#ifndef TCG_ITERATOR_OPS_H
#define TCG_ITERATOR_OPS_H

// tcg includes
#include "traits.h"
#include "ptr.h"

// STD includes
#include <iterator>

namespace tcg
{

//****************************************************************************
//    Traits
//****************************************************************************

template <typename It>
struct iterator_traits : public std::iterator_traits<It> {
	typedef It inheritable_iterator_type;
};

template <typename T>
struct iterator_traits<T *> : public std::iterator_traits<T *> {
	typedef ptr<T> inheritable_iterator_type;
};

//****************************************************************************
//    Derived Iterator  definition
//****************************************************************************

template <typename It, typename Der, typename iterator_tag = typename std::iterator_traits<It>::iterator_category>
struct derived_iterator : public tcg::iterator_traits<It>::inheritable_iterator_type {
	typedef typename tcg::iterator_traits<It>::inheritable_iterator_type base_iterator;

public:
	derived_iterator() : base_iterator() {}
	derived_iterator(const base_iterator &it) : base_iterator(it) {}

	Der &operator++()
	{
		base_iterator::operator++();
		return static_cast<Der &>(*this);
	}
	Der operator++(int) { return Der(base_iterator::operator++(0), static_cast<Der &>(*this)); }
};

template <typename It, typename Der>
struct derived_iterator<It, Der, std::bidirectional_iterator_tag>
	: public derived_iterator<It, Der, std::forward_iterator_tag> {
	typedef typename tcg::iterator_traits<It>::inheritable_iterator_type base_iterator;

public:
	derived_iterator() : _iter() {}
	derived_iterator(const base_iterator &it) : _iter(it) {}

	Der &operator--()
	{
		base_iterator::operator--();
		return static_cast<Der &>(*this);
	}
	Der operator--(int) { return Der(base_iterator::operator--(0), static_cast<Der &>(*this)); }

private:
	typedef derived_iterator<It, Der, std::forward_iterator_tag> _iter;
};

template <typename It, typename Der>
struct derived_iterator<It, Der, std::random_access_iterator_tag>
	: public derived_iterator<It, Der, std::bidirectional_iterator_tag> {
	typedef typename tcg::iterator_traits<It>::inheritable_iterator_type base_iterator;
	typedef typename base_iterator::difference_type difference_type;

public:
	derived_iterator() : _iter() {}
	derived_iterator(const base_iterator &it) : _iter(it) {}

	Der operator+(difference_type d) const
	{
		return Der(static_cast<const base_iterator &>(*this) + d,
				   static_cast<const Der &>(*this));
	}
	Der &operator+=(difference_type d)
	{
		static_cast<base_iterator &>(*this) += d;
		return static_cast<Der &>(*this);
	}

	Der operator-(difference_type d) const
	{
		return Der(static_cast<const base_iterator &>(*this) - d,
				   static_cast<const Der &>(*this));
	}
	Der &operator-=(difference_type d)
	{
		static_cast<base_iterator &>(*this) -= d;
		return static_cast<Der &>(*this);
	}

	difference_type operator-(const Der &other) const
	{
		return static_cast<const base_iterator &>(*this) -
			   static_cast<const base_iterator &>(other);
	}

private:
	typedef derived_iterator<It, Der, std::bidirectional_iterator_tag> _iter;
};

//****************************************************************************
//    Cast Iterator  definition
//****************************************************************************

/*!
  A cast iterator is a utility iterator wrapper that can be used to access
  an iterator's data through a supplied functor intermediary, proving to be
  especially useful when converting data from a container to another with
  minimal effort.
*/

template <typename It, typename Func,
		  typename Val = typename traits<typename function_traits<Func>::ret_type>::referenced_type,
		  typename Ref = typename choose_if_match<typename function_traits<Func>::ret_type &, typename traits<Val>::reference_type>::type,
		  typename Ptr = typename choose_if_match<Ref, void, typename traits<Val>::pointer_type>::type>
class cast_iterator : public derived_iterator<It, cast_iterator<It, Func, Val, Ref, Ptr>>
{
	typedef derived_iterator<It, cast_iterator> iterator;
	typedef typename iterator::base_iterator base_iterator;
	typedef Func function;
	typedef typename function_traits<Func>::ret_type ret_type;

