function rot13(message){
  console.log(message)
  const alphabet = 'abcdefghijklmnopqrstuvwxyz'.split('');
  const alphabetMayo = 'abcdefghijklmnopqrstuvwxyz'.toUpperCase().split('');
  
  let rot = []
  let fin = []
  const arrayMe = message.toLowerCase().split('')
//   console.log(message)
  

  for (let i = 0; i < arrayMe.length; i++) {
    for (let l = 0; l < alphabet.length; l++ ) {
      var a = arrayMe[i]
      var b = alphabet[l]
      var r = alphabet[l + 13];
      if (a === b) {
        if (l > 13) {
          var e = alphabet[l + 13 - 26];
          rot.push(e)
        } else {
          rot.push(r)
        }
    }
  }
}
  
  for(let g = 0; g < arrayMe.length; g++) {
    if ((/[a-zA-Z]/).test(arrayMe[g])) {
      console.log(arrayMe[g])
      fin.push(rot[g])
    } else {
      fin.push(arrayMe[g])
    }
  }
  
  console.log(fin.join(''))
  console.log(rot) 
}



// soluction

function rot13(message) {
  const alphabet = 'abcdefghijklmnopqrstuvwxyz'.split('');
  let rot = [];
  let fin = [];
  const arrayMe = message.split('');

  for (let i = 0; i < arrayMe.length; i++) {
    let a = arrayMe[i];

    if (/[a-zA-Z]/.test(a)) {
      // Es una letra, hacer ROT13
      let isUpperCase = a === a.toUpperCase();
      let lowerA = a.toLowerCase();
      let index = alphabet.indexOf(lowerA);
      let newIndex = (index + 13) % 26;
      let newChar = alphabet[newIndex];

      if (isUpperCase) {
        newChar = newChar.toUpperCase();
      }

      rot.push(newChar);
    } else {
      // No es una letra, mantener el carácter tal cual
      rot.push(a);
    }
  }

  fin = rot.join('');
  return fin;
}

// Ejemplo de uso
console.log(rot13('Hello World!')); // Uryyb Jbeyq!


//The best soluction

function rot13(message) {
  var a = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
  var b = "nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM"
  return message.replace(/[a-z]/gi, c => b[a.indexOf(c)])
}

function rot13(message) {
  var abc = 'abcdefghijklmnopqrstuvwxyzabcdefghijklmABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLM';
  return message.replace(/[a-z]/gi, c => abc[abc.indexOf(c) + 13]);
}

const rot13 = str => str.replace(/[a-z]/gi, letter => String.fromCharCode(letter.charCodeAt(0) + (letter.toLowerCase() <= 'm' ? 13: -13)));