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

// Copyright (c) 2007-2015 Barend Gehrels, Amsterdam, the Netherlands.
// Copyright (c) 2008-2015 Bruno Lalande, Paris, France.
// Copyright (c) 2009-2015 Mateusz Loskot, London, UK.

// This file was modified by Oracle on 2015-2017.
// Modifications copyright (c) 2015-2017, Oracle and/or its affiliates.

// Contributed and/or modified by Vissarion Fysikopoulos, on behalf of Oracle
// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle

// Distributed under 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_ENVELOPE_SEGMENT_HPP
#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_ENVELOPE_SEGMENT_HPP

#include <cstddef>
#include <utility>

#include <boost/numeric/conversion/cast.hpp>

#include <boost/geometry/core/assert.hpp>
#include <boost/geometry/core/coordinate_system.hpp>
#include <boost/geometry/core/coordinate_type.hpp>
#include <boost/geometry/core/cs.hpp>
#include <boost/geometry/core/srs.hpp>
#include <boost/geometry/core/point_type.hpp>
#include <boost/geometry/core/radian_access.hpp>
#include <boost/geometry/core/tags.hpp>

#include <boost/geometry/util/math.hpp>

#include <boost/geometry/geometries/helper_geometry.hpp>

#include <boost/geometry/formulas/vertex_latitude.hpp>

#include <boost/geometry/algorithms/detail/assign_indexed_point.hpp>

#include <boost/geometry/algorithms/detail/envelope/point.hpp>
#include <boost/geometry/algorithms/detail/envelope/transform_units.hpp>

#include <boost/geometry/algorithms/detail/expand/point.hpp>

#include <boost/geometry/algorithms/dispatch/envelope.hpp>

namespace boost { namespace geometry
{

#ifndef DOXYGEN_NO_DETAIL
namespace detail { namespace envelope
{

template <typename CalculationType, typename CS_Tag>
struct envelope_segment_call_vertex_latitude
{
    template <typename T1, typename T2, typename Strategy>
    static inline CalculationType apply(T1 const& lat1,
                                        T2 const& alp1,
                                        Strategy const& )
    {
        return geometry::formula::vertex_latitude<CalculationType, CS_Tag>
            ::apply(lat1, alp1);
    }
};

template <typename CalculationType>
struct envelope_segment_call_vertex_latitude<CalculationType, geographic_tag>
{
    template <typename T1, typename T2, typename Strategy>
    static inline CalculationType apply(T1 const& lat1,
                                        T2 const& alp1,
                                        Strategy const& strategy)
    {
        return geometry::formula::vertex_latitude<CalculationType, geographic_tag>
            ::apply(lat1, alp1, strategy.model());
    }
};

template <typename Units, typename CS_Tag>
struct envelope_segment_convert_polar
{
    template <typename T>
    static inline void pre(T & , T & ) {}

    template <typename T>
    static inline void post(T & , T & ) {}
};

template <typename Units>
struct envelope_segment_convert_polar<Units, spherical_polar_tag>
{
    template <typename T>
    static inline void pre(T & lat1, T & lat2)
    {
        lat1 = math::latitude_convert_ep<Units>(lat1);
        lat2 = math::latitude_convert_ep<Units>(lat2);
    }

    template <typename T>
    static inline void post(T & lat1, T & lat2)
    {
        lat1 = math::latitude_convert_ep<Units>(lat1);
        lat2 = math::latitude_convert_ep<Units>(lat2);
        std::swap(lat1, lat2);
    }
};

template <typename CS_Tag>
class envelope_segment_impl
{
private:

    // degrees or radians
    template <typename CalculationType>
    static inline void swap(CalculationType& lon1,
                            CalculationType& lat1,
                            CalculationType& lon2,
                            CalculationType& lat2)
    {
        std::swap(lon1, lon2);
        std::swap(lat1, lat2);
    }

    // radians
    template <typename CalculationType>
    static inline bool contains_pi_half(CalculationType const& a1,
                                        CalculationType const& a2)
    {
        // azimuths a1 and a2 are assumed to be in radians
        BOOST_GEOMETRY_ASSERT(! math::equals(a1, a2));

        static CalculationType const pi_half = math::half_pi<CalculationType>();

        return (a1 < a2)
                ? (a1 < pi_half && pi_half < a2)
                : (a1 > pi_half && pi_half > a2);
    }

    // radians or degrees
    template <typename Units, typename CoordinateType>
    static inline bool crosses_antimeridian(CoordinateType const& lon1,
                                            CoordinateType const& lon2)
    {
        typedef math::detail::constants_on_spheroid
            <
                CoordinateType, Units
            > constants;

        return math::abs(lon1 - lon2) > constants::half_period(); // > pi
    }

    // degrees or radians
    template <typename Units, typename CalculationType, typename Strategy>
    static inline void compute_box_corners(CalculationType& lon1,
                                           CalculationType& lat1,
                                           CalculationType& lon2,
                                           CalculationType& lat2,
                                           CalculationType a1,
                                           CalculationType a2,
                                           Strategy const& strategy)
    {
        // coordinates are assumed to be in radians
        BOOST_GEOMETRY_ASSERT(lon1 <= lon2);

