Make PR conversation tool windows multi-instance.

Author: grokys

src/GitHub.App/ViewModels/Documents/IssueishPaneViewModel.cs

@@ -36,6 +36,8 @@ public IViewModel Content
             private set => this.RaiseAndSetIfChanged(ref content, value);
         }
 
+        public bool IsInitialized => content != null;
+
         public string PaneCaption
         {
             get => paneCaption;

src/GitHub.Exports/Services/IGitHubToolWindowManager.cs

@@ -3,6 +3,7 @@
 using System.Runtime.InteropServices;
 using GitHub.ViewModels.GitHubPane;
 using GitHub.ViewModels.Documents;
+using GitHub.Primitives;
 
 namespace GitHub.Services
 {
@@ -20,9 +21,19 @@ public interface IGitHubToolWindowManager
         Task<IGitHubPaneViewModel> ShowGitHubPane();
 
         /// <summary>
-        /// Opens a new issue or pull request document pane.
+        /// Shows a document-like tool window pane for an issue or pull request.
         /// </summary>
-        /// <returns>>The view model for the document pane.</returns>
-        Task<IIssueishPaneViewModel> OpenIssueishDocumentPane();
+        /// <param name="address">
+        /// The host address of the server that hosts the issue or pull request.
+        /// </param>
+        /// <param name="owner">The repository owner.</param>
+        /// <param name="repository">The repository name.</param>
+        /// <param name="number">The issue or pull request number.</param>
+        /// <returns>The view model for the document pane.</returns>
+        Task<IIssueishPaneViewModel> ShowIssueishDocumentPane(
+            HostAddress address,
+            string owner,
+            string repository,
+            int number);
     }
 }

src/GitHub.Exports/ViewModels/Documents/IIssueishPaneViewModel.cs

@@ -14,6 +14,12 @@ public interface IIssueishPaneViewModel : IPaneViewModel
         /// </summary>
         IViewModel Content { get; }
 
+        /// <summary>
+        /// Gets a value indicating whether <see cref="Load(IConnection, string, string, int)"/>
+        /// has been called on the view model.
+        /// </summary>
+        bool IsInitialized { get; }
+        
         /// <summary>
         /// Loads an issue or pull request into the view model.
         /// </summary>

src/GitHub.VisualStudio/Commands/OpenIssueishDocumentCommand.cs

@@ -47,9 +47,13 @@ public override async Task Execute(OpenIssueishParams p)
             try
             {
                 var m = serviceProvider.GetService<IGitHubToolWindowManager>();
-                var vm = await m.OpenIssueishDocumentPane();
-                var connection = await connectionManager.GetConnection(p.Address);
-                await vm.Load(connection, p.Owner, p.Repository, p.Number);
+                var vm = await m.ShowIssueishDocumentPane(p.Address, p.Owner, p.Repository, p.Number);
+
+                if (!vm.IsInitialized)
+                {
+                    var connection = await connectionManager.GetConnection(p.Address);
+                    await vm.Load(connection, p.Owner, p.Repository, p.Number);
+                }
             }
             catch (Exception ex)
             {

src/GitHub.VisualStudio/GitHubPackage.cs

@@ -1,20 +1,23 @@
 using System;
-using System.Threading;
-using System.Threading.Tasks;
-using System.ComponentModel.Design;
+using System.Collections.Generic;
 using System.ComponentModel.Composition;
+using System.ComponentModel.Design;
 using System.Runtime.InteropServices;
+using System.Threading;
+using System.Threading.Tasks;
 using GitHub.Api;
 using GitHub.Commands;
-using GitHub.Info;
 using GitHub.Exports;
+using GitHub.Info;
 using GitHub.Logging;
+using GitHub.Primitives;
 using GitHub.Services;
-using GitHub.Settings;
-using GitHub.VisualStudio.Helpers;
-using GitHub.VisualStudio.Commands;
 using GitHub.Services.Vssdk.Commands;
+using GitHub.Settings;
+using GitHub.ViewModels.Documents;
 using GitHub.ViewModels.GitHubPane;
+using GitHub.VisualStudio.Commands;
+using GitHub.VisualStudio.Helpers;
 using GitHub.VisualStudio.Settings;
 using GitHub.VisualStudio.UI;
 using Microsoft.VisualStudio;
@@ -23,7 +26,7 @@
 using Microsoft.VisualStudio.Shell.Interop;
 using Serilog;
 using Task = System.Threading.Tasks.Task;
-using GitHub.ViewModels.Documents;
+using static System.FormattableString;
 
