✨ Develops a crypto price chart widget

docs/widgets.md

@@ -86,6 +86,30 @@ Displays the weather (temperature and conditions) for the next few days for a gi
     units: imperial
 ```
 
+### Crypto Token Price History
+
+Shows recent price history for a given crypto asset, using price data fetched from [CoinGecko](https://www.coingecko.com/)
+
+##### Options
+
+**Field** | **Type** | **Required** | **Description**
+--- | --- | --- | ---
+**`asset`** | `string` |  Required | Name of a crypto asset, coin or token to fetch price data for
+**`currency`** | `string` | _Optional_ | The fiat currency to display results in, expressed as an ISO-4217 alpha code (see [list of currencies](https://www.iban.com/currency-codes)). Defaults to `USD`
+**`numDays`** | `number` |  _Optional_ | The number of days of price history to render. Defaults to `7`, min: `1`, max: `30` days
+
+##### Example
+
+```yaml
+- name: Bitcoin Price
+  icon: fab fa-bitcoin
+  type: crypto-price-chart
+  options:
+    asset: bitcoin
+    currency: GBP
+    numDays: 7
+```
+
 ### TFL Status
 
 Shows real-time tube status of the London Underground. All options are optional.
@@ -101,7 +125,12 @@ Shows real-time tube status of the London Underground. All options are optional.
 ##### Example 
 
 ```yaml
-  - name: TFL Status
+- name: London Underground
+  type: tfl-status
+```
+
+```yaml
+  - name: Commute
     icon: '🚋'
     type: tfl-status
     options:

