/* This file is part of the Palabos library.
 *
 * The Palabos softare is developed since 2011 by FlowKit-Numeca Group Sarl
 * (Switzerland) and the University of Geneva (Switzerland), which jointly
 * own the IP rights for most of the code base. Since October 2019, the
 * Palabos project is maintained by the University of Geneva and accepts
 * source code contributions from the community.
 * 
 * Contact:
 * Jonas Latt
 * Computer Science Department
 * University of Geneva
 * 7 Route de Drize
 * 1227 Carouge, Switzerland
 * jonas.latt@unige.ch
 *
 * The most recent release of Palabos can be downloaded at 
 * <https://palabos.unige.ch/>
 *
 * The library Palabos is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * The library 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "palabos3D.h"
#include "palabos3D.hh"

#include <vector>
#include <cmath>
#include <cstdlib>

using namespace plb;

typedef double T;
#define DESCRIPTOR descriptors::D3Q19Descriptor

// This function object returns a zero velocity, and a pressure which decreases
//   linearly in x-direction. It is used to initialize the particle populations.
class PressureGradient {
public:
    PressureGradient(T deltaP_, plint nx_) : deltaP(deltaP_), nx(nx_)
    { }
    void operator() (plint iX, plint iY, plint iZ, T& density, Array<T,3>& velocity) const
    {
        velocity.resetToZero();
        density = (T)1 - deltaP*DESCRIPTOR<T>::invCs2 / (T)(nx-1) * (T)iX;

    }
private:
    T deltaP;
    plint nx;
};

void readGeometry(std::string fNameIn, std::string fNameOut, MultiScalarField3D<int>& geometry)
{
    const plint nx = geometry.getNx();
    const plint ny = geometry.getNy();
    const plint nz = geometry.getNz();

    Box3D sliceBox(0,0, 0,ny-1, 0,nz-1);
    std::unique_ptr<MultiScalarField3D<int> > slice = generateMultiScalarField<int>(geometry, sliceBox);
    plb_ifstream geometryFile(fNameIn.c_str());
    for (plint iX=0; iX<nx-1; ++iX) {
        if (!geometryFile.is_open()) {
            pcout << "Error: could not open geometry file " << fNameIn << std::endl;
            exit(EXIT_FAILURE);
        }
        geometryFile >> *slice;
        copy(*slice, slice->getBoundingBox(), geometry, Box3D(iX,iX, 0,ny-1, 0,nz-1));
    }

    {
        VtkImageOutput3D<T> vtkOut("porousMedium", 1.0);
        vtkOut.writeData<float>(*copyConvert<int,T>(geometry, geometry.getBoundingBox()), "tag", 1.0);
    }

    {
        std::unique_ptr<MultiScalarField3D<T> > floatTags = copyConvert<int,T>(geometry, geometry.getBoundingBox());
        std::vector<T> isoLevels;
        isoLevels.push_back(0.5);
        typedef TriangleSet<T>::Triangle Triangle;
        std::vector<Triangle> triangles;
        Box3D domain = floatTags->getBoundingBox().enlarge(-1);
        domain.x0++;
        domain.x1--;
        isoSurfaceMarchingCube(triangles, *floatTags, isoLevels, domain);
        TriangleSet<T> set(triangles);
        std::string outDir = fNameOut + "/";
        set.writeBinarySTL(outDir + "porousMedium.stl");
    }
}

void porousMediaSetup(MultiBlockLattice3D<T,DESCRIPTOR>& lattice,
        OnLatticeBoundaryCondition3D<T,DESCRIPTOR>* boundaryCondition,
        MultiScalarField3D<int>& geometry, T deltaP)
{
    const plint nx = lattice.getNx();
    const plint ny = lattice.getNy();
    const plint nz = lattice.getNz();

    pcout << "Definition of inlet/outlet." << std::endl;
    Box3D inlet (0,0, 1,ny-2, 1,nz-2);
    boundaryCondition->addPressureBoundary0N(inlet, lattice);
    setBoundaryDensity(lattice, inlet, (T) 1.);

    Box3D outlet(nx-1,nx-1, 1,ny-2, 1,nz-2);
    boundaryCondition->addPressureBoundary0P(outlet, lattice);
    setBoundaryDensity(lattice, outlet, (T) 1. - deltaP*DESCRIPTOR<T>::invCs2);

    pcout << "Definition of the geometry." << std::endl;
    // Where "geometry" evaluates to 1, use bounce-back.
    defineDynamics(lattice, geometry, new BounceBack<T,DESCRIPTOR>(), 1);
    // Where "geometry" evaluates to 2, use no-dynamics (which does nothing).
    defineDynamics(lattice, geometry, new NoDynamics<T,DESCRIPTOR>(), 2);

    pcout << "Initilization of rho and u." << std::endl;
    initializeAtEquilibrium( lattice, lattice.getBoundingBox(), PressureGradient(deltaP, nx) );

    lattice.initialize();
    delete boundaryCondition;
}

void writeGifs(MultiBlockLattice3D<T,DESCRIPTOR>& lattice, plint iter)
{
    const plint nx = lattice.getNx();
    const plint ny = lattice.getNy();
    const plint nz = lattice.getNz();

    const plint imSize = 600;
    ImageWriter<T> imageWriter("leeloo");

