From fcceb474b275fe38d033074f44148338ef2fa0eb Mon Sep 17 00:00:00 2001
From: praydog <praydog@praydog.com>
Date: Sat, 12 Oct 2024 11:26:43 -0700
Subject: [PATCH] Lua: Add UObject:DANGEROUS_call_member_virtual(args...)

---
 lua-api/lib/src/ScriptContext.cpp | 48 +++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/lua-api/lib/src/ScriptContext.cpp b/lua-api/lib/src/ScriptContext.cpp
index 26ebb541..6bf39850 100644
--- a/lua-api/lib/src/ScriptContext.cpp
+++ b/lua-api/lib/src/ScriptContext.cpp
@@ -465,6 +465,54 @@ int ScriptContext::setup_bindings() {
         "call", [](sol::this_state s, uevr::API::UObject* self, const std::wstring& name, sol::variadic_args args) -> sol::object {
             return lua::utility::call_function(s, self, name, args);
         },
+        "DANGEROUS_call_member_virtual", [](sol::this_state s, uevr::API::UObject* self, size_t index, sol::variadic_args args) -> sol::object {
+            if (args.size() > 3) {
+                throw sol::error("DANGEROUS_call_member_virtual: Too many arguments (max 3)");
+            }
+
+            if (index > 1000) { // Yeah right
+                throw sol::error("DANGEROUS_call_member_virtual: Index too high");
+            }
+
+            void* args_ptr[3]{};
+
+            for (size_t i = 0; i < args.size(); ++i) {
+                if (args[i].is<sol::nil_t>()) {
+                    args_ptr[i] = nullptr;
+                    continue;
+                }
+
+                // Only support basic arguments for now until we can test this more
+                if (args[i].is<uevr::API::UObject*>()) {
+                    args_ptr[i] = args[i].as<uevr::API::UObject*>();
+                } else {
+                    // We dont support floats for now because we'd need to JIT the function call
+                    throw sol::error("DANGEROUS_call_member_virtual: Invalid argument type");
+                }
+            }
+
+            void* result{};
+            using fn_t = void*(*)(uevr::API::UObject*, void*, void*, void*);
+            const auto vtable = *(void***)self;
+            if (vtable == nullptr) {
+                throw sol::error("DANGEROUS_call_member_virtual: Object has no vtable");
+            }
+
+            const auto fn = (fn_t)vtable[index];
+            if (fn == nullptr) {
+                throw sol::error("DANGEROUS_call_member_virtual: Function not found in vtable");
+            }
+
+            try {
+                // We need to wrap this in a try-catch block because who knows what the function does
+                result = fn(self, args_ptr[0], args_ptr[1], args_ptr[2]);
+            } catch (...) {
+                throw sol::error("DANGEROUS_call_member_virtual: Exception thrown");
+                return sol::make_object(s, sol::lua_nil);
+            }
+
+            return sol::make_object(s, result); // TODO: convert?
+        },
         sol::meta_function::index, [](sol::this_state s, uevr::API::UObject* self, sol::object index_obj) -> sol::object {
             if (!index_obj.is<std::string>()) {
                 return sol::make_object(s, sol::lua_nil);