source: frontend/node_modules/enhanced-resolve/lib/DescriptionFileUtils.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").JsonObject} JsonObject */
/** @typedef {import("./Resolver").JsonValue} JsonValue */
/** @typedef {import("./Resolver").ResolveContext} ResolveContext */
/** @typedef {import("./Resolver").ResolveRequest} ResolveRequest */

/**
 * @typedef {object} DescriptionFileInfo
 * @property {JsonObject=} content content
 * @property {string} path path
 * @property {string} directory directory
 */

/**
 * @callback ErrorFirstCallback
 * @param {Error | null=} error
 * @param {DescriptionFileInfo=} result
 */

/**
 * @typedef {object} Result
 * @property {string} path path to description file
 * @property {string} directory directory of description file
 * @property {JsonObject} content content of description file
 */

const CHAR_SLASH = 47;
const CHAR_BACKSLASH = 92;

/**
 * Walk up one directory. Called once per package-root candidate and once per
 * `described-resolve` (to find the enclosing description file), so it's on
 * the resolver's hot path.
 *
 * Previous implementation called `lastIndexOf("/")` and `lastIndexOf("\\")`
 * separately and then picked the larger. For any non-trivial directory
 * string on POSIX, `lastIndexOf("\\")` scans the full string just to return
 * -1. A single reverse char-code scan does the same work in one pass.
 *
 * Any single-character directory is treated as a root — `directory.length
 * <= 1` collapses the `"/"`, `"\\"` and `""` branches into one compare.
 * Without the `"\\"` case, `cdUp("\\")` (reached from a UNC root or a DOS
 * device path like `\\?\…`) would return itself via `slice(0, i || 1)`
 * and trap `loadDescriptionFile` in an infinite loop. Once single-char
 * roots are filtered up front, the reverse scan always produces a
 * strictly shorter string.
 * @param {string} directory directory
 * @returns {string | null} parent directory or null
 */
function cdUp(directory) {
        if (directory.length <= 1) return null;
        for (let i = directory.length - 1; i >= 0; i--) {
                const code = directory.charCodeAt(i);
                if (code === CHAR_SLASH || code === CHAR_BACKSLASH) {
                        return directory.slice(0, i || 1);
                }
        }
        return null;
}

/**
 * @param {Resolver} resolver resolver
 * @param {string} directory directory
 * @param {string[]} filenames filenames
 * @param {DescriptionFileInfo | undefined} oldInfo oldInfo
 * @param {ResolveContext} resolveContext resolveContext
 * @param {ErrorFirstCallback} callback callback
 */
function loadDescriptionFile(
        resolver,
        directory,
        filenames,
        oldInfo,
        resolveContext,
        callback,
) {
        // Hoist the per-filename iterator and the per-level done callback out
        // of `findDescriptionFile`. They both close over `directory`, which we
        // reassign as we walk up the tree, so the same closures keep working
        // across every level — the previous implementation re-allocated both
        // arrows on every recursion step, which adds up on deep walks (multiple
        // `DescriptionFilePlugin` taps per resolve, each climbing several
        // directories looking for `package.json`).
        /**
         * @param {string} filename filename
         * @param {(err?: null | Error, result?: null | Result) => void} iterCallback callback
         * @returns {void}
         */
        const iterFilename = (filename, iterCallback) => {
                const descriptionFilePath = resolver.join(directory, filename);

                /**
                 * @param {(null | Error)=} err error
                 * @param {JsonObject=} resolvedContent content
                 * @returns {void}
                 */
                function onJson(err, resolvedContent) {
                        if (err) {
                                if (resolveContext.log) {
                                        resolveContext.log(
                                                `${descriptionFilePath} (directory description file): ${err}`,
                                        );
                                } else {
                                        err.message = `${descriptionFilePath} (directory description file): ${err}`;
                                }
                                return iterCallback(err);
                        }
                        iterCallback(null, {
                                content: /** @type {JsonObject} */ (resolvedContent),
                                directory,
                                path: descriptionFilePath,
                        });
                }

                if (resolver.fileSystem.readJson) {
                        resolver.fileSystem.readJson(descriptionFilePath, (err, content) => {
                                if (err) {
                                        if (
                                                typeof (/** @type {NodeJS.ErrnoException} */ (err).code) !==
                                                "undefined"
                                        ) {
                                                if (resolveContext.missingDependencies) {
                                                        resolveContext.missingDependencies.add(descriptionFilePath);
                                                }
                                                return iterCallback();
                                        }
                                        if (resolveContext.fileDependencies) {
                                                resolveContext.fileDependencies.add(descriptionFilePath);
                                        }
                                        return onJson(err);
                                }
                                if (resolveContext.fileDependencies) {
                                        resolveContext.fileDependencies.add(descriptionFilePath);
                                }
                                onJson(null, content);
                        });
                } else {
                        resolver.fileSystem.readFile(descriptionFilePath, (err, content) => {
                                if (err) {
                                        if (resolveContext.missingDependencies) {
                                                resolveContext.missingDependencies.add(descriptionFilePath);
                                        }
                                        return iterCallback();
                                }
                                if (resolveContext.fileDependencies) {
                                        resolveContext.fileDependencies.add(descriptionFilePath);
                                }

                                /** @type {JsonObject | undefined} */
                                let json;

                                if (content) {
                                        try {
                                                json = JSON.parse(content.toString());
                                        } catch (/** @type {unknown} */ err_) {
                                                return onJson(/** @type {Error} */ (err_));
                                        }
                                } else {
                                        return onJson(new Error("No content in file"));
                                }

                                onJson(null, json);
                        });
                }
        };
        // Forward-declared so the helpers below can reference each other
        // without falling foul of `no-use-before-define`.
        /** @type {() => void} */
        let findDescriptionFile;
        /**
         * @param {(null | Error)=} err error
         * @param {(null | Result)=} result result
         * @returns {void}
         */
        const onLevelDone = (err, result) => {
                if (err) return callback(err);
                if (result) return callback(null, result);
                const dir = cdUp(directory);
                if (!dir) {
                        return callback();
                }
                directory = dir;
                return findDescriptionFile();
        };
        findDescriptionFile = () => {
                if (oldInfo && oldInfo.directory === directory) {
                        // We already have info for this directory and can reuse it
                        return callback(null, oldInfo);
                }
                forEachBail(filenames, iterFilename, onLevelDone);
        };
        findDescriptionFile();
}

/**
 * @param {JsonObject} content content
 * @param {string | string[]} field field
 * @returns {JsonValue | undefined} field data
 */
function getField(content, field) {
        if (!content) return undefined;
        if (Array.isArray(field)) {
                /** @type {JsonValue} */
                let current = content;
                for (let j = 0; j < field.length; j++) {
                        if (current === null || typeof current !== "object") {
                                current = null;
                                break;
                        }
                        current = /** @type {JsonValue} */ (
                                /** @type {JsonObject} */
                                (current)[field[j]]
                        );
                }
                return current;
        }
        return content[field];
}

module.exports.cdUp = cdUp;
module.exports.getField = getField;
module.exports.loadDescriptionFile = loadDescriptionFile;