src/components/Widgets/CryptoPriceChart.vue

@@ -0,0 +1,182 @@
+<template>
+<div class="crypto-price-chart" :id="chartId"></div>
+</template>
+
+<script>
+import { Chart } from 'frappe-charts/dist/frappe-charts.min.esm';
+import axios from 'axios';
+import WidgetMixin from '@/mixins/WidgetMixin';
+import ErrorHandler from '@/utils/ErrorHandler';
+import { widgetApiEndpoints } from '@/utils/defaults';
+
+export default {
+  mixins: [WidgetMixin],
+  components: {},
+  data() {
+    return {
+      chartData: null,
+      chartDom: null,
+    };
+  },
+  mounted() {
+    this.fetchData();
+  },
+  computed: {
+    /* The crypto asset to fetch price data for */
+    asset() {
+      const userChoice = this.options.asset;
+      if (typeof userChoice === 'string') return userChoice;
+      return 'bitcoin';
+    },
+    /* Number of days worth of history to fetch and display */
+    numDays() {
+      const userChoice = this.options.numDays;
+      if (!Number.isNaN(userChoice) && userChoice < 30 && userChoice > 0.15) {
+        return userChoice;
+      }
+      return 7;
+    },
+    /* The fiat currency to calculate price data in */
+    currency() {
+      const userChoice = this.options.currency;
+      if (typeof userChoice === 'string') return userChoice;
+      return 'USD';
+    },
+    /* The number of data points to render on the chart */
+    dataPoints() {
+      const userChoice = this.options.dataPoints;
+      if (!Number.isNaN(userChoice) && userChoice < 100 && userChoice > 5) {
+        return userChoice;
+      }
+      return 30;
+    },
+    /* The formatted GET request API endpoint to fetch crypto data from */
+    endpoint() {
+      return `${widgetApiEndpoints.cryptoPrices}${this.asset}/`
+      + `market_chart?vs_currency=${this.currency}&days=${this.numDays}`;
+    },
+    /* A sudo-random ID for the chart DOM element */
+    chartId() {
+      return `crypto-price-chart-${Math.round(Math.random() * 10000)}`;
+    },
+    getChartColor() {
+      const cssVars = getComputedStyle(document.documentElement);
+      return cssVars.getPropertyValue('--widget-text-color').trim() || '#7cd6fd';
+    },
+  },
+  methods: {
+    /* Create new chart, using the crypto data */
+    generateChart() {
+      return new Chart(`#${this.chartId}`, {
+        title: `${this.asset} Price Chart`,
+        data: this.chartData,
+        type: 'axis-mixed',
+        height: 200,
+        colors: [this.getChartColor, '#743ee2'],
+        truncateLegends: true,
+        lineOptions: {
+          regionFill: 1,
+          hideDots: 1,
+        },
+        axisOptions: {
+          xIsSeries: true,
+          xAxisMode: 'tick',
+        },
+        tooltipOptions: {
+          formatTooltipY: d => `${d} ${this.currency}`,
+        },
+      });
+    },
+    /* Make GET request to CoinGecko API endpoint */
+    fetchData() {
+      axios.get(this.endpoint)
+        .then((response) => {
+          try {
+            this.lineStatuses = this.processData(response.data);
+          } catch (chartingError) {
+            ErrorHandler('Unable to plot results on chart', chartingError);
+          }
+        })
+        .catch((dataFetchError) => {
+          ErrorHandler('Unable to fetch crypto data', dataFetchError);
+        });
+    },
+    /* Generate price history in a format that can be consumed by the chart
+     * To improve efficiency, only a certain amount of data points are plotted
+     * depending on user preference. An average is then calculated between points
+     */
+    processData(data) {
+      const priceChartData = [];
+      const priceLabels = [];
+      const interval = Math.round(data.prices.length / this.dataPoints);
+      const showTime = this.numDays < 5;
+      // Counters for calculating averages between data points
+      let tmpCounter = 0; let tmpTotal = 0;
+      const incrementAverage = (add) => {
+        tmpCounter += 1; tmpTotal += add;
+        if (add === null) { tmpCounter = 0; tmpTotal = 0; }
+      };
+      // For each data point, calc average, and if interval is right, then append
+      data.prices.forEach((priceGroup, index) => {
+        incrementAverage(priceGroup[1]); // Increment averages
+        if (index % interval === 0) {
+          const price = this.formatPrice(tmpTotal / tmpCounter);
+          priceLabels.push(this.formatDate(priceGroup[0], showTime));
+          priceChartData.push(price);
+          incrementAverage(null); // Reset counter
+        }
+      });
+      // Combine results with chart config
+      this.chartData = {
+        labels: priceLabels,
+        datasets: [
+          {
+            name: 'Price',
+            type: 'bar',
+            values: priceChartData,
+          },
+        ],
+      };
+      // Call chart render function
+      this.renderChart();
+    },
+    /* Uses class data to render the line chart */
+    renderChart() {
+      this.chartDom = this.generateChart();
+    },
+    /* Format the date for a given time stamp, also include time if required */
+    formatDate(timestamp, includeTime) {
+      const localFormat = navigator.language;
+      const dateFormat = { weekday: 'short', day: 'numeric', month: 'short' };
+      const timeFormat = { hour: 'numeric', minute: 'numeric', second: 'numeric' };
+      const date = new Date(timestamp).toLocaleDateString(localFormat, dateFormat);
+      const time = Intl.DateTimeFormat(localFormat, timeFormat).format(timestamp);
+      return `${date} ${includeTime ? time : ''}`;
+    },
+    /* Format the price, rounding to given number of decimal places */
+    formatPrice(price) {
+      let numDecimals = 0;
+      if (price < 10) numDecimals = 1;
+      if (price < 1) numDecimals = 2;
+      if (price < 0.1) numDecimals = 3;
+      if (price < 0.01) numDecimals = 4;
+      if (price < 0.001) numDecimals = 5;
+      return price.toFixed(numDecimals);
+    },
+  },
+};
+</script>
+
+<style lang="scss">
+.crypto-price-chart .chart-container {
+  text.title {
+    text-transform: capitalize;
+    color: var(--widget-text-color);
+  }
+  .axis, .chart-label {
+    fill: var(--widget-text-color);
+    opacity: var(--dimming-factor);
+    &:hover { opacity: 1; }
+  }
+}
+</style>

src/components/Widgets/WidgetBase.vue

@@ -14,6 +14,7 @@
       <Weather v-else-if="widgetType === 'weather'" :options="widgetOptions" />
       <WeatherForecast v-else-if="widgetType === 'weather-forecast'" :options="widgetOptions" />
       <TflStatus v-else-if="widgetType === 'tfl-status'" :options="widgetOptions" />
+      <CryptoPriceChart v-else-if="widgetType === 'crypto-price-chart'" :options="widgetOptions" />
     </Collapsable>
   </div>
 </template>
@@ -23,6 +24,7 @@ import Clock from '@/components/Widgets/Clock.vue';
 import Weather from '@/components/Widgets/Weather.vue';
 import WeatherForecast from '@/components/Widgets/WeatherForecast.vue';
 import TflStatus from '@/components/Widgets/TflStatus.vue';
+import CryptoPriceChart from '@/components/Widgets/CryptoPriceChart.vue';
 import Collapsable from '@/components/LinkItems/Collapsable.vue';
 
 export default {
@@ -33,6 +35,7 @@ export default {
     Weather,
     WeatherForecast,
     TflStatus,
+    CryptoPriceChart,
   },
   props: {
     widget: Object,