minify.js

var chars = 'abcdefghijklmopquwxyz';

//var c = ['block_sss', 'elem__asdf', 'footer__container', 'title', 'title__child','title__child','title__child','title__child'];
var prefix1 = '';
var prefix2 = '';
var prefix1Index = 0;
var prefix2Index = 0;
var currentIndex = 0;
var parts = [];

function minify(classNames) {
  var names = [];

  for (var i = 0; i < classNames.length; i++) {
    var className = classNames[i];

    if (names[className]) {
      names[className]++;
    } else {
      names[className] = 1;
    }
  }

  var max = 0;
  var namesByCount = {};

  for (var name in names) {
    var count = names[name];
    max = Math.max(max, count);

    var key = count.toString();
    if (namesByCount[key]) {
      namesByCount[key].push(name);
    } else {
      namesByCount[key] = [name];
    }
  }

  var sortedClassNames = [];

  for (var i = max; i > 0; i--) {
    var key = i.toString();
    if (namesByCount[key]) {
      sortedClassNames = sortedClassNames.concat(namesByCount[key]);
    }
  }

  // here we got array of classes, sorted by number of their appearance

  var minifiedNames = {};

  for (var i = 0; i < sortedClassNames.length; i++) {
    var className = sortedClassNames[i];
    var minifiedName = getMinifiedName();

    minifiedNames[className] = minifiedName;
  }

  //console.log(minifiedNames);

  return minifiedNames;
}

function getMinifiedName() {
  var c = chars[currentIndex];

  var result = parts.join()

  currentIndex++; 
  if (currentIndex === chars.length) {
    currentIndex = 0;
    prefix1 = chars[prefix1Index];
    prefix1Index++;
    if (prefix1Index === chars.length) {
      prefix1Index = 0;
      prefix2 = chars[prefix2Index];
      prefix2Index++;
    }
  }

  return result;
}

module.exports = minify;