iw5-mod/src/steam/interface.hpp

#pragma once

#ifdef interface
#undef interface
#endif

namespace steam
{
	template <size_t ...>
	struct argument_size_calculator final : std::integral_constant<size_t, 0>
	{
	};

	template <size_t X, size_t ... Xs>
	struct argument_size_calculator<X, Xs...> final : std::integral_constant<
			size_t, X + ((argument_size_calculator<Xs...>::value + (sizeof(void*) - 1)) & ~(sizeof(void*) - 1))>
	{
	};

	class interface final
	{
	public:
		class method final
		{
		public:
			void* pointer = nullptr;
			size_t param_size = 0;
		};

		class method_result final
		{
		public:
			std::string name;
			size_t param_size = 0;
			bool name_found = false;
			bool param_size_found = false;
		};

		interface();
		interface(void* interface_ptr);

		operator bool() const;

		template <typename T, typename... Args>
		T invoke(const std::string& method_name, Args ... args)
		{
			if (!this->interface_ptr_)
			{
				throw std::runtime_error("Invalid interface pointer");
			}

			const auto method_result = this->find_method(method_name);
			if (!method_result.pointer)
			{
				throw std::runtime_error("Unable to find desired method");
			}

			constexpr size_t passed_argc = argument_size_calculator<sizeof(Args)...>::value;
			if (passed_argc != method_result.param_size)
			{
				throw std::runtime_error("Invalid argument count");
			}

			return reinterpret_cast<T(__thiscall*)(void*, Args ...)>(method_result.pointer)(
				this->interface_ptr_, args...);
		}

		template <typename T, typename... Args>
		T invoke(const size_t table_entry, Args ... args)
		{
			if (!this->interface_ptr_)
			{
				throw std::runtime_error("Invalid interface pointer");
			}

			return reinterpret_cast<T(__thiscall*)(void*, Args ...)>((*this->interface_ptr_)[table_entry])(
				this->interface_ptr_, args...);
		}

	private:
		void*** interface_ptr_;
		std::unordered_map<std::string, method> methods_;

		method find_method(const std::string& name);
		method search_method(const std::string& name);

		method_result analyze_method(const void* method_ptr);

		bool is_rdata(void* pointer);
	};
}