#pragma once

#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 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 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