        CalculationType lat1_rad = math::as_radian<Units>(lat1);
        CalculationType lat2_rad = math::as_radian<Units>(lat2);

        if (lat1 > lat2)
        {
            std::swap(lat1, lat2);
            std::swap(lat1_rad, lat2_rad);
            std::swap(a1, a2);
        }

        if (math::equals(a1, a2))
        {
            // the segment must lie on the equator or is very short
            return;
        }

        if (contains_pi_half(a1, a2))
        {
            CalculationType p_max = envelope_segment_call_vertex_latitude
                <CalculationType, CS_Tag>::apply(lat1_rad, a1, strategy);

            CalculationType const mid_lat = lat1 + lat2;
            if (mid_lat < 0)
            {
                // update using min latitude
                CalculationType const lat_min_rad = -p_max;
                CalculationType const lat_min
                    = math::from_radian<Units>(lat_min_rad);

                if (lat1 > lat_min)
                {
                    lat1 = lat_min;
                }
            }
            else
            {
                // update using max latitude
                CalculationType const lat_max_rad = p_max;
                CalculationType const lat_max
                    = math::from_radian<Units>(lat_max_rad);

                if (lat2 < lat_max)
                {
                    lat2 = lat_max;
                }
            }
        }
    }

    template <typename Units, typename CalculationType>
    static inline void special_cases(CalculationType& lon1,
                                     CalculationType& lat1,
                                     CalculationType& lon2,
                                     CalculationType& lat2)
    {
        typedef math::detail::constants_on_spheroid
            <
                CalculationType, Units
            > constants;

        bool is_pole1 = math::equals(math::abs(lat1), constants::max_latitude());
        bool is_pole2 = math::equals(math::abs(lat2), constants::max_latitude());

        if (is_pole1 && is_pole2)
        {
            // both points are poles; nothing more to do:
            // longitudes are already normalized to 0
            // but just in case
            lon1 = 0;
            lon2 = 0;
        }
        else if (is_pole1 && !is_pole2)
        {
            // first point is a pole, second point is not:
            // make the longitude of the first point the same as that
            // of the second point
            lon1 = lon2;
        }
        else if (!is_pole1 && is_pole2)
        {
            // second point is a pole, first point is not:
            // make the longitude of the second point the same as that
            // of the first point
            lon2 = lon1;
        }

        if (lon1 == lon2)
        {
            // segment lies on a meridian
            if (lat1 > lat2)
            {
                std::swap(lat1, lat2);
            }
            return;
        }

        BOOST_GEOMETRY_ASSERT(!is_pole1 && !is_pole2);

        if (lon1 > lon2)
        {
            swap(lon1, lat1, lon2, lat2);
        }

        if (crosses_antimeridian<Units>(lon1, lon2))
        {
            lon1 += constants::period();
            swap(lon1, lat1, lon2, lat2);
        }
    }

    template
    <
        typename Units,
        typename CalculationType,
        typename Box
    >
    static inline void create_box(CalculationType lon1,
                                  CalculationType lat1,
                                  CalculationType lon2,
                                  CalculationType lat2,
                                  Box& mbr)
    {
        typedef typename coordinate_type<Box>::type box_coordinate_type;

        typedef typename helper_geometry
            <
                Box, box_coordinate_type, Units
            >::type helper_box_type;

        helper_box_type helper_mbr;

        geometry::set
            <
                min_corner, 0
            >(helper_mbr, boost::numeric_cast<box_coordinate_type>(lon1));

        geometry::set
            <
                min_corner, 1
            >(helper_mbr, boost::numeric_cast<box_coordinate_type>(lat1));

        geometry::set
            <
                max_corner, 0
            >(helper_mbr, boost::numeric_cast<box_coordinate_type>(lon2));

        geometry::set
            <
                max_corner, 1
            >(helper_mbr, boost::numeric_cast<box_coordinate_type>(lat2));

        transform_units(helper_mbr, mbr);
    }


    template <typename Units, typename CalculationType, typename Strategy>
    static inline void apply(CalculationType& lon1,
                             CalculationType& lat1,
                             CalculationType& lon2,
                             CalculationType& lat2,
                             Strategy const& strategy)
    {
        special_cases<Units>(lon1, lat1, lon2, lat2);

