// Boost.Geometry (aka GGL, Generic Geometry Library)

// Copyright (c) 2012-2014 Barend Gehrels, Amsterdam, the Netherlands.

// Use, modification and distribution is subject to the Boost Software License,
// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

#ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_BUFFER_GET_PIECE_TURNS_HPP
#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_BUFFER_GET_PIECE_TURNS_HPP

#include <boost/range.hpp>

#include <boost/geometry/algorithms/equals.hpp>
#include <boost/geometry/algorithms/expand.hpp>
#include <boost/geometry/algorithms/detail/disjoint/box_box.hpp>
#include <boost/geometry/algorithms/detail/overlay/segment_identifier.hpp>
#include <boost/geometry/algorithms/detail/overlay/get_turn_info.hpp>
#include <boost/geometry/algorithms/detail/sections/section_functions.hpp>


namespace boost { namespace geometry
{


#ifndef DOXYGEN_NO_DETAIL
namespace detail { namespace buffer
{


template
<
    typename Pieces,
    typename Rings,
    typename Turns,
    typename RobustPolicy
>
class piece_turn_visitor
{
    Pieces const& m_pieces;
    Rings const& m_rings;
    Turns& m_turns;
    RobustPolicy const& m_robust_policy;

    template <typename Piece>
    inline bool is_adjacent(Piece const& piece1, Piece const& piece2) const
    {
        if (piece1.first_seg_id.multi_index != piece2.first_seg_id.multi_index)
        {
            return false;
        }

        return piece1.index == piece2.left_index
            || piece1.index == piece2.right_index;
    }

    template <typename Piece>
    inline bool is_on_same_convex_ring(Piece const& piece1, Piece const& piece2) const
    {
        if (piece1.first_seg_id.multi_index != piece2.first_seg_id.multi_index)
        {
            return false;
        }

        return ! m_rings[piece1.first_seg_id.multi_index].has_concave;
    }

    template <typename Range, typename Iterator>
    inline void move_to_next_point(Range const& range, Iterator& next) const
    {
        ++next;
        if (next == boost::end(range))
        {
            next = boost::begin(range) + 1;
        }
    }

    template <typename Range, typename Iterator>
    inline Iterator next_point(Range const& range, Iterator it) const
    {
        Iterator result = it;
        move_to_next_point(range, result);
        // TODO: we could use either piece-boundaries, or comparison with
        // robust points, to check if the point equals the last one
        while(geometry::equals(*it, *result))
        {
            move_to_next_point(range, result);
        }
        return result;
    }

    template <std::size_t Dimension, typename Iterator, typename Box>
    inline void move_begin_iterator(Iterator& it_begin, Iterator it_beyond,
            int& index, int dir, Box const& other_bounding_box)
    {
        for(; it_begin != it_beyond
                && it_begin + 1 != it_beyond
                && detail::section::preceding<Dimension>(dir, *(it_begin + 1),
                    other_bounding_box, m_robust_policy);
            ++it_begin, index++)
        {}
    }

    template <std::size_t Dimension, typename Iterator, typename Box>
    inline void move_end_iterator(Iterator it_begin, Iterator& it_beyond,
            int dir, Box const& other_bounding_box)
    {
        while (it_beyond != it_begin
            && it_beyond - 1 != it_begin
            && it_beyond - 2 != it_begin)
        {
            if (detail::section::exceeding<Dimension>(dir, *(it_beyond - 2),
                        other_bounding_box, m_robust_policy))
            {
                --it_beyond;
            }
            else
            {
                return;
            }
        }
    }

    template <typename Piece, typename Section>
    inline void calculate_turns(Piece const& piece1, Piece const& piece2,
        Section const& section1, Section const& section2)
    {
        typedef typename boost::range_value<Rings const>::type ring_type;
        typedef typename boost::range_value<Turns const>::type turn_type;
        typedef typename boost::range_iterator<ring_type const>::type iterator;

        int const piece1_first_index = piece1.first_seg_id.segment_index;
        int const piece2_first_index = piece2.first_seg_id.segment_index;
        if (piece1_first_index < 0 || piece2_first_index < 0)
        {
            return;
        }

        // Get indices of part of offsetted_rings for this monotonic section:
        int const sec1_first_index = piece1_first_index + section1.begin_index;
        int const sec2_first_index = piece2_first_index + section2.begin_index;

