// The MIT License (MIT) 

// Copyright (c) 2013-2016 Rapptz, ThePhD and contributors

// Permission is hereby granted, free of charge, to any person obtaining a copy of
// this software and associated documentation files (the "Software"), to deal in
// the Software without restriction, including without limitation the rights to
// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:

// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.

// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

#ifndef SOL_FUNCTION_HPP
#define SOL_FUNCTION_HPP

#include "reference.hpp"
#include "stack.hpp"
#include "function_result.hpp"
#include "function_types.hpp"
#include <cstdint>
#include <functional>
#include <memory>

namespace sol {
	template <typename base_t>
	class basic_function : public base_t {
	private:
		void luacall(std::ptrdiff_t argcount, std::ptrdiff_t resultcount) const {
			lua_callk(base_t::lua_state(), static_cast<int>(argcount), static_cast<int>(resultcount), 0, nullptr);
		}

		template<std::size_t... I, typename... Ret>
		auto invoke(types<Ret...>, std::index_sequence<I...>, std::ptrdiff_t n) const {
			luacall(n, sizeof...(Ret));
			return stack::pop<std::tuple<Ret...>>(base_t::lua_state());
		}

		template<std::size_t I, typename Ret>
		Ret invoke(types<Ret>, std::index_sequence<I>, std::ptrdiff_t n) const {
			luacall(n, 1);
			return stack::pop<Ret>(base_t::lua_state());
		}

		template <std::size_t I>
		void invoke(types<void>, std::index_sequence<I>, std::ptrdiff_t n) const {
			luacall(n, 0);
		}

		function_result invoke(types<>, std::index_sequence<>, std::ptrdiff_t n) const {
			int stacksize = lua_gettop(base_t::lua_state());
			int firstreturn = (std::max)(1, stacksize - static_cast<int>(n));
			luacall(n, LUA_MULTRET);
			int poststacksize = lua_gettop(base_t::lua_state());
			int returncount = poststacksize - (firstreturn - 1);
			return function_result(base_t::lua_state(), firstreturn, returncount);
		}

	public:
		basic_function() = default;
		basic_function(const basic_function&) = default;
		basic_function& operator=(const basic_function&) = default;
		basic_function(basic_function&&) = default;
		basic_function& operator=(basic_function&&) = default;
		basic_function(const stack_reference& r) : basic_function(r.lua_state(), r.stack_index()) {}
		basic_function(stack_reference&& r) : basic_function(r.lua_state(), r.stack_index()) {}
		basic_function(lua_State* L, int index = -1) : base_t(L, index) {
#ifdef SOL_CHECK_ARGUMENTS
			stack::check<basic_function>(L, index, type_panic);
#endif // Safety
		}

		template<typename... Args>
		function_result operator()(Args&&... args) const {
			return call<>(std::forward<Args>(args)...);
		}

		template<typename... Ret, typename... Args>
		decltype(auto) operator()(types<Ret...>, Args&&... args) const {
			return call<Ret...>(std::forward<Args>(args)...);
		}

		template<typename... Ret, typename... Args>
		decltype(auto) call(Args&&... args) const {
			base_t::push();
			int pushcount = stack::multi_push_reference(base_t::lua_state(), std::forward<Args>(args)...);
			return invoke(types<Ret...>(), std::make_index_sequence<sizeof...(Ret)>(), pushcount);
		}
	};

	namespace stack {
		template<typename Signature>
		struct getter<std::function<Signature>> {
			typedef meta::bind_traits<Signature> fx_t;
			typedef typename fx_t::args_list args_lists;
			typedef meta::tuple_types<typename fx_t::return_type> return_types;

			template<typename... Args, typename... Ret>
			static std::function<Signature> get_std_func(types<Ret...>, types<Args...>, lua_State* L, int index = -1) {
				sol::function f(L, index);
				auto fx = [f, L, index](Args&&... args) -> meta::return_type_t<Ret...> {
					return f.call<Ret...>(std::forward<Args>(args)...);
				};
				return std::move(fx);
			}

			template<typename... FxArgs>
			static std::function<Signature> get_std_func(types<void>, types<FxArgs...>, lua_State* L, int index = -1) {
				sol::function f(L, index);
				auto fx = [f, L, index](FxArgs&&... args) -> void {
					f(std::forward<FxArgs>(args)...);
				};
				return std::move(fx);
			}

			template<typename... FxArgs>
			static std::function<Signature> get_std_func(types<>, types<FxArgs...> t, lua_State* L, int index = -1) {
				return get_std_func(types<void>(), t, L, index);
			}

			static std::function<Signature> get(lua_State* L, int index) {
				type t = type_of(L, index);
				if (t == type::none || t == type::nil) {
					return nullptr;
				}
				return get_std_func(return_types(), args_lists(), L, index);
			}
		};
	} // stack
} // sol

#endif // SOL_FUNCTION_HPP