config.js

const path = require('path');
const buble = require('rollup-plugin-buble')
// const cjs = require('rollup-plugin-commonjs')
const replace = require('rollup-plugin-replace')
const node = require('rollup-plugin-node-resolve')
const pack = require('../package.json')
const version = process.env.VERSION || pack.version

const moduleName = 'cloud-utils';

const banner =
  `/*!
 * ${moduleName} v${version} (https://github.com/cloud-templates/cloud-utils)
 * API https://cloud-templates.github.io/cloud-utils/
 * Copyright 2017-${(new Date).getFullYear()} ${pack.author.name}. All Rights Reserved
 * Licensed under ${pack.license} (https://github.com/cloud-templates/cloud-utils/blob/master/LICENSE)
 */
 `

const resolve = (p) => {
  return path.resolve(__dirname, '../', p)
}

const builds = {
  // Runtime only (CommonJS). Used by bundlers e.g. Webpack & Browserify
  commonjs: {
    entry: resolve('src/main.js'),
    dest: resolve(`dist/${moduleName}.common.js`),
    format: 'cjs',
    banner
  },
  // Runtime only (ES Modules). Used by bundlers that support ES Modules,
  // e.g. Rollup & Webpack 2
  esm: {
    entry: resolve('src/main.js'),
    dest: resolve(`dist/${moduleName}.esm.js`),
    format: 'es',
    banner
  },
  // runtime-only production build (Browser)
  production: {
    entry: resolve('src/main.js'),
    dest: resolve(`dist/${moduleName}.min.js`),
    format: 'umd',
    env: 'production',
    moduleName,
    banner
  },
  // runtime-only build (Browser)
  development: {
    entry: resolve('src/main.js'),
    dest: resolve(`dist/${moduleName}.js`),
    format: 'umd',
    env: 'development',
    moduleName,
    banner
  }
}

function genConfig(name) {
  const opts = builds[name]
  const config = {
    input: opts.entry,
    external: opts.external,
    plugins: [
      node(),
      buble()
    ].concat(opts.plugins || []),
    output: {
      file: opts.dest,
      format: opts.format,
      banner: opts.banner,
      name: opts.moduleName
    }
  }

  const replacePluginOptions = {'__VERSION__': pack.version}
  if (opts.env) {
    replacePluginOptions['process.env.NODE_ENV'] = JSON.stringify(opts.env)
  }
  config.plugins.push(replace(replacePluginOptions))

  Object.defineProperty(config, '_name', {
    enumerable: false,
    value: name
  })

  return config
}

if (process.env.TARGET) {
  module.exports = genConfig(process.env.TARGET)
} else {
  exports.getBuild = genConfig
  exports.getAllBuilds = () => Object.keys(builds).map(genConfig)
}