/*
 * This file is part of the GROMACS molecular simulation package.
 *
 * Copyright (c) 1991-2000, University of Groningen, The Netherlands.
 * Copyright (c) 2001-2004, The GROMACS development team.
 * Copyright (c) 2013,2014,2015,2016,2017,2018, by the GROMACS development team, led by
 * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
 * and including many others, as listed in the AUTHORS file in the
 * top-level source directory and at http://www.gromacs.org.
 *
 * GROMACS 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 2.1
 * of the License, or (at your option) any later version.
 *
 * GROMACS 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 GROMACS; if not, see
 * http://www.gnu.org/licenses, or write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA.
 *
 * If you want to redistribute modifications to GROMACS, please
 * consider that scientific software is very special. Version
 * control is crucial - bugs must be traceable. We will be happy to
 * consider code for inclusion in the official distribution, but
 * derived work must not be called official GROMACS. Details are found
 * in the README & COPYING files - if they are missing, get the
 * official version at http://www.gromacs.org.
 *
 * To help us fund GROMACS development, we humbly ask that you cite
 * the research papers on the package. Check out http://www.gromacs.org.
 */
#ifndef GMX_TRAJECTORY_ENERGYFRAME_H
#define GMX_TRAJECTORY_ENERGYFRAME_H

#include <map>
#include <string>

#include "gromacs/utility/basedefinitions.h"
#include "gromacs/utility/real.h"

struct t_enxblock;

struct t_energy
{
    //! The current energy.
    real   e;
    //! The running average of the energy
    double eav;
    //! The sum of energies until now.
    double esum;
};

/* The frames that are read/written */
struct t_enxframe
{
    double          t;            /* Timestamp of this frame	                     */
    int64_t         step;         /* MD step	                             */
    int64_t         nsteps;       /* The number of steps between frames            */
    double          dt;           /* The MD time step                              */
    int             nsum;         /* The number of terms for the sums in ener      */
    int             nre;          /* Number of energies			     */
    int             e_size;       /* Size (in bytes) of energies		     */
    int             e_alloc;      /* Allocated size (in elements) of ener          */
    t_energy       *ener;         /* The energies                                  */
    int             nblock;       /* Number of following energy blocks             */
    t_enxblock     *block;        /* The blocks                                    */
    int             nblock_alloc; /* The number of blocks allocated                */
};

namespace gmx
{

/*! \internal
 * \brief Contains the content of an .edr frame read by an EnergyFrameReader
 *
 * The interface of this class is intended to resemble a subset of std::map. */
class EnergyFrame
{
    public:
        //! Convenience type
        using MapType = std::map<std::string, real>;
        //! Convenience type
        using MapConstIterator = MapType::const_iterator;
        //! Constructor
        EnergyFrame(const t_enxframe &enxframe,
                    std::map<std::string, int> indicesOfEnergyFields);
        /*! \brief Return string that helps users identify this frame, containing time and step number.
         *
         * \throws std::bad_alloc  when out of memory */
        std::string frameName() const;
        /*! \brief Return the value read for energy \c name.
         *
         * \throws APIError  if \c name was not registered with EnergyFileReader. */
        const real &at(const std::string &name) const;
        //! Return const interator to first element of values.
        MapConstIterator begin() const;
        //! Return const interator to past the end element of values.
        MapConstIterator end() const;
        //! Return a const interator to the element with \c key, or end() if not found.
        MapConstIterator find(const std::string &key) const;
    private:
        //! Container for energy values, indexed by name
        MapType      values_;
        //! Step number read from the .edr file frame
        std::int64_t step_;
        //! Time read from the .edr file frame
        double       time_;
};

}  // namespace gmx

#endif
