source: imaps-frontend/node_modules/enhanced-resolve/lib/ExtensionAliasPlugin.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 */
/** @typedef {{ alias: string|string[], extension: string }} ExtensionAliasOption */

module.exports = class ExtensionAliasPlugin {
        /**
         * @param {string | ResolveStepHook} source source
         * @param {ExtensionAliasOption} options options
         * @param {string | ResolveStepHook} target target
         */
        constructor(source, options, target) {
                this.source = source;
                this.options = options;
                this.target = target;
        }

        /**
         * @param {Resolver} resolver the resolver
         * @returns {void}
         */
        apply(resolver) {
                const target = resolver.ensureHook(this.target);
                const { extension, alias } = this.options;
                resolver
                        .getHook(this.source)
                        .tapAsync("ExtensionAliasPlugin", (request, resolveContext, callback) => {
                                const requestPath = request.request;
                                if (!requestPath || !requestPath.endsWith(extension)) return callback();
                                const isAliasString = typeof alias === "string";
                                /**
                                 * @param {string} alias extension alias
                                 * @param {(err?: null|Error, result?: null|ResolveRequest) => void} callback callback
                                 * @param {number} [index] index
                                 * @returns {void}
                                 */
                                const resolve = (alias, callback, index) => {
                                        const newRequest = `${requestPath.slice(
                                                0,
                                                -extension.length
                                        )}${alias}`;

                                        return resolver.doResolve(
                                                target,
                                                {
                                                        ...request,
                                                        request: newRequest,
                                                        fullySpecified: true
                                                },
                                                `aliased from extension alias with mapping '${extension}' to '${alias}'`,
                                                resolveContext,
                                                (err, result) => {
                                                        // Throw error if we are on the last alias (for multiple aliases) and it failed, always throw if we are not an array or we have only one alias
                                                        if (!isAliasString && index) {
                                                                if (index !== this.options.alias.length) {
                                                                        if (resolveContext.log) {
                                                                                resolveContext.log(
                                                                                        `Failed to alias from extension alias with mapping '${extension}' to '${alias}' for '${newRequest}': ${err}`
                                                                                );
                                                                        }

                                                                        return callback(null, result);
                                                                }

                                                                return callback(err, result);
                                                        } else {
                                                                callback(err, result);
                                                        }
                                                }
                                        );
                                };
                                /**
                                 * @param {null|Error} [err] error
                                 * @param {null|ResolveRequest} [result] result
                                 * @returns {void}
                                 */
                                const stoppingCallback = (err, result) => {
                                        if (err) return callback(err);
                                        if (result) return callback(null, result);
                                        // Don't allow other aliasing or raw request
                                        return callback(null, null);
                                };
                                if (isAliasString) {
                                        resolve(alias, stoppingCallback);
                                } else if (alias.length > 1) {
                                        forEachBail(alias, resolve, stoppingCallback);
                                } else {
                                        resolve(alias[0], stoppingCallback);
                                }
                        });
        }
};