//
// Software License for AMDiS
//
// Copyright (c) 2010 Dresden University of Technology 
// All rights reserved.
// Authors: Simon Vey, Thomas Witkowski et al.
//
// This file is part of AMDiS
//
// See also license.opensource.txt in the distribution.


#include "parallel/PetscSolverGlobalBlockMatrix.h"
#include "parallel/StdMpi.h"
#include "parallel/MpiHelper.h"

namespace AMDiS {

  void PetscSolverGlobalBlockMatrix::fillPetscMatrix(Matrix<DOFMatrix*> *mat)
  {
    FUNCNAME("PetscSolverGlobalBlockMatrix::fillPetscMatrix()");

    TEST_EXIT_DBG(meshDistributor)("No mesh distributor object defined!\n");
    TEST_EXIT_DBG(mat)("No DOF matrix defined!\n");

    double wtime = MPI::Wtime();
    const FiniteElemSpace *feSpace = meshDistributor->getFeSpace(0);
    nComponents = mat->getNumRows();
    int nRankRows = meshDistributor->getNumberRankDofs(feSpace);
    int nOverallRows = meshDistributor->getNumberOverallDofs(feSpace);

#if (DEBUG != 0)
    MSG("Fill petsc matrix 1 needed %.5f seconds\n", MPI::Wtime() - wtime);
#endif

    nestMat.resize(nComponents * nComponents);

    // === Transfer values from DOF matrices to the PETSc matrix. === 

    for (int i = 0; i < nComponents; i++)
      for (int j = 0; j < nComponents; j++)
	if ((*mat)[i][j]) {
	  MatCreateMPIAIJ(PETSC_COMM_WORLD,
			  nRankRows, nRankRows,
			  nOverallRows, nOverallRows,
			  30, PETSC_NULL, 30, PETSC_NULL,
			  &(nestMat[i * nComponents + j]));
	  setDofMatrix(nestMat[i * nComponents + j], (*mat)[i][j]);
	  MatAssemblyBegin(nestMat[i * nComponents + j], MAT_FINAL_ASSEMBLY);
	  MatAssemblyEnd(nestMat[i * nComponents + j], MAT_FINAL_ASSEMBLY);
	} else {
	  nestMat[i * nComponents + j] = PETSC_NULL;
	}

    MatCreateNest(PETSC_COMM_WORLD, 
		  nComponents, PETSC_NULL, nComponents, PETSC_NULL, 
		  &(nestMat[0]), &petscMatrix);

#if (DEBUG != 0)
    MSG("Fill petsc matrix 2 needed %.5f seconds\n", MPI::Wtime() - wtime);
#endif

    MatAssemblyBegin(petscMatrix, MAT_FINAL_ASSEMBLY);
    MatAssemblyEnd(petscMatrix, MAT_FINAL_ASSEMBLY);

    // === Init PETSc solver. ===
    KSPCreate(PETSC_COMM_WORLD, &solver);
    KSPSetOperators(solver, petscMatrix, petscMatrix, SAME_NONZERO_PATTERN); 
    KSPSetFromOptions(solver);

    KSPGetPC(solver, &pc);
    setBlockPreconditioner(pc);

    MSG("Fill petsc matrix needed %.5f seconds\n", MPI::Wtime() - wtime);
  }


  void PetscSolverGlobalBlockMatrix::fillPetscRhs(SystemVector *vec)
  {
    FUNCNAME("PetscSolverGlobalBlockMatrix::fillPetscRhs()");

    TEST_EXIT_DBG(vec)("NO DOF vector defined!\n");

    nComponents = vec->getSize();
    const FiniteElemSpace *feSpace = meshDistributor->getFeSpace(0);
    int nRankRows = meshDistributor->getNumberRankDofs(feSpace);
    int nOverallRows = meshDistributor->getNumberOverallDofs(feSpace);

    nestVec.resize(nComponents);

    for (int i = 0; i < nComponents; i++) {
      VecCreateMPI(PETSC_COMM_WORLD, nRankRows, nOverallRows, &(nestVec[i]));

      setDofVector(nestVec[i], vec->getDOFVector(i));
      
      VecAssemblyBegin(nestVec[i]);
      VecAssemblyEnd(nestVec[i]);
    }

    VecCreateNest(PETSC_COMM_WORLD, nComponents, PETSC_NULL, 
		  &(nestVec[0]), &petscRhsVec);

    VecAssemblyBegin(petscRhsVec);
    VecAssemblyEnd(petscRhsVec);
  }


  void PetscSolverGlobalBlockMatrix::solvePetscMatrix(SystemVector &vec, 
						      AdaptInfo *adaptInfo)
  {
    FUNCNAME("PetscSolverGlobalBlockMatrix::solvePetscMatrix()");

    const FiniteElemSpace *feSpace = meshDistributor->getFeSpace(0);
    VecDuplicate(petscRhsVec, &petscSolVec);

