Relocate CLI plugin server modules (#57654)

Summary:
Pull Request resolved: #57654

Reorganise these modules under a `src/dev-server/` directory (out of `src/(commands|utils)/`, more clearly identifying this unit of the codebase.

No public API change: the package still exports `startCommand` unchanged.

Renames inside this directory:

- `middleware.js` → `loadCommunityMiddleware.js`
- `runServer.js` → `runDevServer.js`

Changelog: [Internal]

Differential Revision: D113412985

Author: huntie

…y-cli-plugin/src/commands/start/index.js …mmunity-cli-plugin/src/commands/start.jspackages/community-cli-plugin/src/commands/start/index.js renamed to packages/community-cli-plugin/src/commands/start.js packages/community-cli-plugin/src/commands/start/index.js renamed to packages/community-cli-plugin/src/commands/start.js

@@ -10,14 +10,12 @@
 
 import type {Command} from '@react-native-community/cli-types';
 
-import runServer from './runServer';
+import runDevServer from '../dev-server/runDevServer';
 import path from 'node:path';
 
-export type {StartCommandArgs} from './runServer';
-
 const startCommand: Command = {
   name: 'start',
-  func: runServer,
+  func: runDevServer,
   description: 'Start the React Native development server.',
   options: [
     {

packages/community-cli-plugin/src/commands/start/middleware.js

@@ -33,6 +33,7 @@ export default async function isDevServerRunning(
       return 'not_running';
     }
 
+    // FIXME: Depends on @react-native-community/cli-server-api
     const statusResponse = await fetch(`${devServerUrl}/status`);
     const body = await statusResponse.text();
 

…nds/start/OpenDebuggerKeyboardHandler.js …ev-server/OpenDebuggerKeyboardHandler.jspackages/community-cli-plugin/src/commands/start/OpenDebuggerKeyboardHandler.js renamed to packages/community-cli-plugin/src/dev-server/OpenDebuggerKeyboardHandler.js packages/community-cli-plugin/src/commands/start/OpenDebuggerKeyboardHandler.js renamed to packages/community-cli-plugin/src/dev-server/OpenDebuggerKeyboardHandler.js

@@ -0,0 +1,94 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict-local
+ * @format
+ */
+
+import type {Server} from 'connect';
+import type {TerminalReportableEvent} from 'metro';
+
+const debug = require('debug')('ReactNative:CommunityCliPlugin');
+
+type DevServerMiddlewareFactory = (params: {
+  host?: string,
+  port: number,
+  watchFolders: ReadonlyArray<string>,
+}) => {
+  middleware: Server,
+  websocketEndpoints: {[path: string]: ws$WebSocketServer},
+  messageSocketEndpoint: {
+    server: ws$WebSocketServer,
+    broadcast: (
+      method: string,
+      params?: Record<string, unknown> | null,
+    ) => void,
+  },
+  eventsSocketEndpoint: {
+    server: ws$WebSocketServer,
+    reportEvent: (event: TerminalReportableEvent) => void,
+  },
+  ...
+};
+
+// $FlowFixMe[incompatible-type]
+const unusedStubWSServer: ws$WebSocketServer = {};
+// $FlowFixMe[incompatible-type]
+const unusedMiddlewareStub: Server = {};
+
+// FIXME: Several features will break without community middleware
+// (@react-native-community/cli-server-api) and should be migrated into core.
+// e.g. used by packages/react-native/Libraries/Core/Devtools/:
+// - /open-stack-frame
+// - /open-url
+// - /symbolicate
+// e.g. used by ./isDevServerRunning.js:
+// - /status
+const communityMiddlewareFallback: DevServerMiddlewareFactory = () => ({
+  middleware: unusedMiddlewareStub,
+  websocketEndpoints: {},
+  messageSocketEndpoint: {
+    server: unusedStubWSServer,
+    broadcast: (
+      method: string,
+      _params?: Record<string, unknown> | null,
+    ): void => {},
+  },
+  eventsSocketEndpoint: {
+    server: unusedStubWSServer,
+    reportEvent: (event: TerminalReportableEvent) => {},
+  },
+});
+
+/**
+ * Attempt to load the `createDevServerMiddleware` factory from
+ * `@react-native-community/cli` (an optional peer dependency). If it cannot be
+ * found, return a factory that produces stub middleware instead.
+ */
+export default function loadCommunityMiddleware(): DevServerMiddlewareFactory {
+  try {
+    // `@react-native-community/cli` is an optional peer dependency of this
+    // package, and should be a dev dependency of the host project (via the
+    // community template's package.json).
+    const communityCliPath = require.resolve('@react-native-community/cli');
+
+    // Until https://github.com/react-native-community/cli/pull/2605 lands,
+    // we need to find `@react-native-community/cli-server-api` via
+    // `@react-native-community/cli`. Once that lands, we can simply
+    // require('@react-native-community/cli').
+    const communityCliServerApiPath = require.resolve(
+      '@react-native-community/cli-server-api',
+      {paths: [communityCliPath]},
+    );
+    // $FlowFixMe[unsupported-syntax] dynamic import
+    return require(communityCliServerApiPath)
+      .createDevServerMiddleware as CreateDevServerMiddleware;
+  } catch {
+    debug(`⚠️ Unable to find @react-native-community/cli-server-api
+Starting the server without the community middleware.`);
+    return communityMiddlewareFallback;
+  }
+}

