/*
 * GradientWrtParameterProvider.java
 *
 * Copyright (c) 2002-2017 Alexei Drummond, Andrew Rambaut and Marc Suchard
 *
 * This file is part of BEAST.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership and licensing.
 *
 * BEAST is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 *  BEAST is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with BEAST; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA  02110-1301  USA
 */

package dr.inference.hmc;

import dr.inference.model.GradientProvider;
import dr.inference.model.Likelihood;
import dr.inference.model.Parameter;

/**
 * @author Max Tolkoff
 * @author Marc A. Suchard
 */
public interface GradientWrtParameterProvider {

    Likelihood getLikelihood();

    Parameter getParameter();

    int getDimension();

    double[] getGradientLogDensity();

//    void getGradientLogDensity(double[] destination, int offset);

    class ParameterWrapper implements GradientWrtParameterProvider {

        final GradientProvider provider;
        final Parameter parameter;
        final Likelihood likelihood;

        public ParameterWrapper(GradientProvider provider, Parameter parameter, Likelihood likelihood) {
            this.provider = provider;
            this.parameter = parameter;
            this.likelihood = likelihood;
        }

        @Override
        public Likelihood getLikelihood() {
            return likelihood;
        }

        @Override
        public Parameter getParameter() {
            return parameter;
        }

        @Override
        public int getDimension() {
            return parameter.getDimension();
        }

        @Override
        public double[] getGradientLogDensity() {
            return provider.getGradientLogDensity(parameter.getParameterValues());
        }
    }
}