//
// 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/PetscSolverNavierStokes.h"
#include "parallel/PetscHelper.h"
#include "TransformDOF.h"

namespace AMDiS {

  using namespace std;


  PetscErrorCode pcSchurShell(PC pc, Vec x, Vec y)
  {
    void *ctx;
    PCShellGetContext(pc, &ctx);
    NavierStokesSchurData* data = static_cast<NavierStokesSchurData*>(ctx);

    // Project out constant null space
    {
      int vecSize;
      VecGetSize(x, &vecSize);
      PetscScalar vecSum;
      VecSum(x, &vecSum);
      vecSum = vecSum / static_cast<PetscScalar>(-1.0 * vecSize);
      VecShift(x, vecSum); 
    }

    KSPSolve(data->kspLaplace, x, y);
    MatMult(data->matConDif, y, x);
    KSPSolve(data->kspMass, x, y);
  }
  

  PetscSolverNavierStokes::PetscSolverNavierStokes(string name)
    : PetscSolverGlobalMatrix(name),
      pressureComponent(-1),
      pressureNullSpace(true),
      useOldInitialGuess(false),
      velocitySolutionMode(0),
      massSolutionMode(0),
      laplaceSolutionMode(0),
      massMatrixSolver(NULL),
      laplaceMatrixSolver(NULL),
      nu(NULL),
      invTau(NULL),
      solution(NULL),
      phase(NULL)
  {
    Parameters::get(initFileStr + "->navierstokes->pressure component", 
		    pressureComponent);
    TEST_EXIT(pressureComponent >= 0)
      ("For using PETSc stokes solver you must define a pressure component!\n");

    Parameters::get(initFileStr + "->navierstokes->pressure null space",
		    pressureNullSpace);
    TEST_EXIT(pressureNullSpace)("This is not yet tested, may be wrong!\n");

    Parameters::get(initFileStr + "->navierstokes->use old initial guess", 
		    useOldInitialGuess);

    Parameters::get(initFileStr + "->navierstokes->velocity solver", 
		    velocitySolutionMode);

    Parameters::get(initFileStr + "->navierstokes->mass solver", 
		    massSolutionMode);

    Parameters::get(initFileStr + "->navierstokes->laplace solver", 
		    laplaceSolutionMode);
  }


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

    if (useOldInitialGuess) {
      VecSet(getVecSolInterior(), 0.0);
      
      for (int i = 0; i < solution->getSize(); i++)
	setDofVector(getVecSolInterior(), solution->getDOFVector(i), i, true);
      
      vecSolAssembly();
      KSPSetInitialGuessNonzero(kspInterior, PETSC_TRUE);
    }

    PetscSolverGlobalMatrix::solvePetscMatrix(vec, adaptInfo);
  }


  void PetscSolverNavierStokes::initSolver(KSP &ksp)
  {
    FUNCNAME("PetscSolverNavierStokes::initSolver()");

    // Create FGMRES based outer solver
    
    MSG("CREATE POS 1: %p\n", &ksp);
    KSPCreate(domainComm, &ksp);
    KSPSetOperators(ksp, getMatInterior(), getMatInterior(), SAME_NONZERO_PATTERN);
    KSPMonitorSet(ksp, KSPMonitorTrueResidualNorm, PETSC_NULL, PETSC_NULL);
    petsc_helper::setSolver(ksp, "ns_", KSPFGMRES, PCNONE, 1e-6, 1e-8, 10000);
    
    // Create null space information.
    if (pressureNullSpace)
      setConstantNullSpace(ksp, pressureComponent, true);
  }


  void PetscSolverNavierStokes::initPreconditioner(PC pc)
  {
    FUNCNAME("PetscSolverNavierStokes::initPreconditioner()");

    MPI::COMM_WORLD.Barrier();
    double wtime = MPI::Wtime();

    TEST_EXIT(nu)("nu pointer not set!\n");
    TEST_EXIT(invTau)("invtau pointer not set!\n");
    TEST_EXIT(solution)("solution pointer not set!\n");

    int dim = componentSpaces[pressureComponent]->getMesh()->getDim();

    vector<int> velocityComponents;
    velocityComponents.push_back(0);
    velocityComponents.push_back(1);
    if (dim == 3)
      velocityComponents.push_back(2);

