var govScroll = {
  measurements: {
    initial: {},
    current: {},
    max: {},
  },
  config: {
    hasMilestoneOccurred: {
      25: false, // false indicates it has not fired, but should; true indicates it already has (or shouldn't)
      50: false,
      60: false,
      75: false,
      100: false
    }
  },

  // Calculate content height (docHeight), viewport height (winHeight), and trackLength
  getMeasurements: function () {
    var retval = {};

    // external dimensions of window/browser
    retval.outerHeight = window.outerHeight;

    // internal dimensions (viewport)
    retval.innerHeight = (document.documentElement || document.body).clientHeight || window.innerHeight;
    retval.innerHeight = (window.pageYOffset || window.document.documentElement.scrollTop || window.document.body.scrollTop) + retval.innerHeight;

    // actual page dimensions (account for margins, scrollbars, etc)
    retval.pageHeight = Math.max(
      document.body.scrollHeight, document.documentElement.scrollHeight,
      document.body.offsetHeight, document.documentElement.offsetHeight,
      document.body.clientHeight, document.documentElement.clientHeight
    );

    retval.pctFromTop = Math.round((retval.innerHeight / retval.pageHeight) * 100);

    return retval;
  },

  getMaxMeasurements: function (payload) {
    var retval = {};
    for (key in payload) {
      retval[key] = (payload[key] > this.measurements.max[key]) ? payload[key] : this.measurements.max[key];
    }
    return retval;
  },

  getCurrentStatus: function () {
    this.measurements.current = this.getMeasurements();
    this.measurements.max = this.getMaxMeasurements(this.measurements.current);
    this.getMilestoneProgress(this.measurements.current.pctFromTop);
  },

  getMilestoneProgress: function (currentPctViewed) {
    for (milestone in this.config.hasMilestoneOccurred) {
      if ((currentPctViewed >= milestone) && !this.config.hasMilestoneOccurred[milestone]) {
        this.trackMilestone(milestone);
      }
    }
  },

  setMilestoneProgress: function (milestone) {
    if (milestone) {
      this.config.hasMilestoneOccurred[milestone] = true;
    } else {
      for (key in this.config.hasMilestoneOccurred) {
        if (this.measurements.initial.pctFromTop >= key) {
          this.config.hasMilestoneOccurred[key] = true;
        }
      }
    }
  },

  trackMilestone: function (milestone) {
    console.log("TRACKING MILESTONE:", milestone, this.measurements.current);
    // consider a launch direct call rule here: _satellite.trackScroll({milestone: milestone});
    this.setMilestoneProgress(milestone);
  },

  init: function () {
    this.measurements.initial = this.measurements.current = this.measurements.max = this.getMeasurements();
    this.setMilestoneProgress();
    console.log(this.config, this.measurements);
  }
}

govScroll.init();
var scrollTimer = setTimeout(function () {
  if (govScroll.config.hasMilestoneOccurred[60]) {
    console.log("TRACKING TIME+MILESTONE GOAL");
    // consider a launch direct call rule here
  } else {
    console.log("TIME PASSED, BUT NO MILESTONE");
  }
}, 5000);

window.addEventListener("scroll", function () {
  clearTimeout(throttleScroll);

  // throttle code inside scroll to once every 50 milliseconds
  var throttleScroll = setTimeout(function () {
    govScroll.getCurrentStatus();
  }, 50);
}, false);