source: frontend/node_modules/webpack/lib/util/chainedImports.js

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

"use strict";

/** @typedef {import("../Dependency")} Dependency */
/** @typedef {import("../Module")} Module */
/** @typedef {import("../ModuleGraph")} ModuleGraph */
/** @typedef {import("../javascript/JavascriptParser").Range} Range */

/** @typedef {Range[]} IdRanges */

/**
 * @summary Get the subset of ids and their corresponding range in an id chain that should be re-rendered by webpack.
 * Only those in the chain that are actually referring to namespaces or imports should be re-rendered.
 * Deeper member accessors on the imported object should not be re-rendered.  If deeper member accessors are re-rendered,
 * there is a potential loss of meaning with rendering a quoted accessor as an unquoted accessor, or vice versa,
 * because minifiers treat quoted accessors differently.  e.g. import { a } from "./module"; a["b"] vs a.b
 * @param {string[]} untrimmedIds chained ids
 * @param {Range} untrimmedRange range encompassing allIds
 * @param {IdRanges | undefined} ranges cumulative range of ids for each of allIds
 * @param {ModuleGraph} moduleGraph moduleGraph
 * @param {Dependency} dependency dependency
 * @returns {{ trimmedIds: string[], trimmedRange: Range }} computed trimmed ids and cumulative range of those ids
 */
module.exports.getTrimmedIdsAndRange = (
        untrimmedIds,
        untrimmedRange,
        ranges,
        moduleGraph,
        dependency
) => {
        let trimmedIds = trimIdsToThoseImported(
                untrimmedIds,
                moduleGraph,
                dependency
        );
        let trimmedRange = untrimmedRange;
        if (trimmedIds.length !== untrimmedIds.length) {
                // The array returned from dep.idRanges is right-aligned with the array returned from dep.names.
                // Meaning, the two arrays may not always have the same number of elements, but the last element of
                // dep.idRanges corresponds to [the expression fragment to the left of] the last element of dep.names.
                // Use this to find the correct replacement range based on the number of ids that were trimmed.
                const idx =
                        ranges === undefined
                                ? -1 /* trigger failure case below */
                                : ranges.length + (trimmedIds.length - untrimmedIds.length);
                if (idx < 0 || idx >= /** @type {Range[]} */ (ranges).length) {
                        // cspell:ignore minifiers
                        // Should not happen but we can't throw an error here because of backward compatibility with
                        // external plugins in wp5.  Instead, we just disable trimming for now.  This may break some minifiers.
                        trimmedIds = untrimmedIds;
                        // TODO webpack 6 remove the "trimmedIds = ids" above and uncomment the following line instead.
                        // throw new Error("Missing range starts data for id replacement trimming.");
                } else {
                        trimmedRange = /** @type {Range[]} */ (ranges)[idx];
                }
        }

        return { trimmedIds, trimmedRange };
};

/**
 * @summary Determine which IDs in the id chain are actually referring to namespaces or imports,
 * and which are deeper member accessors on the imported object.
 * @param {string[]} ids untrimmed ids
 * @param {ModuleGraph} moduleGraph moduleGraph
 * @param {Dependency} dependency dependency
 * @returns {string[]} trimmed ids
 */
function trimIdsToThoseImported(ids, moduleGraph, dependency) {
        /** @type {string[]} */
        let trimmedIds = [];
        let currentExportsInfo = moduleGraph.getExportsInfo(
                /** @type {Module} */ (moduleGraph.getModule(dependency))
        );
        for (let i = 0; i < ids.length; i++) {
                if (i === 0 && ids[i] === "default") {
                        continue; // ExportInfo for the next level under default is still at the root ExportsInfo, so don't advance currentExportsInfo
                }
                const exportInfo = currentExportsInfo.getExportInfo(ids[i]);
                if (exportInfo.provided === false) {
                        // json imports have nested ExportInfo for elements that things that are not actually exported, so check .provided
                        trimmedIds = ids.slice(0, i);
                        break;
                }
                const nestedInfo = exportInfo.getNestedExportsInfo();
                if (!nestedInfo) {
                        // once all nested exports are traversed, the next item is the actual import so stop there
                        trimmedIds = ids.slice(0, i + 1);
                        break;
                }
                currentExportsInfo = nestedInfo;
        }
        // Never trim to nothing.  This can happen for invalid imports (e.g. import { notThere } from "./module", or import { anything } from "./missingModule")
        return trimmedIds.length ? trimmedIds : ids;
}