/***************************************************************************
                          DistributedVectorView_impl.h  -  description
                             -------------------
    begin                : Sep 20, 2018
    copyright            : (C) 2018 by Tomas Oberhuber et al.
    email                : tomas.oberhuber@fjfi.cvut.cz
 ***************************************************************************/

/* See Copyright Notice in tnl/Copyright */

// Implemented by: Jakub Klinkovský

#pragma once

#include "DistributedVectorView.h"
#include <TNL/Containers/Algorithms/ReductionOperations.h>
#include <TNL/Exceptions/NotImplementedError.h>

namespace TNL {
namespace Containers {

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
typename DistributedVectorView< Real, Device, Index, Communicator >::LocalViewType
DistributedVectorView< Real, Device, Index, Communicator >::
getLocalView()
{
   return BaseType::getLocalView();
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
typename DistributedVectorView< Real, Device, Index, Communicator >::ConstLocalViewType
DistributedVectorView< Real, Device, Index, Communicator >::
getConstLocalView() const
{
   return BaseType::getConstLocalView();
}

template< typename Value,
          typename Device,
          typename Index,
          typename Communicator >
__cuda_callable__
typename DistributedVectorView< Value, Device, Index, Communicator >::ViewType
DistributedVectorView< Value, Device, Index, Communicator >::
getView()
{
   return *this;
}

template< typename Value,
          typename Device,
          typename Index,
          typename Communicator >
__cuda_callable__
typename DistributedVectorView< Value, Device, Index, Communicator >::ConstViewType
DistributedVectorView< Value, Device, Index, Communicator >::
getConstView() const
{
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
String
DistributedVectorView< Real, Device, Index, Communicator >::
getType()
{
   return String( "Containers::DistributedVectorView< " ) +
          TNL::getType< Real >() + ", " +
          Device::getDeviceType() + ", " +
          TNL::getType< Index >() + ", " +
          // TODO: communicators don't have a getType method
          "<Communicator> >";
}


/*
 * Usual Vector methods follow below.
 */

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Vector, typename..., typename >
DistributedVectorView< Real, Device, Index, Communicator >&
DistributedVectorView< Real, Device, Index, Communicator >::
operator=( const Vector& vector )
{
   TNL_ASSERT_EQ( this->getSize(), vector.getSize(),
                  "The sizes of the array views must be equal, views are not resizable." );
   TNL_ASSERT_EQ( this->getLocalRange(), vector.getLocalRange(),
                  "The local ranges must be equal, views are not resizable." );
   TNL_ASSERT_EQ( this->getCommunicationGroup(), vector.getCommunicationGroup(),
                  "The communication groups of the array views must be equal." );

   if( this->getCommunicationGroup() != CommunicatorType::NullGroup ) {
      getLocalView() = vector.getConstLocalView();
   }
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Vector, typename..., typename >
DistributedVectorView< Real, Device, Index, Communicator >&
DistributedVectorView< Real, Device, Index, Communicator >::
operator+=( const Vector& vector )
{
   TNL_ASSERT_EQ( this->getSize(), vector.getSize(),
                  "Vector sizes must be equal." );
   TNL_ASSERT_EQ( this->getLocalRange(), vector.getLocalRange(),
                  "Multiary operations are supported only on vectors which are distributed the same way." );
   TNL_ASSERT_EQ( this->getCommunicationGroup(), vector.getCommunicationGroup(),
                  "Multiary operations are supported only on vectors within the same communication group." );

   if( this->getCommunicationGroup() != CommunicatorType::NullGroup ) {
      getLocalView() += vector.getConstLocalView();
   }
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Vector, typename..., typename >
DistributedVectorView< Real, Device, Index, Communicator >&
DistributedVectorView< Real, Device, Index, Communicator >::
operator-=( const Vector& vector )
{
   TNL_ASSERT_EQ( this->getSize(), vector.getSize(),
                  "Vector sizes must be equal." );
   TNL_ASSERT_EQ( this->getLocalRange(), vector.getLocalRange(),
                  "Multiary operations are supported only on vectors which are distributed the same way." );
   TNL_ASSERT_EQ( this->getCommunicationGroup(), vector.getCommunicationGroup(),
                  "Multiary operations are supported only on vectors within the same communication group." );

   if( this->getCommunicationGroup() != CommunicatorType::NullGroup ) {
      getLocalView() -= vector.getConstLocalView();
   }
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Vector, typename..., typename >
DistributedVectorView< Real, Device, Index, Communicator >&
DistributedVectorView< Real, Device, Index, Communicator >::
operator*=( const Vector& vector )
{
   TNL_ASSERT_EQ( this->getSize(), vector.getSize(),
                  "Vector sizes must be equal." );
   TNL_ASSERT_EQ( this->getLocalRange(), vector.getLocalRange(),
                  "Multiary operations are supported only on vectors which are distributed the same way." );
   TNL_ASSERT_EQ( this->getCommunicationGroup(), vector.getCommunicationGroup(),
                  "Multiary operations are supported only on vectors within the same communication group." );

