Plan document share decisions in app core

src/app_events.cpp

@@ -1,5 +1,6 @@
 #include "pch.h"
 #include "app.h"
+#include "app_core/document_sharing.h"
 #include "renderer_gl/opengl_capabilities.h"
 
 namespace {
@@ -331,7 +332,8 @@ void App::display_file(std::string path)
 
 void App::share_file(std::string path)
 {
-    if (path.empty())
+    const auto plan = pp::app::plan_document_share(path);
+    if (plan == pp::app::DocumentShareAction::show_save_required_warning)
     {
         message_box("Sharing failed", "Please save the document before sharing it.");
         return;