#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <cmath>

#include "svm_rbf.h"

namespace mpt
{

svm_rbf::svm_rbf( const std::string &ay_path, const std::string &vs_path ) : ay(num_support_vectors), vs(num_support_vectors*feature_vector_length)
{
    load_ay( ay_path );
    load_vs( vs_path );
}

svm_rbf::~svm_rbf()
{

}

//   h=histogram representation [1xFEATURE_VECTOR_LENGTH]
//   vs = support vector in histogram representation [NUM_SUPPORT_VECTORSxFEATURE_VECTOR_LENGTH].
//   ay = coefficients of support [NUM_SUPPORT_VECTORSx1]
//    g = gaussian width  [1x1]
double
svm_rbf::decision( const std::vector<double> &histogram, double g )
{
	double y = 0.0;

    if( feature_vector_length != histogram.size() )
    {
        std::cerr << "Bad histogram length. Should be: " << feature_vector_length << ". Is: " << histogram.size() << std::endl;
        return 0.0;
    }

	for( unsigned int i = 0; i < num_support_vectors; ++i )
    {
		double D2 = 0.0;
//        std::vector<double> D(feature_vector_length);

		for( unsigned int j = 0; j < feature_vector_length; j++)
        {
			double D = histogram[j] - vs[i*feature_vector_length + j];
			D2 += D * D;
		}
		y += ay[i] * exp(-0.5*D2/g);
	}

	return y;
}

void
svm_rbf::load_ay( const std::string &path )
{
    unsigned int count = 0;
    std::ifstream ifs( path.c_str() );
    if( ifs.good() )
    {
        double val;
        for( unsigned int i = 0; i < num_support_vectors; ++i )
        {
            if( ifs >> val )
            {
                ay[i] = val;
                ++count;
            }
            else
            {
                // throw an exception
                std::cerr << "Missing value in ay. Index: " << i << std::endl;
            }
        }
	}
    if( count != num_support_vectors )
    {
        // throw an exception
        std::cerr << "Vector ay is not the right size: " << num_support_vectors << std::endl;
    }
}

void
svm_rbf::load_vs( const std::string &path )
{
    const unsigned int size = feature_vector_length * num_support_vectors;
    unsigned int count = 0;

    std::ifstream ifs( path.c_str() );
    if( ifs.good() )
    {
        for (unsigned int i = 0; i < num_support_vectors; i++)
        {
            std::string line;
            std::getline( ifs, line );
            std::stringstream linestream( line );

            for (unsigned int j = 0; j < feature_vector_length; j++)
            {
                double val;
                if( linestream >> val )
                {
                    vs[i*feature_vector_length + j] = val;
                    ++count;
                }
                else
                {
                    // throw an exception
                    std::cerr << "Missing value in vs. Indexes i/j: " << i << "/" << j << std::endl;
                }

            }
        }
    }

    if( count != size )
    {
        // throw an exception
        std::cerr << "Vector vs is not the right size. Should be " << size << ". Is " << count << std::endl;
    }
}

} // end namespace mpt