source: trip-planner-front/node_modules/enhanced-resolve/lib/AliasPlugin.js

/*
        MIT License http://www.opensource.org/licenses/mit-license.php
        Author Tobias Koppers @sokra
*/

"use strict";

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

/** @typedef {import("./Resolver")} Resolver */
/** @typedef {import("./Resolver").ResolveStepHook} ResolveStepHook */
/** @typedef {{alias: string|Array<string>|false, name: string, onlyModule?: boolean}} AliasOption */

module.exports = class AliasPlugin {
        /**
         * @param {string | ResolveStepHook} source source
         * @param {AliasOption | Array<AliasOption>} options options
         * @param {string | ResolveStepHook} target target
         */
        constructor(source, options, target) {
                this.source = source;
                this.options = Array.isArray(options) ? options : [options];
                this.target = target;
        }

        /**
         * @param {Resolver} resolver the resolver
         * @returns {void}
         */
        apply(resolver) {
                const target = resolver.ensureHook(this.target);
                resolver
                        .getHook(this.source)
                        .tapAsync("AliasPlugin", (request, resolveContext, callback) => {
                                const innerRequest = request.request || request.path;
                                if (!innerRequest) return callback();
                                forEachBail(
                                        this.options,
                                        (item, callback) => {
                                                let shouldStop = false;
                                                if (
                                                        innerRequest === item.name ||
                                                        (!item.onlyModule && innerRequest.startsWith(item.name + "/"))
                                                ) {
                                                        const remainingRequest = innerRequest.substr(item.name.length);
                                                        const resolveWithAlias = (alias, callback) => {
                                                                if (alias === false) {
                                                                        const ignoreObj = {
                                                                                ...request,
                                                                                path: false
                                                                        };
                                                                        return callback(null, ignoreObj);
                                                                }
                                                                if (
                                                                        innerRequest !== alias &&
                                                                        !innerRequest.startsWith(alias + "/")
                                                                ) {
                                                                        shouldStop = true;
                                                                        const newRequestStr = alias + remainingRequest;
                                                                        const obj = {
                                                                                ...request,
                                                                                request: newRequestStr,
                                                                                fullySpecified: false
                                                                        };
                                                                        return resolver.doResolve(
                                                                                target,
                                                                                obj,
                                                                                "aliased with mapping '" +
                                                                                        item.name +
                                                                                        "': '" +
                                                                                        alias +
                                                                                        "' to '" +
                                                                                        newRequestStr +
                                                                                        "'",
                                                                                resolveContext,
                                                                                (err, result) => {
                                                                                        if (err) return callback(err);
                                                                                        if (result) return callback(null, result);
                                                                                        return callback();
                                                                                }
                                                                        );
                                                                }
                                                                return callback();
                                                        };
                                                        const stoppingCallback = (err, result) => {
                                                                if (err) return callback(err);

                                                                if (result) return callback(null, result);
                                                                // Don't allow other aliasing or raw request
                                                                if (shouldStop) return callback(null, null);
                                                                return callback();
                                                        };
                                                        if (Array.isArray(item.alias)) {
                                                                return forEachBail(
                                                                        item.alias,
                                                                        resolveWithAlias,
                                                                        stoppingCallback
                                                                );
                                                        } else {
                                                                return resolveWithAlias(item.alias, stoppingCallback);
                                                        }
                                                }
                                                return callback();
                                        },
                                        callback
                                );
                        });
        }
};