// @HEADER
// ***********************************************************************
//
//                      Didasko Tutorial Package
//                 Copyright (2005) Sandia Corporation
//
// Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
// license for use of this work by or on behalf of the U.S. Government.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// 3. Neither the name of the Corporation nor the names of the
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SANDIA CORPORATION OR THE
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Questions about Didasko? Contact Marzio Sala (marzio.sala _AT_ gmail.com)
//
// ***********************************************************************
// @HEADER

// Basic definition of communicator.
// This code should be run with at least two processes

#include "Didasko_ConfigDefs.h"
#if defined(HAVE_DIDASKO_EPETRA) && defined(HAVE_DIDASKO_TRIUTILS)

#include "Epetra_ConfigDefs.h"
#ifdef HAVE_MPI
#include "mpi.h"
#include "Epetra_MpiComm.h"
#else
#include "Epetra_SerialComm.h"
#endif
#include "Epetra_Map.h"
#include "Epetra_MultiVector.h"
#include "Epetra_Vector.h"
#include "Epetra_RowMatrix.h"
#include "Trilinos_Util.h"

class MSRMatrix : public Epetra_Operator
{

  public:

    // constructor
    MSRMatrix(Epetra_Map Map, int * bindx, double * val) :
      bindx_(bindx),
      val_(val),
      Map_(Map)
  {
  }

    // destructor, nothing to do
    ~MSRMatrix()
    {}

    // Apply the RowMatrix to a MultiVector
    int Apply(const Epetra_MultiVector & X, Epetra_MultiVector & Y ) const
    {

      int Nrows = bindx_[0]-1;

      for( int i=0 ; i<Nrows ; i++ ) {
        // diagonal element
        for( int vec=0 ; vec<X.NumVectors() ; ++vec ) {
          Y[vec][i] = val_[i]*X[vec][i];
        }
        // off-diagonal elements
        for( int j=bindx_[i] ; j<bindx_[i+1] ; j++ ) {
          for( int vec=0 ; vec<X.NumVectors() ; ++vec ) {
            Y[vec][bindx_[j]] += val_[j]*X[vec][bindx_[j]];
          }
        }
      }

      return 0;

    } /* Apply */

    // other function, required by Epetra_RowMatrix. Here are almost all
    // void, you may decide to complete the example...
    int SetUseTranspose( bool UseTranspose)
    {
      return(-1); // not implemented
    }

    int ApplyInverse( const Epetra_MultiVector & X,
        Epetra_MultiVector & Y ) const
    {
      return(-1); // not implemented
    }

    double NormInf() const
    {
      return -1;
    }

    const char* Label () const
    {
      return "TriDiagonalOperator";
    }

    bool UseTranspose() const
    {
      return false;
    }

    bool HasNormInf () const
    {
      return true;
    }


    const Epetra_Comm & Comm() const
    {
      return( Map_.Comm() );
    }

    const Epetra_Map & OperatorDomainMap() const
    {
      return( Map_ );
    }

    const Epetra_Map & OperatorRangeMap() const
    {
      return( Map_ );
    }

  private:

    int * bindx_;    /* MSR vector for nonzero indices */
    double * val_;   /* MSR vector for nonzero values */
    Epetra_Map Map_;

}; /* MSRMatrix class */

// =========== //
// main driver //
// ----------- //

int main(int argc, char *argv[])
{

#ifdef HAVE_MPI
  MPI_Init(&argc, &argv);
  // define an Epetra communicator
  Epetra_MpiComm Comm(MPI_COMM_WORLD);
#else
  Epetra_SerialComm Comm;
#endif

  // check number of processes
  if (Comm.NumProc() != 1) {
    if (Comm.MyPID() == 0)
      cerr << "*ERR* can be used only with one process" << endl;
#ifdef HAVE_MPI
    MPI_Finalize();
#endif
    exit(EXIT_SUCCESS);
  }

  // process 0 will read an HB matrix, and store it
  // in the MSR format given by the arrays bindx and val
  int N_global;
  int N_nonzeros;
  double * val = NULL;
  int * bindx = NULL;
  double * x = NULL, * b = NULL, * xexact = NULL;

  FILE* fp = fopen("../HBMatrices/fidap005.rua", "r");
  if (fp == 0)
  {
    cerr << "Matrix file not available" << endl;
#ifdef HAVE_MPI
    MPI_Finalize();
#endif
    exit(EXIT_SUCCESS);
  }
  fclose(fp);

  Trilinos_Util_read_hb("../HBMatrices/fidap005.rua", 0,
      &N_global, &N_nonzeros,
      &val, &bindx,
      &x, &b, &xexact);

  // assign all the elements to process 0
  // (this code can run ONLY with one process, extensions to more
  // processes will require functions to handle update of ghost nodes)
  Epetra_Map Map(N_global,0,Comm);

  MSRMatrix A(Map,bindx,val);

  // define two vectors
  Epetra_Vector xxx(Map);
  Epetra_Vector yyy(Map);

  xxx.Random();

  A.Apply(xxx,yyy);

  cout << yyy;

  double norm2;
  yyy.Norm2(&norm2);

  cout << norm2 << endl;

  // free memory allocated by Trilinos_Util_read_hb
  if (val != NULL) free((void*)val);
  if (bindx != NULL) free((void*)bindx);
  if (x != NULL) free((void*)x);
  if (b != NULL) free((void*)b);
  if (xexact != NULL) free((void*)xexact);;

#ifdef HAVE_MPI
  MPI_Finalize();
#endif

  return(EXIT_SUCCESS);

} /* main */

#else

#include <stdlib.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
  puts("Please configure Didasko with:\n"
      "--enable-epetra\n"
      "--enable-triutils");

  return(0);
}
#endif