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

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

"use strict";

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

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

const slashCode = "/".charCodeAt(0);

module.exports = class SelfReferencePlugin {
        /**
         * @param {string | ResolveStepHook} source source
         * @param {string | string[]} fieldNamePath name path
         * @param {string | ResolveStepHook} target target
         */
        constructor(source, fieldNamePath, target) {
                this.source = source;
                this.target = target;
                this.fieldName = fieldNamePath;
        }

        /**
         * @param {Resolver} resolver the resolver
         * @returns {void}
         */
        apply(resolver) {
                const target = resolver.ensureHook(this.target);
                resolver
                        .getHook(this.source)
                        .tapAsync("SelfReferencePlugin", (request, resolveContext, callback) => {
                                if (!request.descriptionFilePath) return callback();

                                const req = request.request;
                                if (!req) return callback();

                                // Feature is only enabled when an exports field is present
                                const exportsField = DescriptionFileUtils.getField(
                                        request.descriptionFileData,
                                        this.fieldName
                                );
                                if (!exportsField) return callback();

                                const name = DescriptionFileUtils.getField(
                                        request.descriptionFileData,
                                        "name"
                                );
                                if (typeof name !== "string") return callback();

                                if (
                                        req.startsWith(name) &&
                                        (req.length === name.length ||
                                                req.charCodeAt(name.length) === slashCode)
                                ) {
                                        const remainingRequest = `.${req.slice(name.length)}`;

                                        const obj = {
                                                ...request,
                                                request: remainingRequest,
                                                path: /** @type {string} */ (request.descriptionFileRoot),
                                                relativePath: "."
                                        };

                                        resolver.doResolve(
                                                target,
                                                obj,
                                                "self reference",
                                                resolveContext,
                                                callback
                                        );
                                } else {
                                        return callback();
                                }
                        });
        }
};