(function() {
  var useEffect = React.useEffect;
  var useRef = React.useRef;

  function useGlassAdaptivity(enabled) {
    var ref = useRef(null);

    useEffect(function() {
      if (enabled === false) return;
      var el = ref.current;
      if (!el || !window.GlassLuminance) return;
      window.GlassLuminance.observe(el);
      return function() {
        window.GlassLuminance.unobserve(el);
      };
    }, [enabled]);

    return ref;
  }

  window.useGlassAdaptivity = useGlassAdaptivity;
})();