/*
  This file is part of the Open Porous Media project (OPM).

  OPM is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 2 of the License, or
  (at your option) any later version.

  OPM 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 General Public License for more details.

  You should have received a copy of the GNU General Public License
  along with OPM.  If not, see <http://www.gnu.org/licenses/>.

  Consult the COPYING file in the top-level source directory of this
  module for the precise wording of the license and the list of
  copyright holders.
*/
#ifndef HDF5_FILE_HPP
#define HDF5_FILE_HPP

#include <opm/simulators/utils/ParallelCommunication.hpp>

#include <hdf5.h>

#include <string>
#include <vector>

namespace Opm {

//! \brief Class handling simple output to HDF5.
class HDF5File {
public:
    //! \brief Enumeration of file opening modes.
    enum class OpenMode {
        APPEND,    //!< Append to an existing file (creates new if not)
        OVERWRITE, //!< Overwrite and write to an existing file
        READ       //!< Open existing file for reading
    };

    //! \brief Enumeration of dataset modes.
    enum class DataSetMode {
        ROOT_ONLY,     //!< A single dataset created at the root process
        PROCESS_SPLIT  //!< One separate data set for each parallel process
    };

    //! \brief Opens HDF5 file for I/O.
    //! \param fileName Name of file to open
    //! \param mode Open mode for file
    HDF5File(const std::string& fileName,
             OpenMode mode,
             Parallel::Communication comm);

    //! \brief Destructor clears up any opened files.
    ~HDF5File();

    //! \brief Write a char buffer to a specified location in file.
    //! \param group Group ("directory") to write data to
    //! \param dset Data set ("file") to write data to
    //! \param buffer Data to write
    //! \details Throws exception on failure
    void write(const std::string& group,
               const std::string& dset,
               const std::vector<char>& buffer,
               DataSetMode mode = DataSetMode::PROCESS_SPLIT) const;

    //! \brief Read a char buffer from a specified location in file.
    //! \param group Group ("directory") to read data from
    //! \param dset Data set ("file") to read data from
    //! \param buffer Vector to store read data in
    //! \details Throws exception on failure
    void read(const std::string& group,
              const std::string& dset,
              std::vector<char>& buffer,
              DataSetMode Mode = DataSetMode::PROCESS_SPLIT) const;

    //! \brief Lists the entries in a given group.
    //! \details Note: Both datasets and subgroups are returned
    std::vector<std::string> list(const std::string& group) const;

private:
    //! \brief Write data from each process to a separate dataset.
    //! \param grp Handle for group to store dataset in
    //! \param buffer Data to write
    //! \param dset Name of dataset
    void writeSplit(hid_t grp,
                    const std::vector<char>& buffer,
                    const std::string& dset) const;

    //! \brief Write data from root process only.
    //! \param grp Handle for group to store dataset in
    //! \param buffer Data to write
    //! \param dset Name of dataset
    void writeRootOnly(hid_t grp,
                       const std::vector<char>& buffer,
                       const std::string& group,
                       const std::string& dset) const;

    //! \brief Return a dataset creation properly list with compression settings.
    //! \param size Size of dataset
    hid_t getCompression(hsize_t size) const;

    //! \brief Helper function to write a dataset.
    //! \param rank Process rank that should write
    //! \param dataset_id Handle for dataset to write
    //! \param dxpl Dataset transfer property list
    //! \param size Size of dataset
    //! \param data Data to write
    void writeDset(int rank, hid_t dataset_id,
                   hid_t dxpl, hsize_t size, const void* data) const;
    hid_t m_file = H5I_INVALID_HID; //!< File handle
    Parallel::Communication comm_;
};

}

#endif