<template>
  <div>
    <div id="chart">
      <apexchart
        type="area"
        height="350"
        :options="chartOptions"
        :series="series"
      ></apexchart>
    </div>
  </div>
</template>

<script>
import VueApexCharts from 'vue-apexcharts'

// Deterministic daily traffic per channel; stacking shows total site visits
// split into its sources. Each channel is a mean-reverting walk around its
// own base so the composition shifts organically day to day.
function mulberry32(seed) {
  return function () {
    seed |= 0
    seed = (seed + 0x6d2b79f5) | 0
    var t = Math.imul(seed ^ (seed >>> 15), 1 | seed)
    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296
  }
}

function channel(seed, base, spread) {
  var rand = mulberry32(seed)
  var series = []
  var ts = new Date('01 Jun 2025 GMT').getTime()
  var val = base
  for (var i = 0; i < 20; i++) {
    val += (rand() - 0.5) * spread
    val += (base - val) * 0.15
    series.push([ts, Math.max(2, Math.round(val))])
    ts += 86400000
  }
  return series
}

export default {
  components: {
    apexchart: VueApexCharts,
  },
  data: function () {
    return {
      series: [
        {
          name: 'Organic Search',
          data: channel(11, 42, 14),
        },
        {
          name: 'Direct',
          data: channel(23, 26, 9),
        },
        {
          name: 'Social',
          data: channel(35, 15, 8),
        },
      ],
      chartOptions: {
        chart: {
          type: 'area',
          height: 350,
          stacked: true,
          events: {
            selection: function (chart, e) {
              console.log(new Date(e.xaxis.min))
            },
          },
        },
        colors: ['#008FFB', '#00E396', '#FEB019'],
        dataLabels: {
          enabled: false,
        },
        stroke: {
          curve: 'monotoneCubic',
        },
        title: {
          text: 'Website Visits by Channel',
          align: 'left',
        },
        fill: {
          type: 'gradient',
          gradient: {
            opacityFrom: 0.6,
            opacityTo: 0.8,
          },
        },
        legend: {
          position: 'top',
          horizontalAlign: 'left',
        },
        yaxis: {
          labels: {
            formatter: function (val) {
              return val + 'k'
            },
          },
        },
        xaxis: {
          type: 'datetime',
        },
      },
    }
  },
}
</script>

<style>
#chart {
  max-width: 650px;
  margin: 35px auto;
}
</style>