/*
  Copyright 2013--2018 James E. McClure, Virginia Polytechnic & State University
  Copyright Equnior ASA

  This file is part of the Open Porous Media project (OPM).
  OPM 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 3 of the License, or
  (at your option) any later version.
  OPM 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 OPM.  If not, see <http://www.gnu.org/licenses/>.
*/
#include "analysis/distance.h"

/******************************************************************
* A fast distance calculation                                     *
******************************************************************/
template <class TYPE>
void CalcDist(Array<TYPE> &Distance, const Array<char> &ID, const Domain &Dm,
              const std::array<bool, 3> &periodic,
              const std::array<double, 3> &dx) {
    ASSERT(Distance.size() == ID.size());
    std::array<int, 3> n = {Dm.Nx - 2, Dm.Ny - 2, Dm.Nz - 2};
    fillHalo<int> fillData(Dm.Comm, Dm.rank_info, n, {1, 1, 1}, 50, 1,
                           {true, false, false}, periodic);
    Array<int> id(ID.size());
    Array<Vec> vecDist(Distance.size());
    for (size_t i = 0; i < ID.length(); i++)
        id(i) = ID(i) == 0 ? -1 : 1;
    fillData.fill(id);
    CalcVecDist(vecDist, id, Dm, periodic, dx);
    for (size_t i = 0; i < Distance.length(); i++)
        Distance(i) = id(i) * vecDist(i).norm();
}

/******************************************************************
* Vector-based distance calculation                               *
* Initialize cells adjacent to boundaries                         *
******************************************************************/
static void calcVecInitialize(Array<Vec> &d, const Array<int> &ID, double dx,
                              double dy, double dz) {
    d.fill(Vec(1e50, 1e50, 1e50));
    const double dx0 = 0.5 * dx;
    const double dy0 = 0.5 * dy;
    const double dz0 = 0.5 * dz;
    //const double dxy0 = 0.25*sqrt( dx*dx + dy*dy );
    //const double dxz0 = 0.25*sqrt( dx*dx + dz*dz );
    //const double dyz0 = 0.25*sqrt( dy*dy + dz*dz );
    //const double dxyz0 = sqrt( dx*dx + dy*dy + dz*dz );
    int Nx = d.size(0);
    int Ny = d.size(1);
    int Nz = d.size(2);
    for (int k = 1; k < Nz - 1; k++) {
        for (int j = 1; j < Ny - 1; j++) {
            for (int i = 1; i < Nx - 1; i++) {
                int id = ID(i, j, k);
                bool x[2] = {id != ID(i - 1, j, k), id != ID(i + 1, j, k)};
                bool y[2] = {id != ID(i, j - 1, k), id != ID(i, j + 1, k)};
                bool z[2] = {id != ID(i, j, k - 1), id != ID(i, j, k + 1)};
                if (x[0])
                    d(i, j, k) = Vec(dx0, 0, 0);
                if (x[1])
                    d(i, j, k) = Vec(-dx0, 0, 0);
                if (y[0])
                    d(i, j, k) = Vec(0, dy0, 0);
                if (y[1])
                    d(i, j, k) = Vec(0, -dy0, 0);
                if (z[0])
                    d(i, j, k) = Vec(0, 0, dz0);
                if (z[1])
                    d(i, j, k) = Vec(0, 0, -dz0);
                /*if ( x[0] && y[0] )  d(i,j,k) = Vec( dxy0, dxy0, 0 );
                if ( x[0] && y[1] )  d(i,j,k) = Vec( dxy0, -dxy0, 0 );
                if ( x[1] && y[0] )  d(i,j,k) = Vec( -dxy0, dxy0, 0 );
                if ( x[1] && y[1] )  d(i,j,k) = Vec( -dxy0, -dxy0, 0 );
                if ( x[0] && z[0] )  d(i,j,k) = Vec( dxz0, 0, dxz0 ); 
                if ( x[0] && z[1] )  d(i,j,k) = Vec( dxz0, 0, -dxz0 );
                if ( x[1] && z[0] )  d(i,j,k) = Vec( -dxz0, 0, dxz0 );
                if ( x[1] && z[1] )  d(i,j,k) = Vec( -dxz0, 0, -dxz0 );
                if ( y[0] && z[0] )  d(i,j,k) = Vec( 0, dyz0, dyz0 );
                if ( y[0] && z[1] )  d(i,j,k) = Vec( 0, dyz0, -dyz0 );
                if ( y[1] && z[0] )  d(i,j,k) = Vec( 0, -dyz0, dyz0 );
                if ( y[1] && z[1] )  d(i,j,k) = Vec( 0, -dyz0, -dyz0 );*/
            }
        }
    }
}

