index.js

/*
  This program makes a web scraping to get some guitar tablature and transform
  it to an Arduino Program compatible with the tone() Function

  Git-repository: https://github.com/ThiagoAugustoSM/arduino-tablature
  Author: thiagoaugustosm
  License: GNU General Public License v3.0
*/

const request = require('request');
const cheerio = require('cheerio');
const fs = require('fs');

url = 'https://www.cifraclub.com.br/natiruts/andei-so/';
var tabInNotes = [];


// Request to get the html from cifraclub's website
request(url, function(error, response, html){

  if(!error){
    var $ = cheerio.load(html);

    $(".tablatura").each(function(){
      var tab = $(this).text();
      tabInNotes.push(filterTab(tab));
    });

    var arduinoFile = generateFile(tabInNotes);

    // Saving file in the same directory
    fs.writeFile('music.ino', arduinoFile, function (err) {
      if (err) throw err;
      console.log('Saved!');
    });

  }else{
    console.log("ERROR");
  }
})

var typesOfPause = ['-'];
var typesOfNotes = ['A', 'B', 'C', 'D', 'E', 'F', 'G'];
var typesOfBlockLimits = ['|'];
var notes = [
               'NOTE_C', 'NOTE_CS', 'NOTE_D', 'NOTE_DS', 'NOTE_E',
               'NOTE_F', 'NOTE_FS', 'NOTE_G', 'NOTE_GS', 'NOTE_A',
               'NOTE_AS', 'NOTE_B']
/*
  In a normal acoustic guitar tuning the notes of the strings are in this sequence:
  From bottom to top: E4, B3, G3, D3, A2, E2

  Example:

  E4|---------0-------0----------0-------------|
  B3|-----1-----1------------6-----6-----6-----|
  G3|---2---2-----2--------5---5-----5---------|
  D3|-3-------------3----0-------------0-------|
  A2|------------------------------------------|
  E2|------------------------------------------|

  And the sequences would be: (related to the guitar's arm)

  E4 F4 F#4 G4 Ab4 A4 Bb4 B4 C5 C#5 D5 Eb5 E5 F5 F#5 G5 Ab5 A5 Bb5 B5 C6 C#6 D6
  B3 C4 C#4 D4 Eb4 E4 F4 F#4 G4 Ab4 A4 Bb4 B4 C5 C#5 D5 Eb5 E5 F5 F#5 G5 Ab5 A5
  G3 Ab3 A3 Bb3 B3 C4 C#4 D4 Eb4 E4 F4 F#4 G4 Ab4 A4 Bb4 B4 C5 C#5 D5 Eb5 E5 F5
  D3 Eb3 E3 F3 F#3 G3 Ab3 A3 Bb3 B3 C4 C#4 D4 Eb4 E4 F4 F#4 G4 Ab4 A4 Bb4 B4 C5
  A2 Bb2 B2 C3 C#3 D3 Eb3 E3 F3 F#3 G3 Ab3 A3 Bb3 B3 C4 C#4 D4 Eb4 E4 F4 F#4 G4
  E2 F2 F#2 G2 Ab2 A2 Bb2 B2 C3 C#3 D3 Eb3 E3 F3 F#3 G3 Ab3 A3 Bb3 B3 C4 C#4 D4

*/

function isNote(char){
  if(typesOfNotes.indexOf(char) !== -1){
    return true;
  }
  return false;
}

function isNumber(char){
  if(char.charCodeAt(0) >= "0".charCodeAt(0) && char.charCodeAt(0) <= "9".charCodeAt(0)){
    return true;
  }
  return false;
}

function isPause(char){
  if(typesOfPause.indexOf(char) !== -1){
    return true;
  }
  return false;
}

function isBlockLimit(char){
  if(typesOfBlockLimits.indexOf(char) !== -1){
    return true;
  }
  return false;
}

function toNote(mainNote, char){
  if(isPause(char)){
    return "PAUSE";
  }

  // The main ideia is to run through all the scale of string
  // Going from G3 to C4 for Example
  // But running in the notes array as a circular array

  var tuning = parseInt(mainNote.substring(mainNote.length - 1, mainNote.length));
  var frets = parseInt(char);

  var i = 0;
  for(i = notes.indexOf(mainNote.substring(0, mainNote.length - 1));
      frets > 0;
      i = (i + 1) % (notes.length)){
        if(i == 0){
          tuning++;
        }
        frets--;

  }
  return notes[i] + tuning;
}

function filterTab(tab){

  var tabInForm = [];
  var state = 0;
  var actualString = 0; // Counting from bottom to top
  var actualMainNote = "";

  // Running through every char in the tab function
  tab = tab.split('');
  tab.forEach(function(char, index){

    // Working in a state machine to filter the actual data
    // State 0 - Getting the actual tuning of the string
    if(state === 0 && isNote(char)){

      if(char == 'E' && actualString == 0){
        actualMainNote = "NOTE_E4";
      }else if(char == 'B'){
        actualMainNote = "NOTE_B3";
      }else if(char == 'G'){
        actualMainNote = "NOTE_G3";
      }else if(char == 'D'){
        actualMainNote = "NOTE_D3";
      }else if(char == 'A'){
        actualMainNote = "NOTE_A2";
      }else if(char == 'E'){
        actualMainNote = "NOTE_E2";
      }

      tabInForm.push([])
      state = 1;
    }else if(state === 1 && (isPause(char) || isNumber(char))){