    // PETSc.
    KSPSolve(solver, petscRhsVec, petscSolVec);

    // === Transfere values from PETSc's solution vectors to the DOF vectors. ===
    for (int i = 0; i < nComponents; i++) {
      DOFVector<double> &dofvec = *(vec.getDOFVector(i));

      Vec tmp;
      VecNestGetSubVec(petscSolVec, i, &tmp);

      int nRankDofs = meshDistributor->getNumberRankDofs(feSpace);
      PetscScalar *vecPointer;
      VecGetArray(tmp, &vecPointer);

      for (int j = 0; j < nRankDofs; j++)
	dofvec[meshDistributor->mapLocalToDofIndex(feSpace, j)] = vecPointer[j]; 

      VecRestoreArray(tmp, &vecPointer);
    }


    // === Synchronize DOFs at common DOFs, i.e., DOFs that correspond to ===
    // === more than one partition.                                       ===
    meshDistributor->synchVector(vec);


    // === Destroy PETSc's variables. ===
    VecDestroy(&petscRhsVec);
    for (int i = 0; i < nComponents; i++)
      VecDestroy(&(nestVec[i]));

    VecDestroy(&petscSolVec);
  }


  void PetscSolverGlobalBlockMatrix::destroyMatrixData()
  {
    FUNCNAME("PetscSolverGlobalBlockMatrix::destroyMatrixData()");

    for (unsigned int i = 0; i < nestMat.size(); i++)
      if (nestMat[i] != PETSC_NULL)
	MatDestroy(&(nestMat[i]));

    MatDestroy(&petscMatrix);
    KSPDestroy(&solver);
  }


  void PetscSolverGlobalBlockMatrix::setDofMatrix(Mat& petscMat, DOFMatrix* mat)
  {
    FUNCNAME("PetscSolverGlobalBlockMatrix::setDofMatrix()");

    TEST_EXIT(mat)("No DOFMatrix!\n");
    TEST_EXIT(petscMat)("No PETSc matrix!\n");

    const FiniteElemSpace *feSpace = meshDistributor->getFeSpace(0);

    using mtl::tag::row; using mtl::tag::nz; using mtl::begin; using mtl::end;
    namespace traits = mtl::traits;
    typedef DOFMatrix::base_matrix_type Matrix;

    traits::col<Matrix>::type col(mat->getBaseMatrix());
    traits::const_value<Matrix>::type value(mat->getBaseMatrix());

    typedef traits::range_generator<row, Matrix>::type cursor_type;
    typedef traits::range_generator<nz, cursor_type>::type icursor_type;

    vector<int> cols;
    vector<double> values;
    cols.reserve(300);
    values.reserve(300);
    
    // === Traverse all rows of the dof matrix and insert row wise the values ===
    // === to the PETSc matrix.                                               ===

    for (cursor_type cursor = begin<row>(mat->getBaseMatrix()), 
	   cend = end<row>(mat->getBaseMatrix()); cursor != cend; ++cursor) {

      // Global index of the current row DOF.
      int rowIndex = meshDistributor->mapLocalToGlobal(feSpace, *cursor);

      cols.clear();
      values.clear();
      
      for (icursor_type icursor = begin<nz>(cursor), icend = end<nz>(cursor); 
	   icursor != icend; ++icursor) {	
	// Global index of the current column index.
	int colIndex = meshDistributor->mapLocalToGlobal(feSpace, col(*icursor));
	
	// Ignore all zero entries, expect it is a diagonal entry.
	if (value(*icursor) == 0.0 && rowIndex != colIndex)
	  continue;
	
	// Calculate the exact position of the column index in the PETSc matrix.
	cols.push_back(colIndex);
	values.push_back(value(*icursor));
      }

      MatSetValues(petscMat, 1, &rowIndex, cols.size(), 
 		   &(cols[0]), &(values[0]), ADD_VALUES);	
    }
  }
  
  
  void PetscSolverGlobalBlockMatrix::setDofVector(Vec& petscVec, 
						  DOFVector<double>* vec)
  {
    FUNCNAME("PetscSolverGlobalBlockMatrix::setDofVector()");

    const FiniteElemSpace *feSpace = meshDistributor->getFeSpace(0);

    // Traverse all used DOFs in the dof vector.
    DOFVector<double>::Iterator dofIt(vec, USED_DOFS);
    for (dofIt.reset(); !dofIt.end(); ++dofIt) {
      int index = meshDistributor->mapLocalToGlobal(feSpace, dofIt.getDOFIndex());
      double value = *dofIt;

      VecSetValues(petscVec, 1, &index, &value, ADD_VALUES);
    }
  }

}