redux middleware with firebase replay / remote actions

logger.js

import Firebase from 'firebase';

const firebaseUrl = 'https://spatially.firebaseio.com/clients';
const timeOffsetUrl = 'https://spatially.firebaseio.com/.info/serverTimeOffset';
let ref = new Firebase(firebaseUrl);
let timeRef = new Firebase(timeOffsetUrl);
let cachedUid;

export default ({dispatch, getState}) => next => action => {
  // The first action rehydrates, so now we've probably got the uid now
  let result = next(action);

  let { uid } = getState().info || {};

  if (!uid)
    return;

  if (uid !== cachedUid) {
    // Potentially first time!
    if (cachedUid)
      ref.child(cachedUid).child('actions').off();

    // We make sure the event isn't old by correlating events with server time
    timeRef.once('value', snap => {
      let offset = snap.val();
      let acceptedEventTime = Date.now() + offset;
      console.log(offset)

      ref.child(uid).child('actions').limitToLast(1).on('child_added', snap => {
        let action = snap.val();
        if (action.time && action.time + offset > acceptedEventTime) {
          console.log('Running remote action', action);
          dispatch(action);
        } else {
          console.log('got an .. old? event', action);
        }
      });
    });

    cachedUid = uid;
  }

  ref.child(uid).child('state').push(result);

  return result
}