#ifndef TCG_TRAITS_H
#define TCG_TRAITS_H

// tcg includes
#include "sfinae.h"

// STD includes
#include <iterator>

//--------------------------------------------------------------------------

namespace tcg
{

//****************************************************************************
//    TCG traits for generic type concepts
//****************************************************************************

template <typename T>
struct traits {
	typedef T *pointer_type;
	typedef T pointed_type;
	typedef T &reference_type;
	typedef T referenced_type;
	typedef T element_type;
};

template <typename T>
struct traits<T *> {
	typedef T **pointer_type;
	typedef T pointed_type;
	typedef T *&reference_type;
	typedef T *referenced_type;
	typedef T *element_type;
};

template <typename T>
struct traits<T[]> : public traits<T *> {
	typedef T element_type;
};

template <typename T>
struct traits<T &> : public traits<T> {
};

template <>
struct traits<void> {
	typedef void *pointer_type;
	typedef void pointed_type;
	typedef void reference_type;
	typedef void referenced_type;
};

//****************************************************************************
//    Qualifier removers
//****************************************************************************

template <typename T>
struct remove_const {
	typedef T type;
};
template <typename T>
struct remove_const<const T> {
	typedef T type;
};

template <typename T>
struct remove_ref {
	typedef T type;
};
template <typename T>
struct remove_ref<T &> {
	typedef T type;
};

template <typename T>
struct remove_cref {
	typedef typename remove_const<typename remove_ref<T>::type>::type type;
};

//****************************************************************************
//    TCG traits for function types
//****************************************************************************

template <typename Func>
class function_traits
{
	template <typename F, bool>
	struct result;

	template <typename F>
	struct result<F, true> {
		typedef typename F::result_type type;
	};

	template <typename F>
	struct result<F, false> {
		typedef struct {
		} type;
	};

	template <typename Q>
	static typename enable_if_exists<typename Q::result_type,
									 char>::type
	result_fun(Q *);
	static double result_fun(...);

	template <typename F, bool>
	struct argument;

	template <typename F>
	struct argument<F, true> {
		typedef typename F::argument_type type;
	};

	template <typename F>
	struct argument<F, false> {
		typedef void type;
	};
	template <typename Q>

	static typename enable_if_exists<typename Q::argument_type,
									 char>::type
	argument_fun(Q *);
	static double argument_fun(...);

	template <typename F, bool>
	struct first_arg;

	template <typename F>
	struct first_arg<F, true> {
		typedef typename F::first_argument_type type;
	};

	template <typename F>
	struct first_arg<F, false> {
		typedef void type;
	};
	template <typename Q>

	static typename enable_if_exists<typename Q::first_argument_type,
									 char>::type
	first_arg_fun(Q *);
	static double first_arg_fun(...);

	template <typename F, bool>
	struct second_arg;

	template <typename F>
	struct second_arg<F, true> {
		typedef typename F::second_argument_type type;
	};

	template <typename F>
	struct second_arg<F, false> {
		typedef void type;
	};

	template <typename Q>
	static typename enable_if_exists<typename Q::second_argument_type,
									 char>::type
	second_arg_fun(Q *);
	static double second_arg_fun(...);

public:
	enum { has_result = (sizeof(result_fun(typename tcg::traits<Func>::pointer_type())) == sizeof(char)),
		   has_argument = (sizeof(argument_fun(typename tcg::traits<Func>::pointer_type())) == sizeof(char)),
		   has_first_arg = (sizeof(first_arg_fun(typename tcg::traits<Func>::pointer_type())) == sizeof(char)),
		   has_second_arg = (sizeof(second_arg_fun(typename tcg::traits<Func>::pointer_type())) == sizeof(char)) };

	typedef typename result<Func, has_result>::type ret_type;
	typedef typename argument<Func, has_argument>::type arg_type;
	typedef typename first_arg<Func, has_first_arg>::type arg1_type;
	typedef typename second_arg<Func, has_second_arg>::type arg2_type;
};

//-----------------------------------------------------------------------

template <typename Ret>
struct function_traits<Ret()> {
	enum { has_result = true,
		   has_argument = false,
		   has_first_arg = false,
		   has_second_arg = false };

	typedef Ret ret_type;
	typedef void arg_type;
	typedef void arg1_type;
	typedef void arg2_type;
};

template <typename Ret>
struct function_traits<Ret (*)()> : public function_traits<Ret()> {
};

template <typename Ret>
struct function_traits<Ret(&)()> : public function_traits<Ret()> {
};

//-----------------------------------------------------------------------

template <typename Ret, typename Arg>
struct function_traits<Ret(Arg)> {
	enum { has_result = true,
		   has_argument = true,
		   has_first_arg = false,
		   has_second_arg = false };

	typedef Ret ret_type;
	typedef Arg arg_type;
	typedef void arg1_type;
	typedef void arg2_type;
};

template <typename Ret, typename Arg>
struct function_traits<Ret (*)(Arg)> : public function_traits<Ret(Arg)> {
};

template <typename Ret, typename Arg>
struct function_traits<Ret(&)(Arg)> : public function_traits<Ret(Arg)> {
};

//-----------------------------------------------------------------------

template <typename Ret, typename Arg1, typename Arg2>
struct function_traits<Ret(Arg1, Arg2)> {
	enum { has_result = true,
		   has_first_arg = true,
		   has_second_arg = true };

	typedef Ret ret_type;
	typedef Arg1 arg1_type;
	typedef Arg2 arg2_type;
};

template <typename Ret, typename Arg1, typename Arg2>
struct function_traits<Ret (*)(Arg1, Arg2)> : public function_traits<Ret(Arg1, Arg2)> {
};

template <typename Ret, typename Arg1, typename Arg2>
struct function_traits<Ret(&)(Arg1, Arg2)> : public function_traits<Ret(Arg1, Arg2)> {
};

//******************************************************************************
//    TCG traits for output container readers
//******************************************************************************

template <typename Reader, typename OutputData = typename Reader::value_type>
struct container_reader_traits {
	typedef Reader reader_type;
	typedef OutputData value_type;

	static void openContainer(reader_type &reader) { reader.openContainer(); }
	static void addElement(reader_type &reader, const value_type &data) { reader.addElement(data); }
	static void closeContainer(reader_type &reader) { reader.closeContainer(); }
};

//************************************************************************************
//    Notable Test  traits
//************************************************************************************

template <typename T>
struct is_floating_point {
	enum { value = false };
};

template <>
struct is_floating_point<float> {
	enum { value = true };
};

template <>
struct is_floating_point<double> {
	enum { value = true };
};

template <>
struct is_floating_point<long double> {
	enum { value = true };
};

//-----------------------------------------------------------------------

template <typename T>
struct is_function {
	enum { value = function_traits<T>::has_result };
};

template <typename T>
struct is_functor {
	template <typename Q>
	static typename enable_if_exists<typename Q::result_type,
									 char>::type
	result(Q *);

	static double result(...);

	enum { value = (sizeof(result(typename tcg::traits<T>::pointer_type())) == sizeof(char)) };
};

} // namespace tcg

#endif // TCG_TRAITS_H