Prevent self-referencing locations and items as parents (#773)

* prevent current location and descendants from being selected as parent

* prevent an item from showing up in the parent items drop-down for itself

* pass location object to filter function to allow for more flexible filtering

* align exclude prop and fix type comparison, change item filter to array of ItemsObjects to allow for descendant filtering in future

* fix linting prop reference

frontend/composables/use-location-helpers.ts

@@ -1,5 +1,5 @@
 import type { Ref } from "vue";
-import type { TreeItem } from "~~/lib/api/types/data-contracts";
+import type { TreeItem, LocationSummary } from "~~/lib/api/types/data-contracts";
 
 export interface FlatTreeItem {
   id: string;
@@ -35,9 +35,29 @@ function flatTree(tree: TreeItem[]): FlatTreeItem[] {
   return v;
 }
 
-export function useFlatLocations(): Ref<FlatTreeItem[]> {
-  const locations = useLocationStore();
+function filterOutSubtree(tree: TreeItem[], excludeId: string): TreeItem[] {
+  // Recursively filters out a subtree starting from excludeId
+  const result: TreeItem[] = [];
 
+  for (const item of tree) {
+    if (item.id === excludeId) {
+      continue;
+    }
+
+    const newItem = { ...item };
+    if (item.children) {
+      newItem.children = filterOutSubtree(item.children, excludeId);
+    }
+
+    result.push(newItem);
+  }
+
+  return result;
+}
+
+export function useFlatLocations(excludeSubtreeForLocation?: LocationSummary): Ref<FlatTreeItem[]> {
+  const locations = useLocationStore();
+  
   if (locations.tree === null) {
     locations.refreshTree();
   }
@@ -47,6 +67,10 @@ export function useFlatLocations(): Ref<FlatTreeItem[]> {
       return [];
     }
 
-    return flatTree(locations.tree);
+    const filteredTree = excludeSubtreeForLocation
+      ? filterOutSubtree(locations.tree, excludeSubtreeForLocation.id)
+      : locations.tree;
+
+    return flatTree(filteredTree);
   });
 }