    // Copyright (C) 2011  Davis E. King (davis@dlib.net)
    // License: Boost Software License   See LICENSE.txt for the full license.
    #undef DLIB_STRUCTURAL_SVM_ObJECT_DETECTION_PROBLEM_ABSTRACT_H__
    #ifdef DLIB_STRUCTURAL_SVM_ObJECT_DETECTION_PROBLEM_ABSTRACT_H__

    #include "../matrix.h"
    #include "structural_svm_problem_threaded_abstract.h"
    #include <sstream>
    #include "../image_processing/full_object_detection_abstract.h"
    #include "../image_processing/box_overlap_testing.h"

    namespace dlib
    {

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

        class impossible_labeling_error : public dlib::error
        {
            /*!
                WHAT THIS OBJECT REPRESENTS
                    This is the exception thrown by the structural_svm_object_detection_problem
                    when it detects that the image_scanner_type it is working with is incapable
                    of representing the truth rectangles it has been asked to predict.

                    This kind of problem can happen when the test_box_overlap object indicates
                    that two ground truth rectangles overlap and are therefore not allowed to
                    both be output at the same time.  Or alternatively, if there are not enough
                    detection templates to cover the variety of truth rectangle shapes.
            !*/
        };

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

        template <
            typename image_scanner_type,
            typename image_array_type
            >
        class structural_svm_object_detection_problem : public structural_svm_problem_threaded<matrix<double,0,1> >,
                                                        noncopyable
        {
            /*!
                REQUIREMENTS ON image_scanner_type
                    image_scanner_type must be an implementation of
                    dlib/image_processing/scan_image_pyramid_abstract.h or
                    dlib/image_processing/scan_image_boxes_abstract.h

                REQUIREMENTS ON image_array_type
                    image_array_type must be an implementation of dlib/array/array_kernel_abstract.h
                    and it must contain objects which can be accepted by image_scanner_type::load().

                WHAT THIS OBJECT REPRESENTS
                    This object is a tool for learning the parameter vector needed to use
                    a scan_image_pyramid or scan_image_boxes object.

                    It learns the parameter vector by formulating the problem as a structural
                    SVM problem.  The general approach is similar to the method discussed in
                    Learning to Localize Objects with Structured Output Regression by
                    Matthew B. Blaschko and Christoph H. Lampert.  However, the method has
                    been extended to datasets with multiple, potentially overlapping, objects
                    per image and the measure of loss is different from what is described in
                    the paper.

                    In particular, the loss is measured as follows:
                        let FA == the number of false alarms produced by a labeling of an image.
                        let MT == the number of targets missed by a labeling of an image.
                        Then the loss for a particular labeling is the quantity:
                            FA*get_loss_per_false_alarm() + MT*get_loss_per_missed_target()

                    A detection is considered a false alarm if it doesn't match with any
                    of the ground truth rectangles or if it is a duplicate detection of a
                    truth rectangle.  Finally, for the purposes of calculating loss, a match
                    is determined using the following formula where rectangles A and B match
                    if and only if:
                        A.intersect(B).area()/(A+B).area() > get_match_eps()
            !*/
        public:

            structural_svm_object_detection_problem(
                const image_scanner_type& scanner,
                const test_box_overlap& overlap_tester,
                const bool auto_overlap_tester,
                const image_array_type& images,
                const std::vector<std::vector<full_object_detection> >& truth_object_detections,
                unsigned long num_threads = 2
            );
            /*!
                requires
                    - is_learning_problem(images, truth_object_detections)
                    - scanner.get_num_detection_templates() > 0
                    - scanner.load(images[0]) must be a valid expression.
                    - for all valid i, j:
                        - truth_object_detections[i][j].num_parts() == scanner.get_num_movable_components_per_detection_template()
                        - all_parts_in_rect(truth_object_detections[i][j]) == true
                ensures
                    - This object attempts to learn a mapping from the given images to the
                      object locations given in truth_object_detections.  In particular, it
                      attempts to learn to predict truth_object_detections[i] based on
                      images[i].  Or in other words, this object can be used to learn a
                      parameter vector, w, such that an object_detector declared as:
                        object_detector<image_scanner_type> detector(scanner,get_overlap_tester(),w)
                      results in a detector object which attempts to compute the locations of
                      all the objects in truth_object_detections.  So if you called
                      detector(images[i]) you would hopefully get a list of rectangles back
                      that had truth_object_detections[i].size() elements and contained exactly
                      the rectangles indicated by truth_object_detections[i].
                    - if (auto_overlap_tester == true) then
                        - #get_overlap_tester() == a test_box_overlap object that is configured
                          using the find_tight_overlap_tester() routine and the contents of
                          truth_object_detections.
                    - else
                        - #get_overlap_tester() == overlap_tester
                    - #get_match_eps() == 0.5
                    - This object will use num_threads threads during the optimization
                      procedure.  You should set this parameter equal to the number of
                      available processing cores on your machine.
                    - #get_loss_per_missed_target() == 1
                    - #get_loss_per_false_alarm() == 1
            !*/

            test_box_overlap get_overlap_tester (
            ) const;
            /*!
                ensures
                    - returns the overlap tester used by this object.
            !*/

            void set_match_eps (
                double eps
            );
            /*!
                requires
                    - 0 < eps < 1
                ensures
                    - #get_match_eps() == eps
            !*/

            double get_match_eps (
            ) const;
            /*!
                ensures
                    - returns the amount of alignment necessary for a detection to be considered
                      as matching with a ground truth rectangle.  The precise formula for determining
                      if two rectangles match each other is the following, rectangles A and B match
                      if and only if:
                        A.intersect(B).area()/(A+B).area() > get_match_eps()
            !*/

            double get_loss_per_missed_target (
            ) const;
            /*!
                ensures
                    - returns the amount of loss experienced for failing to detect one of the
                      targets.
            !*/

            void set_loss_per_missed_target (
                double loss
            );
            /*!
                requires
                    - loss > 0
                ensures
                    - #get_loss_per_missed_target() == loss
            !*/

            double get_loss_per_false_alarm (
            ) const;
            /*!
                ensures
                    - returns the amount of loss experienced for emitting a false alarm detection.
                      Or in other words, the loss for generating a detection that doesn't correspond
                      to one of the truth rectangles.
            !*/

            void set_loss_per_false_alarm (
                double loss
            );
            /*!
                requires
                    - loss > 0
                ensures
                    - #get_loss_per_false_alarm() == loss
            !*/

        };

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

    }

    #endif // DLIB_STRUCTURAL_SVM_ObJECT_DETECTION_PROBLEM_ABSTRACT_H__