    // Copyright (C) 2013  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_SCAN_IMAGE_bOXES_H__
    #define DLIB_SCAN_IMAGE_bOXES_H__

    #include "scan_image_boxes_abstract.h"
    #include "../matrix.h"
    #include "../geometry.h"
    #include "../image_processing.h"
    #include "../array2d.h"
    #include <vector>
    #include "../image_processing/full_object_detection.h"
    #include "../image_transforms.h"

    namespace dlib
    {

    // ----------------------------------------------------------------------------------------

        class default_box_generator
        {
        public:
            template <typename image_type>
            void operator() (
                const image_type& img,
                std::vector<rectangle>& rects
            ) const
            {
                rects.clear();
                find_candidate_object_locations(img, rects);
            }
        };

        inline void serialize(const default_box_generator&, std::ostream& ) {}
        inline void deserialize(default_box_generator&, std::istream& ) {}

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator = default_box_generator
            >
        class scan_image_boxes : noncopyable
        {

        public:

            typedef matrix<double,0,1> feature_vector_type;

            typedef Feature_extractor_type feature_extractor_type;
            typedef Box_generator box_generator;

            scan_image_boxes (
            );

            template <
                typename image_type
                >
            void load (
                const image_type& img
            );

            inline bool is_loaded_with_image (
            ) const;

            inline void copy_configuration(
                const feature_extractor_type& fe
            );

            inline void copy_configuration(
                const box_generator& bg
            );

            const box_generator& get_box_generator (
            ) const { return detect_boxes; }

            const Feature_extractor_type& get_feature_extractor (
            ) const { return feats; }

            inline void copy_configuration (
                const scan_image_boxes& item
            );

            inline long get_num_dimensions (
            ) const;

            unsigned long get_num_spatial_pyramid_levels (
            ) const;

            void set_num_spatial_pyramid_levels (
                unsigned long levels
            );

            void detect (
                const feature_vector_type& w,
                std::vector<std::pair<double, rectangle> >& dets,
                const double thresh
            ) const;

            void get_feature_vector (
                const full_object_detection& obj,
                feature_vector_type& psi
            ) const;

            full_object_detection get_full_object_detection (
                const rectangle& rect,
                const feature_vector_type& w
            ) const;

            const rectangle get_best_matching_rect (
                const rectangle& rect
            ) const;
            /*!
                requires
                    - is_loaded_with_image() == true
            !*/

            inline unsigned long get_num_detection_templates (
            ) const { return 1; }

            inline unsigned long get_num_movable_components_per_detection_template (
            ) const { return 0; }

            template <typename T, typename U>
            friend void serialize (
                const scan_image_boxes<T,U>& item,
                std::ostream& out
            );

            template <typename T, typename U>
            friend void deserialize (
                scan_image_boxes<T,U>& item,
                std::istream& in
            );

        private:
            static bool compare_pair_rect (
                const std::pair<double, rectangle>& a,
                const std::pair<double, rectangle>& b
            )
            {
                return a.first < b.first;
            }

            void test_coordinate_transforms()
            {
                for (long x = -10; x <= 10; x += 10)
                {
                    for (long y = -10; y <= 10; y += 10)
                    {
                        const rectangle rect = centered_rect(x,y,5,6);
                        rectangle a;

                        a = feats.image_to_feat_space(rect);
                        if (a.width()  > 10000000 || a.height() > 10000000 )
                        {
                            DLIB_CASSERT(false, "The image_to_feat_space() routine is outputting rectangles of an implausibly "
                                         << "\nlarge size.  This means there is probably a bug in your feature extractor.");
                        }
                        a = feats.feat_to_image_space(rect);
                        if (a.width()  > 10000000 || a.height() > 10000000 )
                        {
                            DLIB_CASSERT(false, "The feat_to_image_space() routine is outputting rectangles of an implausibly "
                                         << "\nlarge size.  This means there is probably a bug in your feature extractor.");
                        }
                    }
                }

