add app.start_debug_instance

src/engine/EnginePaths.cpp

@@ -71,6 +71,14 @@ EnginePaths::EnginePaths(CoreParameters& params)
     io::create_subdevice("config", "user", "config");
 }
 
+std::filesystem::path EnginePaths::getResourcesFolder() const {
+    return resourcesFolder;
+}
+
+std::filesystem::path EnginePaths::getUserFilesFolder() const {
+    return userFilesFolder;
+}
+
 io::path EnginePaths::getNewScreenshotFile(const std::string& ext) const {
     auto folder = SCREENSHOTS_FOLDER;
     if (!io::is_directory(folder)) {

src/engine/EnginePaths.hpp

@@ -48,6 +48,9 @@ public:
 
     EnginePaths(CoreParameters& params);
 
+    std::filesystem::path getResourcesFolder() const;
+    std::filesystem::path getUserFilesFolder() const;
+
     io::path getWorldFolderByName(const std::string& name);
     io::path getWorldsFolder() const;
 

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

@@ -1,6 +1,34 @@
 #include "api_lua.hpp"
 
+#include "logic/scripting/scripting.hpp"
+#include "engine/Engine.hpp"
+#include "engine/EnginePaths.hpp"
+#include "network/Network.hpp"
+#include "util/platform.hpp"
+
+using namespace scripting;
+
+static int l_start_debug_instance(lua::State* L) {
+    int port = lua::tointeger(L, 1);
+    if (port == 0) {
+        port = engine->getNetwork().findFreePort();
+        if (port == -1) {
+            throw std::runtime_error("could not find free port");
+        }
+    }
+    const auto& paths = engine->getPaths();
+
+    std::vector<std::string> args {
+        "--res", paths.getResourcesFolder().u8string(),
+        "--dir", paths.getUserFilesFolder().u8string(),
+        "--dbg-server",  "tcp:" + std::to_string(port),
+    };
+    platform::new_engine_instance(std::move(args));
+    return lua::pushinteger(L, port);
+}
+
 const luaL_Reg applib[] = {
-    // see libcore.cpp an stdlib.lua
+    {"start_debug_instance", lua::wrap<l_start_debug_instance>},
+    // for other functions see libcore.cpp and stdlib.lua
     {nullptr, nullptr}
 };