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

    #include "structural_sequence_segmentation_trainer_abstract.h"
    #include "structural_sequence_labeling_trainer.h"
    #include "sequence_segmenter.h"

    namespace dlib
    {

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

        template <
            typename feature_extractor
            >
        class structural_sequence_segmentation_trainer
        {
        public:
            typedef typename feature_extractor::sequence_type sample_sequence_type;
            typedef std::vector<std::pair<unsigned long, unsigned long> > segmented_sequence_type;

            typedef sequence_segmenter<feature_extractor> trained_function_type;

            explicit structural_sequence_segmentation_trainer (
                const feature_extractor& fe_
            ) : trainer(impl_ss::feature_extractor<feature_extractor>(fe_))
            {
                loss_per_missed_segment = 1;
                loss_per_false_alarm = 1;
            }

            structural_sequence_segmentation_trainer (
            )
            {
                loss_per_missed_segment = 1;
                loss_per_false_alarm = 1;
            }

            const feature_extractor& get_feature_extractor (
            ) const { return trainer.get_feature_extractor().fe; }

            void set_num_threads (
                unsigned long num
            )
            {
                trainer.set_num_threads(num);
            }

            unsigned long get_num_threads (
            ) const
            {
                return trainer.get_num_threads();
            }

            void set_epsilon (
                double eps_
            )
            {
                // make sure requires clause is not broken
                DLIB_ASSERT(eps_ > 0,
                    "\t void structural_sequence_segmentation_trainer::set_epsilon()"
                    << "\n\t eps_ must be greater than 0"
                    << "\n\t eps_: " << eps_
                    << "\n\t this: " << this
                    );

                trainer.set_epsilon(eps_);
            }

            double get_epsilon (
            ) const { return trainer.get_epsilon(); }

            void set_max_cache_size (
                unsigned long max_size
            )
            {
                trainer.set_max_cache_size(max_size);
            }

            unsigned long get_max_cache_size (
            ) const
            {
                return trainer.get_max_cache_size();
            }

            void be_verbose (
            )
            {
                trainer.be_verbose();
            }

            void be_quiet (
            )
            {
                trainer.be_quiet();
            }

            void set_oca (
                const oca& item
            )
            {
                trainer.set_oca(item);
            }

            const oca get_oca (
            ) const
            {
                return trainer.get_oca();
            }

            void set_c (
                double C_
            )
            {
                // make sure requires clause is not broken
                DLIB_ASSERT(C_ > 0,
                    "\t void structural_sequence_segmentation_trainer::set_c()"
                    << "\n\t C_ must be greater than 0"
                    << "\n\t C_:    " << C_
                    << "\n\t this: " << this
                    );

                trainer.set_c(C_);
            }

            double get_c (
            ) const
            {
                return trainer.get_c();
            }

            void set_loss_per_missed_segment (
                double loss
            )
            {
                // make sure requires clause is not broken
                DLIB_ASSERT(loss >= 0,
                            "\t void structural_sequence_segmentation_trainer::set_loss_per_missed_segment(loss)"
                            << "\n\t invalid inputs were given to this function"
                            << "\n\t loss: " << loss
                            << "\n\t this: " << this
                );

                loss_per_missed_segment = loss;

                if (feature_extractor::use_BIO_model)
                {
                    trainer.set_loss(impl_ss::BEGIN,  loss_per_missed_segment);
                    trainer.set_loss(impl_ss::INSIDE, loss_per_missed_segment);
                }
                else
                {
                    trainer.set_loss(impl_ss::BEGIN,  loss_per_missed_segment);
                    trainer.set_loss(impl_ss::INSIDE, loss_per_missed_segment);
                    trainer.set_loss(impl_ss::LAST,   loss_per_missed_segment);
                    trainer.set_loss(impl_ss::UNIT,   loss_per_missed_segment);
                }
            }

            double get_loss_per_missed_segment (
            ) const
            {
                return loss_per_missed_segment;
            }

            void set_loss_per_false_alarm (
                double loss
            )
            {
                // make sure requires clause is not broken
                DLIB_ASSERT(loss >= 0,
                            "\t void structural_sequence_segmentation_trainer::set_loss_per_false_alarm(loss)"
                            << "\n\t invalid inputs were given to this function"
                            << "\n\t loss: " << loss
                            << "\n\t this: " << this
                );

                loss_per_false_alarm = loss;

                trainer.set_loss(impl_ss::OUTSIDE,  loss_per_false_alarm);
            }

            double get_loss_per_false_alarm (
            ) const
            {
                return loss_per_false_alarm;
            }

            const sequence_segmenter<feature_extractor> train(
                const std::vector<sample_sequence_type>& x,
                const std::vector<segmented_sequence_type>& y
            ) const
            {

                // make sure requires clause is not broken
                DLIB_ASSERT(is_sequence_segmentation_problem(x,y) == true,
                            "\t sequence_segmenter structural_sequence_segmentation_trainer::train(x,y)"
                            << "\n\t invalid inputs were given to this function"
                            << "\n\t x.size(): " << x.size()
                            << "\n\t is_sequence_segmentation_problem(x,y): " << is_sequence_segmentation_problem(x,y)
                            << "\n\t this: " << this
                );

                std::vector<std::vector<unsigned long> > labels(y.size());
                if (feature_extractor::use_BIO_model)
                {
                    // convert y into tagged BIO labels
                    for (unsigned long i = 0; i < labels.size(); ++i)
                    {
                        labels[i].resize(x[i].size(), impl_ss::OUTSIDE);
                        for (unsigned long j = 0; j < y[i].size(); ++j)
                        {
                            const unsigned long begin = y[i][j].first;
                            const unsigned long end = y[i][j].second;
                            if (begin != end)
                            {
                                labels[i][begin] = impl_ss::BEGIN;
                                for (unsigned long k = begin+1; k < end; ++k)
                                    labels[i][k] = impl_ss::INSIDE;
                            }
                        }
                    }
                }
                else
                {
                    // convert y into tagged BILOU labels
                    for (unsigned long i = 0; i < labels.size(); ++i)
                    {
                        labels[i].resize(x[i].size(), impl_ss::OUTSIDE);
                        for (unsigned long j = 0; j < y[i].size(); ++j)
                        {
                            const unsigned long begin = y[i][j].first;
                            const unsigned long end = y[i][j].second;
                            if (begin != end)
                            {
                                if (begin+1==end)
                                {
                                    labels[i][begin] = impl_ss::UNIT;
                                }
                                else
                                {
                                    labels[i][begin] = impl_ss::BEGIN;
                                    for (unsigned long k = begin+1; k+1 < end; ++k)
                                        labels[i][k] = impl_ss::INSIDE;
                                    labels[i][end-1] = impl_ss::LAST;
                                }
                            }
                        }
                    }
                }

                sequence_labeler<impl_ss::feature_extractor<feature_extractor> > temp;
                temp = trainer.train(x, labels);
                return sequence_segmenter<feature_extractor>(temp.get_weights(), trainer.get_feature_extractor().fe);
            }

        private:

            structural_sequence_labeling_trainer<impl_ss::feature_extractor<feature_extractor> > trainer;
            double loss_per_missed_segment;
            double loss_per_false_alarm;
        };

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

    }

    #endif // DLIB_STRUCTURAL_SEQUENCE_sEGMENTATION_TRAINER_H__