#ifndef PYTHONIC_ITERTOOLS_IFILTER_HPP
#define PYTHONIC_ITERTOOLS_IFILTER_HPP

#include "pythonic/include/itertools/ifilter.hpp"
#include "pythonic/utils/iterator.hpp"
#include "pythonic/itertools/common.hpp"
#include "pythonic/utils/functor.hpp"

PYTHONIC_NS_BEGIN

namespace itertools
{

  namespace details
  {
    template <typename Operator, typename List0>
    bool ifilter_iterator<Operator, List0>::test_filter(std::false_type)
    {
      return op(*iter);
    }

    template <typename Operator, typename List0>
    bool ifilter_iterator<Operator, List0>::test_filter(std::true_type)
    {
      return *iter;
    }

    template <typename Operator, typename List0>
    ifilter_iterator<Operator, List0>::ifilter_iterator(Operator _op,
                                                        List0 &_seq)
        : op(_op), iter(_seq.begin()), iter_end(_seq.end())
    {
      if (!test_filter(std::is_same<types::none_type, Operator>()))
        next_value();
    }

    template <typename Operator, typename List0>
    ifilter_iterator<Operator, List0>::ifilter_iterator(npos, Operator _op,
                                                        List0 &_seq)
        : op(_op), iter(_seq.end()), iter_end(_seq.end())
    {
    }

    template <typename Operator, typename List0>
    typename List0::value_type ifilter_iterator<Operator, List0>::
    operator*() const
    {
      return *iter;
    }

    template <typename Operator, typename List0>
    ifilter_iterator<Operator, List0> &ifilter_iterator<Operator, List0>::
    operator++()
    {
      next_value();
      return *this;
    }

    template <typename Operator, typename List0>
    void ifilter_iterator<Operator, List0>::next_value()
    {
      while (++iter != iter_end) {
        if (test_filter(std::is_same<types::none_type, Operator>()))
          return;
      }
    }

    template <typename Operator, typename List0>
    bool ifilter_iterator<Operator, List0>::
    operator==(ifilter_iterator const &other) const
    {
      return !(iter != other.iter);
    }

    template <typename Operator, typename List0>
    bool ifilter_iterator<Operator, List0>::
    operator!=(ifilter_iterator const &other) const
    {
      return iter != other.iter;
    }

    template <typename Operator, typename List0>
    bool ifilter_iterator<Operator, List0>::
    operator<(ifilter_iterator const &other) const
    {
      return iter != other.iter;
    }

    template <typename Operator, typename List0>
    ifilter<Operator, List0>::ifilter(Operator _op, List0 const &_seq)
        : utils::iterator_reminder<false, List0>(_seq),
          iterator(_op, this->values), end_iter(npos(), _op, this->values)
    {
    }

    template <typename Operator, typename List0>
    typename ifilter<Operator, List0>::iterator &
    ifilter<Operator, List0>::begin()
    {
      return *this;
    }

    template <typename Operator, typename List0>
    typename ifilter<Operator, List0>::iterator const &
    ifilter<Operator, List0>::begin() const
    {
      return *this;
    }

    template <typename Operator, typename List0>
    typename ifilter<Operator, List0>::iterator const &
    ifilter<Operator, List0>::end() const
    {
      return end_iter;
    }
  }

  template <typename Operator, typename List0>
  details::ifilter<typename std::remove_cv<
                       typename std::remove_reference<Operator>::type>::type,
                   typename std::remove_cv<
                       typename std::remove_reference<List0>::type>::type>
  ifilter(Operator &&_op, List0 &&_seq)
  {
    return {std::forward<Operator>(_op), std::forward<List0>(_seq)};
  }
}
PYTHONIC_NS_END
#endif