/**
 * @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;
}

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 = (name: string) =>
          compilation.assets[name].source();
        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,
        });

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

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