            }

            static void add_grid_rects (
                std::vector<rectangle>& rects,
                const rectangle& object_box,
                unsigned int cells_x,
                unsigned int cells_y
            )
            {
                // make sure requires clause is not broken
                DLIB_ASSERT(cells_x > 0 && cells_y > 0,
                    "\t void add_grid_rects()"
                    << "\n\t The number of cells along a dimension can't be zero. "
                    << "\n\t cells_x: " << cells_x
                    << "\n\t cells_y: " << cells_y
                );

                const matrix_range_exp<double>& x = linspace(object_box.left(), object_box.right(), cells_x+1);
                const matrix_range_exp<double>& y = linspace(object_box.top(), object_box.bottom(), cells_y+1);

                for (long j = 0; j+1 < y.size(); ++j)
                {
                    for (long i = 0; i+1 < x.size(); ++i)
                    {
                        const dlib::vector<double,2> tl(x(i),y(j));
                        const dlib::vector<double,2> br(x(i+1),y(j+1));
                        rects.push_back(rectangle(tl,br));
                    }
                }
            }

            void get_feature_extraction_regions (
                const rectangle& rect,
                std::vector<rectangle>& regions
            ) const
            /*!
                ensures
                    - #regions.size() is always the same number no matter what the input is.  The
                      regions also have a consistent ordering.
                    - all the output rectangles are contained within rect.
            !*/
            {
                regions.clear();

                for (unsigned int l = 1; l <= num_spatial_pyramid_levels; ++l)
                {
                    const int cells = (int)std::pow(2.0, l-1.0);
                    add_grid_rects(regions, rect, cells, cells);
                }
            }

            unsigned int get_num_components_per_detection_template(
            ) const
            {
                return (unsigned int)(std::pow(4.0,(double)num_spatial_pyramid_levels)-1)/3;
            }

            feature_extractor_type feats;
            std::vector<rectangle> search_rects;
            bool loaded_with_image;
            unsigned int num_spatial_pyramid_levels;
            box_generator detect_boxes;

            const long box_sizedims;
            const long box_maxsize;
        };

    // ----------------------------------------------------------------------------------------

        template <typename T, typename U>
        void serialize (
            const scan_image_boxes<T,U>& item,
            std::ostream& out
        )
        {
            int version = 1;
            serialize(version, out);
            serialize(item.feats, out);
            serialize(item.search_rects, out);
            serialize(item.loaded_with_image, out);
            serialize(item.num_spatial_pyramid_levels, out);
            serialize(item.detect_boxes, out);
            serialize(item.get_num_dimensions(), out);
        }

    // ----------------------------------------------------------------------------------------

        template <typename T, typename U>
        void deserialize (
            scan_image_boxes<T,U>& item,
            std::istream& in
        )
        {
            int version = 0;
            deserialize(version, in);
            if (version != 1)
                throw serialization_error("Unsupported version found when deserializing a scan_image_boxes object.");

            deserialize(item.feats, in);
            deserialize(item.search_rects, in);
            deserialize(item.loaded_with_image, in);
            deserialize(item.num_spatial_pyramid_levels, in);
            deserialize(item.detect_boxes, in);

            // When developing some feature extractor, it's easy to accidentally change its
            // number of dimensions and then try to deserialize data from an older version of
            // your extractor into the current code.  This check is here to catch that kind of
            // user error.
            long dims;
            deserialize(dims, in);
            if (item.get_num_dimensions() != dims)
                throw serialization_error("Number of dimensions in serialized scan_image_boxes doesn't match the expected number.");
        }

