Realtime Collaborative IDE

A realtime collaborative IDE with code execution, intellisense, and built-in USACO submissions. Designed primarily for Competitive Programming and USACO, with mobile support for coding on the go.

This IDE is built and maintained by Nathan Wang and Benjamin Qi, and is part of the Competitive Programming Initiative.

Running Locally

This project uses the Firebase Realtime Database. This tutorial is helpful (even though Cloud Firestore is not what's being used here). You'll need to install the firebase CLI and Node.js 18.

npm install
npm run dev

npm run dev will start a Firebase emulator for you. By default, the dev server uses a local firebase emulator and the production YJS server. To change these settings, edit src/dev_constants.ts.

Note: If you get a firebase emulators timeout error on Mac, see firebase/firebase-tools#2379 (comment) and Issue #67 in this repo.

Playwright Tests

npm run dev  # Start the dev server in a separate terminal
npm run test

We use Playwright for our e2e tests. The VSCode extension for Playwright can be useful for debugging tests.

Note: If you are using the production YJS servers, the Copy Files test will fail because the YJS_SECURITY_KEY environment variable needs to be set. For local development, feel free to ignore the Copy Files CI test. Alternatively, you can run a local YJS server (see the ide-yjs repository) and use that instead.

Configuring Firebase

You can update the Firebase configuration (if you want to use a custom firebase project, for example) by modifying pages/_app.tsx.

Tech Stack

• Code execution through a custom Serverless Online Judge
• Realtime collaboration with YJS
• Monaco Editor (desktop)
• Codemirror 6 Editor (mobile)
• monaco-languageclient with clangd-12 for LSP
• React
• Jotai
• Next.js
• Typescript
• Tailwind CSS
• Firebase Realtime Database
• Playwright for end-to-end testing
• Deployed with Vercel

Contact Info

If you have any questions, please open an issue or reach out to us at usacoguide@gmail.com.

Misc Notes

LSP Installation

We used Ubuntu 20.04 on Azure, B2s. Open port 3000 on the Azure firewall rules.

1. Install clangd-12

sudo apt update
sudo apt install clangd-12

2. Install node

sudo apt install nodejs npm
sudo npm install -g n
sudo n install lts
sudo n                       # choose v16 or whatever lts is

3. Setup Server

git clone https://github.com/TypeFox/monaco-languageclient.git

cd packages/examples/node

Modify server.ts:

import * as rpc from 'vscode-ws-jsonrpc/cjs';
import { launch } from './json-server-launcher';
import fs from 'fs';
import * as https from 'https';

const privateKey = fs.readFileSync(
  '/etc/letsencrypt/live/lsp.usaco.guide/privkey.pem',
  'utf8'
);
const certificate = fs.readFileSync(
  '/etc/letsencrypt/live/lsp.usaco.guide/fullchain.pem',
  'utf8'
);

process.on('uncaughtException', function (err: any) {
  console.error('Uncaught Exception: ', err.toString());
  if (err.stack) {
    console.error(err.stack);
  }
});

// create the express application
const app = express();
// server the static content, i.e. index.html
app.use(express.static(__dirname));
// start the server
//const server = app.listen(3000);
const httpsServer = https.createServer(
  { key: privateKey, cert: certificate },
  app
);
httpsServer.listen(3000);
// create the web socket
const wss = new ws.Server({
  noServer: true,
  perMessageDeflate: false,
});
httpsServer.on(
  'upgrade',
  (request: http.IncomingMessage, socket: net.Socket, head: Buffer) => {
    // eslint-disable-next-line n/no-deprecated-api
    const pathname = request.url ? url.parse(request.url).pathname : undefined;
    if (pathname === '/sampleServer') {
      wss.handleUpgrade(request, socket, head, webSocket => {
        const socket: rpc.IWebSocket = {
          send: content =>
            webSocket.send(content, error => {
              if (error) {
                throw error;
              }
            }),
          onMessage: cb => webSocket.on('message', cb),
          onError: cb => webSocket.on('error', cb),
          onClose: cb => webSocket.on('close', cb),
          dispose: () => webSocket.close(),
        };
        // launch the server when the web socket is opened
        if (webSocket.readyState === webSocket.OPEN) {
          launch(socket);
        } else {
          webSocket.on('open', () => launch(socket));
        }
      });
    }
  }
);

