Extract hierarchy and project drag semantics

editor/src/Actions/ProjectActionRouter.h

@@ -10,6 +10,10 @@ namespace XCEngine {
 namespace Editor {
 namespace Actions {
 
+inline constexpr const char* ProjectAssetPayloadType() {
+    return "ASSET_ITEM";
+}
+
 inline int FindProjectItemIndex(IProjectManager& projectManager, const AssetItemPtr& item) {
     if (!item) {
         return -1;
@@ -29,6 +33,50 @@ inline int FindProjectItemIndex(IProjectManager& projectManager, const AssetItem
     return -1;
 }
 
+inline const char* GetDraggedProjectAssetPath() {
+    const ImGuiPayload* payload = ImGui::GetDragDropPayload();
+    if (!payload || !payload->IsDataType(ProjectAssetPayloadType())) {
+        return nullptr;
+    }
+
+    return static_cast<const char*>(payload->Data);
+}
+
+inline bool IsProjectAssetBeingDragged(const AssetItemPtr& item) {
+    const char* draggedPath = GetDraggedProjectAssetPath();
+    return item != nullptr && draggedPath != nullptr && item->fullPath == draggedPath;
+}
+
+inline bool AcceptProjectAssetDrop(IProjectManager& projectManager, const AssetItemPtr& targetFolder) {
+    if (!targetFolder || !targetFolder->isFolder || !ImGui::BeginDragDropTarget()) {
+        return false;
+    }
+
+    bool accepted = false;
+    if (const ImGuiPayload* payload = ImGui::AcceptDragDropPayload(ProjectAssetPayloadType())) {
+        const char* draggedPath = static_cast<const char*>(payload->Data);
+        accepted = Commands::MoveAssetToFolder(projectManager, draggedPath, targetFolder);
+    }
+    ImGui::EndDragDropTarget();
+    return accepted;
+}
+
+inline bool BeginProjectAssetDrag(const AssetItemPtr& item, UI::AssetIconKind iconKind) {
+    if (!item || item->fullPath.empty() || !ImGui::BeginDragDropSource(ImGuiDragDropFlags_None)) {
+        return false;
+    }
+
+    ImGui::SetDragDropPayload(ProjectAssetPayloadType(), item->fullPath.c_str(), item->fullPath.length() + 1);
+
+    ImVec2 previewMin = ImGui::GetMousePos();
+    const ImVec2 previewSize = UI::AssetDragPreviewSize();
+    ImVec2 previewMax = ImVec2(previewMin.x + previewSize.x, previewMin.y + previewSize.y);
+    UI::DrawAssetIcon(ImGui::GetForegroundDrawList(), previewMin, previewMax, iconKind);
+
+    ImGui::EndDragDropSource();
+    return true;
+}
+
 inline void DrawProjectAssetContextActions(IEditorContext& context, const AssetItemPtr& item) {
     auto& projectManager = context.GetProjectManager();
     const int itemIndex = FindProjectItemIndex(projectManager, item);