// -*- mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
// vi: set et ts=4 sw=4 sts=4:
/*
  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 EWOMS_ALU_CARTESIANINDEXMAPPER_HH
#define EWOMS_ALU_CARTESIANINDEXMAPPER_HH

#include <opm/parser/eclipse/EclipseState/EclipseState.hpp>

#include <opm/material/common/Exceptions.hpp>

#include <array>
#include <vector>
#include <cassert>
#include <memory>

#include <dune/common/exceptions.hh>
#include <dune/grid/common/datahandleif.hh>
#include <dune/grid/utility/persistentcontainer.hh>

namespace Ewoms
{
    /** \brief Interface class to access the logical Cartesian grid as used in industry
               standard simulator decks.
               */
    template< class Grid >
    class AluCartesianIndexMapper
    {
    public:
        // data handle for communicating global ids during load balance and communication
        template <class GridView>
        class GlobalIndexDataHandle : public Dune::CommDataHandleIF< GlobalIndexDataHandle<GridView>, int >
        {
            // global id
            class GlobalCellIndex
            {
                int idx_;
            public:
                GlobalCellIndex() : idx_(-1) {}
                GlobalCellIndex& operator= ( const int index ) { idx_ = index; return *this; }
                int index() const { return idx_; }
            };

            typedef typename Dune::PersistentContainer< Grid, GlobalCellIndex > GlobalIndexContainer;

            GridView gridView_;
            GlobalIndexContainer globalIndex_;
            std::vector<int>& cartesianIndex_;
        public:
            // constructor copying cartesian index to persistent container
            GlobalIndexDataHandle( const GridView& gridView,
                                   std::vector<int>& cartesianIndex )
                : gridView_( gridView ),
                  globalIndex_( gridView.grid(), 0 ),
                  cartesianIndex_( cartesianIndex )
            {
                globalIndex_.resize();
                initialize();
            }

            // constructor copying cartesian index to persistent container
            GlobalIndexDataHandle( const GlobalIndexDataHandle& other ) = delete ;

            // destrcutor writing load balanced cartesian index back to vector
            ~GlobalIndexDataHandle()
            {
                finalize();
                //std::cout << "CartesianIndex " << cartesianIndex_.size() << std::endl;
                //for( size_t i=0; i<cartesianIndex_.size(); ++i )
                //    std::cout << "cart[ " << i << " ] = " << cartesianIndex_[ i ] << std::endl;
            }

            bool contains ( int dim, int codim ) const { return codim == 0; }
            bool fixedsize( int dim, int codim ) const { return true; }

            //! \brief loop over all internal data handlers and call gather for
            //! given entity
            template<class MessageBufferImp, class EntityType>
            void gather (MessageBufferImp& buff, const EntityType& element ) const
            {
                int globalIdx = globalIndex_[ element ].index();
                buff.write( globalIdx );
            }

            //! \brief loop over all internal data handlers and call scatter for
            //! given entity
            template<class MessageBufferImp, class EntityType>
            void scatter (MessageBufferImp& buff, const EntityType& element, size_t n)
            {
                int globalIdx = -1;
                buff.read( globalIdx );
                if( globalIdx >= 0 )
                {
                    globalIndex_.resize();
                    globalIndex_[ element ] = globalIdx;
                }
            }

            //! \brief loop over all internal data handlers and return sum of data
            //! size of given entity
            template<class EntityType>
            size_t size (const EntityType& en) const
            {
                return 1;
            }

        protected:
            // initialize persistent container from given vector
            void initialize()
            {
                auto idx = cartesianIndex_.begin();
                for(auto it = gridView_.template begin<0>(),
                    end = gridView_.template end<0>(); it != end; ++it, ++idx )
                {
                    globalIndex_[ *it ] = *idx;
                }
            }

            // update vector from given persistent container
            void finalize()
            {
                std::vector< int > newIndex ;
                newIndex.reserve( gridView_.indexSet().size( 0 ) );

                for(auto it = gridView_.template begin<0>(),
                    end = gridView_.template end<0>(); it != end; ++it)
                {
                    newIndex.push_back( globalIndex_[ *it ].index() ) ;
                }

                cartesianIndex_.swap( newIndex );
            }

        };

    public:
        /** \brief dimension of the grid */
        static const int dimension = Grid :: dimension ;

        /** \brief constructor taking grid */
        AluCartesianIndexMapper( const Grid& grid,
                                 const std::array<int, dimension>& cartDims,
                                 const std::vector<int>& cartesianIndex )
            : grid_( grid ),
              cartesianDimensions_( cartDims ),
              cartesianIndex_( cartesianIndex ),
              cartesianSize_( computeCartesianSize() )
        {
        }

        /** \brief return Cartesian dimensions, i.e. number of cells in each direction  */
        const std::array<int, dimension>& cartesianDimensions() const
        {
            return cartesianDimensions_;
        }

        /** \brief return total number of cells in the logical Cartesian grid */
        int cartesianSize() const
        {
            return cartesianSize_;
        }

        /** \brief return number of cells in the active grid */
        int compressedSize() const
        {
            return cartesianIndex_.size();
        }

        /** \brief return index of the cells in the logical Cartesian grid */
        int cartesianIndex( const int compressedElementIndex ) const
        {
            assert( compressedElementIndex < compressedSize() );
            return cartesianIndex_[ compressedElementIndex ];
        }

        /** \brief return index of the cells in the logical Cartesian grid */
        int cartesianIndex( const std::array<int,dimension>& coords ) const
        {
          int cartIndex = coords[ 0 ];
          int factor = cartesianDimensions()[ 0 ];
          for( int i=1; i<dimension; ++i )
          {
              cartIndex += coords[ i ] * factor;
              factor *= cartesianDimensions()[ i ];
          }
          return cartIndex;
        }

        /** \brief return Cartesian coordinate, i.e. IJK, for a given cell */
        void cartesianCoordinate(const int compressedElementIndex, std::array<int,dimension>& coords) const
        {
          int gc = cartesianIndex( compressedElementIndex );
          if( dimension == 3 )
          {
             coords[0] = gc % cartesianDimensions()[0];
             gc /= cartesianDimensions()[0];
             coords[1] = gc % cartesianDimensions()[1];
             coords[2] = gc / cartesianDimensions()[1];
          }
          else if( dimension == 2 )
          {
             coords[0] = gc % cartesianDimensions()[0];
             coords[1] = gc / cartesianDimensions()[0];
          }
          else if( dimension == 1 )
          {
              coords[ 0 ] = gc ;
          }
          else
              throw std::invalid_argument("cartesianCoordinate not implemented for dimension " + std::to_string(dimension) );
        }

        template <class GridView>
        std::unique_ptr< GlobalIndexDataHandle< GridView > > dataHandle( const GridView& gridView )
        {
            typedef GlobalIndexDataHandle< GridView > DataHandle ;
            assert( &grid_ == &gridView.grid() );
            return std::unique_ptr< DataHandle > (new DataHandle( gridView, cartesianIndex_ ));
        }

    protected:
        int computeCartesianSize() const
        {
            int size = cartesianDimensions()[ 0 ];
            for( int d=1; d<dimension; ++d )
                size *= cartesianDimensions()[ d ];
            return size ;
        }

    protected:
        const Grid& grid_;
        const std::array<int, dimension> cartesianDimensions_;
        std::vector<int> cartesianIndex_;
        const int cartesianSize_ ;
    };

} // end namespace Opm
#endif