text: const fs = require('fs');
  const path = require('path');
  const util = require('util');
  const assert = require('assert');
  const yaml = require('js-yaml');
  const { findIndex, isEmpty } = require('lodash');
  const readDirP = require('readdirp');
  const { helpCategoryMap } = require('../client/utils/challenge-types');
  const { showUpcomingChanges } = require('../config/env.json');
  const { curriculum: curriculumLangs } =
    require('../config/i18n/all-langs').availableLangs;
  const { parseMD } = require('../tools/challenge-parser/parser');
  /* eslint-disable max-len */
  const {
    translateCommentsInChallenge
  } = require('../tools/challenge-parser/translation-parser');
  /* eslint-enable max-len*/
  
  const { isAuditedCert } = require('../utils/is-audited');
  const { createPoly } = require('../utils/polyvinyl');
  const { dasherize } = require('../utils/slugs');
  const { getSuperOrder, getSuperBlockFromDir } = require('./utils');
  
  const access = util.promisify(fs.access);
  
  const CHALLENGES_DIR = path.resolve(__dirname, 'challenges');
  const META_DIR = path.resolve(CHALLENGES_DIR, '_meta');
  exports.CHALLENGES_DIR = CHALLENGES_DIR;
  exports.META_DIR = META_DIR;
  
  const COMMENT_TRANSLATIONS = createCommentMap(
    path.resolve(__dirname, 'dictionaries')
  );
  
  function getTranslatableComments(dictionariesDir) {
    const COMMENTS_TO_TRANSLATE = require(path.resolve(
      dictionariesDir,
      'english',
      'comments.json'
    ));
    return Object.values(COMMENTS_TO_TRANSLATE);
  }
  
  exports.getTranslatableComments = getTranslatableComments;
  
  function createCommentMap(dictionariesDir) {
    // get all the languages for which there are dictionaries.
    const languages = fs
      .readdirSync(dictionariesDir)
      .filter(x => x !== 'english');
  
    // get all their dictionaries
    const dictionaries = languages.reduce(
      (acc, lang) => ({
        ...acc,
        [lang]: require(path.resolve(dictionariesDir, lang, 'comments.json'))
      }),
      {}
    );
  
    // get the english dicts
    const COMMENTS_TO_TRANSLATE = require(path.resolve(
      dictionariesDir,
      'english',
      'comments.json'
    ));
  
    const COMMENTS_TO_NOT_TRANSLATE = require(path.resolve(
      dictionariesDir,
      'english',
      'comments-to-not-translate'
    ));
  
    // map from english comment text to translations
    const translatedCommentMap = Object.entries(COMMENTS_TO_TRANSLATE).reduce(
      (acc, [id, text]) => {
        return {
          ...acc,
          [text]: getTranslationEntry(dictionaries, { engId: id, text })
        };
      },
      {}
    );
  
    // map from english comment text to itself
    const untranslatableCommentMap = Object.values(
      COMMENTS_TO_NOT_TRANSLATE
    ).reduce((acc, text) => {
      const englishEntry = languages.reduce(
        (acc, lang) => ({
          ...acc,
          [lang]: text
        }),
        {}
      );
      return {
        ...acc,
        [text]: englishEntry
      };
    }, {});
  
    return { ...translatedCommentMap, ...untranslatableCommentMap };
  }
  
  exports.createCommentMap = createCommentMap;
  
  function getTranslationEntry(dicts, { engId, text }) {
    return Object.keys(dicts).reduce((acc, lang) => {
      const entry = dicts[lang][engId];
      if (entry) {
        return { ...acc, [lang]: entry };
      } else {
        // default to english
        return { ...acc, [lang]: text };
      }
    }, {});
  }
  
  function getChallengesDirForLang(lang) {
    return path.resolve(CHALLENGES_DIR, `${lang}`);
  }
  
  function getMetaForBlock(block) {
    return JSON.parse(
      fs.readFileSync(path.resolve(META_DIR, `${block}/meta.json`), 'utf8')
    );
  }
  
  function parseCert(filePath) {
    return yaml.load(fs.readFileSync(filePath, 'utf8'));
  }
  
  exports.getChallengesDirForLang = getChallengesDirForLang;
  exports.getMetaForBlock = getMetaForBlock;
  