      // Some tab use the 10th fret or more
      if(isNumber(tab[index]) && isNumber(tab[index + 1])){
        tabInForm[actualString].push(toNote(actualMainNote, char + tab[index + 1]));
      }else if(isNumber(tab[index - 1])){
        // This number was already computed in the last element
        // So it is now considered a pause
        tabInForm[actualString].push("PAUSE");
      }else{
        // A number appeared alone in the fret
        tabInForm[actualString].push(toNote(actualMainNote, char));
      }

      // Works because the first block limit after the Note won't be read
      if(isBlockLimit(tab[index + 1])){
        state = 2;
      }
    }else if(state === 2){
      ++actualString;
      state = 0;
    }
  });
  return tabInForm;
}

function generateFile(tabs){
  var text =
`/*
  File Generated by arduino-tablature
  Git-repository: https://github.com/ThiagoAugustoSM/arduino-tablature
  Author: thiagoaugustosm
  License: GNU General Public License v3.0
*/

// Change to your Buzzer Pin
#define buzzerPin 10
// Change the Pause time in miliseconds
#define PAUSE 100

/*************************************************
 * Public Constants
 *************************************************/

#define NOTE_B0  31
#define NOTE_C1  33
#define NOTE_CS1 35
#define NOTE_D1  37
#define NOTE_DS1 39
#define NOTE_E1  41
#define NOTE_F1  44
#define NOTE_FS1 46
#define NOTE_G1  49
#define NOTE_GS1 52
#define NOTE_A1  55
#define NOTE_AS1 58
#define NOTE_B1  62
#define NOTE_C2  65
#define NOTE_CS2 69
#define NOTE_D2  73
#define NOTE_DS2 78
#define NOTE_E2  82
#define NOTE_F2  87
#define NOTE_FS2 93
#define NOTE_G2  98
#define NOTE_GS2 104
#define NOTE_A2  110
#define NOTE_AS2 117
#define NOTE_B2  123
#define NOTE_C3  131
#define NOTE_CS3 139
#define NOTE_D3  147
#define NOTE_DS3 156
#define NOTE_E3  165
#define NOTE_F3  175
#define NOTE_FS3 185
#define NOTE_G3  196
#define NOTE_GS3 208
#define NOTE_A3  220
#define NOTE_AS3 233
#define NOTE_B3  247
#define NOTE_C4  262
#define NOTE_CS4 277
#define NOTE_D4  294
#define NOTE_DS4 311
#define NOTE_E4  330
#define NOTE_F4  349
#define NOTE_FS4 370
#define NOTE_G4  392
#define NOTE_GS4 415
#define NOTE_A4  440
#define NOTE_AS4 466
#define NOTE_B4  494
#define NOTE_C5  523
#define NOTE_CS5 554
#define NOTE_D5  587
#define NOTE_DS5 622
#define NOTE_E5  659
#define NOTE_F5  698
#define NOTE_FS5 740
#define NOTE_G5  784
#define NOTE_GS5 831
#define NOTE_A5  880
#define NOTE_AS5 932
#define NOTE_B5  988
#define NOTE_C6  1047
#define NOTE_CS6 1109
#define NOTE_D6  1175
#define NOTE_DS6 1245
#define NOTE_E6  1319
#define NOTE_F6  1397
#define NOTE_FS6 1480
#define NOTE_G6  1568
#define NOTE_GS6 1661
#define NOTE_A6  1760
#define NOTE_AS6 1865
#define NOTE_B6  1976
#define NOTE_C7  2093
#define NOTE_CS7 2217
#define NOTE_D7  2349
#define NOTE_DS7 2489
#define NOTE_E7  2637
#define NOTE_F7  2794
#define NOTE_FS7 2960
#define NOTE_G7  3136
#define NOTE_GS7 3322
#define NOTE_A7  3520
#define NOTE_AS7 3729
#define NOTE_B7  3951
#define NOTE_C8  4186
#define NOTE_CS8 4435
#define NOTE_D8  4699
#define NOTE_DS8 4978

void setup(){
  pinMode(buzzerPin, OUTPUT);
}

void loop(){
`;


  var numTabs = tabs.length;
  var qntStrings = tabs[0].length;
  // All the tabs have the same size
  var sizeOfTab = tabs[0][0].length;
  var hadSound = false;

  var i = 0, j = 0, k = 0;
  for(i = 0; i < numTabs; i++){
    text += "  // " + (i + 1) + " TAB" + '\n';
    for(k = 0; k < sizeOfTab; k++){
      for(j = 0; j < qntStrings; j++){
        if(tabs[i][j][k] != "PAUSE"){
          text += "  tone(buzzerPin, " + tabs[i][j][k] + ");" + '\n';
          hadSound = true;
        }
      }

      if(hadSound == false){
        text += "  delay(PAUSE);" + '\n';
      }else{
        hadSound = false;
      }
    }
  }
  text += "}";
  console.log(text);
  return text;
}