rollup.config.js

import resolve from 'rollup-plugin-node-resolve'
import { uglify } from 'rollup-plugin-uglify'
import replace from 'rollup-plugin-replace'
import babel from 'rollup-plugin-babel'
import alias from 'rollup-plugin-alias'
import cjs from 'rollup-plugin-commonjs'
import path from 'path'
import getLernaPackages from 'get-lerna-packages'
import { rollup as lernaAliases } from 'lerna-alias'

const flatMap = (iteratee, arr) => [].concat(...arr.map(iteratee))
const uniq = arr => [...new Set(arr)]

const pkg = require(path.resolve(process.cwd(), './package.json'))

const basePlugins = [
  cjs({ exclude: [path.join(__dirname, 'packages', '*/src/**/*')] }),
  resolve(),
  babel({
    presets: [
      [
        '@babel/env',
        {
          loose: true,
          modules: false,
          exclude: ['transform-typeof-symbol']
        }
      ],
      '@babel/stage-0',
      '@babel/react',
      '@babel/flow'
    ],
    plugins: ['codegen', 'closure-elimination'],
    babelrc: false
  })
]

const baseConfig = {
  input: './src/index.js'
}

const baseExternal = ['react', 'prop-types', 'preact']

const mainConfig = Object.assign({}, baseConfig, {
  external: uniq(
    baseExternal.concat(
      flatMap(dir => {
        const {
          dependencies = {},
          peerDependencies = {}
        } = require(`${dir}/package.json`)

        return [...Object.keys(dependencies), ...Object.keys(peerDependencies)]
      }, getLernaPackages())
    )
  ),
  plugins: basePlugins,
  output: [
    {
      file: pkg.main,
      format: 'cjs',
      sourcemap: true
    },
    {
      file: pkg.module,
      format: 'es',
      sourcemap: true
    }
  ]
})

const umdConfig = Object.assign({}, baseConfig, {
  plugins: [alias(lernaAliases())].concat(basePlugins).concat(
    replace({
      'process.env.NODE_ENV': JSON.stringify('production')
    }),
    uglify()
  ),
  output: [
    {
      file: './dist/emotion.umd.min.js',
      format: 'umd',
      name: pkg.name,
      globals: { react: 'React', 'prop-types': 'PropTypes', preact: 'preact' },
      sourcemap: true
    }
  ],
  external: baseExternal
})

export default [mainConfig, umdConfig]