react-native/packages/react-native/scripts/featureflags/generateFiles.js

/**
 * 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.
 *
 * @format
 */

const generateAndroidModules = require('./generateAndroidModules');
const generateCommonCxxModules = require('./generateCommonCxxModules');
const generateJavaScriptModules = require('./generateJavaScriptModules');
const fs = require('fs');

module.exports = function generateFiles(generatorConfig, generatorOptions) {
  const userDefinedFeatureFlagsConfig = JSON.parse(
    fs.readFileSync(generatorConfig.configPath, 'utf8'),
  );

  const featureFlagsConfig = Object.assign(
    {jsOnly: {}, common: {}},
    userDefinedFeatureFlagsConfig,
  );

  fs.mkdirSync(generatorConfig.jsPath, {recursive: true});
  fs.mkdirSync(generatorConfig.commonCxxPath, {recursive: true});
  fs.mkdirSync(generatorConfig.commonNativeModuleCxxPath, {recursive: true});
  fs.mkdirSync(generatorConfig.androidPath, {recursive: true});
  fs.mkdirSync(generatorConfig.androidJniPath, {recursive: true});

  const jsModules = generateJavaScriptModules(
    generatorConfig,
    featureFlagsConfig,
  );

  const commonCxxModules = generateCommonCxxModules(
    generatorConfig,
    featureFlagsConfig,
  );

  const androidModules = generateAndroidModules(
    generatorConfig,
    featureFlagsConfig,
  );

  const generatedFiles = {...jsModules, ...commonCxxModules, ...androidModules};

  if (generatorOptions.verifyUnchanged) {
    const existingModules = {};
    for (const moduleName of Object.keys(generatedFiles)) {
      const existingModule = fs.readFileSync(moduleName, 'utf8');
      existingModules[moduleName] = existingModule;
    }

    const changedFiles = [];
    for (const moduleName of Object.keys(generatedFiles)) {
      const module = generatedFiles[moduleName];
      const existingModule = existingModules[moduleName];

      if (module !== existingModule) {
        changedFiles.push(moduleName);
      }
    }

    if (changedFiles.length > 0) {
      const changedFilesStr = changedFiles
        .map(changedFile => '    ' + changedFile)
        .join('\n');

      throw new Error(
        `Detected changes in generated files for feature flags:\n${changedFilesStr}\n\n` +
          'Please rerun `yarn featureflags-update` and commit the changes.',
      );
    }

    return;
  }

  for (const [modulePath, moduleContents] of Object.entries(generatedFiles)) {
    fs.writeFileSync(modulePath, moduleContents, 'utf8');
  }
};