cloudfoundry/stratos

import * as fs from 'fs';
import * as path from 'path';
import { NormalModuleReplacementPlugin, WatchIgnorePlugin } from 'webpack';

import { StratosConfig } from '../lib/stratos.config';

const importModuleRegex = /src\/frontend\/packages\/core\/src\/custom-import.module.ts/;

const isWindows = process.platform === 'win32';

/**
 * Generates the file _custom-import.module.ts containing the code to import
 * the extensions modules discovered from the packages being included.
 *
 * This also adds a module replacement into the build process, so that this generated file
 * is used instead of the default one in the repository, which does not import
 * any extensions.
 */

export class ExtensionsHandler {

  constructor() { }

  // Write out the _custom-import.module.ts file importing all of the required extensions
  public apply(webpackConfig: any, config: StratosConfig, options: any) {

    // Generate the module file to import the appropriate extensions
    const dir = path.join(config.rootDir, path.dirname(options.main));
    const overrideFile = path.resolve(path.join(dir, './_custom-import.module.ts'));

    fs.writeFileSync(overrideFile, '// This file is auto-generated - DO NOT EDIT\n\n');
    fs.appendFileSync(overrideFile, 'import { NgModule } from \'@angular/core\';\n');

    const moduleImports = {
      imports: []
    };

    const routingModuleImports = {
      imports: []
    };

    config.getExtensions().forEach(e => {
      let modules = [];
      if (e.module) {
        moduleImports.imports.push(e.module);
        modules.push(e.module);
      }
      if (e.routingModule) {
        routingModuleImports.imports.push(e.routingModule);
        modules.push(e.routingModule)
      }

      fs.appendFileSync(overrideFile, 'import { ' + modules.join(', ') + ' } from \'' + e.package + '\';\n');
    });

    this.writeModule(overrideFile, 'CustomImportModule', moduleImports);
    this.writeModule(overrideFile, 'CustomRoutingImportModule', routingModuleImports);

    let regex;
    // On windows, use an absolute path with backslashes escaped
    if (isWindows) {
      let p = path.resolve(path.join(dir, 'custom-import.module.ts'));
      p = p.replace(/\\/g, '\\\\');
      regex = new RegExp(p);
    } else {
      regex = importModuleRegex;
    }

    // Ignore changed in the overrides file - otherwise with ng serve we will build twice
    // The user needs to restart `ng serve` anyway if new extensions are added
    webpackConfig.plugins.push(new WatchIgnorePlugin([overrideFile]));

    webpackConfig.plugins.push(new NormalModuleReplacementPlugin(
      regex,
      overrideFile
    ));
  }

  private writeModule(file: string, name: string, imports: any) {
    fs.appendFileSync(file, '\n@NgModule(\n');
    let json = JSON.stringify(imports, null, 2);
    json = json.replace(/['"]+/g, '');
    fs.appendFileSync(file, json);
    fs.appendFileSync(file, ')\n');
    fs.appendFileSync(file, 'export class ' + name + ' {}\n\n');
  }
}