lua: add log{Verbose,Debug,Warn,Error}

Source/utils/lua.cpp

@@ -3,6 +3,8 @@
 #include <optional>
 #include <string_view>
 
+#include <fmt/args.h>
+#include <fmt/format.h>
 #include <sol/sol.hpp>
 #include <sol/utility/to_string.hpp>
 
@@ -73,6 +75,48 @@ void LuaPanic(sol::optional<std::string> maybe_msg)
 	    maybe_msg.value_or("unknown error"));
 }
 
+void LuaLog(LogPriority priority, std::string_view fmt, sol::variadic_args args)
+{
+	std::string formatted;
+	FMT_TRY
+	{
+		fmt::dynamic_format_arg_store<fmt::format_context> store;
+		for (sol::stack_proxy arg : args) {
+			switch (arg.get_type()) {
+			case sol::type::boolean:
+				store.push_back(arg.as<bool>());
+				break;
+			case sol::type::number:
+				if (lua_isinteger(arg.lua_state(), arg.stack_index())) {
+					store.push_back(arg.as<lua_Integer>());
+				} else {
+					store.push_back(arg.as<lua_Number>());
+				}
+				break;
+			case sol::type::string:
+				store.push_back(arg.as<std::string>());
+				break;
+			default:
+				store.push_back(sol::utility::to_string(sol::object(arg)));
+				break;
+			}
+		}
+		formatted = fmt::vformat(fmt, store);
+	}
+	FMT_CATCH(const fmt::format_error &e)
+	{
+#if FMT_EXCEPTIONS
+		// e.what() is undefined if exceptions are disabled, so we wrap the whole block
+		// with an `FMT_EXCEPTIONS` check.
+		std::string error = StrCat("Format error, fmt: ", fmt, " error: ", e.what());
+		SDL_LogCritical(SDL_LOG_CATEGORY_APPLICATION, "%s", error.c_str());
+		return;
+#endif
+	}
+	SDL_LogMessage(static_cast<int>(LogCategory::Application), static_cast<SDL_LogPriority>(priority),
+	    "%s", formatted.c_str());
+}
+
 } // namespace
 
 void Sol2DebugPrintStack(lua_State *state)
@@ -110,10 +154,14 @@ void LuaInitialize()
 	// Registering devilutionx object table
 	lua.create_named_table(
 	    "devilutionx",
-	    "message", [](std::string_view text) { EventPlrMsg(text, UiFlags::ColorRed); }
+	    "message", [](std::string_view text) { EventPlrMsg(text, UiFlags::ColorRed); },
 	    // TODO: Re-enable once https://github.com/bebbo/amiga-gcc/issues/363 is fixed.
 	    // "drawString", [](std::string_view text, int x, int y) { DrawString(GlobalBackBuffer(), text, { x, y }); }
-	);
+	    "log", [](std::string_view fmt, sol::variadic_args args) { LuaLog(LogPriority::Info, fmt, std::move(args)); },
+	    "logVerbose", [](std::string_view fmt, sol::variadic_args args) { LuaLog(LogPriority::Verbose, fmt, std::move(args)); },
+	    "logDebug", [](std::string_view fmt, sol::variadic_args args) { LuaLog(LogPriority::Debug, fmt, std::move(args)); },
+	    "logWarning", [](std::string_view fmt, sol::variadic_args args) { LuaLog(LogPriority::Warn, fmt, std::move(args)); },
+	    "logError", [](std::string_view fmt, sol::variadic_args args) { LuaLog(LogPriority::Error, fmt, std::move(args)); });
 
 	RunScript("lua/init.lua");
 	RunScript("lua/user.lua");