Avoid LSP request conflicts with Request Forwarding (#190)

* update launch.json

* use request forwarding

* fix warnings

* add changelog

* update comment

Author: mizdra

.changeset/thick-pens-rule.md

@@ -0,0 +1,5 @@
+---
+'css-modules-kit-vscode': patch
+---
+
+fix: avoid LSP request conflicts with Request Forwarding

.vscode/launch.json

@@ -18,7 +18,6 @@
       "args": [
         "--extensionDevelopmentPath=${workspaceFolder}/packages/vscode",
         "--profile-temp",
-        "--disable-extension=vscode.css-language-features",
         "--skip-welcome",
         "--folder-uri=${workspaceFolder}/example",
         "${workspaceFolder}/example/src/index.tsx"

packages/vscode/src/index.ts

@@ -5,7 +5,16 @@ import * as lsp from 'vscode-languageclient/node';
 
 let client: lsp.BaseLanguageClient;
 
-export async function activate(_context: vscode.ExtensionContext) {
+const ORIGINAL_SCHEME = 'css-modules-kit';
+
+type RangeOrRangeWithPlaceholder =
+  | vscode.Range
+  | {
+      range: vscode.Range;
+      placeholder: string;
+    };
+
+export async function activate(context: vscode.ExtensionContext) {
   console.log('[css-modules-kit-vscode] Activated');
 
   // By default, `vscode.typescript-language-features` is not activated when a user opens *.css in VS Code.
@@ -15,7 +24,6 @@ export async function activate(_context: vscode.ExtensionContext) {
     console.log('[css-modules-kit-vscode] Activating `vscode.typescript-language-features`');
     tsExtension.activate();
   }
-
   // Both vscode.css-language-features extension and tsserver receive "rename" requests for *.css.
   // If more than one Provider receives a "rename" request, VS Code will use one of them.
   // In this case, the extension is used to rename. However, we do not want this.
@@ -29,17 +37,71 @@ export async function activate(_context: vscode.ExtensionContext) {
   // If not disabled, "rename" and "references" will behave in a way the user does not want.
   const cssExtension = vscode.extensions.getExtension('vscode.css-language-features');
   if (cssExtension) {
-    // Temporarily commented out
-    // vscode.window
-    //   .showInformationMessage(
-    //     '"Rename Symbol" and "Find All References" do not work in some cases because the "CSS Language Features" extension is enabled. Disabling the extension will make them work.',
-    //     'Show "CSS Language Features" extension',
-    //   )
-    //   .then((selected) => {
-    //     if (selected) {
-    //       vscode.commands.executeCommand('workbench.extensions.search', '@builtin css-language-features');
-    //     }
-    //   });
+    // Both vscode.css-language-features and tsserver subscribe to LSP requests for .css and return responses.
+    //
+    // For requests like "completion" or "references" the merged results of the two responses are displayed
+    // to the user. However, for certain types of requests like "rename" or "documentLink" the response
+    // from one Language Server takes precedence. Which Language Server is prioritized is determined by scoring.
+    //
+    // - https://github.com/microsoft/vscode/issues/115354
+    //
+    // Limiting the discussion to vscode.css-language-features and tsserver, it seems that
+    // vscode.css-language-features takes precedence. As a result, "rename" and "documentLink"
+    // behave unexpectedly.
+    //
+    // - https://github.com/mizdra/css-modules-kit/issues/121
+    // - Case 1 in https://github.com/mizdra/css-modules-kit/issues/133
+    //
+    // Therefore, in this case, we use the VS Code extension API to intercept "rename" and "documentLink"
+    // requests and redirect them to tsserver. This technique is known as "Request Forwarding".
+    //
+    // - https://code.visualstudio.com/api/language-extensions/embedded-languages#request-forwarding
+    //
+    // Using Request Forwarding solves the problem of "rename" and "references" requests.
+    vscode.workspace.registerTextDocumentContentProvider(ORIGINAL_SCHEME, {
+      async provideTextDocumentContent(uri) {
+        // `uri.fsPath` is in the format `/path/to/file.module.css.ts`.
+        const actualFilePath = uri.fsPath.slice(0, -3); // Remove the '.ts' extension
+        const actualFileDocument = await vscode.workspace.openTextDocument(actualFilePath);
+        const text = actualFileDocument.getText();
+        return text;
+      },
+    });
+    context.subscriptions.push(
+      vscode.languages.registerRenameProvider(
+        { language: 'css' },
+        {
+          provideRenameEdits(document, position, newName, _token) {
+            // NOTE: Executing `executeDocumentRenameProvider` on a virtual text document causes a runtime error. This is probably a bug in vscode.
+            return vscode.commands.executeCommand<vscode.WorkspaceEdit>(
+              'vscode.executeDocumentRenameProvider',
+              vscode.Uri.parse(`${ORIGINAL_SCHEME}://${document.fileName}.ts`),
+              position,
+              newName,
+            );
+          },
+          prepareRename(document, position, _token) {
+            return vscode.commands.executeCommand<RangeOrRangeWithPlaceholder>(
+              'vscode.prepareRename',
+              vscode.Uri.parse(`${ORIGINAL_SCHEME}://${document.fileName}.ts`),
+              position,
+            );
+          },
+        },
+      ),
+      vscode.languages.registerDocumentLinkProvider(
+        { language: 'css' },
+        {
+          async provideDocumentLinks(document, _token) {
+            // NOTE: Executing `executeDocumentLinkProvider` on a virtual text document, an empty array is always returned. This is probably a bug in vscode.
+            return vscode.commands.executeCommand<vscode.Location[]>(
+              'vscode.executeLinkProvider',
+              vscode.Uri.parse(`${ORIGINAL_SCHEME}://${document.fileName}.ts`),
+            );
+          },
+        },
+      ),
+    );
   } else {
     // If vscode.css-language-features extension is disabled, start the customized language server for *.css, *.scss, and *.less.
     // The language server is based on the vscode-css-languageservice, but "rename" and "references" features are disabled.