S.UI.Tabs = (function () {
  var labels = document.querySelector('.tabs-labels'),
      triggers = document.querySelectorAll('.tabs-label'),
      panels = document.querySelectorAll('.tabs-panel');

  function activate(i) {
    triggers[i].classList.add('tabs-label--active');
    panels[i].classList.add('tabs-panel--active');
  }

  function bindEvents() {
    labels.addEventListener('click', function (e) {
      var el = e.target,
          index;

      if (el.classList.contains('tabs-label')) {
        for (var t = 0; t < triggers.length; t++) {
          triggers[t].classList.remove('tabs-label--active');
          panels[t].classList.remove('tabs-panel--active');

          if (el === triggers[t]) {
            index = t;
          }
        }

        activate(index);
      }
    });
  }

  return {
    init: function () {
      activate(0);
      bindEvents();
    }
  };
}());