feat: nested folders (#266)

frontend/utils/buildFolderTree.ts

@@ -0,0 +1,36 @@
+import { FolderType, TreeNodeData } from '@/types/folder';
+
+export function buildFolderTree(folders: FolderType[]): TreeNodeData[] {
+  const folderMap = new Map<number, TreeNodeData>();
+
+  folders.forEach((folder) => {
+    folderMap.set(folder.id, {
+      id: folder.id.toString(),
+      name: folder.name,
+      detail: folder.detail,
+      parentFolderId: folder.parentFolderId,
+      projectId: folder.projectId,
+      folderData: folder,
+      children: [],
+    });
+  });
+
+  const tree: TreeNodeData[] = [];
+
+  folders.forEach((folder) => {
+    const currentNode = folderMap.get(folder.id);
+
+    if (!currentNode) return;
+
+    if (folder.parentFolderId === null) {
+      tree.push(currentNode);
+    } else {
+      const parent = folderMap.get(folder.parentFolderId);
+      if (parent && parent.children) {
+        parent.children.push(currentNode);
+      }
+    }
+  });
+
+  return tree;
+}