    // Write velocity-norm at x=0.
    imageWriter.writeScaledGif(createFileName("ux_inlet", iter, 6),
            *computeVelocityNorm(lattice, Box3D(0,0, 0,ny-1, 0,nz-1)),
            imSize, imSize );

    // Write velocity-norm at x=nx/2.
    imageWriter.writeScaledGif(createFileName("ux_half", iter, 6),
            *computeVelocityNorm(lattice, Box3D(nx/2,nx/2, 0,ny-1, 0,nz-1)),
            imSize, imSize );
}

void writeVTK(MultiBlockLattice3D<T,DESCRIPTOR>& lattice, plint iter)
{
    VtkImageOutput3D<T> vtkOut(createFileName("vtk", iter, 6), 1.);
    vtkOut.writeData<float>(*computeVelocityNorm(lattice), "velocityNorm", 1.);
    vtkOut.writeData<3,float>(*computeVelocity(lattice), "velocity", 1.);
}

T computePermeability(MultiBlockLattice3D<T,DESCRIPTOR>& lattice, T nu, T deltaP, Box3D domain )
{
    pcout << "Computing the permeability." << std::endl;

    // Compute only the x-direction of the velocity (direction of the flow).
    plint xComponent = 0;
    plint nx = lattice.getNx();

    T meanU = computeAverage(*computeVelocityComponent(lattice, domain, xComponent));

    pcout << "Average velocity     = " << meanU                         << std::endl;
    pcout << "Lattice viscosity nu = " << nu                            << std::endl;
    pcout << "Grad P               = " << deltaP/(T)(nx-1)              << std::endl;
    pcout << "Permeability         = " << nu*meanU / (deltaP/(T)(nx-1)) << std::endl;

    return meanU;
}

int main(int argc, char **argv)
{
    plbInit(&argc, &argv);

    if (argc!=7) {
        pcout << "Error missing some input parameter\n";
        pcout << "The structure is :\n";
        pcout << "1. Input file name.\n";
        pcout << "2. Output directory name.\n";
        pcout << "3. number of cells in X direction.\n";
        pcout << "4. number of cells in Y direction.\n";
        pcout << "5. number of cells in Z direction.\n";
        pcout << "6. Delta P .\n";
        pcout << "Example: " << argv[0] << " twoSpheres.dat tmp/ 48 64 64 0.00005\n";
        exit (EXIT_FAILURE);
    }
    std::string fNameIn  = argv[1];
    std::string fNameOut = argv[2];

    const plint nx = atoi(argv[3]);
    const plint ny = atoi(argv[4]);
    const plint nz = atoi(argv[5]);
    const T deltaP = atof(argv[6]);

    global::directories().setOutputDir(fNameOut+"/");

    const T omega = 1.0;
    const T nu    = ((T)1/omega- (T)0.5)/DESCRIPTOR<T>::invCs2;

    pcout << "Creation of the lattice." << std::endl;
    MultiBlockLattice3D<T,DESCRIPTOR> lattice(nx,ny,nz, new BGKdynamics<T,DESCRIPTOR>(omega));
    // Switch off periodicity.
    lattice.periodicity().toggleAll(false);

    pcout << "Reading the geometry file." << std::endl;
    MultiScalarField3D<int> geometry(nx,ny,nz);
    readGeometry(fNameIn, fNameOut, geometry);

    pcout << "nu = " << nu << std::endl;
    pcout << "deltaP = " << deltaP << std::endl;
    pcout << "omega = " << omega << std::endl;
    pcout << "nx = " << lattice.getNx() << std::endl;
    pcout << "ny = " << lattice.getNy() << std::endl;
    pcout << "nz = " << lattice.getNz() << std::endl;

    porousMediaSetup(lattice, createLocalBoundaryCondition3D<T,DESCRIPTOR>(), geometry, deltaP);

    // The value-tracer is used to stop the simulation once is has converged.
    // 1st parameter:velocity
    // 2nd parameter:size
    // 3rd parameters:threshold
    // 1st and second parameters ae used for the length of the time average (size/velocity)
    util::ValueTracer<T> converge(1.0,1000.0,1.0e-4);

    pcout << "Simulation begins" << std::endl;
    plint iT=0;

    const plint maxT = 30000;
    for (;iT<maxT; ++iT) {
        if (iT % 20 == 0) {
            pcout << "Iteration " << iT << std::endl;
        }
        if (iT % 500 == 0 && iT>0) {
            writeGifs(lattice,iT);
        }

        lattice.collideAndStream();
        converge.takeValue(getStoredAverageEnergy(lattice),true);

        if (converge.hasConverged()) {
            break;
        }
    }

    pcout << "End of simulation at iteration " << iT << std::endl;

    pcout << "Permeability:" << std::endl << std::endl;
    computePermeability(lattice, nu, deltaP, lattice.getBoundingBox());
    pcout << std::endl;

    pcout << "Writing VTK file ..." << std::endl << std::endl;
    writeVTK(lattice,iT);
    pcout << "Finished!" << std::endl << std::endl;

    return 0;
}
