/*
  Copyright 2018 Google LLC

  Use of this source code is governed by an MIT-style
  license that can be found in the LICENSE file or at
  https://opensource.org/licenses/MIT.
*/

const assert = require('assert');
const path = require('path');
const {getManifest} = require('workbox-build');

const convertStringToAsset = require('./lib/convert-string-to-asset');
const getDefaultConfig = require('./lib/get-default-config');
const formatManifestFilename = require('./lib/format-manifest-filename');
const getAssetHash = require('./lib/get-asset-hash');
const getManifestEntriesFromCompilation =
  require('./lib/get-manifest-entries-from-compilation');
const getWorkboxSWImports = require('./lib/get-workbox-sw-imports');
const readFileWrapper = require('./lib/read-file-wrapper');
const relativeToOutputPath = require('./lib/relative-to-output-path');
const sanitizeConfig = require('./lib/sanitize-config');
const stringifyManifest = require('./lib/stringify-manifest');
const warnAboutConfig = require('./lib/warn-about-config');

/**
 * This class supports taking an existing service worker file which already
 * uses Workbox, and injecting a reference to a [precache manifest]() into it,
 * allowing it to efficiently precache the assets created by a webpack build.
 *
 * Use an instance of `InjectManifest` in the
 * [`plugins` array](https://webpack.js.org/concepts/plugins/#usage) of a
 * webpack config.
 *
 * @module workbox-webpack-plugin
 */
class InjectManifest {
  /**
   * Creates an instance of InjectManifest.
   *
   * @param {Object} [config] See the
   * [configuration guide](/web/tools/workbox/modules/workbox-webpack-plugin#configuration)
   * for all supported options and defaults.
   */
  constructor(config = {}) {
    assert(typeof config.swSrc === 'string', `swSrc must be set to the path ` +
      `to an existing service worker file.`);

    this.config = Object.assign(getDefaultConfig(), {
      // Default to using the same filename as the swSrc file, since that's
      // provided here. (In GenerateSW, that's not available.)
      swDest: path.basename(config.swSrc),
    }, config);
  }

  /**
   * @param {Object} compilation The webpack compilation.
   * @param {Function} readFile The function to use when reading files,
   * derived from compiler.inputFileSystem.
   * @private
   */
  async handleEmit(compilation, readFile) {
    const configWarning = warnAboutConfig(this.config);
    if (configWarning) {
      compilation.warnings.push(configWarning);
    }

    const workboxSWImports = await getWorkboxSWImports(
        compilation, this.config);

    // this.config.modulePathPrefix may or may not have been set by
    // getWorkboxSWImports(), depending on the other config options. If it was
    // set, we need to pull it out and make use of it later, as it can't be
    // used by the underlying workbox-build getManifest() method.
    const modulePathPrefix = this.config.modulePathPrefix;
    delete this.config.modulePathPrefix;

    let entries = getManifestEntriesFromCompilation(compilation, this.config);
    const importScriptsArray = [].concat(this.config.importScripts);

    const sanitizedConfig = sanitizeConfig.forGetManifest(this.config);
    // If there are any "extra" config options remaining after we remove the
    // ones that are used natively by the plugin, then assume that they should
    // be passed on to workbox-build.getManifest() to generate extra entries.
    if (Object.keys(sanitizedConfig).length > 0) {
      // If globPatterns isn't explicitly set, then default to [], instead of
      // the workbox-build.getManifest() default.
      sanitizedConfig.globPatterns = sanitizedConfig.globPatterns || [];

      const {manifestEntries, warnings} = await getManifest(sanitizedConfig);
      compilation.warnings = compilation.warnings.concat(warnings || []);
      entries = entries.concat(manifestEntries);
    }

    const manifestString = stringifyManifest(entries);
    const manifestAsset = convertStringToAsset(manifestString);
    const manifestHash = getAssetHash(manifestAsset);

    const manifestFilename = formatManifestFilename(
        this.config.precacheManifestFilename, manifestHash);

    const pathToManifestFile = relativeToOutputPath(
        compilation, path.join(this.config.importsDirectory, manifestFilename));
    compilation.assets[pathToManifestFile] = manifestAsset;

    importScriptsArray.push((compilation.options.output.publicPath || '') +
      pathToManifestFile.split(path.sep).join('/'));

    // workboxSWImports might be null if importWorkboxFrom is 'disabled'.
    if (workboxSWImports) {
      importScriptsArray.push(...workboxSWImports);
    }

    let originalSWString;
    /**
     * Check if the mentioned file name is in the webpack assets itself
     * or fallback to filesystem.
     */
    if (compilation.assets[this.config.swSrc]) {
      originalSWString = compilation.assets[this.config.swSrc].source();
    } else {
      originalSWString = await readFileWrapper(readFile, this.config.swSrc);
    }

    // compilation.fileDependencies needs absolute paths.
    const absoluteSwSrc = path.resolve(this.config.swSrc);
    if (Array.isArray(compilation.fileDependencies)) {
      // webpack v3
      if (compilation.fileDependencies.indexOf(absoluteSwSrc) === -1) {
        compilation.fileDependencies.push(absoluteSwSrc);
      }
    } else if ('add' in compilation.fileDependencies) {
      // webpack v4; no need to check for membership first, since it's a Set.
      compilation.fileDependencies.add(absoluteSwSrc);
    }

    const importScriptsString = importScriptsArray
        .map(JSON.stringify)
        .join(', ');

    const setConfigString = modulePathPrefix
      ? `workbox.setConfig({modulePathPrefix: ` +
        `${JSON.stringify(modulePathPrefix)}});`
      : '';

    const postInjectionSWString = `importScripts(${importScriptsString});
${setConfigString}
${originalSWString}
`;

    const relSwDest = relativeToOutputPath(compilation, this.config.swDest);
    compilation.assets[relSwDest] = convertStringToAsset(postInjectionSWString);
  }

  /**
   * @param {Object} [compiler] default compiler object passed from webpack
   *
   * @private
   */
  apply(compiler) {
    const readFile = compiler.inputFileSystem.readFile
        .bind(compiler.inputFileSystem);
    if ('hooks' in compiler) {
      // We're in webpack 4+.
      compiler.hooks.emit.tapPromise(
          this.constructor.name,
          (compilation) => this.handleEmit(compilation, readFile)
      );
    } else {
      // We're in webpack 2 or 3.
      compiler.plugin('emit', (compilation, callback) => {
        this.handleEmit(compilation, readFile)
            .then(callback)
            .catch(callback);
      });
    }
  }
}

module.exports = InjectManifest;