/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import { join } from '@angular-devkit/core';
import { DirEntry, Rule } from '@angular-devkit/schematics';
import { NodePackageInstallTask } from '@angular-devkit/schematics/tasks';
import { addPackageJsonDependency, getPackageJsonDependency } from '../../utility/dependencies';

const fileExtensionRegexp = /\.(([cm]?j|t)sx?)$/;

function* visitJavaScriptFiles(directory: DirEntry): IterableIterator<string> {
  for (const path of directory.subfiles) {
    if (!fileExtensionRegexp.test(path)) {
      continue;
    }

    yield join(directory.path, path);
  }

  for (const path of directory.subdirs) {
    if (path === 'node_modules' || path.startsWith('.') || path === 'dist') {
      continue;
    }

    yield* visitJavaScriptFiles(directory.dir(path));
  }
}

export default function (): Rule {
  return (tree, context) => {
    const current = getPackageJsonDependency(tree, 'zone.js');
    if (current && current.version !== '~0.11.4') {
      addPackageJsonDependency(tree, {
        type: current.type,
        name: 'zone.js',
        version: '~0.11.4',
        overwrite: true,
      });

      context.addTask(new NodePackageInstallTask());
    }

    for (const path of visitJavaScriptFiles(tree.root)) {
      const buffer = tree.read(path);
      if (!buffer) {
        return;
      }

      const content = buffer.toString();
      if (!content.includes('zone.js/dist/')) {
        continue;
      }

      // RegExp that replaces
      // - import 'zone.js/dist/zone-testing' -> import 'zone.js/testing'
      // - require('zone.js/dist/zone-testing') -> require('zone.js/testing')
      // - import 'zone.js/dist/zone' -> import 'zone.js'
      // - require('zone.js/dist/zone') -> require('zone.js')
      // - import 'zone.js/dist/zone-error' -> import 'zone.js/plugins/zone-error'
      // - require('zone.js/dist/zone-error') -> require('zone.js/plugins/zone-error')
      tree.overwrite(
        path,
        content.replace(
          /(?<=(?:require\s*\(|import\s+)['"]zone\.js)\/dist\/zone-?\w*(?=['"]\)?)/g,
          (match) => {
            switch (match) {
              case '/dist/zone':
              case '/dist/zone-evergreen':
                return '';
              case '/dist/zone-testing':
              case '/dist/zone-evergreen-testing':
                return '/testing';
              case '/dist/zone-node':
                return '/node';
              case '/dist/zone-mix':
                return '/mix';
              default:
                return `/plugins${match.substr(5)}`;
            }
          },
        ),
      );
    }
  };
}