_normaliseArticles.js

const Rx = require('rx');
const fse = require('fs-extra');

const { titleify } = require('./seed/utils');

const { Observable } = Rx;

const metaRE = /---[\W\w]*?---\n*?/;
const isAFileRE = /(\.md|\.jsx?|\.html?)$/;
const shouldBeIgnoredRE = /^(\_|\.)/;
const isAStubRE = /This\sis\sa\sstub\.\s\[Help\sour\scommunity\sexpand\sit\]/;

const articlesDir = `${process.cwd()}/src/pages/articles`;

function readDir(dir) {
  return fse.readdirSync(dir)
  .filter(item => !isAFileRE.test(item))
  .filter(file => !shouldBeIgnoredRE.test(file));
}

function appendStub(title, path) {
  const pathArr = path.split('/');
  const filePath = pathArr
    .slice(pathArr.indexOf('articles') + 1)
    .join('/')
    .toLowerCase();
/* eslint-disable max-len */
  return `
## ${title}

This is a stub. [Help our community expand it](https://github.com/freecodecamp/guides/tree/master/src/pages/articles/${filePath}/index.md).

[This quick style guide will help ensure your pull request gets accepted](https://github.com/freecodecamp/guides/blob/master/README.md).

<!-- The article goes here, in GitHub-flavored Markdown. Feel free to add YouTube videos, images, and CodePen/JSBin embeds  -->

#### More Information:
<!-- Please add any articles you think might be helpful to read before writing the article -->


`;
}
/* eslint-enable max-len */

function normaliseMeta(dirLevel) {
  const filePath = `${dirLevel}/index.md`;
  fse.open(filePath, 'r', (err) => {
    if (err) {
      if (err.code === 'ENOENT') {
        console.error(
          'index.md does not exist in %s',
          filePath.replace(/index\.md$/, '')
          );
        return fse.ensureFile(filePath)
          .then(() => {
            console.log('%s created', filePath);
            return normaliseMeta(dirLevel);
          })
          .catch(err => {
            console.error(err);
          });
      }
      throw err;
    }
    fse.readFile(filePath, 'utf-8')
      .then(content => {
        const title = dirLevel
          .split('/')
          .slice(-1)
          .join('');
        const pageTitle = titleify(title);
        const newMeta = (
`---
title: ${pageTitle}
---`);
        let normailised = content
          .replace(metaRE, '');
        if (
          normailised.length < 30 ||
          isAStubRE.test(content)
        ) {
          normailised = appendStub(pageTitle, dirLevel);
        }
        fse.writeFile(filePath, newMeta.concat(normailised));
      })
      .catch(err => {
        console.error('something went wrong', err);
      });
    return null;
  });
}

function applyNormaliser(dirLevel) {
  return Observable.from(readDir(dirLevel))
    .flatMap(dir => {
      const dirPath = `${dirLevel}/${dir}`;
      const subDirs = readDir(dirPath);
      if (!subDirs) {
        normaliseMeta(dirPath);
        return Observable.of(null);
      }
      normaliseMeta(dirPath);
      return applyNormaliser(dirPath);
    });
}

applyNormaliser(articlesDir)
  .subscribe((dir)=> {
    if (dir) {
      applyNormaliser(dir);
    }
  },
  err => {
      throw err;
    },
    () => {
      normaliseMeta(articlesDir);
      console.info('\n\nNormalisation Completed\n\n');
    });