service.js

import Ember from 'ember';

const { Service, inject, run } = Ember;

const TWO_HOURS = 2 * 60 * 60 * 1000;
const TWO_DAYS = 2 * 24 * 60 * 60 * 1000;

/**
 * Ticking clock service.
 * We use this service to sync all our momentjs udpates every second
 * and not start one timer for each message.
 */
export default Service.extend({
  store: inject.service('store'),

  init: function() {
    run.later(this, this.tick, 1000);
  },

  tick: function() {
    let messageRecords = this.get('store').peekAll('chat-message');
    messageRecords.forEach(message => {
      let timeAgoStr = this.timeAgoString(message.get('createdAt'));
      message.set('timeago', timeAgoStr);
      console.log('TIMESET');
    });
    run.later(this, this.tick, 1000);
  },

  /**
   * Compare message date to current. If it has been less than 2 hours ago
   * we use relative time otherwise we show the day + time.
   */
  timeAgoString: function(date) {
    var now = new Date();

    // Handles the slight out of sync clocks than can result in
    // showing `in a few seconds` instead of `a few seconds ago`.
    date = date > now ? now : date;

    var elapsedTime = now - date;

    if (elapsedTime < TWO_HOURS) {
      return moment(date).fromNow();
    }

    if (elapsedTime < TWO_DAYS) {
      return moment(date).format('ddd, h:m A');
    }

    return moment(date).format('MMM, DD h:m A');
  },
});