Refactor ImportCommand

This is a preparation for the introduction of subtypes.

Author: MDoerner

Rubberduck.Core/UI/CodeExplorer/Commands/ImportCommand.cs

@@ -1,8 +1,10 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Windows.Forms;
 using Rubberduck.Navigation.CodeExplorer;
+using Rubberduck.Parsing.VBA;
 using Rubberduck.Resources;
 using Rubberduck.VBEditor.Events;
 using Rubberduck.VBEditor.SafeComWrappers;
@@ -24,15 +26,18 @@ public class ImportCommand : CodeExplorerCommandBase
         private readonly IFileSystemBrowserFactory _dialogFactory;
         private readonly IList<string> _importableExtensions;
         private readonly string _filterExtensions;
+        private readonly IParseManager _parseManager;
 
         public ImportCommand(
-            IVBE vbe, 
-            IFileSystemBrowserFactory dialogFactory, 
-            IVbeEvents vbeEvents) 
+            IVBE vbe,
+            IFileSystemBrowserFactory dialogFactory,
+            IVbeEvents vbeEvents,
+            IParseManager parseManager)
             : base(vbeEvents)
         {
             _vbe = vbe;
             _dialogFactory = dialogFactory;
+            _parseManager = parseManager;
 
             AddToCanExecuteEvaluation(SpecialEvaluateCanExecute);
 
@@ -44,6 +49,7 @@ public ImportCommand(
             _filterExtensions = string.Join("; ", _importableExtensions.Select(ext => $"*.{ext}"));
 
             AddToCanExecuteEvaluation(SpecialEvaluateCanExecute);
+            AddToOnExecuteEvaluation(SpecialEvaluateCanExecute);
         }
 
         public sealed override IEnumerable<Type> ApplicableNodeTypes => ApplicableNodes;
@@ -61,37 +67,42 @@ private bool ThereIsAValidActiveProject()
             }
         }
 
-        protected override void OnExecute(object parameter)
+        private (IVBProject project, bool needsDisposal) TargetProject(object parameter)
         {
-            if (!CanExecute(parameter))
+            var targetProject = TargetProjectFromParameter(parameter);
+            if (targetProject != null)
             {
-                return;
+                return (targetProject, false);
             }
 
-            var usingFreshProjectWrapper = false;
-            var project = (parameter as CodeExplorerItemViewModel)?.Declaration?.Project;
+            targetProject = TargetProjectFromVbe();
+
+            return (targetProject, targetProject != null);
+        }
+
+        private static IVBProject TargetProjectFromParameter(object parameter)
+        {
+            return (parameter as CodeExplorerItemViewModel)?.Declaration?.Project;
+        }
 
-            if (project == null)
+        private IVBProject TargetProjectFromVbe()
+        {
+            if (_vbe.ProjectsCount == 1)
             {
-                if (_vbe.ProjectsCount == 1)
-                {
-                    usingFreshProjectWrapper = true;
-                    using (var projects = _vbe.VBProjects)
-                    {
-                        project = projects[1];
-                    }
-                }
-                else if (ThereIsAValidActiveProject())
+                using (var projects = _vbe.VBProjects)
                 {
-                    usingFreshProjectWrapper = true;
-                    project = _vbe.ActiveVBProject;
-                }
-                else
-                {
-                    return;
+                    return projects[1];
                 }
             }
 
+            var activeProject = _vbe.ActiveVBProject;
+            return activeProject != null && !activeProject.IsWrappingNullReference
+                ? activeProject
+                : null;
+        }
+
+        protected virtual ICollection<string> FilesToImport(object parameter)
+        {
             using (var dialog = _dialogFactory.CreateOpenFileDialog())
             {
                 dialog.AddExtension = true;
@@ -100,42 +111,71 @@ protected override void OnExecute(object parameter)
                 dialog.CheckPathExists = true;
                 dialog.Multiselect = true;
                 dialog.ShowHelp = false;
-                dialog.Title = RubberduckUI.ImportCommand_OpenDialog_Title;
-                dialog.Filter = 
+                dialog.Title = FileDialogTitle;
+                dialog.Filter =
                     $"{RubberduckUI.ImportCommand_OpenDialog_Filter_VBFiles} ({_filterExtensions})|{_filterExtensions}|" +
                     $"{RubberduckUI.ImportCommand_OpenDialog_Filter_AllFiles}, (*.*)|*.*";
 
-                if (project == null || dialog.ShowDialog() != DialogResult.OK)
+                if (dialog.ShowDialog() != DialogResult.OK)
                 {
-                    if (usingFreshProjectWrapper)
-                    {
-                        project?.Dispose();
-                    }
-                    return;
+                    return new List<string>();
                 }
 
-                var fileExists = dialog.FileNames.Select(s => s.Split('.').Last());
-                if (fileExists.Any(fileExt => !_importableExtensions.Contains(fileExt)))
+                var fileNames = dialog.FileNames;
+                var fileExtensions = fileNames.Select(Path.GetExtension);
+                if (fileExtensions.Any(fileExt => !_importableExtensions.Contains(fileExt)))
                 {
-                    if (usingFreshProjectWrapper)
-                    {
-                        project.Dispose();
-                    }
-                    return;
+                    return new List<string>();
                 }
 
-                foreach (var filename in dialog.FileNames)
+                return fileNames;
+            }
+        }
+
+        protected virtual string FileDialogTitle => RubberduckUI.ImportCommand_OpenDialog_Title;
+
+        private void ImportFilesWithSuspension(IEnumerable<string> filesToImport, IVBProject targetProject)
+        {
+            var suspensionResult = _parseManager.OnSuspendParser(this, new[] {ParserState.Ready}, () => ImportFiles(filesToImport, targetProject));
+            if (suspensionResult != SuspensionResult.Completed)
+            {
+                Logger.Warn("File import failed due to suspension failure.");
+            }
+        }
+
+        protected virtual void ImportFiles(ICollection<string> filesToImport, IVBProject targetProject)
+        {
+            using (var components = targetProject.VBComponents)
+            {
+                foreach (var filename in filesToImport)
                 {
-                    using (var components = project.VBComponents)
-                    {
-                        components.Import(filename);
-                    }
+                    //We have to dispose the return value.
+                    using (components.Import(filename)) {}
                 }
             }
+        }
+
+        protected override void OnExecute(object parameter)
+        {
+            var (targetProject, targetProjectNeedsDisposal) = TargetProject(parameter);
+
+            if (targetProject == null)
+            {
+                return;
+            }
+
+            var filesToImport = FilesToImport(parameter);
+
+            if (!filesToImport.Any())
+            {
+                return;
+            }
+
+            ImportFilesWithSuspension(filesToImport, targetProject);
 
-            if (usingFreshProjectWrapper)
+            if (targetProjectNeedsDisposal)
             {
-                project.Dispose();
+                targetProject.Dispose();
             }
         }
     }

RubberduckTests/CodeExplorer/MockedCodeExplorer.cs

@@ -339,7 +339,7 @@ public void ExecuteAddTestModuleWithStubsCommand()
 
         public void ExecuteImportCommand()
         {
-            ViewModel.ImportCommand = new ImportCommand(Vbe.Object, BrowserFactory.Object, VbeEvents.Object);
+            ViewModel.ImportCommand = new ImportCommand(Vbe.Object, BrowserFactory.Object, VbeEvents.Object, State);
             ViewModel.ImportCommand.Execute(ViewModel.SelectedItem);
         }