feat(playground): integrate language server support with WebSocket connection handling

src/app/playground/page.tsx

@@ -1,8 +1,10 @@
 "use client";
 
 import * as monaco from "monaco-editor";
+import { connectToLanguageServer } from "@/lib/lsp";
 import { useEffect, useRef, useState } from "react";
-import { Editor } from "@monaco-editor/react";
+import { Editor, loader } from "@monaco-editor/react";
+import { MonacoLanguageClient } from "monaco-languageclient";
 import { Tabs, TabsList, TabsTrigger } from "@/components/ui/tabs";
 import { ScrollArea, ScrollBar } from "@/components/ui/scroll-area";
 import { COriginal, CplusplusOriginal, JavaOriginal } from "devicons-react";
@@ -39,10 +41,14 @@ int main() {
   },
 };
 
+loader.config({ monaco });
+
 export default function PlaygroundPage() {
-  const editorRef = useRef<monaco.editor.IStandaloneCodeEditor | null>(null);
+  const [language, setLanguage] = useState<string>("c");
-  const [language, setLanguage] = useState<keyof typeof files>("c");
   const file = files[language];
+  const editorRef = useRef<monaco.editor.IStandaloneCodeEditor | null>(null);
+  const webSocketRef = useRef<WebSocket | null>(null);
+  const languageClientRef = useRef<MonacoLanguageClient | null>(null);
 
   useEffect(() => {
     if (editorRef.current) {
@@ -55,6 +61,15 @@ export default function PlaygroundPage() {
           column: lastLineLength + 1,
         });
         editorRef.current.focus();
+        if (webSocketRef.current) {
+          webSocketRef.current.close();
+          webSocketRef.current = null;
+        }
+        connectToLanguageServer(language, webSocketRef).then(
+          (languageClient) => {
+            languageClientRef.current = languageClient;
+          }
+        );
       }
     }
   }, [language]);
@@ -127,6 +142,11 @@ export default function PlaygroundPage() {
                 column: lastLineLength + 1,
               });
               editorRef.current.focus();
+              connectToLanguageServer(language, webSocketRef).then(
+                (languageClient) => {
+                  languageClientRef.current = languageClient;
+                }
+              );
             }
           }
         }}

src/lib/lsp.ts

@@ -0,0 +1,94 @@
+import {
+  toSocket,
+  WebSocketMessageReader,
+  WebSocketMessageWriter,
+} from "vscode-ws-jsonrpc";
+import {
+  CloseAction,
+  ErrorAction,
+  MessageTransports,
+} from "vscode-languageclient";
+import { RefObject } from "react";
+import normalizeUrl from "normalize-url";
+import { MonacoLanguageClient } from "monaco-languageclient";
+
+const LSP_SUPPORTED_LANGUAGES: {
+  [key: string]: { hostname: string; port: number; path: string };
+} = {
+  c: {
+    hostname: "localhost",
+    port: 30001,
+    path: "/clangd",
+  },
+  cpp: {
+    hostname: "localhost",
+    port: 30002,
+    path: "/clangd",
+  },
+};
+
+function createUrl(hostname: string, port: number, path: string): string {
+  const protocol = location.protocol === "https:" ? "wss" : "ws";
+  return normalizeUrl(`${protocol}://${hostname}:${port}${path}`);
+}
+
+const languageClientConfig = {
+  name: "Language Client",
+  clientOptions: {
+    documentSelector: ["c", "cpp"],
+    errorHandler: {
+      error: () => ({ action: ErrorAction.Continue }),
+      closed: () => ({ action: CloseAction.DoNotRestart }),
+    },
+  },
+};
+
+function createLanguageClient(
+  transports: MessageTransports
+): MonacoLanguageClient {
+  return new MonacoLanguageClient({
+    ...languageClientConfig,
+    connectionProvider: {
+      get: () => Promise.resolve(transports),
+    },
+  });
+}
+
+export async function connectToLanguageServer(
+  language: string,
+  webSocketRef: RefObject<WebSocket | null>
+): Promise<MonacoLanguageClient> {
+  return new Promise((resolve, reject) => {
+    let url: string;
+    if (language in LSP_SUPPORTED_LANGUAGES) {
+      const { hostname, port, path } = LSP_SUPPORTED_LANGUAGES[language];
+      url = createUrl(hostname, port, path);
+    } else {
+      reject(new Error("Unsupported language"));
+      return;
+    }
+
+    const webSocket = new WebSocket(url);
+    webSocketRef.current = webSocket;
+
+    webSocket.onopen = () => {
+      console.log("WebSocket connection opened successfully.");
+      const socket = toSocket(webSocket);
+      const reader = new WebSocketMessageReader(socket);
+      const writer = new WebSocketMessageWriter(socket);
+      const languageClient = createLanguageClient({ reader, writer });
+      languageClient.start();
+      resolve(languageClient);
+    };
+
+    webSocket.onclose = () => {
+      console.log("WebSocket connection closed.");
+      reject(new Error("WebSocket connection closed unexpectedly."));
+    };
+
+    webSocket.onerror = (error) => {
+      console.error("WebSocket connection error:", error);
+      reject(new Error(`WebSocket connection error: ${error}`));
+    };
+  });
+}