function generateData() {
  var unit = document.getElementById('unit').value;

  function unitLessThanDay() {
    return unit === 'second' || unit === 'minute' || unit === 'hour';
  }

  function beforeNineThirty(date) {
    return date.hour() < 9 || (date.hour() === 9 && date.minute() < 30);
  }

  // Returns true if outside 9:30am-4pm on a weekday
  function outsideMarketHours(date) {
    if (date.isoWeekday() > 5) {
      return true;
    }
    if (unitLessThanDay() && (beforeNineThirty(date) || date.hour() > 16)) {
      return true;
    }
    return false;
  }

  function randomNumber(min, max) {
    return Math.random() * (max - min) + min;
  }

  function randomBar(date, lastClose) {
    var open = randomNumber(lastClose * 0.95, lastClose * 1.05).toFixed(2);
    var close = randomNumber(open * 0.95, open * 1.05).toFixed(2);
    return {
      t: date.valueOf(),
      y: close
    };
  }

  var date = moment('Jan 01 1990', 'MMM DD YYYY');
  var now = moment();
  var data = [];
  var lessThanDay = unitLessThanDay();
  for (; data.length < 600 && date.isBefore(now); date = date.clone().add(1, unit).startOf(unit)) {
    if (outsideMarketHours(date)) {
      if (!lessThanDay || !beforeNineThirty(date)) {
        date = date.clone().add(date.isoWeekday() >= 5 ? 8 - date.isoWeekday() : 1, 'day');
      }
      if (lessThanDay) {
        date = date.hour(9).minute(30).second(0);
      }
    }
    data.push(randomBar(date, data.length > 0 ? data[data.length - 1].y : 30));
  }

  return data;
}

var ctx = document.getElementById('chart1').getContext('2d');
ctx.canvas.width = 1000;
ctx.canvas.height = 300;

var color = Chart.helpers.color;
var cfg = {
  data: {
    datasets: [{
      label: 'Jamies super mega graph',
      backgroundColor: color(window.chartColors.stocklock).alpha(0.5).rgbString(),
      borderColor: window.chartColors.stocklock,
      data: generateData(),
      type: 'line',
      pointRadius: 0,
      fill: false,
      lineTension: 0,
      borderWidth: 2
    }]
  },
  options: {
    animation: {
      duration: 0
    },
    scales: {
      xAxes: [{
        type: 'time',
        distribution: 'series',
        offset: true,
        ticks: {
          major: {
            enabled: true,
            fontStyle: 'bold'
          },
          source: 'data',
          autoSkip: true,
          autoSkipPadding: 75,
          maxRotation: 0,
          sampleSize: 100
        },
        afterBuildTicks: function(scale, ticks) {
          var majorUnit = scale._majorUnit;
          var firstTick = ticks[0];
          var i, ilen, val, tick, currMajor, lastMajor;

          val = moment(ticks[0].value);
          if ((majorUnit === 'minute' && val.second() === 0)
              || (majorUnit === 'hour' && val.minute() === 0)
              || (majorUnit === 'day' && val.hour() === 9)
              || (majorUnit === 'month' && val.date() <= 3 && val.isoWeekday() === 1)
              || (majorUnit === 'year' && val.month() === 0)) {
            firstTick.major = true;
          } else {
            firstTick.major = false;
          }
          lastMajor = val.get(majorUnit);

          for (i = 1, ilen = ticks.length; i < ilen; i++) {
            tick = ticks[i];
            val = moment(tick.value);
            currMajor = val.get(majorUnit);
            tick.major = currMajor !== lastMajor;
            lastMajor = currMajor;
          }
          return ticks;
        }
      }],
      yAxes: [{
        gridLines: {
          drawBorder: false
        },
        scaleLabel: {
          display: true,
          labelString: 'Closing price ($)'
        }
      }]
    },
    tooltips: {
      intersect: false,
      mode: 'index',
      callbacks: {
        label: function(tooltipItem, myData) {
          var label = myData.datasets[tooltipItem.datasetIndex].label || '';
          if (label) {
            label += ': ';
          }
          label += parseFloat(tooltipItem.value).toFixed(2);
          return label;
        }
      }
    }
  }
};

var chart = new Chart(ctx, cfg);

document.getElementById('update').addEventListener('click', function() {
  var dataset = chart.config.data.datasets[0];
  dataset.type = 'bar';
  dataset.data = generateData();
  chart.update();
});