Recognize pre-existing ObjectStateUDT

If an existing ObjectStateUDT (from a prior encapuslate field operation)
can be found, then setup the refactoring to add to the ObjectStateUDT.

Author: BZngr

Rubberduck.Core/UI/Refactorings/EncapsulateField/EncapsulateFieldViewModel.cs

@@ -367,6 +367,14 @@ private void ManageEncapsulationFlagsAndSelectedItem(object param = null)
             var selected = _lastCheckedBoxes.FirstOrDefault();
             if (_lastCheckedBoxes.Count == EncapsulationFields.Where(f => f.EncapsulateFlag).Count())
             {
+                _lastCheckedBoxes = EncapsulationFields.Where(f => f.EncapsulateFlag).ToList();
+                if (EncapsulationFields.Where(f => f.EncapsulateFlag).Count() == 0
+                    && EncapsulationFields.Count() > 0)
+                {
+                    SetSelectedField(EncapsulationFields.First());
+                    return;
+                }
+                SetSelectedField(_lastCheckedBoxes.First());
                 return;
             }
 
@@ -390,6 +398,11 @@ private void ManageEncapsulationFlagsAndSelectedItem(object param = null)
 
             _lastCheckedBoxes = EncapsulationFields.Where(ef => ef.EncapsulateFlag).ToList();
 
+            SetSelectedField(selected);
+        }
+
+        private void SetSelectedField(IEncapsulatedFieldViewData selected)
+        {
             _masterDetail.SelectionTargetID = selected?.TargetID ?? null;
             OnPropertyChanged(nameof(SelectedField));
             if (_masterDetail.DetailUpdateRequired)

Rubberduck.Refactorings/EncapsulateField/EncapsulateFIeldResources.cs

@@ -12,12 +12,14 @@ namespace Rubberduck.Refactorings.EncapsulateField
     public class EncapsulateFieldResources
     {
         public static string PreviewEndOfChangesMarker
-            => "'<===== No Changes below this line =====>";
+            => "'<===== Property and Declaration changes above this line =====>";
 
         public static string DefaultPropertyParameter => "value";
 
         public static string DefaultStateUDTFieldName => "this";
 
+        //TODO: Is it meaningful to change the Type prefix for different cultures?
+        //If not, remove this declaration
         public static string StateUserDefinedTypeIdentifierPrefix => "T";
 
         public static string GroupBoxHeaderSuffix = "Encapsulation Property Name:";

Rubberduck.Refactorings/EncapsulateField/EncapsulateFieldModel.cs

@@ -66,7 +66,7 @@ public bool ConvertFieldsToUDTMembers
 
         public string PreviewRefactoring() => _previewDelegate(this);
 
-        private List<IObjectStateUDT>  _objStateCandidates;
+        private HashSet<IObjectStateUDT>  _objStateCandidates;
         public IEnumerable<IObjectStateUDT> ObjectStateUDTCandidates
         {
             get
@@ -76,7 +76,7 @@ public IEnumerable<IObjectStateUDT> ObjectStateUDTCandidates
                     return _objStateCandidates;
                 }
 
-                _objStateCandidates = new List<IObjectStateUDT>();
+                _objStateCandidates = new HashSet<IObjectStateUDT>();
                 foreach (var candidate in UDTFieldCandidates.Where(udt => udt.CanBeObjectStateUDT))
                 {
                     _objStateCandidates.Add(new ObjectStateUDT(candidate));

Rubberduck.Refactorings/EncapsulateField/EncapsulateFieldRefactoring.cs

@@ -92,7 +92,13 @@ protected override EncapsulateFieldModel InitializeModel(Declaration target)
             var selected = candidates.Single(c => c.Declaration == target);
             selected.EncapsulateFlag = true;
 
-            if (!TryRetrieveExistingObjectStateUDT(target, candidates, out var objectStateUDT))
+            var forceUseOfObjectStateUDT = false;
+            if (TryRetrieveExistingObjectStateUDT(target, candidates, out var objectStateUDT))
+            {
+                objectStateUDT.IsSelected = true;
+                forceUseOfObjectStateUDT = true;
+            }
+            else
             {
                 objectStateUDT = _encapsulationCandidateFactory.CreateStateUDTField();
                 objectStateUDT.IsSelected = true;
@@ -110,6 +116,7 @@ protected override EncapsulateFieldModel InitializeModel(Declaration target)
                 .OrderBy(c => c.Selection)
                             .FirstOrDefault()?.Context.Start.TokenIndex ?? null;
 
+            Model.ConvertFieldsToUDTMembers = forceUseOfObjectStateUDT;
             return Model;
         }