Call Roslyn to format new code behind documents (#9263)

Fixes #4330
Fixes #8766
Includes #9262 so just review from
8a2b8af
onwards

Goes with dotnet/roslyn#69878 and
dotnet/vscode-csharp#6329

I logged #9264 to follow up with a
better test, though strictly speaking the one I've added id exhaustive
:)

Behaviour of Extract to Code Behind before this change. Note the many
using statements and block scoped namespace.

![ExtractToCodeBehindBefore](https://github.com/dotnet/razor/assets/754264/10ac5595-b3b2-44c2-a1a7-66664d3c8f1b)

Behaviour after this change. Note the file scoped namespace, and file
header.

![ExtractToCodeBehindAfter](https://github.com/dotnet/razor/assets/754264/65160715-bc98-4336-b19d-37f9b14adf94)

The squiggle on `NavigationManager` is due to an `.editorconfig` rule I
have on in that project, requiring `this.` qualification, so is
unrelated.

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/CodeActions/Razor/ExtractToCodeBehindCodeActionResolver.cs

@@ -9,6 +9,7 @@
 using Microsoft.AspNetCore.Razor.Language;
 using Microsoft.AspNetCore.Razor.Language.Intermediate;
 using Microsoft.AspNetCore.Razor.LanguageServer.CodeActions.Models;
+using Microsoft.AspNetCore.Razor.LanguageServer.CodeActions.Razor;
 using Microsoft.AspNetCore.Razor.LanguageServer.Common;
 using Microsoft.AspNetCore.Razor.LanguageServer.Extensions;
 using Microsoft.AspNetCore.Razor.PooledObjects;
@@ -29,13 +30,16 @@ internal sealed class ExtractToCodeBehindCodeActionResolver : IRazorCodeActionRe
 
     private readonly DocumentContextFactory _documentContextFactory;
     private readonly LanguageServerFeatureOptions _languageServerFeatureOptions;
+    private readonly ClientNotifierServiceBase _languageServer;
 
     public ExtractToCodeBehindCodeActionResolver(
         DocumentContextFactory documentContextFactory,
-        LanguageServerFeatureOptions languageServerFeatureOptions)
+        LanguageServerFeatureOptions languageServerFeatureOptions,
+        ClientNotifierServiceBase languageServer)
     {
         _documentContextFactory = documentContextFactory ?? throw new ArgumentNullException(nameof(documentContextFactory));
-        _languageServerFeatureOptions = languageServerFeatureOptions;
+        _languageServerFeatureOptions = languageServerFeatureOptions ?? throw new ArgumentNullException(nameof(languageServerFeatureOptions));
+        _languageServer = languageServer ?? throw new ArgumentNullException(nameof(languageServer));
     }
 
     public string Action => LanguageServerConstants.CodeActions.ExtractToCodeBehindAction;
@@ -93,8 +97,8 @@ public ExtractToCodeBehindCodeActionResolver(
         }
 
         var className = Path.GetFileNameWithoutExtension(path);
-        var codeBlockContent = text.GetSubTextString(new CodeAnalysis.Text.TextSpan(actionParams.ExtractStart, actionParams.ExtractEnd - actionParams.ExtractStart));
-        var codeBehindContent = GenerateCodeBehindClass(className, actionParams.Namespace, codeBlockContent, codeDocument);
+        var codeBlockContent = text.GetSubTextString(new CodeAnalysis.Text.TextSpan(actionParams.ExtractStart, actionParams.ExtractEnd - actionParams.ExtractStart)).Trim();
+        var codeBehindContent = await GenerateCodeBehindClassAsync(documentContext.Project, codeBehindUri, className, actionParams.Namespace, codeBlockContent, codeDocument, cancellationToken).ConfigureAwait(false);
 
         var start = codeDocument.Source.Lines.GetLocation(actionParams.RemoveStart);
         var end = codeDocument.Source.Lines.GetLocation(actionParams.RemoveEnd);
@@ -169,17 +173,7 @@ private static string GenerateCodeBehindPath(string path)
         return codeBehindPath;
     }
 
-    /// <summary>
-    /// Generate a complete C# compilation unit containing a partial class
-    /// with the given name, body contents, and the namespace and all
-    /// usings from the existing code document.
-    /// </summary>
-    /// <param name="className">Name of the resultant partial class.</param>
-    /// <param name="namespaceName">Name of the namespace to put the resultant class in.</param>
-    /// <param name="contents">Class body contents.</param>
-    /// <param name="razorCodeDocument">Existing code document we're extracting from.</param>
-    /// <returns></returns>
-    private string GenerateCodeBehindClass(string className, string namespaceName, string contents, RazorCodeDocument razorCodeDocument)
+    private async Task<string> GenerateCodeBehindClassAsync(CodeAnalysis.Razor.ProjectSystem.IProjectSnapshot project, Uri codeBehindUri, string className, string namespaceName, string contents, RazorCodeDocument razorCodeDocument, CancellationToken cancellationToken)
     {
         using var _ = StringBuilderPool.GetPooledObject(out var builder);
 
@@ -210,12 +204,32 @@ private string GenerateCodeBehindClass(string className, string namespaceName, s
         builder.AppendLine(contents);
         builder.Append('}');
 
