/* ----------------------------------------------------------------------
   LAMMPS - Large-scale Atomic/Molecular Massively Parallel Simulator
   https://www.lammps.org/, Sandia National Laboratories
   LAMMPS development team: developers@lammps.org

   Copyright (2003) Sandia Corporation.  Under the terms of Contract
   DE-AC04-94AL85000 with Sandia Corporation, the U.S. Government retains
   certain rights in this software.  This software is distributed under
   the GNU General Public License.

   See the README file in the top-level LAMMPS directory.
------------------------------------------------------------------------- */

#include "angle.h"
#include "atom.h"
#include "atom_masks.h"
#include "comm.h"
#include "error.h"
#include "force.h"
#include "math_const.h"
#include "memory.h"
#include "suffix.h"

using namespace LAMMPS_NS;
using namespace MathConst;

static constexpr double FOURTH = 0.25;

/* ---------------------------------------------------------------------- */

Angle::Angle(LAMMPS *_lmp) : Pointers(_lmp)
{
  energy = 0.0;
  virial[0] = virial[1] = virial[2] = virial[3] = virial[4] = virial[5] = 0.0;
  writedata = 1;
  reinitflag = 1;

  allocated = 0;
  suffix_flag = Suffix::NONE;
  born_matrix_enable = 0;

  maxeatom = maxvatom = maxcvatom = 0;
  eatom = nullptr;
  vatom = nullptr;
  cvatom = nullptr;
  setflag = nullptr;
  centroidstressflag = CENTROID_AVAIL;

  execution_space = Host;
  datamask_read = ALL_MASK;
  datamask_modify = ALL_MASK;

  copymode = 0;
}

/* ---------------------------------------------------------------------- */

Angle::~Angle()
{
  if (copymode) return;

  memory->destroy(eatom);
  memory->destroy(vatom);
  memory->destroy(cvatom);
}

/* ----------------------------------------------------------------------
   check if all coeffs are set
------------------------------------------------------------------------- */

void Angle::init()
{
  if (!allocated && atom->nangletypes) error->all(FLERR, "Angle coeffs are not set");
  for (int i = 1; i <= atom->nangletypes; i++)
    if (setflag[i] == 0) error->all(FLERR, "All angle coeffs are not set");

  init_style();
}

/* ----------------------------------------------------------------------
   check that there are no arguments
------------------------------------------------------------------------- */

void Angle::settings(int narg, char **args)
{
  if (narg > 0)
    error->all(FLERR, "Illegal angle_style {} argument: {}", force->angle_style, args[0]);
}

/* ----------------------------------------------------------------------
   setup for energy, virial computation
   see integrate::ev_set() for bitwise settings of eflag/vflag
   set the following flags, values are otherwise set to 0:
     evflag       != 0 if any bits of eflag or vflag are set
     eflag_global != 0 if ENERGY_GLOBAL bit of eflag set
     eflag_atom   != 0 if ENERGY_ATOM bit of eflag set
     eflag_either != 0 if eflag_global or eflag_atom is set
     vflag_global != 0 if VIRIAL_PAIR or VIRIAL_FDOTR bit of vflag set
     vflag_atom   != 0 if VIRIAL_ATOM bit of vflag set
     vflag_atom   != 0 if VIRIAL_CENTROID bit of vflag set
                       and centroidstressflag != CENTROID_AVAIL
     cvflag_atom  != 0 if VIRIAL_CENTROID bit of vflag set
                       and centroidstressflag = CENTROID_AVAIL
     vflag_either != 0 if any of vflag_global, vflag_atom, cvflag_atom is set
------------------------------------------------------------------------- */

void Angle::ev_setup(int eflag, int vflag, int alloc)
{
  int i, n;

  evflag = 1;

  eflag_either = eflag;
  eflag_global = eflag & ENERGY_GLOBAL;
  eflag_atom = eflag & ENERGY_ATOM;

  vflag_global = vflag & (VIRIAL_PAIR | VIRIAL_FDOTR);
  vflag_atom = vflag & VIRIAL_ATOM;
  if (vflag & VIRIAL_CENTROID && centroidstressflag != CENTROID_AVAIL) vflag_atom = 1;
  cvflag_atom = 0;
  if (vflag & VIRIAL_CENTROID && centroidstressflag == CENTROID_AVAIL) cvflag_atom = 1;
  vflag_either = vflag_global || vflag_atom || cvflag_atom;

