/**
 * @license
 * Copyright Google Inc. 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 * as path from 'path';
import { Compiler, compilation } from 'webpack';
import { RawSource } from 'webpack-sources';
import {
  CrossOriginValue,
  FileInfo,
  augmentIndexHtml,
} from '../utilities/index-file/augment-index-html';
import { IndexHtmlTransform } from '../utilities/index-file/write-index-html';
import { stripBom } from '../utilities/strip-bom';

export interface IndexHtmlWebpackPluginOptions {
  input: string;
  output: string;
  baseHref?: string;
  entrypoints: string[];
  deployUrl?: string;
  sri: boolean;
  noModuleEntrypoints: string[];
  moduleEntrypoints: string[];
  postTransform?: IndexHtmlTransform;
  crossOrigin?: CrossOriginValue;
  lang?: string;
}

function readFile(filename: string, compilation: compilation.Compilation): Promise<string> {
  return new Promise<string>((resolve, reject) => {
    compilation.inputFileSystem.readFile(filename, (err: Error, data: Buffer) => {
      if (err) {
        reject(err);

        return;
      }

      resolve(stripBom(data.toString()));
    });
  });
}

export class IndexHtmlWebpackPlugin {
  private _options: IndexHtmlWebpackPluginOptions;

  constructor(options?: Partial<IndexHtmlWebpackPluginOptions>) {
    this._options = {
      input: 'index.html',
      output: 'index.html',
      entrypoints: ['polyfills', 'main'],
      noModuleEntrypoints: [],
      moduleEntrypoints: [],
      sri: false,
      ...options,
    };
  }

  apply(compiler: Compiler) {
    compiler.hooks.emit.tapPromise('index-html-webpack-plugin', async compilation => {
      // Get input html file
      const inputContent = await readFile(this._options.input, compilation);
      compilation.fileDependencies.add(this._options.input);

      // Get all files for selected entrypoints
      const files: FileInfo[] = [];
      const noModuleFiles: FileInfo[] = [];
      const moduleFiles: FileInfo[] = [];

      for (const [entryName, entrypoint] of compilation.entrypoints) {
        const entryFiles: FileInfo[] = ((entrypoint && entrypoint.getFiles()) || []).map(
          (f: string): FileInfo => ({
            name: entryName,
            file: f,
            extension: path.extname(f),
          }),
        );

        if (this._options.noModuleEntrypoints.includes(entryName)) {
          noModuleFiles.push(...entryFiles);
        } else if (this._options.moduleEntrypoints.includes(entryName)) {
          moduleFiles.push(...entryFiles);
        } else {
          files.push(...entryFiles);
        }
      }

      const loadOutputFile = async (name: string) => {
        const data = compilation.assets[name].source();

        return typeof data === 'string' ? data : data.toString();
      };
      let indexSource = await augmentIndexHtml({
        input: this._options.input,
        inputContent,
        baseHref: this._options.baseHref,
        deployUrl: this._options.deployUrl,
        sri: this._options.sri,
        crossOrigin: this._options.crossOrigin,
        files,
        noModuleFiles,
        loadOutputFile,
        moduleFiles,
        entrypoints: this._options.entrypoints,
        lang: this._options.lang,
      });

      if (this._options.postTransform) {
        indexSource = await this._options.postTransform(indexSource);
      }

      // Add to compilation assets
      compilation.assets[this._options.output] = new RawSource(indexSource);
    });
  }
}