-        // Sadly we can't use a "real" workspace here, because we don't have access. If we use our workspace, it wouldn't have the right settings
-        // for C# formatting, only Razor formatting, and we have no access to Roslyn's real workspace, since it could be in another process.
-        // TODO: Rather than format here, call Roslyn via LSP to format, and remove and sort usings: https://github.com/dotnet/razor/issues/8766
-        var node = CSharpSyntaxTree.ParseText(builder.ToString()).GetRoot();
-        node = Formatter.Format(node, s_workspace);
+        var newFileContent = builder.ToString();
+
+        var parameters = new FormatNewFileParams()
+        {
+            Project = new TextDocumentIdentifier
+            {
+                Uri = new Uri(project.FilePath, UriKind.Absolute)
+            },
+            Document = new TextDocumentIdentifier
+            {
+                Uri = codeBehindUri
+            },
+            Contents = newFileContent
+        };
+        var fixedContent = await _languageServer.SendRequestAsync<FormatNewFileParams, string?>(CustomMessageNames.RazorFormatNewFileEndpointName, parameters, cancellationToken).ConfigureAwait(false);
+
+        if (fixedContent is null)
+        {
+            // Sadly we can't use a "real" workspace here, because we don't have access. If we use our workspace, it wouldn't have the right settings
+            // for C# formatting, only Razor formatting, and we have no access to Roslyn's real workspace, since it could be in another process.
+            var node = await CSharpSyntaxTree.ParseText(newFileContent).GetRootAsync(cancellationToken).ConfigureAwait(false);
+            node = Formatter.Format(node, s_workspace);
+
+            return node.ToFullString();
+        }
 
-        return node.ToFullString();
+        return fixedContent;
     }
 }

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/CodeActions/Razor/FormatNewFileParams.cs

@@ -0,0 +1,20 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System.Runtime.Serialization;
+using Microsoft.VisualStudio.LanguageServer.Protocol;
+
+namespace Microsoft.AspNetCore.Razor.LanguageServer.CodeActions.Razor;
+
+[DataContract]
+internal record FormatNewFileParams
+{
+    [DataMember(Name = "document")]
+    public required TextDocumentIdentifier Document { get; set; }
+
+    [DataMember(Name = "project")]
+    public required TextDocumentIdentifier Project { get; set; }
+
+    [DataMember(Name = "contents")]
+    public required string Contents { get; set; }
+}

src/Razor/src/Microsoft.AspNetCore.Razor.LanguageServer/Common/CustomMessageNames.cs

@@ -34,6 +34,8 @@ internal static class CustomMessageNames
     public const string RazorFoldingRangeEndpoint = "razor/foldingRange";
     public const string RazorHtmlFormattingEndpoint = "razor/htmlFormatting";
     public const string RazorHtmlOnTypeFormattingEndpoint = "razor/htmlOnTypeFormatting";
+    public const string RazorSimplifyMethodEndpointName = "razor/simplifyMethod";
+    public const string RazorFormatNewFileEndpointName = "razor/formatNewFile";
 
     // VS Windows only at the moment, but could/should be migrated
     public const string RazorDocumentSymbolEndpoint = "razor/documentSymbol";
@@ -52,8 +54,6 @@ internal static class CustomMessageNames
 
     public const string RazorReferencesEndpointName = "razor/references";
 
-    public const string RazorSimplifyMethodEndpointName = "razor/simplifyMethod";
-
     // Called to get C# diagnostics from Roslyn when publishing diagnostics for VS Code
     public const string RazorCSharpPullDiagnosticsEndpointName = "razor/csharpPullDiagnostics";
 }

src/Razor/src/Microsoft.VisualStudio.LanguageServerClient.Razor/Endpoints/FormatNewFile.cs

@@ -0,0 +1,38 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT license. See License.txt in the project root for license information.
+
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Razor.LanguageServer.CodeActions.Razor;
+using Microsoft.AspNetCore.Razor.LanguageServer.Common;
+using Microsoft.VisualStudio.LanguageServer.Protocol;
+using Newtonsoft.Json.Linq;
+using StreamJsonRpc;
+
+namespace Microsoft.VisualStudio.LanguageServerClient.Razor;
+
+internal partial class RazorCustomMessageTarget
+{
+    [JsonRpcMethod(CustomMessageNames.RazorFormatNewFileEndpointName, UseSingleObjectParameterDeserialization = true)]
+    public async Task<string?> FormatNewFileAsync(FormatNewFileParams request, CancellationToken cancellationToken)
+    {
+        // This endpoint is special because it deals with a file that doesn't exist yet, so there is no document syncing necessary!
+        var response = await _requestInvoker.ReinvokeRequestOnServerAsync<FormatNewFileParams, string?>(
+            RazorLSPConstants.RoslynFormatNewFileEndpointName,
+            RazorLSPConstants.RazorCSharpLanguageServerName,
+            SupportsFormatNewFile,
+            request,
+            cancellationToken).ConfigureAwait(false);
+
+        return response.Result;
+    }
+
+    private static bool SupportsFormatNewFile(JToken token)
+    {
+        var serverCapabilities = token.ToObject<VSInternalServerCapabilities>();
+
+        return serverCapabilities?.Experimental is JObject experimental
+            && experimental.TryGetValue(RazorLSPConstants.RoslynFormatNewFileEndpointName, out var supportsFormatNewFile)
+            && supportsFormatNewFile.ToObject<bool>();
+    }
+}

src/Razor/src/Microsoft.VisualStudio.LanguageServerClient.Razor/RazorLSPConstants.cs

@@ -22,4 +22,6 @@ internal static class RazorLSPConstants
     public const string HtmlLSPDelegationContentTypeName = "html-delegation";
 
     public const string RoslynSimplifyMethodEndpointName = "roslyn/simplifyMethod";
+
+    public const string RoslynFormatNewFileEndpointName = "roslyn/formatNewFile";
 }