Verbesserung der Fehlerbehandlung und Protokollierung

Neue Konstanten und Wiederholungslogik in `ActiveDirectoryInterface.vb` hinzugefügt, um vorübergehende AD-Fehler zu handhaben. Funktion `IsTransientAdException` implementiert. Verbesserte Benutzer-Synchronisierungslogik in `SyncUsers.MSSQL.vb`, um unnötige Löschvorgänge zu vermeiden. Versionsnummern in `AssemblyInfo.vb` aktualisiert. Warnmeldungen und Index-Typ-Überprüfung in `Windream.vb` verbessert. NLog-Verwaltung in `Windream.vbproj` auf NuGet umgestellt und entsprechende Referenz aus `packages.config` entfernt.

Interfaces/ActiveDirectoryInterface/SyncUsers.MSSQL.vb

@@ -26,6 +26,11 @@ Namespace SyncUsers
             Dim oCreatedUsers As New List(Of ADUser)
             Dim oUpdatedUsers As New List(Of ADUser)
 
+            If Users Is Nothing Then
+                _logger.Warn("SyncUsers aborted: Users is Nothing. Skipping sync and delete step for group [{0}].", GroupName)
+                Return oSyncedUsers
+            End If
+
             Try
                 _logger.Debug("Getting group Id for group {0}", GroupName)
                 oGroupId = GetGroupId(GroupName)
@@ -45,7 +50,6 @@ Namespace SyncUsers
                 Dim oUserId As Long
                 Dim oUserExists As Boolean
 
-                ' Check if user already exists
                 Try
                     _logger.Debug("Checking if user [{0}] exists", oUser)
                     oUserId = GetUserId(oUser.samAccountName)
@@ -57,38 +61,32 @@ Namespace SyncUsers
                     Continue For
                 End Try
 
-                ' Collect user ids from existing users
-                If oUserExists Then
-                    oSyncedUserIds.Add(oUserId)
-                End If
-
-                ' Create or update user
                 Try
                     If Not oUserExists Then
                         _logger.Debug("Creating new user for [{0}]", oUser)
                         oUserId = CreateUser(oUser)
                         _logger.Debug("User created with Id [{0}]", oUserId)
                         _logger.Info("Added new User [{0}]", oUser)
-
                         oCreatedUsers.Add(oUser)
                     Else
                         _logger.Debug("Updating user [{0}]", oUser)
                         oUserId = UpdateUser(oUser)
                         If oUserId <> 0 Then
-                            _logger.Debug("User created with Id [{0}]", oUserId)
+                            _logger.Debug("User updated with Id [{0}]", oUserId)
                             _logger.Info("Updated User [{0}]", oUser)
-
                             oUpdatedUsers.Add(oUser)
                         End If
                     End If
-
                 Catch ex As Exception
                     _logger.Error(ex)
                     _logger.Warn("Could Not create/update user [{0}]. Skipping.", oUser)
                     Continue For
                 End Try
 
-                ' Add custom attributes to user
+                If oUserId > 0 Then
+                    oSyncedUserIds.Add(oUserId)
+                End If
+
                 Try
                     AddCustomAttributesToUser(oUser, oUserId)
                 Catch ex As Exception
@@ -96,7 +94,6 @@ Namespace SyncUsers
                     _logger.Debug("Could Not add custom attributes to user {0}. Continuing.", oUser)
                 End Try
 
-                ' Add the user to group
                 Try
                     If AddUserToGroup(oUserId, oGroupId) Then
                         _logger.Info("User [{0}] added to group [{1}]", oUser, GroupName)
@@ -110,26 +107,33 @@ Namespace SyncUsers
                 oSyncedUsers.Add(oUser)
             Next
 
-            ' Delete users that are assigned to the group but no longer exist in active directory
-            Dim oUserIdString = String.Join(",", oSyncedUserIds)
-            If oSyncedUserIds.Count = 0 Then
-                _logger.Info("Group {0} does not contain any users.", GroupName)
-                oUserIdString = 0
+            ' Safety: never delete relations on empty source result
+            If Users.Count = 0 Then
+                _logger.Warn("Safety stop: AD returned 0 users for group [{0}]. Delete step skipped.", GroupName)
+                Return oSyncedUsers
             End If
-            Dim oSQL As String = $"DELETE FROM TBDD_GROUPS_USER WHERE USER_ID NOT IN ({oUserIdString}) AND GROUP_ID = {oGroupId}"
-            Dim oDeletedRelations = _mssql.GetScalarValue(oSQL)
+
+            If oSyncedUserIds.Count > 0 Then
+                Dim oUserIdString = String.Join(",", oSyncedUserIds.Distinct())
+                Dim oSQL As String = $"DELETE FROM TBDD_GROUPS_USER WHERE USER_ID NOT IN ({oUserIdString}) AND GROUP_ID = {oGroupId}"
+                Dim oDeleteResult = _mssql.ExecuteNonQuery(oSQL)
+
+                If oDeleteResult Then
+                    _logger.Info("User-group relations cleanup executed for group [{0}].", GroupName)
+                Else
+                    _logger.Warn("User-group relations cleanup failed for group [{0}].", GroupName)
+                End If
+            Else
+                _logger.Warn("Safety stop: No synced user IDs collected for group [{0}]. Delete step skipped.", GroupName)
+            End If
+
             If oCreatedUsers.Count > 0 Then
                 _logger.Info("Created [{0}] new users", oCreatedUsers.Count)
             End If
             _logger.Info("Updated [{0}] users", oUpdatedUsers.Count)
-            If oDeletedRelations > 0 Then
-                _logger.Info("Removed [{0}] users from Group [{1}]", oDeletedRelations, GroupName)
-            End If
-
 
             Return oSyncedUsers
         End Function
-
         Private Function AddUserToGroup(UserId As Integer, GroupId As Integer) As Boolean Implements ISyncUsers.AddUserToGroup
             Try
                 Dim oSQL = $"SELECT COUNT(*) FROM TBDD_GROUPS_USER WHERE USER_ID = {UserId} And GROUP_ID = {GroupId}"