Allow to create new root structure nodes (areas, iterations) when there are no sub-nodes (#2760)

Fixes #2759

Author: MrHinsh

src/MigrationTools.Clients.TfsObjectModel/Tools/TfsNodeStructureTool.cs

@@ -1,29 +1,22 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Text;
 using System.Text.RegularExpressions;
 using System.Xml;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.TeamFoundation.Common;
 using Microsoft.TeamFoundation.Server;
-using Microsoft.TeamFoundation.Work.WebApi;
 using MigrationTools.Clients;
 using MigrationTools.DataContracts;
 using MigrationTools.Endpoints;
-using MigrationTools.Enrichers;
 using MigrationTools.Exceptions;
 using MigrationTools.FieldMaps;
-using MigrationTools.Processors;
 using MigrationTools.Processors.Infrastructure;
 using MigrationTools.Services;
 using MigrationTools.Tools.Infrastructure;
 using Newtonsoft.Json;
-using Serilog.Context;
-using Serilog.Events;
-using static Microsoft.TeamFoundation.WorkItemTracking.Client.Node;
 using ILogger = Serilog.ILogger;
 
 
@@ -199,7 +192,6 @@ private NodeInfo GetOrCreateNode(string nodePath, DateTime? startDate, DateTime?
                             Log.LogDebug("  Not Found:", currentAncestorPath);
                             parentNode = null;
                         }
-
                     }
                 }
                 else
@@ -286,7 +278,8 @@ public void ProcessorExecutionBegin(TfsProcessor processor)
                     Log.LogInformation("Migrating all Nodes before the Processor run.");
                     MigrateAllNodeStructures();
                     RefreshForProcessorType(processor);
-                } else
+                }
+                else
                 {
                     Log.LogInformation("SKIP: Migrating all Nodes before the Processor run.");
                 }
@@ -397,13 +390,15 @@ private string GetSystemPath(string newUserPath, TfsNodeStructureType structureT
         private static string GetUserFriendlyPath(string systemNodePath)
         {
             // Shape of the path is \SourceProject\StructureType\Rest\Of\The\Path, user-friendly shape skips StructureType and initial \
-            var match = Regex.Match(systemNodePath, @"^\\(?<sourceProject>[^\\]+)\\[^\\]+\\(?<restOfThePath>.*)$");
+            var match = Regex.Match(systemNodePath, @"^\\(?<sourceProject>[^\\]+)\\[^\\]+(\\(?<restOfThePath>.*))?$");
             if (!match.Success)
             {
                 throw new InvalidOperationException($"This path is not a valid area or iteration path: {systemNodePath}");
             }
+            string sourceProject = match.Groups["sourceProject"].Value;
+            string restOfThePath = match.Groups["restOfThePath"].Success ? match.Groups["restOfThePath"].Value : string.Empty;
 
-            return $"{match.Groups["sourceProject"].Value}\\{match.Groups["restOfThePath"].Value}";
+            return restOfThePath == string.Empty ? sourceProject : $"{sourceProject}\\{restOfThePath}";
         }
 
         private void MigrateAllNodeStructures()
@@ -471,6 +466,11 @@ private void ProcessCommonStructure(string treeTypeSource, string localizedTreeT
 
             _pathToKnownNodeMap[structureParent.Path] = structureParent;
 
+            if (Options.MigrateRootNodes)
+            {
+                XmlElement mainNode = sourceTree.ChildNodes.OfType<XmlElement>().First();
+                CreateNewRootNode(mainNode, nodeStructureType);
+            }
             if (sourceTree.ChildNodes[0].HasChildNodes)
             {
                 // The XPath would look like this: /Nodes/Node[Name=Area]/Children/...
@@ -479,6 +479,20 @@ private void ProcessCommonStructure(string treeTypeSource, string localizedTreeT
             }
         }
 
+        private void CreateNewRootNode(XmlElement node, TfsNodeStructureType nodeStructureType)
+        {
+            string userFriendlyPath = GetUserFriendlyPath(node.Attributes["Path"].Value);
+            string newUserPath = GetNewNodeName(userFriendlyPath, nodeStructureType);
+            string newSystemPath = GetSystemPath(newUserPath, nodeStructureType, _targetLanguageMaps);
+            if (!Regex.IsMatch(newSystemPath, @"\\" + nodeStructureType + @"\\?$"))
+            {
+                // Do not do anything if there is no node name after structure type for the new (target) node.
+                // For example, if the path is just "\Project\Area" or "\Project\Iteration".
+                // This will happen if there are no mappings for nodes.
+                GetOrCreateNode(newSystemPath, null, null);
+            }
+        }
+
         private List<string> _matchedPath = new List<string>();
 
         /// <summary>

src/MigrationTools.Clients.TfsObjectModel/Tools/TfsNodeStructureToolOptions.cs

@@ -30,6 +30,15 @@ public sealed class TfsNodeStructureToolOptions : ToolOptions, ITfsNodeStructure
         /// </summary>
         public bool ShouldCreateMissingRevisionPaths { get; set; }
         public bool ReplicateAllExistingNodes { get; set; }
+
+        /// <summary>
+        /// By default, only child nodes in node structures are migrated. Turning this on migrates even the root node
+        /// (default area/iteration). This is useful, when you do not have any child areas ion source, but want to migrate
+        /// default area in source to some sub-area in target project. You have to set proper mapping for this to work.
+        /// If after mapping the target node is still just root node (so it is not migrated under some child node),
+        /// nothing happens – so migrating root nodes works only if the are remapped to some child node in target project.
+        /// </summary>
+        public bool MigrateRootNodes { get; set; } = false;
     }
 
     public class NodeOptions