Allow navigation from editable diff to code view

This allows navigation from View Changes in Solution to Code View.
It also allows navigation from the default Team Explorer changes diff
view (Compare with Unmodified...) to code view.

Author: jcansdale

src/GitHub.App/Services/PullRequestEditorService.cs

@@ -18,6 +18,7 @@
 using Microsoft.VisualStudio.Text.Editor;
 using Microsoft.VisualStudio.Text.Projection;
 using Microsoft.VisualStudio.TextManager.Interop;
+using EnvDTE;
 using Task = System.Threading.Tasks.Task;
 
 namespace GitHub.Services
@@ -275,6 +276,25 @@ static bool RaiseWhenAvailable(string guid, int id, object param)
             return false;
         }
 
+        public void OpenActiveDocumentInCodeView(IVsTextView sourceView)
+        {
+            var dte = serviceProvider.GetService<DTE>();
+            // Not sure how to get a file name directly from IVsTextView. Using DTE.ActiveDocument.FullName.
+            var fullPath = dte.ActiveDocument.FullName;
+            // VsShellUtilities.OpenDocument with VSConstants.LOGVIEWID.Code_guid always open a new Code view.
+            // Using DTE.ItemOperations.OpenFile with Constants.vsViewKindCode instead,
+            dte.ItemOperations.OpenFile(fullPath, EnvDTE.Constants.vsViewKindCode);
+            var codeView = FindActiveView();
+            NavigateToEquivalentPosition(sourceView, codeView);
+        }
+
+        public bool IsEditableDiff(ITextView textView)
+        {
+            var readOnly = textView.Options.GetOptionValue(DefaultTextViewOptions.ViewProhibitUserInputId);
+            var isDiff = IsDiff(textView);
+            return !readOnly && isDiff;
+        }
+
         public void NavigateToEquivalentPosition(IVsTextView sourceView, IVsTextView targetView)
         {
             int line;
@@ -574,6 +594,8 @@ async Task<string> GetBaseFileName(IPullRequestSession session, IPullRequestSess
             }
         }
 
+        static bool IsDiff(ITextView textView) => textView.Roles.Contains("DIFF");
+
         static IDifferenceViewer GetDiffViewer(IVsWindowFrame frame)
         {
             object docView;

src/GitHub.Exports.Reactive/Services/IPullRequestEditorService.cs

@@ -58,5 +58,21 @@ public interface IPullRequestEditorService
         /// <param name="sourceView">The text view to navigate from.</param>
         /// <param name="targetView">The text view to navigate to.</param>
         void NavigateToEquivalentPosition(IVsTextView sourceView, IVsTextView targetView);
+
+        /// <summary>
+        /// Check to see if text view is an ediatable document.
+        /// </summary>
+        /// <param name="textView">The text view to check.</param>
+        /// <returns>True if text view is editable and part of a diff view.</returns>
+        bool IsEditableDiff(ITextView textView);
+
+        /// <summary>
+        /// Open the active document in a new code view.
+        /// </summary>
+        /// <remarks>
+        /// If the active document is part of a diff view, open in a new code view.
+        /// </remarks>
+        /// <param name="sourceView">The source view to use the line and position from.</param>
+        void OpenActiveDocumentInCodeView(IVsTextView sourceView);
     }
 }

src/GitHub.VisualStudio/Commands/GoToSolutionOrPullRequestFileCommand.cs

@@ -65,6 +65,14 @@ public override async Task Execute()
 
                 var textView = editorAdapter.Value.GetWpfTextView(sourceView);
 
+                bool isEditableDiff = pullRequestEditorService.Value.IsEditableDiff(textView);
+                if (isEditableDiff)
+                {
+                    // Open active document in Code View
+                    pullRequestEditorService.Value.OpenActiveDocumentInCodeView(sourceView);
+                    return;
+                }
+
                 var info = sessionManager.Value.GetTextBufferInfo(textView.TextBuffer);
                 if (info != null)
                 {
@@ -144,6 +152,15 @@ void OnBeforeQueryStatus(object sender, EventArgs e)
                 }
 
                 var textView = editorAdapter.Value.GetWpfTextView(sourceView);
+
+                if (pullRequestEditorService.Value.IsEditableDiff(textView))
+                {
+                    // Active text view is editable diff
+                    Text = "Open File in Code View";
+                    Visible = true;
+                    return;
+                }
+
                 var info = sessionManager.Value.GetTextBufferInfo(textView.TextBuffer);
                 if (info != null)
                 {