@Override
  public void onDataFetched(List<Meter> meters) {
    mMeters = meters;
    mSwipeRefreshLayout.setRefreshing(false);
    showProgress(false);

    // only reading one meter.
    // TODO: graph multiple meters?
    Meter meter = mMeters.get(0);
    setData(meter.getReadings().size(), 1000);
  }
  private void setData(int count, float range) {

    // only using first meter for now.
    // TODO: graph multiple meters?
    Meter meter = mMeters.get(0);
    List<MeterReading> readings = meter.getReadings();

    ArrayList<Entry> averageEntries = new ArrayList<Entry>();

    // build up X-axis labels; e.g., dates.
    // build up Y-axis with values;
    // skip first date as we can't determine consumption.
    ArrayList<String> xVals = new ArrayList<String>();
    ArrayList<BarEntry> yVals1 = new ArrayList<BarEntry>();
    float runningTotal = 0;
    float dailyAverage;
    for (int lv = 1; lv < count; lv++) {
      MeterReading prevReading = readings.get(lv - 1);
      MeterReading currReading = readings.get(lv);

      xVals.add(removeYearFromDate(currReading.getTimeStamp()));
      float val = (currReading.getConsumption() - prevReading.getConsumption()) * 10;
      yVals1.add(new BarEntry(val, lv - 1));

      // calc & store daily average.
      runningTotal += val;
      dailyAverage = runningTotal / lv;
      averageEntries.add(new Entry(dailyAverage, lv - 1));
    }

    // TODO: allow name to be updated.
    BarDataSet set1 = new BarDataSet(yVals1, "mine");
    set1.setBarSpacePercent(35f);

    ArrayList<BarDataSet> dataSets = new ArrayList<BarDataSet>();
    dataSets.add(set1);

    // bar chart data
    BarData barData = new BarData(xVals, dataSets);
    barData.setValueFormatter(new MyValueFormatter());
    barData.setValueTextSize(10f);

    // line chart data
    LineData lineData = new LineData();
    LineDataSet set = new LineDataSet(averageEntries, "average");
    int lineColor = Color.rgb(251, 169, 165);
    set.setColor(lineColor);
    set.setLineWidth(1.5f);
    set.setDrawCircles(false);
    set.setFillColor(lineColor);
    set.setDrawCubic(true);
    set.setDrawValues(false);
    set.setAxisDependency(YAxis.AxisDependency.LEFT);
    lineData.addDataSet(set);

    CombinedData combinedData = new CombinedData(getDates(meter.getReadings()));
    combinedData.setData(barData);
    combinedData.setData(lineData);

    mChart.setData(combinedData);
    mChart.invalidate();
  }