
<script setup>

import moment from 'moment-timezone';
import { onMounted, onUnmounted, useTemplateRef, watch } from 'vue';
import Chart from 'chart.js/auto';
import { prettyDecimalSize } from 'pankow/utils';

const LIVE_REFRESH_INTERVAL_MSECS = 500;
const LIVE_REFRESH_HISTORY_MSECS = 5*60*1000; // last 5 mins

const graphNode = useTemplateRef('graphNode');

let graph = null;
let liveRefreshIntervalId = null;
let yscaleUnit = null;

const props = defineProps({
  title: String,
  subtext: String,
  period: Object, // { hours, format, tooltpFormat }
  datasetLabels: {
    type: Array,
    validator: (val) => Array.isArray(val) && val.every(item => typeof item === 'string')
  },
  datasetColors: {
    type: Array,
    validator: (val) => Array.isArray(val) && val.every(item => typeof item === 'string')
  },
  yscale: String, // cpu, memory
  memory: Object,
  cpu: Object,
});

function createGraphOptions({ yscale, period, displayLegend }) {
  const now = Date.now();

  return {
    maintainAspectRatio: false,
    plugins: {
      legend: {
        display: displayLegend,
        position: 'bottom'
      },
      tooltip: {
        callbacks: {
          title: (tooltipItem) => moment(tooltipItem[0].raw.x).format(period.tooltipFormat),
          label: (tooltipItem) => {
            const datasetLabel = tooltipItem.chart.data.datasets[tooltipItem.datasetIndex].label;
            return `${datasetLabel}: ${yscale.ticks.callback(tooltipItem.raw.y)}`;
          }
        }
      }
    },
    scales: {
      x: {
        // we used to use 'time' type but it relies on the data to generate ticks. we may not have data for our time periods
        type: 'linear',
        min: now - (period.hours === 0 ? LIVE_REFRESH_HISTORY_MSECS : period.hours*60*60*1000),
        max: now,
        ticks: {
          autoSkip: true, // skip tick labels as needed
          autoSkipPadding: 20, // padding between ticks
          maxRotation: 0, // don't rotate the labels
          count: 7, // tick labels to show. anything more than 7 will not work for "7 days"
          callback: function (value) {
            if (period.hours === 0) return `${5-(value-this.min)/60000}min`;
            return moment(value).format(period.format);
          },
          stepSize: period.hours === 0 ? 60*1000 : null // // for realtime graph, generate steps of 1min and appropriate tick text
        },
        grid: {
          drawOnChartArea: false,
        },
      },
      y: yscale,
    },
    interaction: {
      intersect: false,
      mode: 'nearest',
      axis: 'x'
    }
  };
}

function transformData(data) {
  const x = data[1]*1000; // convert to msecs
  let y;
  if (props.yscale === 'memory') {
    y = yscaleUnit === 'GiB' ? (data[0] / 1024 / 1024 / 1024).toFixed(2) : (data[0] / 1024 / 1024).toFixed(2);
  } else { // in non-memory case, for relative values like cpu, if null make it 0
    y = data[0] || 0;
  }
  return { x, y };
}

function setData(...data) {
  for (const [index, items] of data.entries()) {
    graph.data.datasets[index].data = items.map(transformData);
  }
  graph.update('none');
}

function pruneGraphData(dataset, options) {
  while (dataset.data.length && (dataset.data[0].x < options.scales.x.min)) { // remove elements beyond our time window
    dataset.data.shift();
  }
}

function advance() {
  graph.options.scales.x.min += LIVE_REFRESH_INTERVAL_MSECS;
  graph.options.scales.x.max += LIVE_REFRESH_INTERVAL_MSECS;
  graph.update('none');
}

function pushData(...data) {
  for (const [index, item] of data.entries()) {
    graph.data.datasets[index].data.push(transformData(item));
    pruneGraphData(graph.data.datasets[index], graph.options);
  }
  graph.update('none');
}

function onPeriodChanged() {
  if (liveRefreshIntervalId) {
    clearInterval(liveRefreshIntervalId);
    liveRefreshIntervalId = null;
  }

  const data = { datasets: [] };

  for (const [index, label] of props.datasetLabels.entries()) {
    data.datasets.push({
      label: label,
      data: [],
      pointRadius: 0,
      borderWidth: 1, // https://www.chartjs.org/docs/latest/charts/line.html#line-styling
      tension: 0.4,
      showLine: true,
      fill: true,
      color: props.datasetColors[index],
      stack: 'stackgroup' // put them all in same stackgroup
    });
  }

