#ifndef JENSENSHANNON_H
#define JENSENSHANNON_H

#include "KullbackLeibler.h"

#include "../../Assertions.h"
#include <string>


namespace Divergence {

template <typename Scalar> class JensenShannon {

public:
    /** Calculate the Jensen Shannon Divergece from a set of sample densities
     *  Info: https://en.wikipedia.org/wiki/Jensen–Shannon_divergence
     * @param P is the vector containing the densities of a set of samples
     * @param Q is a vector containg the densities of the same samples set then P
    */
    static inline Scalar getGeneralFromSamples(Eigen::VectorXd P, Eigen::VectorXd Q, LOGMODE mode){
        // normalize
        P /= P.sum();
        Q /= Q.sum();

        Assert::isNear((double)P.sum(), 1.0, 0.01,"Normalization failed.. this shouldn't happen");
        Assert::isNear((double)Q.sum(), 1.0, 0.01, "Normalization failed.. this shouldn't happen");

        Eigen::VectorXd M = 0.5 * (P + Q);

        return (0.5 * KullbackLeibler<Scalar>::getGeneralFromSamples(P, M, mode)) + (0.5 * KullbackLeibler<Scalar>::getGeneralFromSamples(Q, M, mode));
    }
};

}

#endif // JENSENSHANNON_H