move menu pages loader to Lua & add gui.load_document, file.ext(), file.prefix() & add core:gui_util module

src/logic/scripting/lua/libs/libgui.cpp

@@ -787,6 +787,23 @@ static int l_gui_alert(lua::State* L) {
     return 0;
 }
 
+static int l_gui_load_document(lua::State* L) {
+    auto filename = lua::require_string(L, 1);
+    auto alias = lua::require_string(L, 2);
+    auto args = lua::tovalue(L, 3);
+    
+    auto documentPtr = UiDocument::read(
+        scripting::get_root_environment(),
+        alias,
+        engine->getPaths().resolve(fs::u8path(filename)),
+        filename  
+    );
+    auto document = documentPtr.get();
+    engine->getAssets()->store(std::move(documentPtr), alias);
+    scripting::on_ui_open(document, {args});
+    return 0;
+}
+
 const luaL_Reg guilib[] = {
     {"get_viewport", lua::wrap<l_gui_getviewport>},
     {"getattr", lua::wrap<l_gui_getattr>},
@@ -798,6 +815,7 @@ const luaL_Reg guilib[] = {
     {"escape_markup", lua::wrap<l_gui_escape_markup>},
     {"confirm", lua::wrap<l_gui_confirm>},
     {"alert", lua::wrap<l_gui_alert>},
+    {"load_document", lua::wrap<l_gui_load_document>},
     {"__reindex", lua::wrap<l_gui_reindex>},
     {NULL, NULL}
 };

src/logic/scripting/scripting_hud.cpp

@@ -4,6 +4,7 @@
 #include "engine/Engine.hpp"
 #include "files/files.hpp"
 #include "frontend/hud.hpp"
+#include "frontend/UiDocument.hpp"
 #include "graphics/render/WorldRenderer.hpp"
 #include "objects/Player.hpp"
 #include "lua/libs/api_lua.hpp"
@@ -93,3 +94,15 @@ void scripting::load_hud_script(
     register_event(env, "on_hud_render", packid + ":.hudrender");
     register_event(env, "on_hud_close", packid + ":.hudclose");
 }
+
+gui::PageLoaderFunc scripting::create_page_loader() {
+    auto L = lua::get_main_state();
+    if (lua::getglobal(L, "__vc_page_loader")) {
+        auto func = lua::create_lambda(L);
+        return [func](const std::string& name) -> std::shared_ptr<gui::UINode> {
+            auto docname = func({name}).asString();
+            return engine->getAssets()->require<UiDocument>(docname).getRoot();
+        };
+    }
+    return nullptr;
+}

src/logic/scripting/scripting_hud.hpp

@@ -1,6 +1,8 @@
 #pragma once
 
 #include <filesystem>
+#include <functional>
+#include <memory>
 #include <string>
 
 #include "typedefs.hpp"
@@ -10,6 +12,11 @@ namespace fs = std::filesystem;
 class Hud;
 class WorldRenderer;
 
+namespace gui {
+    class UINode;
+    using PageLoaderFunc = std::function<std::shared_ptr<UINode>(const std::string&)>;
+}
+
 namespace scripting {
     extern Hud *hud;
     extern WorldRenderer* renderer;
@@ -29,4 +36,6 @@ namespace scripting {
         const fs::path& file,
         const std::string& fileName
     );
+
+    gui::PageLoaderFunc create_page_loader(); 
 }