public:
	typedef Ref reference;
	typedef Ptr pointer;
	typedef Val value_type;

public:
	cast_iterator() : iterator(), m_func() {}
	cast_iterator(const Func &func) : iterator(), m_func(func) {}

	cast_iterator(const base_iterator &it) : iterator(it), m_func() {}
	cast_iterator(const base_iterator &it, const Func &func) : iterator(it), m_func(func) {}

	cast_iterator(const base_iterator &it, const cast_iterator &other)
		: iterator(it), m_func(other.m_func) {}

	ret_type operator*() { return m_func(iterator::operator*()); }
	pointer operator->() { return ptr(0); }

private:
	Func m_func;

private:
	template <typename T>
	pointer ptr(T, typename tcg::enable_if<tcg::type_mismatch<pointer, void>::value, T>::type = 0) const
	{
		return &operator*();
	}

	void ptr(char) const {}
};

//==========================================================================

//  Utility maker function

template <typename It, typename Func>
inline cast_iterator<It, Func> make_cast_it(const It &it, Func func)
{
	return cast_iterator<It, Func>(it, func);
}

//***********************************************************************
//    Step Iterator class
//***********************************************************************

/*!
  The Step Iterator class is a simple random access iterator wrapper which
  moves by a fixed number of items.

\warning The size of the container referenced by the wrapped iterator should
  always be a multiple of the specified step.
*/

template <typename RanIt>
class step_iterator
	: public std::iterator<std::random_access_iterator_tag,
						   typename std::iterator_traits<RanIt>::value_type,
						   typename std::iterator_traits<RanIt>::difference_type,
						   typename std::iterator_traits<RanIt>::pointer,
						   typename std::iterator_traits<RanIt>::reference>
{
	RanIt m_it;
	typename step_iterator::difference_type m_step;

public:
	step_iterator() {}
	step_iterator(const RanIt &it, typename step_iterator::difference_type step) : m_it(it), m_step(step) {}

	step_iterator &operator++()
	{
		m_it += m_step;
		return *this;
	}

	step_iterator &operator--()
	{
		m_it -= m_step;
		return *this;
	}

	step_iterator operator++(int)
	{
		step_iterator it(*this);
		operator++();
		return it;
	}

	step_iterator operator--(int)
	{
		step_iterator it(*this);
		operator--();
		return it;
	}

	step_iterator &operator+=(const typename step_iterator::difference_type &val)
	{
		m_it += val * m_step;
		return *this;
	}

	step_iterator &operator-=(const typename step_iterator::difference_type &val)
	{
		m_it -= val * m_step;
		return *this;
	}

	typename step_iterator::difference_type operator-(const step_iterator &it) const
	{
		return (m_it - it.m_it) / m_step;
	}

	step_iterator operator+(const typename step_iterator::difference_type &val) const
	{
		step_iterator it(*this);
		it += val;
		return it;
	}

	step_iterator operator-(const typename step_iterator::difference_type &val) const
	{
		step_iterator it(*this);
		it -= val;
		return it;
	}

	typename step_iterator::reference operator*() const { return *m_it; }
	typename step_iterator::pointer operator->() const { return m_it.operator->(); }

	const RanIt &it() const { return m_it; }
	int step() const { return m_step; }

	bool operator==(const step_iterator &it) const { return m_it == it.m_it; }
	bool operator!=(const step_iterator &it) const { return !operator==(it); }

	bool operator<(const step_iterator &it) const { return m_it < it.m_it; }
	bool operator>(const step_iterator &it) const { return m_it > it.m_it; }
	bool operator<=(const step_iterator &it) const { return m_it <= it.m_it; }
	bool operator>=(const step_iterator &it) const { return m_it >= it.m_it; }
};

} //namespace tcg

#endif //TCG_ITERATOR_OPS_H