/**
 * @license
 * Copyright (c) 2016 The Polymer Project Authors. All rights reserved.
 * This code may only be used under the BSD style license found at
 * http://polymer.github.io/LICENSE.txt
 * The complete set of authors may be found at
 * http://polymer.github.io/AUTHORS.txt
 * The complete set of contributors may be found at
 * http://polymer.github.io/CONTRIBUTORS.txt
 * Code distributed by Google as part of the polymer project is also
 * subject to an additional IP rights grant found at
 * http://polymer.github.io/PATENTS.txt
 */

import File = require('vinyl');
import {ResolvedUrl} from 'polymer-analyzer';
import {Bundler, Options, BundleManifest, generateShellMergeStrategy} from 'polymer-bundler';
import {ProjectConfig} from 'polymer-project-config';

import {BuildAnalyzer} from './analyzer';
import {FileMapUrlLoader} from './file-map-url-loader';
import {pathFromUrl, urlFromPath, LocalFsPath} from './path-transformers';
import {AsyncTransformStream} from './streams';

export {Options} from 'polymer-bundler';

export class BuildBundler extends AsyncTransformStream<File, File> {
  config: ProjectConfig;

  private _buildAnalyzer: BuildAnalyzer;
  private _bundler: Bundler;

  // A map of urls to file objects.  As the transform stream handleds files
  // coming into the stream, it collects all files here.  After bundlling,
  // we remove files from this set that have been inlined and replace
  // entrypoint/fragment files with bundled versions.
  files = new Map<ResolvedUrl, File>();

  constructor(
      config: ProjectConfig, buildAnalyzer: BuildAnalyzer,
      options: Options = {}) {
    super({objectMode: true});

    this.config = config;

    this._buildAnalyzer = buildAnalyzer;

    const bundlerOptions = {...options};

    const urlLoader = new FileMapUrlLoader(
        this.files, bundlerOptions.analyzer || buildAnalyzer.analyzer);
    bundlerOptions.analyzer =
        (bundlerOptions.analyzer || buildAnalyzer.analyzer)._fork({urlLoader});

    if (bundlerOptions.strategy === undefined &&
        this.config.shell !== undefined) {
      bundlerOptions.strategy = generateShellMergeStrategy(
          bundlerOptions.analyzer.resolveUrl(urlFromPath(
              this.config.root as LocalFsPath,
              this.config.shell as LocalFsPath))!);
    }

    this._bundler = new Bundler(bundlerOptions);
  }

  protected async *
      _transformIter(files: AsyncIterable<File>): AsyncIterable<File> {
    for await (const file of files) {
      this._mapFile(file);
    }
    await this._buildBundles();
    for (const file of this.files.values()) {
      yield file;
    }
  }

  private async _buildBundles() {
    // Tell the analyzer about changed files so it can purge them from its cache
    // before using the analyzer for bundling.
    await this._bundler.analyzer.filesChanged(
        this._getFilesChangedSinceInitialAnalysis());

    const {documents, manifest} =
        await this._bundler.bundle(await this._generateBundleManifest());
    // Remove the bundled files from the file map so they are not emitted later.
    this._unmapBundledFiles(manifest);

    // Map the bundles into the file map.
    for (const [url, document] of documents) {
      this._mapFile(new File({
        path: pathFromUrl(
            this.config.root as LocalFsPath,
            this._bundler.analyzer.urlResolver.relative(url)),
        contents: Buffer.from(document.content),
      }));
    }
  }

  private async _generateBundleManifest(): Promise<BundleManifest> {
    const entrypoints = this.config.allFragments.map(
        (e) => this._bundler.analyzer.resolveUrl(
            urlFromPath(this.config.root as LocalFsPath, e as LocalFsPath))!);
    return this._bundler.generateManifest(entrypoints);
  }

  private _getFilesChangedSinceInitialAnalysis(): string[] {
    const filesChanged = [];
    for (const [url, originalFile] of this._buildAnalyzer.files) {
      const downstreamFile =
          this.files.get(this._buildAnalyzer.analyzer.resolveUrl(url)!);
      if (downstreamFile == null) {
        throw new Error(
            `Internal error: could not find downstreamFile at ${url}`);
      }
      if (downstreamFile.contents!.toString() !==
          originalFile.contents!.toString()) {
        filesChanged.push(url);
      }
    }
    return filesChanged;
  }

  private _mapFile(file: File) {
    this.files.set(
        this._buildAnalyzer.analyzer.resolveUrl(urlFromPath(
            this.config.root as LocalFsPath, file.path as LocalFsPath))!,
        file);
  }

  /**
   * Removes all of the inlined files in a bundle manifest from the filemap.
   */
  private _unmapBundledFiles(manifest: BundleManifest) {
    for (const {
           files,
           inlinedHtmlImports,
           inlinedScripts,
           inlinedStyles,
         } of manifest.bundles.values()) {
      for (const url
               of [...files,
                   ...inlinedHtmlImports,
                   ...inlinedScripts,
                   ...inlinedStyles]) {
        // Don't unmap the bundle file url itself.
        if (!manifest.bundles.has(url)) {
          this.files.delete(url);
        }
      }
    }
  }
}