/*  Lattice Boltzmann sample, written in C++, using the OpenLB
 *  library
 *
 *  Copyright (C) 2007, 2012 Jonas Latt, Mathias J. Krause
 *  Vojtech Cvrcek, Peter Weisbrod
 *  E-mail contact: info@openlb.net
 *  The most recent release of OpenLB can be downloaded at
 *  <http://www.openlb.net/>
 *
 *  This program 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.
 *
 *  This program 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 this program; if not, write to the Free
 *  Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 *  Boston, MA  02110-1301, USA.
 */

#include "olb2D.h"
#ifndef OLB_PRECOMPILED
#include "olb2D.hh"
#endif

#include <vector>

using namespace olb;
using namespace olb::descriptors;

typedef double T;

#define DESCRIPTOR D2Q9Descriptor

const T lx  = 4.0;            // length of the channel
const T ly  = 1.0;            // height of the channel
const int N = 50;             // resolution of the model
const T Re  = 100.;           // Reynolds number
const T baseTau = 0.8;        // Relaxation time of coarsest grid
const T maxPhysT = 60.;       // max. simulation time in s, SI unit
const T physInterval = 0.25;  // interval for the convergence check in s
const T residuum = 1e-5;      // residuum for the convergence check


void prepareGeometry(Grid2D<T,DESCRIPTOR>& grid)
{
  OstreamManager clout(std::cout,"prepareGeometry");
  clout << "Prepare Geometry ..." << std::endl;

  auto& converter = grid.getConverter();
  auto& sGeometry = grid.getSuperGeometry();

  sGeometry.rename(0,1);

  const T physSpacing = converter.getPhysDeltaX();

  // Set material number for bounce back boundaries
  {
    const Vector<T,2> wallExtend {lx+physSpacing,  physSpacing/2};
    const Vector<T,2> wallOrigin {-physSpacing/4, -physSpacing/4};

    IndicatorCuboid2D<T> lowerWall(wallExtend, wallOrigin);
    sGeometry.rename(1,2,lowerWall);

    IndicatorCuboid2D<T> upperWall(wallExtend, wallOrigin + Vector<T,2> {0,ly});
    sGeometry.rename(1,2,upperWall);
  }

  // Set material number for inflow and outflow
  {
    const Vector<T,2> extend { physSpacing/2,  ly};
    const Vector<T,2> origin {-physSpacing/4, -physSpacing/4};

    IndicatorCuboid2D<T> inflow(extend, origin);
    sGeometry.rename(1,3,inflow);

    IndicatorCuboid2D<T> outflow(extend, origin + Vector<T,2> {lx,0});
    sGeometry.rename(1,4,outflow);
  }

  sGeometry.clean();
  sGeometry.innerClean();
  sGeometry.checkForErrors();
  sGeometry.print();

  clout << "Prepare Geometry ... OK" << std::endl;
}

void prepareLattice(Grid2D<T,DESCRIPTOR>& grid,
                    Dynamics<T, DESCRIPTOR>& bulkDynamics,
                    sOnLatticeBoundaryCondition2D<T,DESCRIPTOR>& sBoundaryCondition)
{
  OstreamManager clout(std::cout,"prepareLattice");
  clout << "Prepare lattice ..." << std::endl;

  auto& converter = grid.getConverter();
  auto& sGeometry = grid.getSuperGeometry();
  auto& sLattice  = grid.getSuperLattice();

  const T omega = converter.getLatticeRelaxationFrequency();

  sLattice.defineDynamics(sGeometry, 0, &instances::getNoDynamics<T, DESCRIPTOR>());
  sLattice.defineDynamics(sGeometry, 1, &bulkDynamics); // bulk
  sLattice.defineDynamics(sGeometry, 2, &instances::getBounceBack<T, DESCRIPTOR>());
  sLattice.defineDynamics(sGeometry, 3, &bulkDynamics); // inflow
  sLattice.defineDynamics(sGeometry, 4, &bulkDynamics); // outflow

  sBoundaryCondition.addVelocityBoundary(sGeometry, 3, omega);
  sBoundaryCondition.addVelocityBoundary(sGeometry, 4, omega);

  const T Lx = converter.getLatticeLength(lx);
  const T Ly = converter.getLatticeLength(ly);
  const T p0 = 8.*converter.getLatticeViscosity()*converter.getCharLatticeVelocity()*Lx/(Ly*Ly);
  AnalyticalLinear2D<T,T> rho(-p0/lx*DESCRIPTOR<T>::invCs2, 0, p0*DESCRIPTOR<T>::invCs2+1);

  const T maxVelocity = converter.getCharLatticeVelocity();
  const T radius = ly/2;
  std::vector<T> axisPoint{0, ly/2};
  std::vector<T> axisDirection{1, 0};
  Poiseuille2D<T> u(axisPoint, axisDirection, maxVelocity, radius);

  sLattice.defineRhoU(sGeometry, 1, rho, u);
  sLattice.iniEquilibrium(sGeometry, 1, rho, u);
  sLattice.defineRhoU(sGeometry, 2, rho, u);
  sLattice.iniEquilibrium(sGeometry, 2, rho, u);

