const node = require('rollup-plugin-node-resolve');
const commonjs = require('rollup-plugin-commonjs');

// Parse the stamp file produced by Bazel from the version control system
let version = '<unknown>';
if (bazel_stamp_file) {
  const versionTag = require('fs')
                         .readFileSync(bazel_stamp_file, {encoding: 'utf-8'})
                         .split('\n')
                         .find(s => s.startsWith('BUILD_SCM_VERSION'));
  // Don't assume BUILD_SCM_VERSION exists
  if (versionTag) {
    version = versionTag.split(' ')[1].trim();
  }
}

// Add 'use strict' to the bundle, https://github.com/angular/angular/pull/40456
// When rollup build esm bundle of zone.js, there will be no 'use strict'
// since all esm bundles are `strict`, but when webpack load the esm bundle,
// because zone.js is a module without export and import, webpack is unable
// to determine the bundle is `esm` module or not, so it doesn't add the 'use strict'
// which webpack does to all other `esm` modules which has export or import.
// And it causes issues such as https://github.com/angular/angular/issues/40215
// `this` should be `undefined` but is assigned with `Window` instead.
const banner = `'use strict';
/**
 * @license Angular v${version}
 * (c) 2010-2020 Google LLC. https://angular.io/
 * License: MIT
*/`;

module.exports = {
  plugins: [
    node({
      mainFields: ['es2015', 'module', 'jsnext:main', 'main'],
    }),
    commonjs(),
  ],
  output: {name: 'Zone', banner},
}