Feature: Implement iCal integration for calendar, improve styling (#2376)

* Feature: Implement iCal integration, improve calendar/agenda styling

* Delete calendar.jsx

* Calendar proxy handler

* code style

* Add some basic error handling

---------

Co-authored-by: shamoon <4887959+shamoon@users.noreply.github.com>

src/widgets/calendar/proxy.js

@@ -0,0 +1,33 @@
+import getServiceWidget from "utils/config/service-helpers";
+import { httpProxy } from "utils/proxy/http";
+import createLogger from "utils/logger";
+
+const logger = createLogger("calendarProxyHandler");
+
+export default async function calendarProxyHandler(req, res) {
+  const { group, service, endpoint } = req.query;
+
+  if (group && service) {
+    const widget = await getServiceWidget(group, service);
+    const integration = widget.integrations?.find((i) => i.name === endpoint);
+
+    if (integration) {
+      if (!integration.url) {
+        return res.status(403).json({ error: "No integration URL specified" });
+      }
+
+      const [status, contentType, data] = await httpProxy(integration.url);
+
+      if (contentType) res.setHeader("Content-Type", contentType);
+
+      if (status !== 200) {
+        logger.debug(`HTTTP ${status} retrieving data from integration URL ${integration.url} : ${data}`);
+        return res.status(status).send(data);
+      }
+
+      return res.status(status).json({ data: data.toString() });
+    }
+  }
+
+  return res.status(400).json({ error: "Invalid integration" });
+}