Modify json-server-launcher.ts:

//import * as path from 'path';
import * as rpc from 'vscode-ws-jsonrpc/cjs';
import * as server from 'vscode-ws-jsonrpc/cjs/server';
import * as lsp from 'vscode-languageserver';
import { start } from './json-server';
import { Message } from 'vscode-languageserver';

export function launch(socket: rpc.IWebSocket) {
  const reader = new rpc.WebSocketMessageReader(socket);
  const writer = new rpc.WebSocketMessageWriter(socket);
  const asExternalProccess =
    process.argv.findIndex(value => value === '--external') !== -1;
  if (asExternalProccess) {
    // start the language server as an external process
    //const extJsonServerPath = path.resolve(__dirname, 'ext-json-server.js');
    const socketConnection = server.createConnection(reader, writer, () =>
      socket.dispose()
    );
    //const serverConnection = server.createServerProcess('JSON', 'node', [extJsonServerPath]);
    const serverConnection = server.createServerProcess('CPP', 'clangd-12');
    if (serverConnection) {
      server.forward(socketConnection, serverConnection, message => {
        if (Message.isRequest(message)) {
          if (message.method === lsp.InitializeRequest.type.method) {
            const initializeParams = message.params as lsp.InitializeParams;
            initializeParams.processId = process.pid;
          }
        }
        return message;
      });
    }
  } else {
    // start the language server inside the current process
    start(reader, writer);
  }
}

Then:

# "cannot find module 'semver' error when running npm install?
# See https://stackoverflow.com/questions/33870520/npm-install-cannot-find-module-semver
npm install
npm run build
node dist/server.js --external

To keep the server running:

sudo apt install tmux
tmux
node dist/server.js --external

# https://askubuntu.com/questions/8653/how-to-keep-processes-running-after-ending-ssh-session
ctrl+b d

# later, to get back into the session
tmux attach -t 0

Firepad / YJS Browser Incompatibility

See FirebaseExtended/firepad#315 and yjs/y-monaco#6.

Replace something similar to

var n = this.configurationService.getValue('files.eol', {
  overrideIdentifier: t,
  resource: e,
});
return n && 'auto' !== n ? n : d.isLinux || d.isMacintosh ? '\n' : '\r\n';

with

var n = this.configurationService.getValue('files.eol', {
  overrideIdentifier: t,
  resource: e,
});
return n && 'auto' !== n ? n : d.isLinux || d.isMacintosh ? '\n' : '\n';

using package-patch.

Monaco Workers

Run

mkdir ./public/monaco-workers
cp -r ./node_modules/monaco-editor-workers/dist/workers/editorWorker* ./public/monaco-workers

This is used by MonacoEditor.tsx (Monaco uses web workers).

Troubleshooting firebase emulators:exec

If firebase emulators:exec fails for unknown reason, try running firebase emulators:exec "yarn playwright test" || cat firebase-debug.log.

Tests that should be written

• Compile error, stdout, stderr
• Too large input
• Too large output
• Classrooms
• Copying files (#64, this broke already lol)

Updating Monaco Editor

Make sure Monaco is compatible with monaco-languageclient!! https://github.com/TypeFox/monaco-languageclient/blob/main/docs/versions-and-history.md#monaco-editor--codingamemonaco-vscode-api-compatibility-table

1. npm install monaco-editor@latest

2. Modify node_modules/monaco-editor/esm/vs/editor/standalone/browser/standaloneServices.js:

   -        return (isLinux || isMacintosh) ? '\n' : '\r\n';
   +        return (isLinux || isMacintosh) ? '\n' : '\n';
   

   See patches/monaco-editor+??.patch for more details

3. npx patch-package monaco-editor

4. Commit the updated patch to Github

5. rm -r ./public/monaco-workers

6. mkdir ./public/monaco-workers

7. cp -r ./node_modules/monaco-editor-workers/dist/workers/editorWorker* ./public/monaco-workers

8. Test that everything works: LSP, browser sync, cross-platform sync, etc