feat: reverse shares (#86)

* add first concept

* add reverse share funcionality to frontend

* allow creator to limit share expiration

* moved reverse share in seperate module

* add table to manage reverse shares

* delete complete share if reverse share was deleted

* optimize function names

* add db migration

* enable reverse share email notifications

* fix config variable descriptions

* fix migration for new installations

frontend/src/pages/upload/[reverseShareToken].tsx

@@ -0,0 +1,43 @@
+import { LoadingOverlay } from "@mantine/core";
+import { useModals } from "@mantine/modals";
+import { GetServerSidePropsContext } from "next";
+import { useEffect, useState } from "react";
+import Upload from ".";
+import showErrorModal from "../../components/share/showErrorModal";
+import shareService from "../../services/share.service";
+
+export function getServerSideProps(context: GetServerSidePropsContext) {
+  return {
+    props: { reverseShareToken: context.params!.reverseShareToken },
+  };
+}
+
+const Share = ({ reverseShareToken }: { reverseShareToken: string }) => {
+  const modals = useModals();
+  const [isLoading, setIsLoading] = useState(true);
+
+  const [maxShareSize, setMaxShareSize] = useState(0);
+
+  useEffect(() => {
+    shareService
+      .setReverseShare(reverseShareToken)
+      .then((reverseShareTokenData) => {
+        setMaxShareSize(parseInt(reverseShareTokenData.maxShareSize));
+        setIsLoading(false);
+      })
+      .catch(() => {
+        showErrorModal(
+          modals,
+          "Invalid Link",
+          "This link is invalid. Please check your link."
+        );
+        setIsLoading(false);
+      });
+  }, []);
+
+  if (isLoading) return <LoadingOverlay visible />;
+
+  return <Upload isReverseShare maxShareSize={maxShareSize} />;
+};
+
+export default Share;