Fix creation of diff

UI/ViewModels/PatchDialogViewModel.cs

@@ -27,8 +27,8 @@ namespace pEp.UI.ViewModels
         private ConfigFile          _SelectedFile           = null;
         private FlowDocument        _VisibleDiff            = null;
 
-        private const string FILE_A_PREFIX = "---a";
-        private const string FILE_B_PREFIX = "+++b";
+        private const string FILE_A_PREFIX = "--- a/";
+        private const string FILE_B_PREFIX = "+++ b/";
 
         #endregion
 
@@ -330,6 +330,10 @@ namespace pEp.UI.ViewModels
         /// <returns>The diff between the two files.</returns>
         private string CreateDiff(string fileNameA, string fileNameB)
         {
+            // Use UNIX file names
+            fileNameA = fileNameA.Replace('\\', '/');
+            fileNameB = fileNameB.Replace('\\', '/');
+
             if (!(File.Exists(fileNameA) && File.Exists(fileNameB)))
             {
                 Log.ErrorAndFailInDebugMode("CreateDiff: Input file doesn't exist.");
@@ -412,7 +416,7 @@ namespace pEp.UI.ViewModels
                                 break;
                             }
                         }
-                        index++;
+                        index = (index >= 0) ? index : 0;
                         newFileIndex = newLines[index].Position ?? 1;
                         oldFileIndex = oldLines[index].Position ?? 1;
                     }
@@ -459,7 +463,7 @@ namespace pEp.UI.ViewModels
                 return null;
             }
 
-            return diff.Insert(0, $"{ PatchDialogViewModel.FILE_A_PREFIX }/{ fileNameB }\n{ PatchDialogViewModel.FILE_B_PREFIX }/{ fileNameB }\n").TrimEnd('\n');
+            return diff.Insert(0, $"{ PatchDialogViewModel.FILE_A_PREFIX }{ fileNameB }\n{ PatchDialogViewModel.FILE_B_PREFIX }{ fileNameB }\n").TrimEnd('\n');
         }
 
         /// <summary>
@@ -534,21 +538,31 @@ namespace pEp.UI.ViewModels
         /// <returns>The root URI</returns>
         private string GetRootUri()
         {
-            string rootUri = this.ConfigFiles.First()?.FileName;
+            string firstFileName = this.ConfigFiles.First()?.FileName;
+            if (string.IsNullOrEmpty(firstFileName))
+            {
+                Log.ErrorAndFailInDebugMode("GetRootUri: First file name is empty");
+                return null;
+            }
+
+            string rootUri = Directory.GetParent(firstFileName).FullName.Replace('\\', '/');
 
             foreach (ConfigFile modifiedFile in this.ConfigFiles)
             {
-                for (int i = 0; i < modifiedFile.FileName.Length; i++)
+                string folderName = Directory.GetParent(modifiedFile.FileName).FullName.Replace('\\', '/');
+                int i = 0;
+                while ((i < folderName.Length) &&
+                        (i < rootUri.Length))
                 {
-                    if ((rootUri.Length <= i) ||
-                        (modifiedFile.FileName[i] == rootUri[i]))
+                    if (folderName[i] != rootUri[i])
                     {
-                        continue;
+                        break;
                     }
 
-                    rootUri = rootUri.Substring(0, i);
-                    break;
+                    i++;
                 }
+
+                rootUri = rootUri.Substring(0, i);
             }
 
             return rootUri;
@@ -578,8 +592,8 @@ namespace pEp.UI.ViewModels
             }
 
             // Remove root parts of URI
-            diff = diff.Replace(PatchDialogViewModel.FILE_A_PREFIX + "/" + this.Dialog.Patch.Uri, PatchDialogViewModel.FILE_A_PREFIX + "/");
-            diff = diff.Replace(PatchDialogViewModel.FILE_B_PREFIX + "/" + this.Dialog.Patch.Uri, PatchDialogViewModel.FILE_B_PREFIX + "/");
+            diff = diff.Replace(PatchDialogViewModel.FILE_A_PREFIX + this.Dialog.Patch.Uri + "/", PatchDialogViewModel.FILE_A_PREFIX);
+            diff = diff.Replace(PatchDialogViewModel.FILE_B_PREFIX + this.Dialog.Patch.Uri + "/", PatchDialogViewModel.FILE_B_PREFIX);
 
             return diff.TrimEnd('\n');
         }
@@ -673,7 +687,7 @@ namespace pEp.UI.ViewModels
 
             return document;
         }
-        
+
         #endregion
     }
 }