   if( this->getCommunicationGroup() != CommunicatorType::NullGroup ) {
      getLocalView() *= vector.getConstLocalView();
   }
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Vector, typename..., typename >
DistributedVectorView< Real, Device, Index, Communicator >&
DistributedVectorView< Real, Device, Index, Communicator >::
operator/=( const Vector& vector )
{
   TNL_ASSERT_EQ( this->getSize(), vector.getSize(),
                  "Vector sizes must be equal." );
   TNL_ASSERT_EQ( this->getLocalRange(), vector.getLocalRange(),
                  "Multiary operations are supported only on vectors which are distributed the same way." );
   TNL_ASSERT_EQ( this->getCommunicationGroup(), vector.getCommunicationGroup(),
                  "Multiary operations are supported only on vectors within the same communication group." );

   if( this->getCommunicationGroup() != CommunicatorType::NullGroup ) {
      getLocalView() /= vector.getConstLocalView();
   }
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Scalar, typename..., typename >
DistributedVectorView< Real, Device, Index, Communicator >&
DistributedVectorView< Real, Device, Index, Communicator >::
operator=( Scalar c )
{
   if( this->getCommunicationGroup() != CommunicatorType::NullGroup ) {
      getLocalView() = c;
   }
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Scalar, typename..., typename >
DistributedVectorView< Real, Device, Index, Communicator >&
DistributedVectorView< Real, Device, Index, Communicator >::
operator+=( Scalar c )
{
   if( this->getCommunicationGroup() != CommunicatorType::NullGroup ) {
      getLocalView() += c;
   }
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Scalar, typename..., typename >
DistributedVectorView< Real, Device, Index, Communicator >&
DistributedVectorView< Real, Device, Index, Communicator >::
operator-=( Scalar c )
{
   if( this->getCommunicationGroup() != CommunicatorType::NullGroup ) {
      getLocalView() -= c;
   }
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Scalar, typename..., typename >
DistributedVectorView< Real, Device, Index, Communicator >&
DistributedVectorView< Real, Device, Index, Communicator >::
operator*=( Scalar c )
{
   if( this->getCommunicationGroup() != CommunicatorType::NullGroup ) {
      getLocalView() *= c;
   }
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Scalar, typename..., typename >
DistributedVectorView< Real, Device, Index, Communicator >&
DistributedVectorView< Real, Device, Index, Communicator >::
operator/=( Scalar c )
{
   if( this->getCommunicationGroup() != CommunicatorType::NullGroup ) {
      getLocalView() /= c;
   }
   return *this;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename ResultType >
ResultType
DistributedVectorView< Real, Device, Index, Communicator >::
sum() const
{
   const auto group = this->getCommunicationGroup();
   ResultType result = Containers::Algorithms::ParallelReductionSum< Real, ResultType >::initialValue();
   if( group != CommunicatorType::NullGroup ) {
      const ResultType localResult = getConstLocalView().sum();
      CommunicatorType::Allreduce( &localResult, &result, 1, MPI_SUM, group );
   }
   return result;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
   template< typename Vector >
typename DistributedVectorView< Real, Device, Index, Communicator >::NonConstReal
DistributedVectorView< Real, Device, Index, Communicator >::
scalarProduct( const Vector& v ) const
{
   const auto group = this->getCommunicationGroup();
   NonConstReal result = Containers::Algorithms::ParallelReductionScalarProduct< Real, typename Vector::RealType >::initialValue();
   if( group != CommunicatorType::NullGroup ) {
      const Real localResult = getConstLocalView().scalarProduct( v.getConstLocalView() );
      CommunicatorType::Allreduce( &localResult, &result, 1, MPI_SUM, group );
   }
   return result;
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
void
DistributedVectorView< Real, Device, Index, Communicator >::
computePrefixSum()
{
   throw Exceptions::NotImplementedError("Distributed prefix sum is not implemented yet.");
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
void
DistributedVectorView< Real, Device, Index, Communicator >::
computePrefixSum( IndexType begin, IndexType end )
{
   throw Exceptions::NotImplementedError("Distributed prefix sum is not implemented yet.");
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
void
DistributedVectorView< Real, Device, Index, Communicator >::
computeExclusivePrefixSum()
{
   throw Exceptions::NotImplementedError("Distributed prefix sum is not implemented yet.");
}

template< typename Real,
          typename Device,
          typename Index,
          typename Communicator >
void
DistributedVectorView< Real, Device, Index, Communicator >::
computeExclusivePrefixSum( IndexType begin, IndexType end )
{
   throw Exceptions::NotImplementedError("Distributed prefix sum is not implemented yet.");
}

} // namespace Containers
} // namespace TNL