feat: use node to call codegen (#685)

### Summary

We were using `npx` to call the React Native Community CLI
for codegen. However, not every environment has `npx` available. This
adds custom logic to invoke the RNCCLI only using the node binary.

This also emits a better error message when the user doesn't have
`@react-native-community/cli` installed on their library project.

### Test plan
1. Create a new architecture supported library
3. Call `yarn bob build --target codegen`
3. Make sure the command passes without any problems

packages/react-native-builder-bob/src/targets/codegen.ts

@@ -1,10 +1,10 @@
 import kleur from 'kleur';
 import type { Input } from '../types';
 import { patchCodegen } from '../utils/patchCodegen';
-import { spawn } from '../utils/spawn';
 import fs from 'fs-extra';
 import path from 'path';
 import del from 'del';
+import { runRNCCli } from '../utils/runRNCCli';
 
 type Options = Input;
 
@@ -33,11 +33,9 @@ export default async function build({ root, report }: Options) {
   }
 
   try {
-    await spawn('npx', ['@react-native-community/cli', 'codegen'], {
-      stdio: 'ignore',
-    });
+    await runRNCCli(['codegen']);
 
-    patchCodegen(root, packageJson, report);
+    await patchCodegen(root, packageJson, report);
 
     report.success('Generated native code with codegen');
   } catch (e: unknown) {
@@ -47,14 +45,24 @@ export default async function build({ root, report }: Options) {
           `Errors found while generating codegen files:\n${e.stdout.toString()}`
         );
       } else if ('message' in e && typeof e.message === 'string') {
-        report.error(e.message);
+        if (
+          e.message.includes(
+            "Error: Cannot find module '@react-native-community/cli/package.json'"
+          )
+        ) {
+          report.error(
+            "You don't have `@react-native-community/cli` in your root package's dev dependencies. Please install it and make sure it uses the same version as your application."
+          );
+        } else {
+          report.error(e.message);
+        }
       } else {
         throw e;
       }
     } else {
       throw e;
     }
 
-    throw new Error('Failed generate the codegen files.');
+    process.exit(1);
   }
 }

packages/react-native-builder-bob/src/utils/runRNCCli.ts

@@ -0,0 +1,54 @@
+import { type SpawnOptions } from 'node:child_process';
+import { spawn } from './spawn';
+import path from 'node:path';
+import fs from 'fs-extra';
+import assert from 'node:assert';
+
+// This is a special case for calling bob from the XCode scripts
+// XCode scripts don't have the node binary properly set
+// We expose an env value for node instead.
+const NODE_BINARY = process.env['NODE_BINARY'] || 'node';
+
+/**
+ * Runs the React Native Community CLI with the specified arguments
+ */
+export async function runRNCCli(
+  args: string[],
+  options: SpawnOptions = {
+    stdio: 'ignore',
+  }
+) {
+  const rncCliBinaryName = await getCliBinaryName();
+
+  const RNC_CLI_BINARY_PATH = path.resolve(
+    process.cwd(), // We are always expected to run in the library
+    'node_modules',
+    '.bin',
+    rncCliBinaryName
+  );
+
+  return await spawn(NODE_BINARY, [RNC_CLI_BINARY_PATH, ...args], options);
+}
+
+async function getCliBinaryName(): Promise<string> {
+  const rncCliPackagePath = await spawn(NODE_BINARY, [
+    '-e',
+    `console.log(require.resolve('@react-native-community/cli/package.json'))`,
+  ]);
+
+  const rncCliPackage = await fs.readJson(rncCliPackagePath);
+  const binProperty = rncCliPackage.bin as Record<string, string>;
+  assert(
+    typeof binProperty === 'object',
+    "React Native CLI doesn't specify proper binaries"
+  );
+
+  const binaries = Object.keys(binProperty);
+  const rncCliBinaryName = binaries[0] as string;
+  assert(
+    typeof rncCliBinaryName === 'string',
+    "React Native Community CLI doesn't have any binaries to run"
+  );
+
+  return rncCliBinaryName;
+}