    // ----------------------------------------------------------------------------------------
    // ----------------------------------------------------------------------------------------
    //                         scan_image_boxes member functions
    // ----------------------------------------------------------------------------------------
    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        scan_image_boxes<Feature_extractor_type,Box_generator>::
        scan_image_boxes (
        ) :
            loaded_with_image(false),
            num_spatial_pyramid_levels(3),
            box_sizedims(20),
            box_maxsize(1200)
        {
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        template <
            typename image_type
            >
        void scan_image_boxes<Feature_extractor_type,Box_generator>::
        load (
            const image_type& img
        )
        {
            feats.load(img);
            detect_boxes(img, search_rects);
            loaded_with_image = true;
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        bool scan_image_boxes<Feature_extractor_type,Box_generator>::
        is_loaded_with_image (
        ) const
        {
            return loaded_with_image;
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        void scan_image_boxes<Feature_extractor_type,Box_generator>::
        copy_configuration(
            const feature_extractor_type& fe
        )
        {
            test_coordinate_transforms();
            feats.copy_configuration(fe);
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        void scan_image_boxes<Feature_extractor_type,Box_generator>::
        copy_configuration(
            const box_generator& bg
        )
        {
            detect_boxes = bg;
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        void scan_image_boxes<Feature_extractor_type,Box_generator>::
        copy_configuration (
            const scan_image_boxes& item
        )
        {
            feats.copy_configuration(item.feats);
            detect_boxes = item.detect_boxes;
            num_spatial_pyramid_levels = item.num_spatial_pyramid_levels;
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        unsigned long scan_image_boxes<Feature_extractor_type,Box_generator>::
        get_num_spatial_pyramid_levels (
        ) const
        {
            return num_spatial_pyramid_levels;
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        void scan_image_boxes<Feature_extractor_type,Box_generator>::
        set_num_spatial_pyramid_levels (
            unsigned long levels
        )
        {
            // make sure requires clause is not broken
            DLIB_ASSERT(levels > 0,
                "\t void scan_image_boxes::set_num_spatial_pyramid_levels()"
                << "\n\t Invalid inputs were given to this function "
                << "\n\t levels: " << levels
                << "\n\t this: " << this
                );

            num_spatial_pyramid_levels = levels;
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        long scan_image_boxes<Feature_extractor_type,Box_generator>::
        get_num_dimensions (
        ) const
        {
            return feats.get_num_dimensions()*get_num_components_per_detection_template() + box_sizedims*2;
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        void scan_image_boxes<Feature_extractor_type,Box_generator>::
        detect (
            const feature_vector_type& w,
            std::vector<std::pair<double, rectangle> >& dets,
            const double thresh
        ) const
        {
            // make sure requires clause is not broken
            DLIB_ASSERT(is_loaded_with_image() &&
                        w.size() >= get_num_dimensions(),
                "\t void scan_image_boxes::detect()"
                << "\n\t Invalid inputs were given to this function "
                << "\n\t is_loaded_with_image(): " << is_loaded_with_image()
                << "\n\t w.size():               " << w.size()
                << "\n\t get_num_dimensions():   " << get_num_dimensions()
                << "\n\t this: " << this
                );

            dets.clear();

            array<integral_image_generic<double> > saliency_images(get_num_components_per_detection_template());

            array2d<double> temp_img(feats.nr(), feats.nc());

            // build saliency images
            for (unsigned long i = 0; i < saliency_images.size(); ++i)
            {
                const unsigned long offset = 2*box_sizedims + feats.get_num_dimensions()*i;

                // make the basic saliency image for the i-th feature extraction region
                for (long r = 0; r < feats.nr(); ++r)
                {
                    for (long c = 0; c < feats.nc(); ++c)
                    {
                        const typename feature_extractor_type::descriptor_type& descriptor = feats(r,c);

                        double sum = 0;
                        for (unsigned long k = 0; k < descriptor.size(); ++k)
                        {
                            sum += w(descriptor[k].first + offset)*descriptor[k].second;
                        }
                        temp_img[r][c] = sum;
                    }
                }

                // now convert base saliency image into final integral image
                saliency_images[i].load(temp_img);
            }

            // now search the saliency images
            std::vector<rectangle> regions;
            const rectangle bounds = get_rect(feats);
            for (unsigned long i = 0; i < search_rects.size(); ++i)
            {
                const rectangle rect = feats.image_to_feat_space(search_rects[i]).intersect(bounds);
                if (rect.is_empty())
                    continue;
                get_feature_extraction_regions(rect, regions);
                double score = 0;
                for (unsigned long k = 0; k < regions.size(); ++k)
                {
                    score += saliency_images[k].get_sum_of_area(regions[k]);
                }
                const double width = search_rects[i].width();
                const double height = search_rects[i].height();

