Plan save-version targets in app core

src/app_dialogs.cpp

@@ -292,30 +292,19 @@ void App::dialog_save_ver()
         return;
     }
 
-    int current = 0;
-    std::string next = doc_name + ".01";
-    std::string base = doc_name;
-
-    std::regex r(R"((.*)\.(\w{2})$)");
-    std::smatch m;
-    if (std::regex_search(doc_name, m, r))
-    {
-        base = m[1].str();
-        current = atoi(m[2].str().c_str());
+    const auto target = pp::app::find_next_document_version_target(
+        doc_dir,
+        doc_name,
+        [](const std::string& path) {
+            return Asset::exist(path);
+        });
+    if (!target) {
+        message_box("Saving Error", target.status().message);
+        return;
     }
 
-    for (int i = current + 1; i < 99; i++)
-    {
-        static char tmp_name[256];
-        sprintf(tmp_name, "%s.%02d", base.c_str(), i);
-        next = tmp_name;
-        if (Asset::exist(doc_dir + "/" + next + ".ppi"))
-            continue;
-        break;
-    }
-
-    doc_name = next;
-    doc_path = doc_dir + "/" + next + ".ppi";
+    doc_name = target.value().name;
+    doc_path = target.value().path;
     canvas->m_canvas->m_unsaved = true;
     title_update();
     canvas->m_canvas->project_save(doc_path);