Add locale support (#228)

src/components/poll/language-selector.tsx

@@ -0,0 +1,27 @@
+import clsx from "clsx";
+import Cookies from "js-cookie";
+import { useRouter } from "next/router";
+import { useTranslation } from "next-i18next";
+
+export const LanguageSelect: React.VoidFunctionComponent<{
+  className?: string;
+  onChange?: (language: string) => void;
+}> = ({ className, onChange }) => {
+  const { t } = useTranslation("common");
+  const router = useRouter();
+  return (
+    <select
+      className={clsx("input", className)}
+      defaultValue={router.locale}
+      onChange={(e) => {
+        Cookies.set("NEXT_LOCALE", e.target.value, {
+          expires: 365,
+        });
+        onChange?.(e.target.value);
+      }}
+    >
+      <option value="en">{t("english")}</option>
+      <option value="de">{t("german")}</option>
+    </select>
+  );
+};