Do not accept empty patches (no modifications)

UI/ViewModels/PatchDialogViewModel.cs

@@ -9,6 +9,7 @@ using System.Collections.ObjectModel;
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
+using System.Windows;
 using System.Windows.Documents;
 using System.Windows.Media;
 
@@ -366,8 +367,7 @@ namespace pEp.UI.ViewModels
              * => The modified part.
              * => Three unchanged lines (if available) after the modified part.
              */
-            string diff = $"{ PatchDialogViewModel.FILE_A_PREFIX }/{ fileNameB }\n{ PatchDialogViewModel.FILE_B_PREFIX }/{ fileNameB }\n";
-
+            string diff = null;
             SideBySideDiffModel sideBySideDiffModel = SideBySideDiffBuilder.Diff(fileA, fileB);
             List<DiffPiece> newLines = sideBySideDiffModel.NewText.Lines;
             List<DiffPiece> oldLines = sideBySideDiffModel.OldText.Lines;
@@ -443,7 +443,12 @@ namespace pEp.UI.ViewModels
                 }
             }
 
-            return diff.TrimEnd('\n');
+            if (string.IsNullOrEmpty(diff))
+            {
+                return null;
+            }
+
+            return diff.Insert(0, $"{ PatchDialogViewModel.FILE_A_PREFIX }/{ fileNameB }\n{ PatchDialogViewModel.FILE_B_PREFIX }/{ fileNameB }\n").TrimEnd('\n');
         }
 
         /// <summary>
@@ -472,28 +477,35 @@ namespace pEp.UI.ViewModels
                     File.Copy(fileName, originalFileName, true);
                 }
 
-                // Open temp file in VS Code for the user to edit
-                Process openCodeProcess = new Process
+                // Open temp file in Notepad for the user to edit
+                using (Process modifyFileProcess = Process.Start(new ProcessStartInfo
                 {
-                    StartInfo = new ProcessStartInfo
-                    {
-                        FileName = "code",
-                        Arguments = fileName,
-                        UseShellExecute = true,
-                        CreateNoWindow = true
-                    }
-                };
-                openCodeProcess.Start();
-                openCodeProcess.WaitForExit();
+                    FileName = "Notepad.exe",
+                    Arguments = fileName,
+                    UseShellExecute = false,
+                    CreateNoWindow = true
+                }))
+                {
+                    modifyFileProcess.WaitForExit();
+                }
+
+                // If changes were made, add or update file, otherwise show notification
+                if (this.CreateDiff(originalFileName, fileName) is string diff)
+                {
+                    this.ConfigFiles.Remove(this.ConfigFiles.Where(f => (f.FileName?.Equals(fileName) == true) && f.TempFileName?.Equals(tempFileName) == true).FirstOrDefault());
+                    this.ConfigFiles.Add(new ConfigFile(fileName, tempFileName, diff));
+
+                    // Select the created diff in the UI
+                    this.SelectedFile = this.ConfigFiles.Last();
+                }
+                else
+                {
+                    MessageBox.Show("No changes were made. Ignoring selected file.");
+                }
 
-                string diff = this.CreateDiff(originalFileName, fileName);
-                this.ConfigFiles.Remove(this.ConfigFiles.Where(f => (f.FileName?.Equals(fileName) == true) && f.TempFileName?.Equals(tempFileName) == true).FirstOrDefault());
-                this.ConfigFiles.Add(new ConfigFile(fileName, tempFileName, diff));
+                // Always update the respective files
                 File.Copy(fileName, tempFileName, true);
                 File.Copy(originalFileName, fileName, true);
-
-                // Select the created diff in the UI
-                this.SelectedFile = this.ConfigFiles.Last();
             }
             catch (Exception ex)
             {