  // CPU and Memory graph have known min/max set and auto-scaling gets disabled
  // Disk and Network graphs auto-scale the y values.

  let yscale = null;

  if (props.yscale === 'cpu') {
    yscale = {
      type: 'linear',
      min: 0,
      max: 4 * 100,
      ticks: {
        callback: (value) => `${value.toFixed(2)}%`,
        maxTicksLimit: 6 // max tick labels to show
      },
      beginAtZero: true,
    };
  } else if (props.yscale === 'memory') {
    const giB = 1024 * 1024 * 1024;
    const roundedMemoryGiB = Math.ceil(props.memory / giB);
    yscaleUnit = roundedMemoryGiB === 1 ? 'MiB' : 'GiB';
    const roundedMemory = yscaleUnit === 'GiB' ? roundedMemoryGiB : roundedMemoryGiB * 1024;

    yscale = {
      type: 'linear',
      min: 0,
      max: roundedMemory,
      ticks: {
        stepSize: yscaleUnit === 'GiB' ? 1 : 256,
        autoSkip: true, // skip tick labels as needed
        autoSkipPadding: 20, // padding between ticks
        callback: (value) => `${value} ${yscaleUnit}`,
        maxTicksLimit: 8 // max tick labels to show
      },
      beginAtZero: true,
      stacked: true,
    };
  } else if (props.yscale === 'disk') {
    yscale = {
      type: 'linear',
      min: 0,
      grace: 100*1000, // add 100kBps. otherwise, the yaxis auto-scales to data and the values appear too dramatic
      ticks: {
        callback: (value) => `${prettyDecimalSize(value)}ps`,
        maxTicksLimit: 6 // max tick labels to show
      },
      beginAtZero: true,
      stacked: false,
    };
  } else if (props.yscale === 'network') {
    yscale = {
      type: 'linear',
      min: 0,
      grace: 50*1000, // add 50kBps. otherwise, the yaxis auto-scales to data and the values appear too dramatic
      ticks: {
        callback: (value) => `${prettyDecimalSize(value)}ps`,
        maxTicksLimit: 6 // max tick labels to show
      },
      beginAtZero: true,
      stacked: false,
    };
  }

  // this sets a min 'x' based on current timestamp. so it has to re-created every time the period changes
  const graphOptions = createGraphOptions({ yscale, period: props.period, displayLegend: props.datasetLabels.length > 1 });

  if (!graph) {
    graph = new Chart(graphNode.value, { type: 'line', data, options: graphOptions });
  } else {
    graph.data = data;
    graph.options = graphOptions;
    graph.update('none');
  }

  // advances the time window. this is independent of incoming data vis pushData()
  if (props.period.hours === 0) liveRefreshIntervalId = setInterval(advance, LIVE_REFRESH_INTERVAL_MSECS);
}

watch(() => props.period, onPeriodChanged);

onMounted(async function () {
    await onPeriodChanged();
});

onUnmounted(async function () {
  if (liveRefreshIntervalId) clearInterval(liveRefreshIntervalId);
});

defineExpose({
  setData,
  pushData,
});

</script>

<template>
  <div>
    <label>{{ title }} <span class="pull-right text-small">{{ subtext }}</span></label>
    <div class="graph">
      <canvas ref="graphNode"></canvas>
    </div>
  </div>
</template>

<style scoped>

.graphs label {
  margin: 16px 0;
}

.graph {
  position: relative;
  width: 100%;
  height: 160px;
}

</style>