  // This recursively walks the directories starting at root, and calls cb for
  // each file/directory and only resolves once all the callbacks do.
  const walk = (root, target, options, cb) => {
    return new Promise(resolve => {
      let running = 1;
      function done() {
        if (--running === 0) {
          resolve(target);
        }
      }
      readDirP(root, options)
        .on('data', file => {
          running++;
          cb(file, target).then(done);
        })
        .on('end', done);
    });
  };
  
  exports.getChallengesForLang = async function getChallengesForLang(lang) {
    // english determines the shape of the curriculum, all other languages mirror
    // it.
    const root = getChallengesDirForLang('english');
    // scaffold the curriculum, first set up the superblocks, then recurse into
    // the blocks
    const curriculum = await walk(
      root,
      {},
      { type: 'directories', depth: 0 },
      buildSuperBlocks
    );
    Object.entries(curriculum).forEach(([name, superBlock]) => {
      assert(!isEmpty(superBlock.blocks), `superblock ${name} has no blocks`);
    });
    const cb = (file, curriculum) => buildChallenges(file, curriculum, lang);
    // fill the scaffold with the challenges
    return walk(
      root,
      curriculum,
      { type: 'files', fileFilter: ['*.md', '*.yml'] },
      cb
    );
  };
  
  async function buildBlocks({ basename: blockName }, curriculum, superBlock) {
    const metaPath = path.resolve(META_DIR, `${blockName}/meta.json`);
  
    if (fs.existsSync(metaPath)) {
      // try to read the file, if the meta path does not exist it should be a certification.
      // As they do not have meta files.
  
      const blockMeta = JSON.parse(fs.readFileSync(metaPath));
  
      const { isUpcomingChange } = blockMeta;
  
      if (typeof isUpcomingChange !== 'boolean') {
        throw Error(
          `meta file at ${metaPath} is missing 'isUpcomingChange', it must be 'true' or 'false'`
        );
      }
  
      if (!isUpcomingChange || showUpcomingChanges) {
        // add the block to the superBlock
        const blockInfo = { meta: blockMeta, challenges: [] };
        curriculum[superBlock].blocks[blockName] = blockInfo;
      }
    } else {
      curriculum['certifications'].blocks[blockName] = { challenges: [] };
    }
  }
  
  async function buildSuperBlocks({ path, fullPath }, curriculum) {
    const superBlock = getSuperBlockFromDir(getBaseDir(path));
    curriculum[superBlock] = { blocks: {} };
  
    const cb = (file, curriculum) => buildBlocks(file, curriculum, superBlock);
    return walk(fullPath, curriculum, { depth: 1, type: 'directories' }, cb);
  }
  
  async function buildChallenges({ path: filePath }, curriculum, lang) {
    // path is relative to getChallengesDirForLang(lang)
    const block = getBlockNameFromPath(filePath);
    const superBlockDir = getBaseDir(filePath);
    const superBlock = getSuperBlockFromDir(superBlockDir);
    let challengeBlock;
  
    // TODO: this try block and process exit can all go once errors terminate the
    // tests correctly.
    try {
      challengeBlock = curriculum[superBlock].blocks[block];
      if (!challengeBlock) {
        // this should only happen when a isUpcomingChange block is skipped
        return;
      }
    } catch (e) {
      console.log(`failed to create superBlock from ${superBlockDir}`);
      // eslint-disable-next-line no-process-exit
      process.exit(1);
    }
    const { meta } = challengeBlock;
    const isCert = path.extname(filePath) === '.yml';
    // TODO: there's probably a better way, but this makes sure we don't build any
    // of the new curriculum when we don't want it.
    if (
      !showUpcomingChanges &&
      meta?.superBlock === '2022/javascript-algorithms-and-data-structures'
    ) {
      return;
    }
    const createChallenge = generateChallengeCreator(CHALLENGES_DIR, lang);
    const challenge = isCert
      ? await createCertification(CHALLENGES_DIR, filePath, lang)
      : await createChallenge(filePath, meta);
  
    challengeBlock.challenges = [...challengeBlock.challenges, challenge];
  }
  
  async function parseTranslation(transPath, dict, lang, parse = parseMD) {
    const translatedChal = await parse(transPath);
  
    const { challengeType } = translatedChal;
    // challengeType 11 is for video challenges and 3 is for front-end projects
    // neither of which have seeds.
    return challengeType !== 11 && challengeType !== 3
      ? translateCommentsInChallenge(translatedChal, lang, dict)
      : translatedChal;
  }
  
  async function createCertification(basePath, filePath) {
    function getFullPath(pathLang) {
      return path.resolve(__dirname, basePath, pathLang, filePath);
    }
    // TODO: restart using isAudited() once we can determine a) the superBlocks
    // (plural) a certification belongs to and b) get that info from the parsed
    // certification, rather than the path. ASSUMING that this is used by the
    // client.  If not, delete this comment and the lang param.
    return parseCert(getFullPath('english'));
  }
  
  // This is a slightly weird abstraction, but it lets us define helper functions
  // without passing around a ton of arguments.
  function generateChallengeCreator(basePath, lang) {
    function getFullPath(pathLang, filePath) {
      return path.resolve(__dirname, basePath, pathLang, filePath);
    }
  
    async function validate(filePath, superBlock) {
      const invalidLang = !curriculumLangs.includes(lang);
      if (invalidLang)
        throw Error(`${lang} is not a accepted language.
  Trying to parse ${filePath}`);
  
      const missingEnglish =
        lang !== 'english' && !(await hasEnglishSource(basePath, filePath));
      if (missingEnglish)
        throw Error(`Missing English challenge for
  ${filePath}
  It should be in
  ${getFullPath('english', filePath)}
  `);
  
      const missingAuditedChallenge =
        isAuditedCert(lang, superBlock) &&
        !fs.existsSync(getFullPath(lang, filePath));
      if (missingAuditedChallenge)
        throw Error(`Missing ${lang} audited challenge for
  ${filePath}
  
