iTunes Custom Sort

app.js

const inFile = './Game.xml';
const outFileDiscover = './GameDiscover.xml';
const outFileExploit = './GameExploit.xml';
const fs = require('fs');

const regexIndexOf = (str, regex, end) => {
    var match = str.match(regex);
    return match.index + (end ? match[0].length : 0);
};

const stringBetween = (str, a, b) => {
  const start = regexIndexOf(str, a, true);
  const length = regexIndexOf(str, b) - start;
  return str.substr(start, length);
};

const readTracks = (filename) => {
  const file = fs.readFileSync(filename, 'utf8');
  const trackBody = stringBetween(file, /<key>Tracks<\/key>\s*<dict>/, /<\/dict>\s*<key>Playlists<\/key>/);
  const dictBodies = trackBody.split('<dict>');
  const trackSections = dictBodies.filter(dictBody => { 
    return dictBody.indexOf('Track ID') !== -1; 
  });
  const trackObjects = trackSections.map(trackSection => {
    const trackId = trackSection.split('<key>Track ID</key><integer>')[1].split('</integer>')[0];
    const playCount = trackSection.indexOf('<key>Play Count</key><integer>') === -1 ? 0 : trackSection.split('<key>Play Count</key><integer>')[1].split('</integer>')[0];
    const skipCount = trackSection.indexOf('<key>Skip Count</key><integer>') === -1 ? 0 : trackSection.split('<key>Skip Count</key><integer>')[1].split('</integer>')[0];
    return {
      trackId: trackId,
      playCount: playCount,
      skipCount: skipCount,
      trueCount: playCount - skipCount
    };
  });
  return trackObjects;
};

const sortDiscover = (a, b) => {
  if (a.skipCount == b.skipCount) {
    return a.playCount - b.playCount;
  } else {
    return a.skipCount - b.skipCount;
  }
};

const sortExploit = (a, b) => {
  return b.trueCount - a.trueCount;
};

const generatePlaylistString = (trackObjects, sortLambda) => {
  trackObjects.sort(sortLambda);
  const playlistString = trackObjects.reduce((str, trackObject) => {
    return str + '<dict><key>Track ID</key><integer>' + trackObject.trackId + '</integer></dict>';
  }, '');
  return playlistString;
};

const writePlaylist = (inFile, outFile, playlistString, name) => {
  const file = fs.readFileSync(inFile, 'utf8');
  const nameUpdatedFile = file.split('<key>Name</key><string>Game</string>').join('<key>Name</key><string>' + name + '</string>');
  const listRemoved = nameUpdatedFile.split('<key>Playlist Items</key>')[0] + '<key>Playlist Items</key><array>';
  const listInjected = listRemoved + playlistString + '</array></dict></array></dict></plist>';
  fs.writeFileSync(outFile, listInjected, 'utf8');
};

const trackObjects = readTracks(inFile);
const playlistStringDiscover = generatePlaylistString(trackObjects, sortDiscover);
writePlaylist(inFile, outFileDiscover, playlistStringDiscover, 'GameDiscover');
const playlistStringExploit = generatePlaylistString(trackObjects, sortExploit);
writePlaylist(inFile, outFileExploit, playlistStringExploit, 'GameExploit');