    PCSetType(pc, PCFIELDSPLIT);
    PCFieldSplitSetType(pc, PC_COMPOSITE_SCHUR);
    PCFieldSplitSetSchurFactType(pc, PC_FIELDSPLIT_SCHUR_FACT_FULL);

    createFieldSplit(pc, "velocity", velocityComponents);
    createFieldSplit(pc, "pressure", pressureComponent);
    PCSetFromOptions(pc);

    KSPSetUp(kspInterior);

    KSP *subKsp;
    int nSubKsp;
    PCFieldSplitGetSubKSP(pc, &nSubKsp, &subKsp);


    TEST_EXIT(nSubKsp == 2)
      ("Wrong numer of KSPs inside of the fieldsplit preconditioner!\n");

    KSP kspVelocity = subKsp[0];
    KSP kspSchur = subKsp[1];
    PetscFree(subKsp);

    switch (velocitySolutionMode) {
    case 0:      
      petsc_helper::setSolver(kspVelocity, "", 
 			      KSPRICHARDSON, PCHYPRE, 0.0, 1e-14, 1);
      break;
    case 1:
      petsc_helper::setSolverWithLu(kspVelocity, "", KSPPREONLY, 
				    PCLU, MATSOLVERMUMPS , 0.0, 1e-14, 1);
      break;
    default:
      ERROR_EXIT("No velocity solution mode %d available!\n", velocitySolutionMode);
    }
    

    KSPSetType(kspSchur, KSPPREONLY);
    PC pcSub;
    KSPGetPC(kspSchur, &pcSub);
    PCSetType(pcSub, PCSHELL);
    PCShellSetApply(pcSub, pcSchurShell);
    PCShellSetContext(pcSub, &matShellContext);

    if (pressureNullSpace)
      setConstantNullSpace(kspSchur);

    // === Mass matrix solver ===

    const FiniteElemSpace *pressureFeSpace = componentSpaces[pressureComponent];
    DOFMatrix massMatrix(pressureFeSpace, pressureFeSpace);
    {
      Operator massOp(pressureFeSpace, pressureFeSpace);
      ZeroOrderTerm *massTerm = NULL;
      if (!phase)
	massTerm = new Simple_ZOT;
      else
	massTerm = new VecAtQP_ZOT(phase, &idFct);
      massOp.addTerm(massTerm);
      massMatrix.assembleOperator(massOp);
      delete massTerm;
    }
    massMatrixSolver = createSubSolver(pressureComponent, "mass_");
    massMatrixSolver->fillPetscMatrix(&massMatrix);


    // === Laplace matrix solver ===

    DOFMatrix laplaceMatrix(pressureFeSpace, pressureFeSpace);
    {
      Operator laplaceOp(pressureFeSpace, pressureFeSpace);
      SecondOrderTerm *laplaceTerm = NULL;      
      if (!phase)
	laplaceTerm = new Simple_SOT;
      else
	laplaceTerm = new VecAtQP_SOT(phase, &idFct);
      laplaceOp.addTerm(laplaceTerm);
      laplaceMatrix.assembleOperator(laplaceOp);
      delete laplaceTerm;
    }
    laplaceMatrixSolver = createSubSolver(pressureComponent, string("laplace_"));
    laplaceMatrixSolver->fillPetscMatrix(&laplaceMatrix);


    // === Create convection-diffusion operator ===

    DOFVector<double> vx(pressureFeSpace, "vx");
    DOFVector<double> vy(pressureFeSpace, "vy");
    DOFVector<double> vz(pressureFeSpace, "vz");
    DOFVector<double> vp(pressureFeSpace, "vp");
    vx.interpol(solution->getDOFVector(0));
    vy.interpol(solution->getDOFVector(1));
    if (dim == 3)
      vz.interpol(solution->getDOFVector(2));

    DOFMatrix conDifMatrix(pressureFeSpace, pressureFeSpace);

    {
      Operator conDifOp(pressureFeSpace, pressureFeSpace);
      
