replace all links of all md files in a folder recursively with a new downloaded file link

index.js

const fs = require('fs')
const path = require('path')
const http = require('https')
const { promisify } = require('util')
const promisifiedReadFile = promisify(fs.readFile)
const promisifiedWriteFile = promisify(fs.writeFile)

// loops over all files in a directory recursively and returns filepaths to .md files
function getMdFilePaths (startPath) {
  if (!fs.existsSync(startPath)) {
    throw new Error(`directory ${startPath} does not exist't exist`)
  }

  const files = fs.readdirSync(startPath)

  return files.flatMap(file => {
    const filename = path.join(startPath, file)
    const pathextend = path.parse(filename)
    const stat = fs.lstatSync(filename)
    if (stat.isDirectory()) {
      return getMdFilePaths(filename) // recurse
    } else if (pathextend.ext === '.md') {
      return filename
    } else {
      return null
    }
  })
    .filter(Boolean)
}

function processMdFiles (mdFiles) {
  return Promise.all(
    mdFiles.map(async (filePath) => processMdFile(filePath, mdFiles))
  )
}

async function processMdFile (filePath) {
  // copied from https://www.regextester.com/96504
  const URL_REGEX = /(?:(?:https?|ftp):\/\/|\b(?:[a-z\d]+\.))(?:(?:[^\s()<>]+|\((?:[^\s()<>]+|(?:\([^\s()<>]+\)))?\))+(?:\((?:[^\s()<>]+|(?:\(?:[^\s()<>]+\)))?\)|[^\s`!()\[\]{};:'".,<>?«»“”‘’]))?/
  const fileContent = await promisifiedReadFile(filePath, { encoding: 'utf8' })
  const directoryOfFile = path.dirname(filePath)
  console.log('processing ' + filePath)
  const match = fileContent.match(URL_REGEX)
  console.log({ match })

  if (match) {
    const matchedUrl = match[0]
    const newFilePath = await downloadFile(matchedUrl, directoryOfFile)
    console.log('file downloaded', newFilePath)

    const newFileContent = fileContent.replace(URL_REGEX, newFilePath)

    console.log('new content', newFileContent)
    console.log(`replacing ${filePath} with ${newFileContent}`)
    // TODO uncomment this to replace the original files with the new content
    await promisifiedWriteFile(filePath, newFileContent)

    return newFileContent
  } else {
    return fileContent
  }
}

async function downloadFile (url, outputPath) {
  return new Promise((resolve, reject) => {
    // get file name from response https://stackoverflow.com/questions/20132064/node-js-download-file-using-content-disposition-as-filename

    http.get(url, (response) => {
      const fileNameFromContentDispositionHeader = response.headers['content-disposition'] ? response.headers['content-disposition'].split('\'\'') : null

      const filename = fileNameFromContentDispositionHeader ? fileNameFromContentDispositionHeader[1] : `document ${Math.random()}.html` // response.headers.date
      const newFilePath = path.join(outputPath, filename)
      const writeStream = fs.createWriteStream(newFilePath)

      response.pipe(writeStream)
      writeStream.on('finish', () => {
        // resolve the promise with the filePath once the file is created
        writeStream.close(() => {
          resolve(newFilePath)
        })
      })

      writeStream.on('error', (err) => {
        // delete the corrupted file and reject the promise if an error occurs
        // fs.unlink(outputPath)
        reject(err)
      })
    })
  })
}

// run the program
(async function main () {
  const START_PATH = 'root'
  const mdFiles = getMdFilePaths(START_PATH)
  console.log({ mdFiles })
  await processMdFiles(mdFiles)
})()