/******************************************************************
* Vector-based distance calculation                               *
* Update interior cells                                           *
******************************************************************/
static double calcVecUpdateInterior(Array<Vec> &d, double dx, double dy,
                                    double dz) {
    double err = 0;
    int Nx = d.size(0);
    int Ny = d.size(1);
    int Nz = d.size(2);
    // Propagate (+,+,+)
    for (int k = 1; k < Nz; k++) {
        for (int j = 1; j < Ny; j++) {
            for (int i = 1; i < Nx; i++) {
                auto vx = d(i - 1, j, k);
                auto vy = d(i, j - 1, k);
                auto vz = d(i, j, k - 1);
                vx.x += dx;
                vy.y += dy;
                vz.z += dz;
                auto v = std::min(std::min(vx, vy), vz);
                double d1 = v.norm2();
                double d2 = d(i, j, k).norm2();
                if (d1 < d2) {
                    d(i, j, k) = v;
                    err = std::max(err, sqrt(d2) - sqrt(d1));
                }
            }
        }
    }
    // Propagate (-,-,-)
    for (int k = Nz - 2; k >= 0; k--) {
        for (int j = Ny - 2; j >= 0; j--) {
            for (int i = Nx - 2; i >= 0; i--) {
                auto vx = d(i + 1, j, k);
                auto vy = d(i, j + 1, k);
                auto vz = d(i, j, k + 1);
                vx.x -= dx;
                vy.y -= dy;
                vz.z -= dz;
                auto v = std::min(std::min(vx, vy), vz);
                double d1 = v.norm2();
                double d2 = d(i, j, k).norm2();
                if (d1 < d2) {
                    d(i, j, k) = v;
                    err = std::max(err, sqrt(d2) - sqrt(d1));
                }
            }
        }
    }
    return err;
}

/******************************************************************
* Vector-based distance calculation                               *
******************************************************************/
void CalcVecDist(Array<Vec> &d, const Array<int> &ID0, const Domain &Dm,
                 const std::array<bool, 3> &periodic,
                 const std::array<double, 3> &dx) {
    std::array<int, 3> N = {Dm.Nx, Dm.Ny, Dm.Nz};
    std::array<int, 3> n = {Dm.Nx - 2, Dm.Ny - 2, Dm.Nz - 2};
    // Create ID with ghosts
    Array<int> ID(N[0], N[1], N[2]);
    fillHalo<int> fillDataID(Dm.Comm, Dm.rank_info, n, {1, 1, 1}, 50, 1,
                             {true, true, true}, periodic);
    fillDataID.copy(ID0, ID);
    // Fill ghosts with nearest neighbor
    for (int k = 1; k < N[2] - 1; k++) {
        for (int j = 1; j < N[1] - 1; j++) {
            ID(0, j, k) = ID(1, j, k);
            ID(N[0] - 1, j, k) = ID(N[0] - 2, j, k);
        }
    }
    for (int k = 1; k < N[2] - 1; k++) {
        for (int i = 0; i < N[0]; i++) {
            ID(i, 0, k) = ID(i, 1, k);
            ID(i, N[1] - 1, k) = ID(i, N[1] - 2, k);
        }
    }
    for (int i = 0; i < N[0]; i++) {
        for (int j = 0; j < N[1]; j++) {
            ID(i, j, 0) = ID(i, j, 1);
            ID(i, j, N[2] - 1) = ID(i, j, N[2] - 2);
        }
    }
    // Communicate ghosts
    fillDataID.fill(ID);
    // Create communicator for distance
    fillHalo<Vec> fillData(Dm.Comm, Dm.rank_info, n, {1, 1, 1}, 50, 1,
                           {true, false, false}, periodic);
    // Calculate the local distances
    calcVecInitialize(d, ID, dx[0], dx[1], dx[2]);
    double err = 1e100;
    double tol = 0.5 * std::min(std::min(dx[0], dx[1]), dx[2]);
    for (int it = 0; it <= 50 && err > tol; it++) {
        err = calcVecUpdateInterior(d, dx[0], dx[1], dx[2]);
    }
    // Calculate the global distances
    int N_it = Dm.nprocx() + Dm.nprocy() + Dm.nprocz() + 100;
    for (int it = 0; it < N_it; it++) {
        // Update ghosts
        fillData.fill(d);
        // Update distance
        double err = calcVecUpdateInterior(d, dx[0], dx[1], dx[2]);
        // Check if we are finished
        err = Dm.Comm.maxReduce(err);
        if (err < tol)
            break;
    }
}

// Explicit instantiations
template void CalcDist<float>(Array<float> &, const Array<char> &,
                              const Domain &, const std::array<bool, 3> &,
                              const std::array<double, 3> &);
template void CalcDist<double>(Array<double> &, const Array<char> &,
                               const Domain &, const std::array<bool, 3> &,
                               const std::array<double, 3> &);