Add ability to fetch menu items for a virtual root

app/controllers/api/v1/Menu.controller.js

@@ -12,6 +12,46 @@ class Menu extends Controller {
     }
 
     async get_items(req, res) {
+        const virtual_root = req.query.virtualRootPageId
+        const Page = this.models.get('api:Page')
+        const page_only = req.query.type === 'page'
+
+        if ( !virtual_root ) {
+            return this.get_top_level_menu(req, res);
+        } else {
+            const root_page = await Page.findOne({ UUID: virtual_root })
+            if ( !root_page || !(await root_page.is_accessible_by(req.user, 'view')) ) {
+                return res.status(404)
+                    .message('Invalid virtual root page ID.')
+                    .api()
+            }
+
+            const nodes = await this._build_menu_object(root_page, [], page_only)
+            const menu = []
+
+            const virtual_page = {
+                id: root_page.UUID,
+                children: [...(await root_page.get_menu_items(page_only)), ...nodes],
+                name: root_page.is_shared() ? root_page.Name + ' ⁽ˢʰᵃʳᵉᵈ⁾' : root_page.Name,
+                shared: root_page.is_shared(),
+                type: PageType.Note,
+            };
+
+            menu.push({
+                id: 0,
+                name: 'Virtual Tree Root',
+                children: [virtual_page],
+                noDelete: true,
+                noChildren: true,
+                virtual: true,
+                type: PageType.Branch,
+            })
+
+            return res.api(menu)
+        }
+    }
+
+    async get_top_level_menu(req, res) {
         const Page = this.models.get('api:Page')
         const page_only = req.query.type === 'page'