  Explanation:
  
  Challenges that have been already audited cannot fall back to their English versions. If you are seeing this, please update, and approve these Challenges on Crowdin first, followed by downloading them to the main branch using the GitHub workflows.
      `);
    }
  
    function addMetaToChallenge(challenge, meta) {
      const challengeOrder = findIndex(
        meta.challengeOrder,
        ([id]) => id === challenge.id
      );
  
      challenge.block = meta.name ? dasherize(meta.name) : null;
      challenge.hasEditableBoundaries = !!meta.hasEditableBoundaries;
      challenge.order = meta.order;
      // const superOrder = getSuperOrder(meta.superBlock);
      // NOTE: Use this version when a super block is in beta.
      const superOrder = getSuperOrder(meta.superBlock, {
        // switch this back to SHOW_NEW_CURRICULUM when we're ready to beta the JS superblock
        showNewCurriculum: process.env.SHOW_UPCOMING_CHANGES === 'true'
      });
      if (superOrder !== null) challenge.superOrder = superOrder;
      /* Since there can be more than one way to complete a certification (using the
     legacy curriculum or the new one, for instance), we need a certification
     field to track which certification this belongs to. */
      const dupeCertifications = [
        {
          certification: 'responsive-web-design',
          dupe: '2022/responsive-web-design'
        },
        {
          certification: 'javascript-algorithms-and-data-structures',
          dupe: '2022/javascript-algorithms-and-data-structures'
        }
      ];
      const hasDupe = dupeCertifications.find(
        cert => cert.dupe === meta.superBlock
      );
      challenge.certification = hasDupe ? hasDupe.certification : meta.superBlock;
      challenge.superBlock = meta.superBlock;
      challenge.challengeOrder = challengeOrder;
      challenge.isPrivate = challenge.isPrivate || meta.isPrivate;
      challenge.required = (meta.required || []).concat(challenge.required || []);
      challenge.template = meta.template;
      challenge.time = meta.time;
      challenge.helpCategory =
        challenge.helpCategory || helpCategoryMap[challenge.block];
      challenge.translationPending =
        lang !== 'english' && !isAuditedCert(lang, meta.superBlock);
      challenge.usesMultifileEditor = !!meta.usesMultifileEditor;
      if (challenge.challengeFiles) {
        // The client expects the challengeFiles to be an array of polyvinyls
        challenge.challengeFiles = challengeFilesToPolys(
          challenge.challengeFiles
        );
      }
      if (challenge.solutions?.length) {
        // The test runner needs the solutions to be arrays of polyvinyls so it
        // can sort them correctly.
        challenge.solutions = challenge.solutions.map(challengeFilesToPolys);
      }
    }
  
    async function createChallenge(filePath, maybeMeta) {
      const meta = maybeMeta
        ? maybeMeta
        : require(path.resolve(
            META_DIR,
            `${getBlockNameFromPath(filePath)}/meta.json`
          ));
  
      await validate(filePath, meta.superBlock);
  
      const useEnglish =
        lang === 'english' ||
        !isAuditedCert(lang, meta.superBlock) ||
        !fs.existsSync(getFullPath(lang, filePath));
  
      const challenge = await (useEnglish
        ? parseMD(getFullPath('english', filePath))
        : parseTranslation(
            getFullPath(lang, filePath),
            COMMENT_TRANSLATIONS,
            lang
          ));
  
      addMetaToChallenge(challenge, meta);
  
      return challenge;
    }
    return createChallenge;
  }
  
  function challengeFilesToPolys(files) {
    return files.reduce((challengeFiles, challengeFile) => {
      return [
        ...challengeFiles,
        {
          ...createPoly(challengeFile),
          seed: challengeFile.contents.slice(0)
        }
      ];
    }, []);
  }
  
  async function hasEnglishSource(basePath, translationPath) {
    const englishRoot = path.resolve(__dirname, basePath, 'english');
    return await access(
      path.join(englishRoot, translationPath),
      fs.constants.F_OK
    )
      .then(() => true)
      .catch(() => false);
  }
  
  function getBaseDir(filePath) {
    const [baseDir] = filePath.split(path.sep);
    return baseDir;
  }
  
  function getBlockNameFromPath(filePath) {
    const [, block] = filePath.split(path.sep);
    return block;
  }
  
  exports.hasEnglishSource = hasEnglishSource;
  exports.parseTranslation = parseTranslation;
  exports.generateChallengeCreator = generateChallengeCreator;
  