        CalculationType lon1_rad = math::as_radian<Units>(lon1);
        CalculationType lat1_rad = math::as_radian<Units>(lat1);
        CalculationType lon2_rad = math::as_radian<Units>(lon2);
        CalculationType lat2_rad = math::as_radian<Units>(lat2);
        CalculationType alp1, alp2;
        strategy.apply(lon1_rad, lat1_rad, lon2_rad, lat2_rad, alp1, alp2);

        compute_box_corners<Units>(lon1, lat1, lon2, lat2, alp1, alp2, strategy);
    }

    template <typename Units, typename CalculationType, typename Strategy>
    static inline void apply(CalculationType& lon1,
                             CalculationType& lat1,
                             CalculationType& lon2,
                             CalculationType& lat2,
                             Strategy const& strategy,
                             CalculationType alp1)
    {
        special_cases<Units>(lon1, lat1, lon2, lat2);

        CalculationType lon1_rad = math::as_radian<Units>(lon1);
        CalculationType lat1_rad = math::as_radian<Units>(lat1);
        CalculationType lon2_rad = math::as_radian<Units>(lon2);
        CalculationType lat2_rad = math::as_radian<Units>(lat2);
        CalculationType alp2;
        strategy.apply(lon2_rad, lat2_rad, lon1_rad, lat1_rad, alp2);
        alp2 += math::pi<CalculationType>();

        compute_box_corners<Units>(lon1, lat1, lon2, lat2, alp1, alp2, strategy);
    }

public:
    template
    <
        typename Units,
        typename CalculationType,
        typename Box,
        typename Strategy
    >
    static inline void apply(CalculationType lon1,
                             CalculationType lat1,
                             CalculationType lon2,
                             CalculationType lat2,
                             Box& mbr,
                             Strategy const& strategy)
    {
        typedef envelope_segment_convert_polar<Units, typename cs_tag<Box>::type> convert_polar;

        convert_polar::pre(lat1, lat2);

        apply<Units>(lon1, lat1, lon2, lat2, strategy);

        convert_polar::post(lat1, lat2);

        create_box<Units>(lon1, lat1, lon2, lat2, mbr);
    }

    template
    <
        typename Units,
        typename CalculationType,
        typename Box,
        typename Strategy
    >
    static inline void apply(CalculationType lon1,
                             CalculationType lat1,
                             CalculationType lon2,
                             CalculationType lat2,
                             Box& mbr,
                             Strategy const& strategy,
                             CalculationType alp1)
    {
        typedef envelope_segment_convert_polar<Units, typename cs_tag<Box>::type> convert_polar;

        convert_polar::pre(lat1, lat2);

        apply<Units>(lon1, lat1, lon2, lat2, strategy, alp1);

        convert_polar::post(lat1, lat2);

        create_box<Units>(lon1, lat1, lon2, lat2, mbr);
    }
};

template <std::size_t Dimension, std::size_t DimensionCount>
struct envelope_one_segment
{
    template<typename Point, typename Box, typename Strategy>
    static inline void apply(Point const& p1,
                             Point const& p2,
                             Box& mbr,
                             Strategy const& strategy)
    {
        envelope_one_point<Dimension, DimensionCount>::apply(p1, mbr, strategy);
        detail::expand::point_loop
            <
                Dimension,
                DimensionCount
            >::apply(mbr, p2, strategy);
    }
};


template <std::size_t DimensionCount>
struct envelope_segment
{
    template <typename Point, typename Box, typename Strategy>
    static inline void apply(Point const& p1,
                             Point const& p2,
                             Box& mbr,
                             Strategy const& strategy)
    {
        // first compute the envelope range for the first two coordinates
        strategy.apply(p1, p2, mbr);

        // now compute the envelope range for coordinates of
        // dimension 2 and higher
        envelope_one_segment<2, DimensionCount>::apply(p1, p2, mbr, strategy);
    }

    template <typename Segment, typename Box, typename Strategy>
    static inline void apply(Segment const& segment, Box& mbr,
                             Strategy const& strategy)
    {
        typename point_type<Segment>::type p[2];
        detail::assign_point_from_index<0>(segment, p[0]);
        detail::assign_point_from_index<1>(segment, p[1]);
        apply(p[0], p[1], mbr, strategy);
    }
};

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


#ifndef DOXYGEN_NO_DISPATCH
namespace dispatch
{


template <typename Segment>
struct envelope<Segment, segment_tag>
{
    template <typename Box, typename Strategy>
    static inline void apply(Segment const& segment,
                             Box& mbr,
                             Strategy const& strategy)
    {
        typename point_type<Segment>::type p[2];
        detail::assign_point_from_index<0>(segment, p[0]);
        detail::assign_point_from_index<1>(segment, p[1]);
        detail::envelope::envelope_segment
            <
               dimension<Segment>::value
            >::apply(p[0], p[1], mbr, strategy);
    }
};

} // namespace dispatch
#endif // DOXYGEN_NO_DISPATCH

}} // namespace boost::geometry

#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_ENVELOPE_SEGMENT_HPP
