// ── Reproducible synthetic data (seeded PRNG, no network) ──────────────
function mulberry32(a) {
  return function () {
    a |= 0
    a = (a + 0x6d2b79f5) | 0
    var t = Math.imul(a ^ (a >>> 15), 1 | a)
    t = (t + Math.imul(t ^ (t >>> 7), 61 | t)) ^ t
    return ((t ^ (t >>> 14)) >>> 0) / 4294967296
  }
}
var rng = mulberry32(1357924680)

function gauss(mean, sd) {
  var u = 0,
    v = 0
  while (u === 0) u = rng()
  while (v === 0) v = rng()
  return mean + sd * Math.sqrt(-2 * Math.log(u)) * Math.cos(2 * Math.PI * v)
}

function sample(n, mean, sd) {
  var out = []
  for (var i = 0; i < n; i++) {
    out.push(Math.round(gauss(mean, sd) * 10) / 10)
  }
  return out
}

// Daily afternoon temperature (°C) across the year — each dot is one day,
// coloured by how warm it was (cool → warm along the ramp). [month, mean, sd]
// follow a seasonal arc, so the colour gradient sweeps low → high → low.
var MONTHS = [
  ['Jan', 4, 3],
  ['Feb', 6, 3],
  ['Mar', 11, 3.5],
  ['Apr', 15, 4],
  ['May', 20, 4],
  ['Jun', 24, 4],
  ['Jul', 27, 3.5],
  ['Aug', 26, 3.5],
  ['Sep', 21, 4],
  ['Oct', 15, 4.5],
  ['Nov', 9, 3.5],
  ['Dec', 5, 3],
].map(function (m) {
  return { name: m[0], data: sample(110, m[1], m[2]) }
})

// Gaussian KDE → [[value, density], ...]. The chart renders the profile you
// supply; the smoothness is a property of this bandwidth, computed here.
function kde(values, bw) {
  var min = Math.min.apply(null, values) - bw
  var max = Math.max.apply(null, values) + bw
  var N = values.length
  var profile = []
  for (var x = min; x <= max; x += 0.4) {
    var sum = 0
    for (var k = 0; k < N; k++) {
      var d = (x - values[k]) / bw
      sum += Math.exp(-0.5 * d * d)
    }
    profile.push([Math.round(x * 100) / 100, sum / (N * bw)])
  }
  return profile
}

// A sequential cool→warm colour ramp (low → high).
var COLOR_RAMP = ['#2c7bb6', '#abd9e9', '#ffffbf', '#fdae61', '#d7191c']

var options = {
  series: [
    {
      name: 'Temperature',
      data: MONTHS.map(function (m) {
        return {
          x: m.name,
          y: { density: kde(m.data, 1.5), points: m.data },
        }
      }),
    },
  ],
  chart: {
    type: 'violin',
    height: 560,
  },
  title: {
    text: 'Afternoon temperature through the year — dots coloured by value',
  },
  // muted grey violins so the colour-graded dots are the focus
  colors: ['#b8c4cc'],
  stroke: { width: 1, colors: ['#90a4ae'] },
  fill: { opacity: 0.6 },
  legend: { show: false },
  yaxis: {
    title: { text: 'Temperature (°C)' },
  },
  plotOptions: {
    violin: {
      points: {
        show: true,
        size: 5,
        jitter: 0.8,
        opacity: 1,
        strokeColor: '#fff',
        strokeWidth: 1,
        // colour each observation by its value along the ramp
        colorScale: { colors: COLOR_RAMP, min: 0, max: 32 },
      },
    },
  },
}

var chart = new ApexCharts(document.querySelector('#chart'), options)
chart.render()