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

    #include "structural_sequence_labeling_trainer_abstract.h"
    #include "../algs.h"
    #include "../optimization.h"
    #include "structural_svm_sequence_labeling_problem.h"
    #include "num_nonnegative_weights.h"

    namespace dlib
    {

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

        template <
            typename feature_extractor
            >
        class structural_sequence_labeling_trainer
        {
        public:
            typedef typename feature_extractor::sequence_type sample_sequence_type;
            typedef std::vector<unsigned long> labeled_sequence_type;

            typedef sequence_labeler<feature_extractor> trained_function_type;

            explicit structural_sequence_labeling_trainer (
                const feature_extractor& fe_
            ) : fe(fe_)
            {
                set_defaults();
            }

            structural_sequence_labeling_trainer (
            )
            {
                set_defaults();
            }

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

            unsigned long num_labels (
            ) const { return fe.num_labels(); }

            void set_num_threads (
                unsigned long num
            )
            {
                num_threads = num;
            }

            unsigned long get_num_threads (
            ) const
            {
                return num_threads;
            }

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

                eps = eps_;
            }

            double get_epsilon (
            ) const { return eps; }

            void set_max_cache_size (
                unsigned long max_size
            )
            {
                max_cache_size = max_size;
            }

            unsigned long get_max_cache_size (
            ) const
            {
                return max_cache_size;
            }

            void be_verbose (
            )
            {
                verbose = true;
            }

            void be_quiet (
            )
            {
                verbose = false;
            }

            void set_oca (
                const oca& item
            )
            {
                solver = item;
            }

            const oca get_oca (
            ) const
            {
                return solver;
            }

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

                C = C_;
            }

            double get_c (
            ) const
            {
                return C;
            }

            double get_loss (
                unsigned long label
            ) const
            {
                // make sure requires clause is not broken
                DLIB_ASSERT(label < num_labels(),
                            "\t void structural_sequence_labeling_trainer::get_loss()"
                            << "\n\t invalid inputs were given to this function"
                            << "\n\t label:        " << label
                            << "\n\t num_labels(): " << num_labels()
                            << "\n\t this:         " << this
                            );

                return loss_values[label];
            }

            void set_loss (
                unsigned long label,
                double value
            )
            {
                // make sure requires clause is not broken
                DLIB_ASSERT(label < num_labels() && value >= 0,
                            "\t void structural_sequence_labeling_trainer::set_loss()"
                            << "\n\t invalid inputs were given to this function"
                            << "\n\t label:        " << label
                            << "\n\t num_labels(): " << num_labels()
                            << "\n\t value:        " << value
                            << "\n\t this:         " << this
                            );

                loss_values[label] = value;
            }

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

                // make sure requires clause is not broken
                DLIB_ASSERT(is_sequence_labeling_problem(x,y) == true &&
                            contains_invalid_labeling(get_feature_extractor(), x, y) == false,
                            "\t sequence_labeler structural_sequence_labeling_trainer::train(x,y)"
                            << "\n\t invalid inputs were given to this function"
                            << "\n\t x.size(): " << x.size()
                            << "\n\t is_sequence_labeling_problem(x,y): " << is_sequence_labeling_problem(x,y)
                            << "\n\t contains_invalid_labeling(get_feature_extractor(),x,y): " << contains_invalid_labeling(get_feature_extractor(),x,y)
                            << "\n\t this: " << this
                );

    #ifdef ENABLE_ASSERTS
                for (unsigned long i = 0; i < y.size(); ++i)
                {
                    for (unsigned long j = 0; j < y[i].size(); ++j)
                    {
                        // make sure requires clause is not broken
                        DLIB_ASSERT(y[i][j] < num_labels(),
                                    "\t sequence_labeler structural_sequence_labeling_trainer::train(x,y)"
                                    << "\n\t The given labels in y are invalid."
                                    << "\n\t y[i][j]: " << y[i][j]
                                    << "\n\t num_labels(): " << num_labels()
                                    << "\n\t i: " << i
                                    << "\n\t j: " << j
                                    << "\n\t this: " << this
                        );
                    }
                }
    #endif

                structural_svm_sequence_labeling_problem<feature_extractor> prob(x, y, fe, num_threads);
                matrix<double,0,1> weights;
                if (verbose)
                    prob.be_verbose();

                prob.set_epsilon(eps);
                prob.set_c(C);
                prob.set_max_cache_size(max_cache_size);
                for (unsigned long i = 0; i < loss_values.size(); ++i)
                    prob.set_loss(i,loss_values[i]);

                solver(prob, weights, num_nonnegative_weights(fe));

                return sequence_labeler<feature_extractor>(weights,fe);
            }

        private:

            double C;
            oca solver;
            double eps;
            bool verbose;
            unsigned long num_threads;
            unsigned long max_cache_size;
            std::vector<double> loss_values;

            void set_defaults ()
            {
                C = 100;
                verbose = false;
                eps = 0.1;
                num_threads = 2;
                max_cache_size = 5;
                loss_values.assign(num_labels(), 1);
            }

            feature_extractor fe;
        };

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

    }

    #endif // DLIB_STRUCTURAL_SEQUENCE_LABELING_TRAiNER_H__