refactor(new_editor): streamline internal layout and command routing

new_editor/app/Features/Hierarchy/HierarchyModel.cpp

@@ -79,6 +79,46 @@ bool ExtractNodeRecursive(
     return false;
 }
 
+HierarchyNode CloneNodeRecursive(
+    const HierarchyNode& source,
+    const std::function<std::string()>& allocateNodeId) {
+    HierarchyNode duplicate = {};
+    duplicate.nodeId = allocateNodeId();
+    duplicate.label = source.label;
+    duplicate.children.reserve(source.children.size());
+    for (const HierarchyNode& child : source.children) {
+        duplicate.children.push_back(CloneNodeRecursive(child, allocateNodeId));
+    }
+    return duplicate;
+}
+
+bool DuplicateNodeRecursive(
+    std::vector<HierarchyNode>& nodes,
+    std::string_view nodeId,
+    const std::function<std::string()>& allocateNodeId,
+    std::string& duplicatedNodeId) {
+    for (std::size_t index = 0u; index < nodes.size(); ++index) {
+        if (nodes[index].nodeId == nodeId) {
+            HierarchyNode duplicate = CloneNodeRecursive(nodes[index], allocateNodeId);
+            duplicatedNodeId = duplicate.nodeId;
+            nodes.insert(
+                nodes.begin() + static_cast<std::ptrdiff_t>(index + 1u),
+                std::move(duplicate));
+            return true;
+        }
+
+        if (DuplicateNodeRecursive(
+                nodes[index].children,
+                nodeId,
+                allocateNodeId,
+                duplicatedNodeId)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 void BuildTreeItemsRecursive(
     const std::vector<HierarchyNode>& nodes,
     std::uint32_t depth,
@@ -178,6 +218,22 @@ std::string HierarchyModel::CreateChild(
     return parent->children.back().nodeId;
 }
 
+std::string HierarchyModel::DuplicateNode(std::string_view nodeId) {
+    if (nodeId.empty() || !ContainsNode(nodeId)) {
+        return {};
+    }
+
+    std::string duplicatedNodeId = {};
+    const auto allocateNodeId = [this]() {
+        return AllocateNodeId();
+    };
+    if (!DuplicateNodeRecursive(m_roots, nodeId, allocateNodeId, duplicatedNodeId)) {
+        return {};
+    }
+
+    return duplicatedNodeId;
+}
+
 bool HierarchyModel::DeleteNode(std::string_view nodeId) {
     if (nodeId.empty()) {
         return false;