similarSongsRandomizer.js

let songsByKey = require('./songsByKey.json');

const altKeys = [
  'C',
  'Db',
  'D',
  'Eb',
  'E',
  'F',
  'Gb',
  'G',
  'Ab',
  'A',
  'Bb',
  'B',
  'A-',
  'Bb-',
  'B-',
  'C-',
  'C#-',
  'D-',
  'Eb-',
  'E-',
  'F-',
  'F#-',
  'G-',
  'G#-',
];

const longAltKeys = [
  'C',
  'Db',
  'D',
  'Eb',
  'E',
  'F',
  'Gb',
  'G',
  'Ab',
  'A',
  'Bb',
  'B',
  'C',
  'Db',
  'D',
  'Eb',
  'E',
  'F',
  'Gb',
  'G',
  'Ab',
  'A',
  'Bb',
  'B',
  'A-',
  'Bb-',
  'B-',
  'C-',
  'C#-',
  'D-',
  'Eb-',
  'E-',
  'F-',
  'F#-',
  'G-',
  'G#-',
  'A-',
  'Bb-',
  'B-',
  'C-',
  'C#-',
  'D-',
  'Eb-',
  'E-',
  'F-',
  'F#-',
  'G-',
  'G#-',
];

exports.getFirstRandomSong = function () {
  let randKey;
  let randSong;
  do {
    randKey = Math.floor(Math.random() * altKeys.length);
    //console.log("ok, randkey = " + randKey)
    randSong = Math.floor(Math.random() * songsByKey[altKeys[randKey]].length);
    //console.log("ok, randSong = " + randSong)
    firstSong = songsByKey[altKeys[randKey]][randSong];
    //console.log("ok, firstSong = " + firstSong)
    //console.log("ok, title = " + firstSong.title)
    //console.log("ok, firstSong = " + firstSong)
    // console.log("ok, title = " + firstSong.title)
  } while (firstSong == undefined);

  //firstSong = songsByKey['C'][1]
  //console.log(firstSong)

  return firstSong;
};

exports.getSameKeySong = function (songByKey) {
  let key;
  let keyIndex;
  //let nextSong
  do {
    key = songByKey.key;
    //console.log("ok, key = " + key)
    keyIndex = altKeys.indexOf(key);
    //console.log("ok, keyIndex = " + keyIndex)
    //var nextSong = songs[Math.floor(Math.random() * songs.length)];

    randInKeySong = Math.floor(
      Math.random() * songsByKey[altKeys[keyIndex]].length
    );
    //console.log("ok, RandInKeySong = " + randInKeySong)
    nextSong = songsByKey[altKeys[keyIndex]][randInKeySong];
    //console.log("ok, nextSong = " + nextSong)
    //console.log("ok nextKey = " + nextSong.key)
    //console.log("ok, title = " + nextSong.title)
    // it repeats the operation untill it gets the same key
  } while (nextSong == undefined);
  return nextSong;
};

// Arrays of Keys
const keys = ['C', 'Db', 'D', 'Eb', 'E', 'F', 'Gb', 'G', 'Ab', 'A', 'Bb', 'B'];
// The minor key has a different order in respect to the major ones for an easier implementation
const minorKeys = [
  'A-',
  'Bb-',
  'B-',
  'C-',
  'C#-',
  'D-',
  'Eb-',
  'E-',
  'F-',
  'F#-',
  'G-',
  'G#-',
];

// with similar Key I intended: same key, correspondend major-minor, its IV or V.
exports.getSimilarKeySong = function (songByKey) {
  let key;
  let currentKeyIndex;
  let nextSong;
  do {
    // I'm searching the correspondent key on the two arrays
    // If its a majorkey, the minor index will result -1 and viceversa
    key = songByKey.key;
    //console.log("key = " + key)
    // sto assumendo che l'indexOf sia un firstIndexOf
    currentKeyIndex = longAltKeys.indexOf(key);
    //console.log("currentKeyIndex = " + currentKeyIndex)
    // let nextSong
    randomCase = Math.ceil(Math.random() * 3);
    //console.log("randomCase = " + randomCase)
    if (randomCase == 1) {
      if (currentKeyIndex < 24) {
        nextKeyIndex = currentKeyIndex + 24;
      } else {
        nextKeyIndex = currentKeyIndex - 24;
      }
    } else if (randomCase == 2) {
      nextKeyIndex = currentKeyIndex + 5;
    } else if (randomCase == 3) {
      nextKeyIndex = currentKeyIndex + 7;
    }
    //console.log("nextKeyIndex = " + nextKeyIndex)
    simKeySong = Math.floor(
      Math.random() * songsByKey[longAltKeys[nextKeyIndex]].length
    );
    //console.log("ok, SimKeySong = " + simKeySong)
    nextSong = songsByKey[longAltKeys[nextKeyIndex]][simKeySong];
    //console.log("ok, nextSong = " + nextSong)
  } while (nextSong == undefined);

  //console.log("ok nextKey = " + nextSong.key)
  //console.log("ok, title = " + nextSong.title)

  return nextSong;
};

exports.getTargetKeySong = function (key) {
  let targetKeyIndex;
  let nextSong;
  do {
    //let nextSong
    targetKeyIndex = altKeys.indexOf(key);
    //console.log("targetKeyIndex = " + targetKeyIndex)
    targetKeySong = Math.floor(
      Math.random() * songsByKey[altKeys[targetKeyIndex]].length
    );
    //console.log("targetKeySong = " + targetKeySong)
    nextSong = songsByKey[altKeys[targetKeyIndex]][targetKeySong];
    //console.log("nextSong = " + nextSong)
    // console.log("ok nextKey = " + nextSong.key)
    // console.log("ok, title = " + nextSong.title)
  } while (nextSong == undefined);
  return nextSong;
};

exports.getRandomSong = function () {
  let randKey;
  let randSong;
  let nextSong;
  do {
    //let nextSong
    randKey = Math.floor(Math.random() * altKeys.length);
    //console.log("ok, randkey = " + randKey)
    randSong = Math.floor(Math.random() * songsByKey[altKeys[randKey]].length);
    //console.log("ok, randSong = " + randSong)
    nextSong = songsByKey[altKeys[randKey]][randSong];
    //console.log("ok, nextSong = " + nextSong)
    //console.log("ok, title = " + nextSong.title)
    //console.log("ok, title = " + nextSong.key)
  } while (nextSong == undefined);

  //firstSong = songsByKey['F'][1]
  //console.log(nextSong.key)

  return nextSong;
};