.Warn("Be careful: oExistsDT is nothing!")
-                                    End If
-                                Else
-                                    _logger.Warn("Be careful: oMD5CheckSum is nothing!")
-                                End If
 
                                 ' Check if there are more than one ZUGFeRD files
                                 If oZUGFeRDCount = 1 Then
@@ -691,4 +667,74 @@ Public Class ImportZUGFeRDFiles
             Return False
         End Try
     End Function
+
+    ''' <summary>
+    ''' Generates the MD5 Checksum of a file and checks it against the histroy table TBEDM_ZUGFERD_HISTORY_IN
+    ''' </summary>
+    ''' <param name="pFilePath">The path of the file to be checked</param>
+    ''' <param name="pIgnoreRejectionStatus">Should the check take into account the rejection status of the file?</param>
+    ''' <returns>The MD5 Checksum of the file, or an empty string, if the Checksum could not be created</returns>
+    ''' <exception cref="MD5HashException">Throws, when the file should be rejected, ie. if it already exists in the table</exception>
+    Private Function Check_MD5Sum(pFilePath As String, pIgnoreRejectionStatus As Boolean) As String
+        Dim oMD5CheckSum = CreateMD5(pFilePath)
+
+        ' Exit if MD5 could not be created
+        If oMD5CheckSum = String.Empty Then
+            _logger.Warn("MD5 Checksum is nothing for file [{0}]!", pFilePath)
+            Return oMD5CheckSum
+        End If
+
+        ' Check if Checksum exists in History Table
+        Dim oCheckCommand = $"SELECT * FROM TBEDM_ZUGFERD_HISTORY_IN WHERE GUID = (SELECT MAX(GUID) FROM TBEDM_ZUGFERD_HISTORY_IN WHERE UPPER(MD5HASH) = UPPER('{oMD5CheckSum}'))"
+        Dim oTable As DataTable = _firebird.GetDatatable(oCheckCommand, Firebird.TransactionMode.NoTransaction)
+
+        ' If History entries could not be fetched, just return the MD5 Checksum
+        If IsNothing(oTable) Then
+            _logger.Warn("Be careful: oExistsDT is nothing for file [{0}]!", pFilePath)
+            Return oMD5CheckSum
+        End If
+
+        ' If Checksum does not exist in History entries, just return the MD5 Checksum
+        If oTable.Rows.Count = 0 Then
+            _logger.Debug("File [{0}] was not found in History!", pFilePath)
+            Return oMD5CheckSum
+        End If
+
+        ' ====================================================
+        ' Checksum exists in History entries, reject!
+        ' ====================================================
+
+        Dim oRejected As Boolean
+        Dim oHistoryId As Integer
+
+        ' Try to read Rejected Status and History Id
+        Try
+            Dim oRow As DataRow = oTable.Rows.Item(0)
+            oRejected = DirectCast(oRow.Item("REJECTED"), Boolean)
+            oHistoryId = oRow.Item("GUID")
+
+        Catch ex As Exception
+            _logger.Warn("Error while converting REJECTED: " & ex.Message)
+            oRejected = False
+
+        End Try
+
+        ' If the file was already rejected, it is allowed to be processed again, 
+        ' even if the Checksum exists in the history entries (default case)
+        ' Which means, if it was not rejected before, it will be rejected in any case!
+        '
+        ' This logic can be overwritten by the ForceRejection parameter.
+        ' If it is set to true, the file will be rejected if the file exists in the history entries,
+        ' regardless of the rejected parameter.
+        If oRejected = False Or pIgnoreRejectionStatus = True Then
+            Throw New MD5HashException($"There is already an identical invoice! - HistoryID [{oHistoryId}]")
+
+        Else
+            _logger.Info("File has already been processed")
+            _logger.Info("ZuGFeRDFile already has been processed, but formerly obviously was rejected!")
+
+        End If
+
+        Return oMD5CheckSum
+    End Function
 End Class