feat: script for iCal generation

- make use of ical-generator
- use prefix to specify yaml front matter containing permalink for jekyll
- NOTE that X-attributes are not yet able to be specified in this manner
  - REF: sebbo2002/ical-generator#185

.scripts/generate-webinar-ical.js

@@ -0,0 +1,83 @@
+#!/usr/bin/env node
+
+const fs = require('fs');
+
+const icalGenerator = require('ical-generator');
+
+const webinarsJson = require('../_data/webinars.json');
+
+const events = webinarsJson.events.map(processEvent);
+
+const icalData = {
+  domain: 'developers.rsk.co/',
+  prodId: '//developers.rsk.co//events-calendar//EN',
+  name: 'RSK and RIF Webinars',
+  timezone: 'Etc/UTC',
+  scale: 'gregorian',
+  ttl: 3600,
+  organizer: 'RSK',
+  events,
+};
+
+const ical = icalGenerator(icalData);
+
+const icalPrefix = '---\npermalink: /webinars/calendar.ical\n---\n';
+const icalSuffix = '\n';
+const icalPath = './webinars/calendar.ical';
+
+fs.writeFile(
+  icalPath,
+  icalPrefix + ical.toString() + icalSuffix,
+  function (err) {
+    if (err) {
+      throw err;
+    } else {
+      console.log(`iCal output successfully: ${icalPath}`);
+    }
+  },
+);
+
+function processEvent(event) {
+  switch (event.type) {
+    case 'event/1':
+      return processEventV1(event);
+    default:
+      throw new Error(`Unsupported type: ${event.type}`);
+  }
+}
+
+function processEventV1(event) {
+  const {
+    id,
+    timestamp,
+    url,
+    location,
+    category,
+    language,
+    title,
+    subtitle,
+    lastModified,
+  } = event;
+  const timestampDate = new Date(timestamp);
+  const lastModifiedDate = new Date(lastModified);
+  return {
+    uid: id,
+    start: timestampDate,
+    timestamp: timestampDate,
+    lastModified: lastModifiedDate,
+    url,
+    summary: ([title, subtitle].join(' ')),
+    location,
+    categories: [
+      {
+        name: category,
+      },
+    ],
+    // NOTE that X-attributes are not yet able to be specified in this manner
+    // REF: https://github.com/sebbo2002/ical-generator/pull/185
+    x: [
+      ['LANGUAGE', language],
+    ],
+    status: 'confirmed',
+  };
+}