source: frontend/node_modules/enhanced-resolve/lib/RootsPlugin.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Ivan Kopeykin @vankop
*/

"use strict";

const forEachBail = require("./forEachBail");

/** @typedef {import("./Resolver")} Resolver */
/** @typedef {import("./Resolver").ResolveRequest} ResolveRequest */
/** @typedef {import("./Resolver").ResolveStepHook} ResolveStepHook */

class RootsPlugin {
        /**
         * @param {string | ResolveStepHook} source source hook
         * @param {Set<string>} roots roots
         * @param {string | ResolveStepHook} target target hook
         */
        constructor(source, roots, target) {
                this.roots = [...roots];
                this.source = source;
                this.target = target;
        }

        /**
         * @param {Resolver} resolver the resolver
         * @returns {void}
         */
        apply(resolver) {
                const target = resolver.ensureHook(this.target);

                resolver
                        .getHook(this.source)
                        .tapAsync("RootsPlugin", (request, resolveContext, callback) => {
                                const req = request.request;
                                if (!req) return callback();
                                if (!req.startsWith("/")) return callback();

                                forEachBail(
                                        this.roots,
                                        /**
                                         * @param {string} root root
                                         * @param {(err?: null | Error, result?: null | ResolveRequest) => void} callback callback
                                         * @returns {void}
                                         */
                                        (root, callback) => {
                                                const path = resolver.join(root, req.slice(1));
                                                /** @type {ResolveRequest} */
                                                const obj = {
                                                        ...request,
                                                        path,
                                                        relativePath: request.relativePath && path,
                                                };
                                                resolver.doResolve(
                                                        target,
                                                        obj,
                                                        `root path ${root}`,
                                                        resolveContext,
                                                        callback,
                                                );
                                        },
                                        callback,
                                );
                        });
        }
}

module.exports = RootsPlugin;