                score += dot(linpiece(width,  linspace(0, box_maxsize, box_sizedims+1)), rowm(w, range(0,box_sizedims-1)));
                score += dot(linpiece(height, linspace(0, box_maxsize, box_sizedims+1)), rowm(w, range(box_sizedims,2*box_sizedims-1)));

                if (score >= thresh)
                {
                    dets.push_back(std::make_pair(score, search_rects[i]));
                }
            }

            std::sort(dets.rbegin(), dets.rend(), compare_pair_rect);
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        const rectangle scan_image_boxes<Feature_extractor_type,Box_generator>::
        get_best_matching_rect (
            const rectangle& rect
        ) const
        {
            // make sure requires clause is not broken
            DLIB_ASSERT(is_loaded_with_image(),
                "\t const rectangle scan_image_boxes::get_best_matching_rect()"
                << "\n\t Invalid inputs were given to this function "
                << "\n\t is_loaded_with_image(): " << is_loaded_with_image()
                << "\n\t this: " << this
                );

            double best_score = -1;
            rectangle best_rect;
            for (unsigned long i = 0; i < search_rects.size(); ++i)
            {
                const double score = (rect.intersect(search_rects[i])).area()/(double)(rect+search_rects[i]).area();
                if (score > best_score)
                {
                    best_score = score;
                    best_rect = search_rects[i];
                }
            }
            return best_rect;
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        full_object_detection scan_image_boxes<Feature_extractor_type,Box_generator>::
        get_full_object_detection (
            const rectangle& rect,
            const feature_vector_type& /*w*/
        ) const
        {
            return full_object_detection(rect);
        }

    // ----------------------------------------------------------------------------------------

        template <
            typename Feature_extractor_type,
            typename Box_generator
            >
        void scan_image_boxes<Feature_extractor_type,Box_generator>::
        get_feature_vector (
            const full_object_detection& obj,
            feature_vector_type& psi
        ) const
        {
            // make sure requires clause is not broken
            DLIB_ASSERT(is_loaded_with_image() &&
                        psi.size() >= get_num_dimensions() &&
                        obj.num_parts() == 0,
                "\t void scan_image_boxes::get_feature_vector()"
                << "\n\t Invalid inputs were given to this function "
                << "\n\t is_loaded_with_image(): " << is_loaded_with_image()
                << "\n\t psi.size():             " << psi.size()
                << "\n\t get_num_dimensions():   " << get_num_dimensions()
                << "\n\t obj.num_parts():                            " << obj.num_parts()
                << "\n\t this: " << this
                );

            const rectangle best_rect = get_best_matching_rect(obj.get_rect());
            const rectangle mapped_rect = feats.image_to_feat_space(best_rect).intersect(get_rect(feats));
            if (mapped_rect.is_empty())
                return;

            std::vector<rectangle> regions;
            get_feature_extraction_regions(mapped_rect, regions);

            // pull features out of all the boxes in regions.
            for (unsigned long j = 0; j < regions.size(); ++j)
            {
                const rectangle rect = regions[j];

                const unsigned long template_region_id = j;
                const unsigned long offset = box_sizedims*2 + feats.get_num_dimensions()*template_region_id;
                for (long r = rect.top(); r <= rect.bottom(); ++r)
                {
                    for (long c = rect.left(); c <= rect.right(); ++c)
                    {
                        const typename feature_extractor_type::descriptor_type& descriptor = feats(r,c);
                        for (unsigned long k = 0; k < descriptor.size(); ++k)
                        {
                            psi(descriptor[k].first + offset) += descriptor[k].second;
                        }
                    }
                }
            }

            const double width = best_rect.width();
            const double height = best_rect.height();
            set_rowm(psi, range(0,box_sizedims-1))              += linpiece(width,  linspace(0, box_maxsize, box_sizedims+1));
            set_rowm(psi, range(box_sizedims,box_sizedims*2-1)) += linpiece(height, linspace(0, box_maxsize, box_sizedims+1));
        }

    // ----------------------------------------------------------------------------------------

    }

    #endif // DLIB_SCAN_IMAGE_bOXES_H__