var chart;
var chartSeries = {};
var latestTimeReported = {};

function requestData() {

  $.ajax({
    url: 'chartdata.php',
    success: function(seriesUpdate) {

      //in case initializer of highcharts is too quick - skip the update
      if (!chart) {
        setTimeout(requestData, 1000);
        return;
      }

      $.each(seriesUpdate, function (serieIndex, serieUpdate) {
        var existingSerie = chartSeries[serieUpdate.name];
        var newPoint = serieUpdate.data[0];
        var lastInsertedTime = latestTimeReported[serieUpdate.name];          

        if (lastInsertedTime  && lastInsertedTime < newPoint[0]) {
          console.log('Attempt inserting old data!!!!');
          return;
        }

        latestTimeReported[serieUpdate.name] = newPoint[0];

        if (existingSerie) {
          var shift = existingSerie.data.length > 20;
          existingSerie.addPoint(newPoint , true, shift);
        } else {
          var newSerie = chart.addSeries({                        
            name: serieUpdate.name,
            data: serieUpdate.data
          }, true);
          chartSeries[serieUpdate.name] = newSerie;
        }

      });

      // call it again after one second
      setTimeout(requestData, 1000);
    },
    cache: false
  });
}

$(document).ready(function() {
    chart = new Highcharts.Chart({
        chart: {
            renderTo: 'container',
            defaultSeriesType: 'spline',
            events: {
                load: requestData
            }
        },
        title: {
            text: 'Live random data'
        },
        xAxis: {
            type: 'datetime',
            tickPixelInterval: 150,
            maxZoom: 20 * 1000
        },
        yAxis: {
            minPadding: 0.2,
            maxPadding: 0.2,
            title: {
                text: 'Value',
                margin: 80
            }
        },
        series: []
    });