text: /*
  MIT License http://www.opensource.org/licenses/mit-license.php
  Author Tobias Koppers @sokra
  */
  "use strict";
  
  const DescriptionFileUtils = require("./DescriptionFileUtils");
  
  module.exports = class DescriptionFilePlugin {
  	constructor(source, filenames, target) {
  		this.source = source;
  		this.filenames = [].concat(filenames);
  		this.target = target;
  	}
  
  	apply(resolver) {
  		const target = resolver.ensureHook(this.target);
  		resolver
  			.getHook(this.source)
  			.tapAsync(
  				"DescriptionFilePlugin",
  				(request, resolveContext, callback) => {
  					const directory = request.path;
  					DescriptionFileUtils.loadDescriptionFile(
  						resolver,
  						directory,
  						this.filenames,
  						resolveContext,
  						(err, result) => {
  							if (err) return callback(err);
  							if (!result) {
  								if (resolveContext.missing) {
  									this.filenames.forEach(filename => {
  										resolveContext.missing.add(
  											resolver.join(directory, filename)
  										);
  									});
  								}
  								if (resolveContext.log)
  									resolveContext.log("No description file found");
  								return callback();
  							}
  							const relativePath =
  								"." +
  								request.path
  									.substr(result.directory.length)
  									.replace(/\\/g, "/");
  							const obj = Object.assign({}, request, {
  								descriptionFilePath: result.path,
  								descriptionFileData: result.content,
  								descriptionFileRoot: result.directory,
  								relativePath: relativePath
  							});
  							resolver.doResolve(
  								target,
  								obj,
  								"using description file: " +
  									result.path +
  									" (relative path: " +
  									relativePath +
  									")",
  								resolveContext,
  								(err, result) => {
  									if (err) return callback(err);
  
  									// Don't allow other processing
  									if (result === undefined) return callback(null, null);
  									callback(null, result);
  								}
  							);
  						}
  					);
  				}
  			);
  	}
  };
  