Port of hoverable body class support from JS to CLJS

body-class.cljs

(defn setup-scroll-watcher
  [body-class]
  (let [body-class (name body-class)
        listener (shared/listen js/window :scroll)
        debounced (shared/debounce listener 200)]
  
    (dom/add-class! (.-body js/document) body-class)

    (go
      (loop []
        (<! listener)
        (dom/remove-class! (.-body js/document) body-class)
        (<! debounced)
        (dom/add-class! (.-body js/document) body-class)
        (recur)))))

(defn set-body-class-when-not-scrolling!
  ([body-class] (set-body-class-when-not-scrolling! body-class (not (.-touch js/Modernizr))))
  ([body-class mouse-detected]
    (if mouse-detected
      (setup-scroll-watcher body-class)
      (go
        (<! (shared/listen-once js/document :mousemove))
        (set-body-class-when-not-scrolling! body-class true)))))

body-class.js

ww.util.mouseEventsDetected = !Modernizr['touch'];

ww.util.listeningForFirstMouseEvent = false;
ww.util.listenForFirstMouseEvent = function(cb) {
  if (ww.util.listeningForFirstMouseEvent) { return; }

  ww.util.listeningForFirstMouseEvent = true;

  goog.events.listenOnce(document, 'mousemove', function() {
    ww.util.mouseEventsDetected = true;
    ww.util.listeningForFirstMouseEvent = false;

    cb();
  });
};

ww.util.isScrolling = window['isScrolling'] = false;

/**
 * Add a 'hoverable' body class when :hover events should
 * be attached (eg not scrolling or on touch device).
 * @param {String} clsName Name of the class to apply. Default: hoverable.
 */
ww.util.applyBodyClassWhenNotScrolling = function(clsName) {
  clsName = clsName || 'hoverable';

  if (!ww.util.mouseEventsDetected) {
    ww.util.listenForFirstMouseEvent(function() {
      ww.util.applyBodyClassWhenNotScrolling(clsName);
    });
    return;
  }

  goog.dom.classes.add(document.body, clsName);

  var debouncedOnScroll = ww.util.debounce(function() {
    ww.util.isScrolling = window['isScrolling'] = false;
    goog.dom.classes.add(document.body, clsName);
  }, 200);

  goog.events.listen(window, 'scroll', function() {
    if (!ww.util.isScrolling) {
      ww.util.isScrolling = window['isScrolling'] = true;
      goog.dom.classes.remove(document.body, clsName);
    }

    debouncedOnScroll();
  });
};