#pragma once

#include "tuple.hpp"

namespace sol {
namespace meta {
namespace meta_detail {

template<class F>
struct check_deducible_signature {
    struct nat {};
    template<class G>
    static auto test(int) -> decltype(&G::operator(), void());
    template<class>
    static auto test(...) -> nat;

    using type = std::is_void<decltype(test<F>(0))>;
};
} // meta_detail

template<class F>
struct has_deducible_signature : meta_detail::check_deducible_signature<F>::type { };

namespace meta_detail {

template <std::size_t I, typename T>
struct void_tuple_element : meta::tuple_element<I, T> {};

template <std::size_t I>
struct void_tuple_element<I, std::tuple<>> { typedef void type; };

template <std::size_t I, typename T>
using void_tuple_element_t = typename void_tuple_element<I, T>::type;

template <bool has_c_variadic, typename T, typename R, typename... Args>
struct basic_traits {
private:
	typedef std::conditional_t<std::is_void<T>::value, int, T>& first_type;

public:
	static const bool is_member_function = std::is_void<T>::value;
	static const bool has_c_var_arg = has_c_variadic;
	static const std::size_t arity = sizeof...(Args);
	static const std::size_t free_arity = sizeof...(Args) + static_cast<std::size_t>(!std::is_void<T>::value);
	typedef types<Args...> args_list;
	typedef std::tuple<Args...> args_tuple;
	typedef T object_type;
	typedef R return_type;
	typedef tuple_types<R> returns_list;
	typedef R(function_type)(Args...);
	typedef std::conditional_t<std::is_void<T>::value, args_list, types<first_type, Args...>> free_args_list;
	typedef std::conditional_t<std::is_void<T>::value, R(Args...), R(first_type, Args...)> free_function_type;
	typedef std::conditional_t<std::is_void<T>::value, R(*)(Args...), R(*)(first_type, Args...)> free_function_pointer_type;
	typedef std::remove_pointer_t<free_function_pointer_type> signature_type;
	template<std::size_t i>
	using arg_at = void_tuple_element_t<i, args_tuple>;
};

template<typename Signature, bool b = has_deducible_signature<Signature>::value>
struct fx_traits : basic_traits<false, void, void> {};

// Free Functions
template<typename R, typename... Args>
struct fx_traits<R(Args...), false> : basic_traits<false, void, R, Args...> {
	typedef R(*function_pointer_type)(Args...);
};

template<typename R, typename... Args>
struct fx_traits<R(*)(Args...), false> : basic_traits<false, void, R, Args...> {
	typedef R(*function_pointer_type)(Args...);
};

template<typename R, typename... Args>
struct fx_traits<R(Args..., ...), false> : basic_traits<true, void, R, Args...> {
	typedef R(*function_pointer_type)(Args..., ...);
};

template<typename R, typename... Args>
struct fx_traits<R(*)(Args..., ...), false> : basic_traits<true, void, R, Args...> {
	typedef R(*function_pointer_type)(Args..., ...);
};

// Member Functions
/* C-Style Variadics */
template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args...), false> : basic_traits<false, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args...);
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args..., ...), false> : basic_traits<true, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args..., ...);
};

/* Const Volatile */
template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args...) const, false> : basic_traits<false, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args...) const;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args..., ...) const, false> : basic_traits<true, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args..., ...) const;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args...) const volatile, false> : basic_traits<false, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args...) const volatile;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args..., ...) const volatile, false> : basic_traits<true, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args..., ...) const volatile;
};

/* Member Function Qualifiers */
template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args...) &, false> : basic_traits<false, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args...) &;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args..., ...) &, false> : basic_traits<true, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args..., ...) &;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args...) const &, false> : basic_traits<false, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args...) const &;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args..., ...) const &, false> : basic_traits<true, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args..., ...) const &;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args...) const volatile &, false> : basic_traits<false, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args...) const volatile &;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args..., ...) const volatile &, false> : basic_traits<true, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args..., ...) const volatile &;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args...) &&, false> : basic_traits<false, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args...) &&;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args..., ...) &&, false> : basic_traits<true, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args..., ...) &&;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args...) const &&, false> : basic_traits<false, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args...) const &&;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args..., ...) const &&, false> : basic_traits<true, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args..., ...) const &&;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args...) const volatile &&, false> : basic_traits<false, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args...) const volatile &&;
};

template<typename T, typename R, typename... Args>
struct fx_traits<R(T::*)(Args..., ...) const volatile &&, false> : basic_traits<true, T, R, Args...> {
	typedef R(T::* function_pointer_type)(Args..., ...) const volatile &&;
};

template<typename Signature>
struct fx_traits<Signature, true> : fx_traits<typename fx_traits<decltype(&Signature::operator())>::function_type, false> {};

template<typename Signature, bool b = std::is_member_object_pointer<Signature>::value>
struct callable_traits : fx_traits<std::decay_t<Signature>> {

};

template<typename R, typename T>
struct callable_traits<R(T::*), true> {
    typedef R Arg;
    typedef T object_type;
    using signature_type = R(T::*);
    static const bool is_member_function = false;
    static const std::size_t arity = 1;
    static const std::size_t free_arity = 2;
    typedef std::tuple<Arg> args_tuple;
    typedef R return_type;
    typedef types<Arg> args_list;
    typedef meta::tuple_types<R> returns_list;
    typedef R(function_type)(T&, R);
    typedef R(*function_pointer_type)(T&, R);
    typedef R(*free_function_pointer_type)(T&, R);
    template<std::size_t i>
    using arg_at = void_tuple_element_t<i, args_tuple>;
};
} // meta_detail

template<typename Signature>
struct bind_traits : meta_detail::callable_traits<Signature> {};

template<typename Signature>
using function_args_t = typename bind_traits<Signature>::args_list;

template<typename Signature>
using function_signature_t = typename bind_traits<Signature>::signature_type;

template<typename Signature>
using function_return_t = typename bind_traits<Signature>::return_type;

} // meta
} // sol