/**
 * 加载.env*环境变量文件，用于将定义的环境变量注入DefinePlugin
 */
const fs = require('fs');
const path = require('path');
const paths = require('./paths');

// 确保在env.js之后包含paths.js,以便读取.env变量
delete require.cache[require.resolve('./paths')];

const { NODE_ENV } = process.env;
if (!NODE_ENV) {
  throw new Error('Node的环境变量“NODE_ENV”未定义！');
}

const dotenvFiles = [
  `${paths.dotenv}.${NODE_ENV}.local`,
  `${paths.dotenv}.${NODE_ENV}`,
  NODE_ENV !== 'test' && `${paths.dotenv}.local`,
  paths.dotenv,
].filter(Boolean);

// 从.env*文件中加载环境变量
/* eslint-disable import/no-extraneous-dependencies */
dotenvFiles.forEach(dotenvFile => {
  if (fs.existsSync(dotenvFile)) {
    require('dotenv-expand')(
      require('dotenv').config({
        path: dotenvFile,
      })
    );
  }
});

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);

const SETTING = /^_SETTING_/i;
function getClientEnvironment(publicUrl) {
  /* eslint-disable no-param-reassign */
  const raw = Object.keys(process.env)
    .filter(key => SETTING.test(key))
    .reduce(
      (env, key) => {
        const newKey = key.substr(9);
        env[newKey] = process.env[key];
        return env;
      },
      {
        NODE_ENV: process.env.NODE_ENV || 'development',
        PUBLIC_URL: publicUrl,
      }
    );
  // 将所有变量值进行字符串化，以便传入DefinePlugin插件
  /* eslint-disable no-param-reassign */
  const stringified = {
    'process.env': Object.keys(raw).reduce((env, key) => {
      env[key] = JSON.stringify(raw[key]);
      return env;
    }, {}),
  };

  return { raw, stringified };
}

module.exports = getClientEnvironment;