      ZeroOrderTerm *conDif0 = NULL;
      SecondOrderTerm *conDif1 = NULL;
      FirstOrderTerm *conDif2 = NULL, *conDif3 = NULL, *conDif4 = NULL;

      if (!phase) {
	MSG("INIT WITHOUT PHASE!\n");
	
	conDif0 = new Simple_ZOT(*invTau);
	conDifOp.addTerm(conDif0);
	conDif1 = new Simple_SOT(*nu);
	conDifOp.addTerm(conDif1);
	conDif2 = new VecAtQP_FOT(&vx, &idFct, 0);
	conDifOp.addTerm(conDif2, GRD_PHI);
	conDif3 = new VecAtQP_FOT(&vy, &idFct, 1);
	conDifOp.addTerm(conDif3, GRD_PHI);
	
	if (dim == 3) {
	  conDif4 = new VecAtQP_FOT(&vz, &idFct, 2);	
	  conDifOp.addTerm(conDif4, GRD_PHI);
	}
      } else {
	MSG("INIT WITH PHASE: %e %e\n", *nu, *invTau);
	
	vp.interpol(phase);
	conDif0 = new VecAtQP_ZOT(&vp, new MultConstFct(*invTau));
	conDifOp.addTerm(conDif0);	
	conDif1 = new VecAtQP_SOT(&vp, new MultConstFct(*nu));
	conDifOp.addTerm(conDif1);	
	conDif2 = new Vec2AtQP_FOT(&vx, &vp, new Multiplier3(), 0);
	conDifOp.addTerm(conDif2, GRD_PHI);
	
	conDif3 = new Vec2AtQP_FOT(&vy, &vp, new Multiplier3(), 1);
	conDifOp.addTerm(conDif3, GRD_PHI);
	
	if (dim == 3) {
	  conDif4 = new Vec2AtQP_FOT(&vz, &vp, new Multiplier3(), 2);
	  conDifOp.addTerm(conDif4, GRD_PHI);
	}
      }

      conDifMatrix.assembleOperator(conDifOp);

      delete conDif0;
      delete conDif1;
      delete conDif2;
      delete conDif3;
      if (dim == 3)
	delete conDif4;
    }

    conDifMatrixSolver = createSubSolver(pressureComponent, "condif_");
    conDifMatrixSolver->fillPetscMatrix(&conDifMatrix);


    // === Setup solver ===

    matShellContext.kspMass = massMatrixSolver->getSolver();
    matShellContext.kspLaplace = laplaceMatrixSolver->getSolver();
    matShellContext.matConDif = conDifMatrixSolver->getMatInterior();    

    switch (massSolutionMode) {
    case 0:
      petsc_helper::setSolver(matShellContext.kspMass, "mass_", 
			      KSPCG, PCJACOBI, 0.0, 1e-14, 2);
      break;
    case 1:
      petsc_helper::setSolverWithLu(matShellContext.kspMass, "mass_", KSPRICHARDSON, 
				    PCLU, MATSOLVERMUMPS, 0.0, 1e-14, 1);
      break;
    default:
      ERROR_EXIT("No mass solution mode %d available!\n", massSolutionMode);
    }

    switch (laplaceSolutionMode) {
    case 0:
      petsc_helper::setSolver(matShellContext.kspLaplace, "laplace_", 
 			      KSPRICHARDSON, PCHYPRE, 0.0, 1e-14, 1);
      break;
    case 1:
      petsc_helper::setSolverWithLu(matShellContext.kspLaplace, "mass_", 
				    KSPRICHARDSON, PCLU, MATSOLVERMUMPS, 
				    0.0, 1e-14, 1);
      break;
    default:
      ERROR_EXIT("No laplace solution mode %d available!\n", laplaceSolutionMode);
    }

    setConstantNullSpace(matShellContext.kspLaplace);

    MSG("Setup of Navier-Stokes preconditioner needed %.5f seconds\n", 
	MPI::Wtime() - wtime);
  }


  void PetscSolverNavierStokes::exitPreconditioner(PC pc)
  {
    FUNCNAME("PetscSolverNavierStokes::exitPreconditioner()");

    massMatrixSolver->destroyMatrixData();
    massMatrixSolver->destroyVectorData();
    laplaceMatrixSolver->destroyMatrixData();
    laplaceMatrixSolver->destroyVectorData();
    conDifMatrixSolver->destroyMatrixData();
    conDifMatrixSolver->destroyVectorData();

    delete massMatrixSolver;
    massMatrixSolver = NULL;

    delete laplaceMatrixSolver;
    laplaceMatrixSolver = NULL;

    delete conDifMatrixSolver;
    conDifMatrixSolver = NULL;
  }
}