HBO Max downloader

const fs = require('fs');
const path = require('path');
const https = require('https');
const parser = require('fast-xml-parser');

let file;
let baseURL;
const langs = {};

const options = {
  ignoreAttributes : false,
  parseNodeValue : true,
  parseAttributeValue : true,
};

if(process.argv[2]){
  loadFile(process.argv[2]);
}
else {
  error(`Usage: node ${path.basename(__filename)} [MDP url]`);
}

function error(message){
  console.log("\x1b[31m", message, "\x1b[0m");
  process.exit();
}

function loadFile(url) {
  baseURL = url.substr(0, url.lastIndexOf("/")+1);

  https.get(url, function (res) {
    var data = '';
    res.on('data', function (chunk) {
      data += chunk;
    });
    res.on('end', function () {
      readXML(data);
    });
  }).on('error', function (err) {
    error(err.message);
  });
}

function readXML(xml){
  const data = parser.parse(xml, options);
  if(data.MPD?.Period?.AdaptationSet){
    data.MPD.Period.AdaptationSet.forEach((adaptation) => {
      if(adaptation["@_contentType"]=="text"){
        langs[adaptation["@_lang"]]=adaptation.Representation.SegmentTemplate["@_media"];
      }
    });
    selectLang();
  }
  else {
    error("Invalid XML");
  }
}

function selectLang(){
  console.log("Availaible languages:");
  for (const lang in langs) {
    console.log(lang);
  }

  const readline = require('readline').createInterface({
    input: process.stdin,
    output: process.stdout
  });

  readline.question('Select language: ', lang => {
    downloadLanguage(lang);
    readline.close();
  });
}

function downloadLanguage(lang) {
  console.log(`Donwloading ${lang}...`);
  file = fs.createWriteStream(`${lang}.vtt`, { flags: 'a' });
  download(lang);
}

function download(lang, count=1) {
  const url = baseURL+langs[lang].replace("$Number$",count);

  https.get(url, function(res) {
    if(res.statusCode==200){
      res.on('data', (chunk) => {
        file.write(chunk);
      });
      res.on('end', () => {
        download(lang, count+1);
      });
    }
    else {
      console.log("Done!");
      file.end();
      selectLang();
    }
  }).on('error', function(err) {
    file.end();
    error(err.message);
  });
}