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

    #include "structural_assignment_trainer_abstract.h"
    #include "../algs.h"
    #include "../optimization.h"
    #include "structural_svm_assignment_problem.h"
    #include "num_nonnegative_weights.h"

    namespace dlib
    {

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

        template <
            typename feature_extractor
            >
        class structural_assignment_trainer
        {
        public:
            typedef typename feature_extractor::lhs_element lhs_element;
            typedef typename feature_extractor::rhs_element rhs_element;
            typedef std::pair<std::vector<lhs_element>, std::vector<rhs_element> > sample_type;
            typedef std::vector<long> label_type;
            typedef assignment_function<feature_extractor> trained_function_type;

            structural_assignment_trainer (
            )
            {
                set_defaults();
            }

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

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

            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_assignment_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_assignment_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;
            }

            bool forces_assignment(
            ) const { return force_assignment; }

            void set_forces_assignment (
                bool new_value
            )
            {
                force_assignment = new_value;
            }

            const assignment_function<feature_extractor> train (
                const std::vector<sample_type>& samples,
                const std::vector<label_type>& labels
            ) const
            {
                // make sure requires clause is not broken
    #ifdef ENABLE_ASSERTS
                if (force_assignment)
                {
                    DLIB_ASSERT(is_forced_assignment_problem(samples, labels),
                                "\t assignment_function structural_assignment_trainer::train()"
                                << "\n\t invalid inputs were given to this function"
                                << "\n\t is_forced_assignment_problem(samples,labels): " << is_forced_assignment_problem(samples,labels)
                                << "\n\t is_assignment_problem(samples,labels):        " << is_assignment_problem(samples,labels)
                                << "\n\t is_learning_problem(samples,labels):          " << is_learning_problem(samples,labels)
                    );
                }
                else
                {
                    DLIB_ASSERT(is_assignment_problem(samples, labels),
                                "\t assignment_function structural_assignment_trainer::train()"
                                << "\n\t invalid inputs were given to this function"
                                << "\n\t is_assignment_problem(samples,labels): " << is_assignment_problem(samples,labels)
                                << "\n\t is_learning_problem(samples,labels):   " << is_learning_problem(samples,labels)
                    );
                }
    #endif

                structural_svm_assignment_problem<feature_extractor> prob(samples,labels, fe, force_assignment, num_threads);

                if (verbose)
                    prob.be_verbose();

                prob.set_c(C);
                prob.set_epsilon(eps);
                prob.set_max_cache_size(max_cache_size);

                matrix<double,0,1> weights;

                // Take the min here because we want to prevent the user from accidentally
                // forcing the bias term to be non-negative.
                const unsigned long num_nonneg = std::min(fe.num_features(),num_nonnegative_weights(fe));
                solver(prob, weights, num_nonneg);

                const double bias = weights(weights.size()-1);
                return assignment_function<feature_extractor>(colm(weights,0,weights.size()-1), bias,fe,force_assignment);

            }

        private:

            bool force_assignment;
            double C;
            oca solver;
            double eps;
            bool verbose;
            unsigned long num_threads;
            unsigned long max_cache_size;

            void set_defaults ()
            {
                force_assignment = false;
                C = 100;
                verbose = false;
                eps = 0.01;
                num_threads = 2;
                max_cache_size = 5;
            }

            feature_extractor fe;
        };

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

    }

    #endif // DLIB_STRUCTURAL_ASSiGNMENT_TRAINER_H__