 namespace GitHub.VisualStudio
 {
@@ -162,7 +165,7 @@ public ServiceProviderExports([Import(typeof(SVsServiceProvider))] IServiceProvi
     [ProvideService(typeof(IUsageService), IsAsyncQueryable = true)]
     [ProvideService(typeof(IVSGitExt), IsAsyncQueryable = true)]
     [ProvideService(typeof(IGitHubToolWindowManager))]
-    [ProvideToolWindow(typeof(IssueishDocumentPane), DocumentLikeTool = true)]
+    [ProvideToolWindow(typeof(IssueishDocumentPane), DocumentLikeTool = true, MultiInstances = true)]
     [Guid(ServiceProviderPackageId)]
     public sealed class ServiceProviderPackage : AsyncPackage, IServiceProviderPackage, IGitHubToolWindowManager
     {
@@ -217,10 +220,43 @@ public async Task<IGitHubPaneViewModel> ShowGitHubPane()
             return await gitHubPane.GetViewModelAsync();
         }
 
-        public async Task<IIssueishPaneViewModel> OpenIssueishDocumentPane()
+        public async Task<IIssueishPaneViewModel> ShowIssueishDocumentPane(
+            HostAddress address,
+            string owner,
+            string repository,
+            int number)
+        {
+            var id = Invariant($"{address.WebUri}|{owner}/{repository}#{number}");
+            var pane = GetOrCreateToolWindow<IssueishDocumentPane>(id);
+
+            if (pane != null && pane.Frame is IVsWindowFrame frame)
+            {
+                ErrorHandler.ThrowOnFailure(frame.Show());
+                return await pane.GetViewModelAsync();
+            }
+
+            return null;
+        }
+
+        T GetOrCreateToolWindow<T>(string id) where T : AsyncPaneBase
         {
-            var pane = (IssueishDocumentPane)ShowToolWindow(new Guid(IssueishDocumentPane.IssueishDocumentPaneGuid));
-            return await pane.GetViewModelAsync();
+            for (var i = 0; i < int.MaxValue; ++i)
+            {
+                var result = (T)FindToolWindow(typeof(T), i, false);
+
+                if (result != null && result.Id == id)
+                {
+                    return result;
+                }
+                else if (result == null)
+                {
+                    result = (T)FindToolWindow(typeof(T), i, true);
+                    result.Id = id;
+                    return result;
+                }
+            }
+
+            return null;
         }
 
         static ToolWindowPane ShowToolWindow(Guid windowGuid)

src/GitHub.VisualStudio/UI/AsyncPaneBase.cs

@@ -12,7 +12,15 @@
 
 namespace GitHub.VisualStudio.UI
 {
-    public class AsyncPaneBase<TViewModel> : ToolWindowPane
+    public class AsyncPaneBase : ToolWindowPane
+    {
+        /// <summary>
+        /// Gets or sets an ID string that identifies the content of the pane.
+        /// </summary>
+        public string Id { get; set; }
+    }
+
+    public class AsyncPaneBase<TViewModel> : AsyncPaneBase
         where TViewModel : IPaneViewModel
     {
         readonly ContentPresenter contentPresenter;

src/GitHub.VisualStudio/UI/IssueishDocumentPane.cs

@@ -11,6 +11,9 @@ namespace GitHub.VisualStudio.UI
     [Guid(IssueishDocumentPaneGuid)]
     public class IssueishDocumentPane : AsyncPaneBase<IIssueishPaneViewModel>
     {
+        /// <summary>
+        /// The guid of the document pane.
+        /// </summary>
         public const string IssueishDocumentPaneGuid = "9506846C-4CEC-4DDA-87E7-A99CDCD4E35B";
     }
 }