/*
  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 {generateSWString} = require('workbox-build');
const path = require('path');

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 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 creating a new, ready-to-use service worker file as
 * part of the webpack compilation process.
 *
 * Use an instance of `GenerateSW` in the
 * [`plugins` array](https://webpack.js.org/concepts/plugins/#usage) of a
 * webpack config.
 *
 * @module workbox-webpack-plugin
 */
class GenerateSW {
  /**
   * Creates an instance of GenerateSW.
   *
   * @param {Object} [config] See the
   * [configuration guide](/web/tools/workbox/modules/workbox-webpack-plugin#configuration)
   * for all supported options and defaults.
   */
  constructor(config = {}) {
    this.config = Object.assign(getDefaultConfig(), {
      // Hardcode this default filename, since we don't have swSrc to read from
      // (like we do in InjectManifest).
      swDest: 'service-worker.js',
    }, config);
  }

  /**
   * @param {Object} compilation The webpack compilation.
   * @private
   */
  async handleEmit(compilation) {
    const configWarning = warnAboutConfig(this.config);
    if (configWarning) {
      compilation.warnings.push(configWarning);
    }

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

    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'.
    let workboxSWImport;
    if (workboxSWImports) {
      if (workboxSWImports.length === 1) {
        // When importWorkboxFrom is 'cdn' or 'local', or a chunk name
        // that only contains one JavaScript asset, then this will be a one
        // element array, containing just the Workbox SW code.
        workboxSWImport = workboxSWImports[0];
      } else {
        // If importWorkboxFrom was a chunk name that contained multiple
        // JavaScript assets, then we don't know which contains the Workbox SW
        // code. Just import them first as part of the "main" importScripts().
        importScriptsArray.unshift(...workboxSWImports);
      }
    }

    const sanitizedConfig = sanitizeConfig.forGenerateSWString(this.config);
    // If globPatterns isn't explicitly set, then default to [], instead of
    // the workbox-build.generateSWString() default.
    sanitizedConfig.globPatterns = sanitizedConfig.globPatterns || [];
    sanitizedConfig.importScripts = importScriptsArray;
    sanitizedConfig.workboxSWImport = workboxSWImport;
    const {swString, warnings} = await generateSWString(sanitizedConfig);
    compilation.warnings = compilation.warnings.concat(warnings || []);

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

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

module.exports = GenerateSW;