Calibre web widget (#1829)

* Add widget for calibre-web with reverse-proxy auth

---------

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

src/widgets/calibreweb/proxy.js

@@ -0,0 +1,73 @@
+import { xml2json } from "xml-js";
+
+import { formatApiCall } from "utils/proxy/api-helpers";
+import { httpProxy } from "utils/proxy/http";
+import getServiceWidget from "utils/config/service-helpers";
+import createLogger from "utils/logger";
+import widgets from "widgets/widgets";
+
+const proxyName = "calibreWebProxyHandler";
+const logger = createLogger(proxyName);
+
+async function getWidget(req) {
+  const { group, service } = req.query;
+
+  if (!group || !service) {
+    logger.debug("Invalid or missing service '%s' or group '%s'", service, group);
+    return null;
+  }
+
+  const widget = await getServiceWidget(group, service);
+
+  if (!widget) {
+    logger.debug("Invalid or missing widget for service '%s' in group '%s'", service, group);
+    return null;
+  }
+
+  return widget;
+}
+
+async function apiCall(widget, endpoint) {
+  const { api } = widgets[widget.type];
+  const apiUrl = new URL(formatApiCall(api, { endpoint, ...widget }));
+  const headers = {
+      Authorization: `Basic ${Buffer.from(`${widget.username}:${widget.password}`).toString("base64")}`
+  };
+
+  const [status, contentType, data] = await httpProxy(apiUrl, {
+    withCredentials: true,
+    credentials: "include",
+    headers,
+  });
+
+  if (status !== 200) {
+    logger.error("Error getting data from CalibreWeb: %s status %d. Data: %s", apiUrl, status, data);
+    return { status, contentType, data: null };
+  }
+
+  try {
+    const dataDecoded = xml2json(data.toString(), { compact: true });
+    return {status, data: JSON.parse(dataDecoded), contentType};
+  } catch (e) {
+    logger.error("Error decoding CalibreWeb API data. Data: %s", data.toString());
+    return {status, data: null, contentType};
+  }
+}
+
+export default async function calibreWebProxyHandler(req, res) {
+  const widget = await getWidget(req);
+  
+  const { endpoint } = req.query;
+
+  if (!widget) {
+    return res.status(400).json({ error: "Invalid proxy service type" });
+  }
+
+  const { status, data } = await apiCall(widget, endpoint);
+
+  if (status !== 200) {
+    return res.status(status).json({error: {message: "HTTP error communicating with CalibreWeb API", data: Buffer.from(data).toString()}});
+  }
+
+  return res.status(status).json(data);
+}