Add qBittorrent Widget

- extract cookie jar functionality into its own file
- use i18n for more strings in existing widgets

completes: #152
associated: #123

src/utils/proxies/qbittorrent.js

@@ -0,0 +1,58 @@
+import { formatApiCall } from "utils/api-helpers";
+import { addCookieToJar, setCookieHeader } from "utils/cookie-jar";
+import { httpProxy } from "utils/http";
+import getServiceWidget from "utils/service-helpers";
+
+async function login(widget, params) {
+  const loginUrl = new URL(`${widget.url}/api/v2/auth/login`);
+  const loginBody = `username=${encodeURI(widget.username)}&password=${encodeURI(widget.password)}`;
+
+  // using fetch intentionally, for login only, as the httpProxy method causes qBittorrent to
+  // complain about header encoding
+  return fetch(loginUrl, {
+    method: "POST",
+    headers: { "Content-Type": "application/x-www-form-urlencoded" },
+    body: loginBody
+  })
+  .then(async response => {
+    addCookieToJar(loginUrl, response.headers);
+    setCookieHeader(loginUrl, params);
+    const data = await response.text();
+    return ([response.status, data]);
+  })
+  .catch(err => ([500, err]));
+}
+
+export default async function qbittorrentProxyHandler(req, res) {
+  const { group, service, endpoint } = req.query;
+
+  if (!group || !service) {
+    return res.status(400).json({ error: "Invalid proxy service type" });
+  }
+
+  const widget = await getServiceWidget(group, service);
+
+  if (!widget) {
+    return res.status(400).json({ error: "Invalid proxy service type" });
+  }
+
+  const url = new URL(formatApiCall(widget.type, { endpoint, ...widget }));
+  const params = { method: "GET", headers: {} };
+  setCookieHeader(url, params);
+
+  if (!params.headers.Cookie) {
+    const [status, data] = await login(widget, params);
+
+    if (status !== 200) {
+      return res.status(status).end(data);
+    }
+    if (data.toString() !== 'Ok.') {
+      return res.status(401).end(data);
+    }
+  }
+
+  const [status, contentType, data] = await httpProxy(url, params);
+
+  if (contentType) res.setHeader("Content-Type", contentType);
+  return res.status(status).send(data);
+}