feat: Nested document sharing (#2075)

* migration

* frontend routing, api permissioning

* feat: apiVersion=2

* feat: re-writing document links to point to share

* poc nested documents on share links

* fix: nested shareId permissions

* ui and language tweaks, comments

* breadcrumbs

* Add icons to reference list items

* refactor: Breadcrumb component

* tweaks

* Add shared parent note

app/scenes/Document/components/PublicReferences.js

@@ -0,0 +1,57 @@
+// @flow
+import { observer } from "mobx-react";
+import * as React from "react";
+import { useTranslation } from "react-i18next";
+import Subheading from "components/Subheading";
+import ReferenceListItem from "./ReferenceListItem";
+import { type NavigationNode } from "types";
+
+type Props = {|
+  shareId: string,
+  documentId: string,
+  sharedTree: NavigationNode,
+|};
+
+function PublicReferences(props: Props) {
+  const { t } = useTranslation();
+  const { shareId, documentId, sharedTree } = props;
+
+  // The sharedTree is the entire document tree starting at the shared document
+  // we must filter down the tree to only the part with the document we're
+  // currently viewing
+  const children = React.useMemo(() => {
+    let result;
+
+    function findChildren(node) {
+      if (!node) return;
+      if (node.id === documentId) {
+        result = node.children;
+      } else {
+        node.children.forEach((node) => {
+          if (result) {
+            return;
+          }
+          findChildren(node);
+        });
+      }
+      return result;
+    }
+
+    return findChildren(sharedTree) || [];
+  }, [documentId, sharedTree]);
+
+  if (!children.length) {
+    return null;
+  }
+
+  return (
+    <>
+      <Subheading>{t("Nested documents")}</Subheading>
+      {children.map((node) => (
+        <ReferenceListItem key={node.id} document={node} shareId={shareId} />
+      ))}
+    </>
+  );
+}
+
+export default observer(PublicReferences);