module.exports = function(api) {
  var validEnv = ['development', 'test', 'production']
  var currentEnv = api.env()

  if (!validEnv.includes(currentEnv)) {
    throw new Error(
      'Please specify a valid `NODE_ENV` or ' +
        '`BABEL_ENV` environment variables. Valid values are "development", ' +
        '"test", and "production". Instead, received: ' +
        JSON.stringify(currentEnv) +
        '.'
    )
  }

  return {
    presets: [
      '@babel/preset-env',
      '@babel/preset-react',
      '@babel/preset-typescript',
    ],
    env: {
      test: {
        presets: [
          [
            '@babel/preset-env',
            {
              targets: {
                node: '12',
              },
              modules: 'commonjs',
              useBuiltIns: false,
              debug: false,
            }
          ],
          '@babel/preset-react',
          'jest'
        ]
      }
    },
    plugins: [
      '@babel/plugin-syntax-dynamic-import',
      '@babel/plugin-proposal-object-rest-spread',
      '@babel/plugin-proposal-class-properties',
    ],
  }
}