        // index of last point in section, beyond-end is one further
        int const sec1_last_index = piece1_first_index + section1.end_index;
        int const sec2_last_index = piece2_first_index + section2.end_index;

        // get geometry and iterators over these sections
        ring_type const& ring1 = m_rings[piece1.first_seg_id.multi_index];
        iterator it1_first = boost::begin(ring1) + sec1_first_index;
        iterator it1_beyond = boost::begin(ring1) + sec1_last_index + 1;

        ring_type const& ring2 = m_rings[piece2.first_seg_id.multi_index];
        iterator it2_first = boost::begin(ring2) + sec2_first_index;
        iterator it2_beyond = boost::begin(ring2) + sec2_last_index + 1;

        // Set begin/end of monotonic ranges, in both x/y directions
        int index1 = sec1_first_index;
        move_begin_iterator<0>(it1_first, it1_beyond, index1,
                    section1.directions[0], section2.bounding_box);
        move_end_iterator<0>(it1_first, it1_beyond,
                    section1.directions[0], section2.bounding_box);
        move_begin_iterator<1>(it1_first, it1_beyond, index1,
                    section1.directions[1], section2.bounding_box);
        move_end_iterator<1>(it1_first, it1_beyond,
                    section1.directions[1], section2.bounding_box);

        int index2 = sec2_first_index;
        move_begin_iterator<0>(it2_first, it2_beyond, index2,
                    section2.directions[0], section1.bounding_box);
        move_end_iterator<0>(it2_first, it2_beyond,
                    section2.directions[0], section1.bounding_box);
        move_begin_iterator<1>(it2_first, it2_beyond, index2,
                    section2.directions[1], section1.bounding_box);
        move_end_iterator<1>(it2_first, it2_beyond,
                    section2.directions[1], section1.bounding_box);

        turn_type the_model;
        the_model.operations[0].piece_index = piece1.index;
        the_model.operations[0].seg_id = piece1.first_seg_id;
        the_model.operations[0].seg_id.segment_index = index1; // override

        iterator it1 = it1_first;
        for (iterator prev1 = it1++;
                it1 != it1_beyond;
                prev1 = it1++, the_model.operations[0].seg_id.segment_index++)
        {
            the_model.operations[1].piece_index = piece2.index;
            the_model.operations[1].seg_id = piece2.first_seg_id;
            the_model.operations[1].seg_id.segment_index = index2; // override

            iterator next1 = next_point(ring1, it1);

            iterator it2 = it2_first;
            for (iterator prev2 = it2++;
                    it2 != it2_beyond;
                    prev2 = it2++, the_model.operations[1].seg_id.segment_index++)
            {
                iterator next2 = next_point(ring2, it2);

                // TODO: internally get_turn_info calculates robust points.
                // But they are already calculated.
                // We should be able to use them.
                // this means passing them to this visitor,
                // and iterating in sync with them...
                typedef detail::overlay::get_turn_info
                    <
                        detail::overlay::assign_null_policy
                    > turn_policy;

                turn_policy::apply(*prev1, *it1, *next1,
                                    *prev2, *it2, *next2,
                                    false, false, false, false,
                                    the_model, m_robust_policy,
                                    std::back_inserter(m_turns));
            }
        }
    }

public:

    piece_turn_visitor(Pieces const& pieces,
            Rings const& ring_collection,
            Turns& turns,
            RobustPolicy const& robust_policy)
        : m_pieces(pieces)
        , m_rings(ring_collection)
        , m_turns(turns)
        , m_robust_policy(robust_policy)
    {}

    template <typename Section>
    inline void apply(Section const& section1, Section const& section2,
                    bool first = true)
    {
        boost::ignore_unused_variable_warning(first);

        typedef typename boost::range_value<Pieces const>::type piece_type;
        piece_type const& piece1 = m_pieces[section1.ring_id.source_index];
        piece_type const& piece2 = m_pieces[section2.ring_id.source_index];

        if ( piece1.index == piece2.index
          || is_adjacent(piece1, piece2)
          || is_on_same_convex_ring(piece1, piece2)
          || detail::disjoint::disjoint_box_box(section1.bounding_box,
                    section2.bounding_box) )
        {
            return;
        }

        calculate_turns(piece1, piece2, section1, section2);
    }
};


}} // namespace detail::buffer
#endif // DOXYGEN_NO_DETAIL


}} // namespace boost::geometry

#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_BUFFER_GET_PIECE_TURNS_HPP