  sLattice.defineRhoU(sGeometry, 3, rho, u);
  sLattice.iniEquilibrium(sGeometry, 3, rho, u);
  sLattice.defineRhoU(sGeometry, 4, rho, u);
  sLattice.iniEquilibrium(sGeometry, 4, rho, u);

  sLattice.initialize();

  clout << "Prepare lattice ... OK" << std::endl;
}

void getResults(const std::string& prefix,
                Grid2D<T,DESCRIPTOR>& grid,
                int iT, Timer<T>& timer, bool hasConverged)
{
  OstreamManager clout(std::cout,"getResults");

  auto& converter = grid.getConverter();
  auto& sLattice  = grid.getSuperLattice();
  auto& sGeometry = grid.getSuperGeometry();

  SuperVTMwriter2D<T> vtmWriter(prefix + "poiseuille2d");
  SuperLatticePhysVelocity2D<T, DESCRIPTOR> velocity(sLattice, converter);
  SuperLatticePhysPressure2D<T, DESCRIPTOR> pressure(sLattice, converter);
  SuperLatticeGeometry2D<T, DESCRIPTOR> geometry(sLattice, sGeometry);
  vtmWriter.addFunctor(geometry);
  vtmWriter.addFunctor(velocity);
  vtmWriter.addFunctor(pressure);

  const int statIter = converter.getLatticeTime(maxPhysT/10.);

  if (iT==0) {
    vtmWriter.createMasterFile();
  }

  if (iT%100==0) {
    vtmWriter.write(iT);
  }

  if (iT%statIter==0 || hasConverged) {
    timer.update(iT);
    timer.printStep();

    sLattice.getStatistics().print(iT,converter.getPhysTime(iT));
  }
}

int main(int argc, char* argv[])
{
  olbInit(&argc, &argv);
  singleton::directories().setOutputDir("./tmp/");
  OstreamManager clout(std::cout,"main");

  const Vector<T,2> coarseOrigin {0.0, 0.0};
  const Vector<T,2> coarseExtend {lx, ly};
  IndicatorCuboid2D<T> coarseCuboid(coarseExtend, coarseOrigin);

  Grid2D<T,DESCRIPTOR> coarseGrid(coarseCuboid, N, baseTau, Re);
  prepareGeometry(coarseGrid);

  const Vector<T,2> fineExtend {2.0, 0.5};
  const Vector<T,2> fineOrigin {1.0, (ly-fineExtend[1])/2};

  auto& fineGrid = coarseGrid.refine(fineOrigin, fineExtend);
  prepareGeometry(fineGrid);

  auto refinedOverlap = fineGrid.getRefinedOverlap();
  coarseGrid.getSuperGeometry().rename(1,0,*refinedOverlap);
  coarseGrid.getSuperGeometry().rename(2,0,*refinedOverlap);

  BGKdynamics<T, DESCRIPTOR> coarseBulkDynamics(
    coarseGrid.getConverter().getLatticeRelaxationFrequency(),
    instances::getBulkMomenta<T, DESCRIPTOR>());

  sOnLatticeBoundaryCondition2D<T, DESCRIPTOR> coarseSBoundaryCondition(coarseGrid.getSuperLattice());
  createLocalBoundaryCondition2D<T, DESCRIPTOR>(coarseSBoundaryCondition);

  prepareLattice(coarseGrid, coarseBulkDynamics, coarseSBoundaryCondition);

  BGKdynamics<T, DESCRIPTOR> fineBulkDynamics(
    fineGrid.getConverter().getLatticeRelaxationFrequency(),
    instances::getBulkMomenta<T, DESCRIPTOR>());

  sOnLatticeBoundaryCondition2D<T, DESCRIPTOR> fineSBoundaryCondition(fineGrid.getSuperLattice());
  createLocalBoundaryCondition2D<T, DESCRIPTOR>(fineSBoundaryCondition);

  prepareLattice(fineGrid, fineBulkDynamics, fineSBoundaryCondition);

  clout << "starting simulation..." << endl;
  Timer<T> timer(
    coarseGrid.getConverter().getLatticeTime(maxPhysT),
    coarseGrid.getSuperGeometry().getStatistics().getNvoxel());
  util::ValueTracer<T> converge(
    fineGrid.getConverter().getLatticeTime(physInterval),
    residuum);
  timer.start();

  for (int iT = 0; iT < coarseGrid.getConverter().getLatticeTime(maxPhysT); ++iT) {
    if (converge.hasConverged()) {
      clout << "Simulation converged." << endl;
      break;
    }

    coarseGrid.collideAndStream();

    getResults(
      "coarse_",
      coarseGrid,
      iT,
      timer,
      converge.hasConverged());
    getResults(
      "fine_",
      fineGrid,
      iT,
      timer,
      converge.hasConverged());

    converge.takeValue(fineGrid.getSuperLattice().getStatistics().getAverageEnergy(), true);
  }

  timer.stop();
  timer.printSummary();
}