charts.js

const { CanvasRenderService } = require('chartjs-node-canvas');
const queryString = require('query-string');
const vsprintf = require("sprintf-js").vsprintf;
const request = require("request");
const smooth = require('array-smooth');
const moment = require("moment");

function getCoinGeckoData(options, callback) {
  var queryParams = {
    vs_currency: options.vsCurrency,
    days: options.days
  };

  var packetData = {
    uri: vsprintf("https://api.coingecko.com/api/v3/coins/smartcrytotech/market_chart?%s", [queryString.stringify(queryParams)]),
    method: "GET",
    json: true
  };

  request(packetData, function (error, response, body) {
    callback(body);
  });
}

function getCustomChart(options, chartData, resultCallback) {
  function makeConfiguration(data) {
    var timeLabels = [];
    var dataPoints = [];
    var dataLength = data.length;
    var durationAsMS = moment.duration(options.days / dataLength, 'd').asMilliseconds();

    data.forEach(function (value) {
      dataPoints.push(value[1]);
    });

    for (i = dataLength - 1; i >= 0; i--) {
      timeLabels.push(moment().subtract(durationAsMS * (i + 1), 'ms').format(options.dateFormat));
    }

    return {
      type: 'line',
      data: {
        labels: timeLabels,
        datasets: [{
          data: smooth(dataPoints, 3),
          backgroundColor: 'rgba(255,165,0,0.2)',
          fill: true,
          borderWidth: 2,
          pointRadius: 0,
          borderColor: '#FFA500'
        }]
      },
      options: {
        animation: false,
        responsive: true,
        maintainAspectRatio: false,
        legend: {
          display: false,
          labels: {
            display: false
          }
        },
        scales: {
          yAxes: [{
            ticks: {
              maxTicksLimit: 5,
              fontSize: 10,
              callback: function (value, index, values) {
                return options.priceSymbol + value.toFixed(options.priceDecimals);
              }
            },
            gridLines: {
              color: 'rgba(255,255,255,.08)'
            }
          }],
          xAxes: [{
            ticks: {
              autoSkip: true,
              maxTicksLimit: options.xPoints,
              maxRotation: 0,
              minRotation: 0
            },
            gridLines: {
              color: 'rgba(255, 255, 255, .08)'
            },
          }]
        },
        hover: {
          mode: 'nearest',
          intersect: true
        }
      }
    };
  }

  const chartCallback = (Chart) => {
    // Global config example: https://www.chartjs.org/docs/latest/configuration/
    Chart.defaults.global.elements.rectangle.borderWidth = 2;
    // Global plugin example: https://www.chartjs.org/docs/latest/developers/plugins.html
    Chart.plugins.register({
      // plugin implementation
    });
    // New chart type example: https://www.chartjs.org/docs/latest/developers/charts.html
    Chart.controllers.MyType = Chart.DatasetController.extend({
      // chart implementation
    });
  };

  (async () => {
    const canvasRenderService = new CanvasRenderService(options.width, options.height, chartCallback);
    resultCallback(await canvasRenderService.renderToBuffer(makeConfiguration(chartData)));
  })();
}

module.exports = {
  getPriceChart: function (options, resultCallback) {
    getCoinGeckoData(options, function (data) {
      getCustomChart(options, data.prices, resultCallback);
    });
  },
  getVolumeChart: function (options, resultCallback) {
    getCoinGeckoData(options, function (data) {
      getCustomChart(options, data.total_volumes, resultCallback);
    });
  },
  getMarketcapChart: function (options, resultCallback) {
    getCoinGeckoData(options, function (data) {
      getCustomChart(options, data.market_caps, resultCallback);
    });
  }
};