'use strict';
 
 const fs = require('fs');
 const path = require('path');
 const paths = require('./paths');
 
 // Make sure that including paths.js after env.js will read .env variables.
 delete require.cache[require.resolve('./paths')];
 
 const NODE_ENV = process.env.NODE_ENV;
 if (!NODE_ENV) {
   throw new Error(
     'The NODE_ENV environment variable is required but was not specified.'
   );
 }
 
 // https://github.com/bkeepers/dotenv#what-other-env-files-can-i-use
 var dotenvFiles = [
   `${paths.dotenv}.${NODE_ENV}.local`,
   `${paths.dotenv}.${NODE_ENV}`,
   // Don't include `.env.local` for `test` environment
   // since normally you expect tests to produce the same
   // results for everyone
   NODE_ENV !== 'test' && `${paths.dotenv}.local`,
   paths.dotenv,
 ].filter(Boolean);
 
 // Load environment variables from .env* files. Suppress warnings using silent
 // if this file is missing. dotenv will never modify any environment variables
 // that have already been set.  Variable expansion is supported in .env files.
 // https://github.com/motdotla/dotenv
 // https://github.com/motdotla/dotenv-expand
 dotenvFiles.forEach(dotenvFile => {
   if (fs.existsSync(dotenvFile)) {
     require('dotenv-expand')(
       require('dotenv').config({
         path: dotenvFile,
       })
     );
   }
 });
 
 // We support resolving modules according to `NODE_PATH`.
 // This lets you use absolute paths in imports inside large monorepos:
 // https://github.com/facebookincubator/create-react-app/issues/253.
 // It works similar to `NODE_PATH` in Node itself:
 // https://nodejs.org/api/modules.html#modules_loading_from_the_global_folders
 // Note that unlike in Node, only *relative* paths from `NODE_PATH` are honored.
 // Otherwise, we risk importing Node.js core modules into an app instead of Webpack shims.
 // https://github.com/facebookincubator/create-react-app/issues/1023#issuecomment-265344421
 // We also resolve them to make sure all tools using them work consistently.
 const appDirectory = fs.realpathSync(process.cwd());
 process.env.NODE_PATH = (process.env.NODE_PATH || '')
   .split(path.delimiter)
   .filter(folder => folder && !path.isAbsolute(folder))
   .map(folder => path.resolve(appDirectory, folder))
   .join(path.delimiter);
 
 // Grab NODE_ENV and REACT_APP_* environment variables and prepare them to be
 // injected into the application via DefinePlugin in Webpack configuration.
 const REACT_APP = /^REACT_APP_/i;
 
 function getClientEnvironment(publicUrl) {
   const raw = Object.keys(process.env)
     .filter(key => REACT_APP.test(key))
     .reduce(
       (env, key) => {
         env[key] = process.env[key];
         return env;
       },
       {
         // Useful for determining whether we’re running in production mode.
         // Most importantly, it switches React into the correct mode.
         NODE_ENV: process.env.NODE_ENV || 'development',
         // Useful for resolving the correct path to static assets in `public`.
         // For example, <img src={process.env.PUBLIC_URL + '/img/logo.png'} />.
         // This should only be used as an escape hatch. Normally you would put
         // images into the `src` and `import` them in code to get their paths.
         PUBLIC_URL: publicUrl,
       }
     );
   // Stringify all values so we can feed into Webpack DefinePlugin
   const stringified = {
     'process.env': Object.keys(raw).reduce((env, key) => {
       env[key] = JSON.stringify(raw[key]);
       return env;
     }, {}),
   };
 
   return { raw, stringified };
 }
 
 module.exports = getClientEnvironment;