Extract layer rename planning

src/app_dialogs.cpp

@@ -1,6 +1,7 @@
 #include "pch.h"
 #include "app.h"
 #include "action.h"
+#include "app_core/document_layer.h"
 #include "app_core/document_resize.h"
 #include "app_core/document_export.h"
 #include "app_core/document_session.h"
@@ -605,6 +606,17 @@ void App::dialog_layer_rename()
 
     dialog->btn_ok->on_click = [this,dialog](Node*)
     {
+        const auto old_name = layers->m_current_layer->m_label_text;
+        const auto plan = pp::app::plan_document_layer_rename(old_name, dialog->get_name());
+        if (!plan)
+            return;
+        if (plan.value().action == pp::app::DocumentLayerRenameAction::no_op_same_name)
+        {
+            dialog->destroy();
+            App::I->hideKeyboard();
+            return;
+        }
+
         struct ActionLayerRename : public Action
         {
             std::string m_old_name;
@@ -628,9 +640,13 @@ void App::dialog_layer_rename()
         };
         auto layer_node = std::static_pointer_cast<NodeLayer>(layers->m_current_layer->shared_from_this());
         auto* layer = canvas->m_canvas->m_layers[canvas->m_canvas->m_current_layer_idx].get();
-        ActionManager::add(new ActionLayerRename(layers->m_current_layer->m_label_text, dialog->get_name(), layer_node, layer));
-        layer_node->set_name(dialog->get_name().c_str());
-        layer->m_name = dialog->get_name();
+        ActionManager::add(new ActionLayerRename(
+            plan.value().old_name,
+            plan.value().new_name,
+            layer_node,
+            layer));
+        layer_node->set_name(plan.value().new_name.c_str());
+        layer->m_name = plan.value().new_name;
         dialog->destroy();
         App::I->hideKeyboard();
     };