'use strict';

module.exports = translate;

function translate(rnaStrand) {
  var proteins = [];

  if (rnaStrand) {
    for (var i = 0; i < rnaStrand.length; i+=3) {
      var protein = getProtein(rnaStrand.substring(i, i + 3));

      if (protein) {

        if (protein === "STOP") {
          break;
        }

        if (protein === "INVALID") {
          throw new Error('Invalid codon');
        }

        proteins.push(protein);
      }
    }
  }

  return proteins;
}

function getProtein(codon) {
  switch (codon) {
    case "AUG":
      return "Methionine";

    case "UUU":
    case "UUC":
      return "Phenylalanine";

    case "UUA":
    case "UUG":
      return "Leucine";

    case "UCU":
    case "UCC":
    case "UCA":
    case "UCG":
      return "Serine";

    case "UAU":
    case "UAC":
      return "Tyrosine";

    case "UGU":
    case "UGC":
      return "Cysteine";

    case "UGG":
      return "Tryptophan";

    case "UAA":
    case "UAG":
    case "UGA":
      return "STOP";

    default:
      return "INVALID";
  }
}