…/src/commands/start/attachKeyHandlers.js …ugin/src/dev-server/attachKeyHandlers.jspackages/community-cli-plugin/src/commands/start/attachKeyHandlers.js renamed to packages/community-cli-plugin/src/dev-server/attachKeyHandlers.js packages/community-cli-plugin/src/commands/start/attachKeyHandlers.js renamed to packages/community-cli-plugin/src/dev-server/attachKeyHandlers.js

@@ -11,19 +11,19 @@
 import type {Config} from '@react-native-community/cli-types';
 import type {Reporter, TerminalReportableEvent, TerminalReporter} from 'metro';
 
-import createDevMiddlewareLogger from '../../utils/createDevMiddlewareLogger';
-import isDevServerRunning from '../../utils/isDevServerRunning';
-import loadMetroConfig from '../../utils/loadMetroConfig';
-import * as version from '../../utils/version';
+import loadMetroConfig from '../utils/loadMetroConfig';
 import attachKeyHandlers from './attachKeyHandlers';
-import {createDevServerMiddleware} from './middleware';
+import createDevMiddlewareLogger from './createDevMiddlewareLogger';
+import isDevServerRunning from './isDevServerRunning';
+import loadCommunityMiddleware from './loadCommunityMiddleware';
+import * as version from './version';
 import {createDevMiddleware} from '@react-native/dev-middleware';
 import * as Metro from 'metro';
 import path from 'node:path';
 import url from 'node:url';
 import {styleText} from 'node:util';
 
-export type StartCommandArgs = {
+export type DevServerOptions = {
   assetPlugins?: string[],
   cert?: string,
   customLogReporterPath?: string,
@@ -43,10 +43,10 @@ export type StartCommandArgs = {
   clientLogs: boolean,
 };
 
-async function runServer(
+async function runDevServer(
   _argv: Array<string>,
   cliConfig: Config,
-  args: StartCommandArgs,
+  args: DevServerOptions,
 ) {
   const metroConfig = await loadMetroConfig(cliConfig, {
     config: args.config,
@@ -107,12 +107,13 @@ async function runServer(
   const ReporterImpl = getReporterImpl(args.customLogReporterPath);
   const terminalReporter = new ReporterImpl(terminal);
 
+  const createCommunityMiddleware = loadCommunityMiddleware();
   const {
     middleware: communityMiddleware,
     websocketEndpoints: communityWebsocketEndpoints,
     messageSocketEndpoint,
     eventsSocketEndpoint,
-  } = createDevServerMiddleware({
+  } = createCommunityMiddleware({
     host: hostname,
     port,
     watchFolders,
@@ -186,4 +187,4 @@ function getReporterImpl(
   }
 }
 
-export default runServer;
+export default runDevServer;