  // reallocate per-atom arrays if necessary

  if (eflag_atom && atom->nmax > maxeatom) {
    maxeatom = atom->nmax;
    if (alloc) {
      memory->destroy(eatom);
      memory->create(eatom, comm->nthreads * maxeatom, "angle:eatom");
    }
  }
  if (vflag_atom && atom->nmax > maxvatom) {
    maxvatom = atom->nmax;
    if (alloc) {
      memory->destroy(vatom);
      memory->create(vatom, comm->nthreads * maxvatom, 6, "angle:vatom");
    }
  }
  if (cvflag_atom && atom->nmax > maxcvatom) {
    maxcvatom = atom->nmax;
    if (alloc) {
      memory->destroy(cvatom);
      memory->create(cvatom, comm->nthreads * maxcvatom, 9, "angle:cvatom");
    }
  }

  // zero accumulators

  if (eflag_global) energy = 0.0;
  if (vflag_global)
    for (i = 0; i < 6; i++) virial[i] = 0.0;
  if (eflag_atom && alloc) {
    n = atom->nlocal;
    if (force->newton_bond) n += atom->nghost;
    for (i = 0; i < n; i++) eatom[i] = 0.0;
  }
  if (vflag_atom && alloc) {
    n = atom->nlocal;
    if (force->newton_bond) n += atom->nghost;
    for (i = 0; i < n; i++) {
      vatom[i][0] = 0.0;
      vatom[i][1] = 0.0;
      vatom[i][2] = 0.0;
      vatom[i][3] = 0.0;
      vatom[i][4] = 0.0;
      vatom[i][5] = 0.0;
    }
  }
  if (cvflag_atom && alloc) {
    n = atom->nlocal;
    if (force->newton_bond) n += atom->nghost;
    for (i = 0; i < n; i++) {
      cvatom[i][0] = 0.0;
      cvatom[i][1] = 0.0;
      cvatom[i][2] = 0.0;
      cvatom[i][3] = 0.0;
      cvatom[i][4] = 0.0;
      cvatom[i][5] = 0.0;
      cvatom[i][6] = 0.0;
      cvatom[i][7] = 0.0;
      cvatom[i][8] = 0.0;
      cvatom[i][9] = 0.0;
    }
  }
}

/* ----------------------------------------------------------------------
   tally energy and virial into global and per-atom accumulators
   virial = r1F1 + r2F2 + r3F3 = (r1-r2) F1 + (r3-r2) F3 = del1*f1 + del2*f3
   called by standard 3-body angles
------------------------------------------------------------------------- */

void Angle::ev_tally(int i, int j, int k, int nlocal, int newton_bond, double eangle, double *f1,
                     double *f3, double delx1, double dely1, double delz1, double delx2,
                     double dely2, double delz2)
{
  double eanglethird, v[6];

  if (eflag_either) {
    if (eflag_global) {
      if (newton_bond)
        energy += eangle;
      else {
        eanglethird = THIRD * eangle;
        if (i < nlocal) energy += eanglethird;
        if (j < nlocal) energy += eanglethird;
        if (k < nlocal) energy += eanglethird;
      }
    }
    if (eflag_atom) {
      eanglethird = THIRD * eangle;
      if (newton_bond || i < nlocal) eatom[i] += eanglethird;
      if (newton_bond || j < nlocal) eatom[j] += eanglethird;
      if (newton_bond || k < nlocal) eatom[k] += eanglethird;
    }
  }

  if (vflag_either) {
    v[0] = delx1 * f1[0] + delx2 * f3[0];
    v[1] = dely1 * f1[1] + dely2 * f3[1];
    v[2] = delz1 * f1[2] + delz2 * f3[2];
    v[3] = delx1 * f1[1] + delx2 * f3[1];
    v[4] = delx1 * f1[2] + delx2 * f3[2];
    v[5] = dely1 * f1[2] + dely2 * f3[2];

    if (vflag_global) {
      if (newton_bond) {
        virial[0] += v[0];
        virial[1] += v[1];
        virial[2] += v[2];
        virial[3] += v[3];
        virial[4] += v[4];
        virial[5] += v[5];
      } else {
        if (i < nlocal) {
          virial[0] += THIRD * v[0];
          virial[1] += THIRD * v[1];
          virial[2] += THIRD * v[2];
          virial[3] += THIRD * v[3];
          virial[4] += THIRD * v[4];
          virial[5] += THIRD * v[5];
        }
        if (j < nlocal) {
          virial[0] += THIRD * v[0];
          virial[1] += THIRD * v[1];
          virial[2] += THIRD * v[2];
          virial[3] += THIRD * v[3];
          virial[4] += THIRD * v[4];
          virial[5] += THIRD * v[5];
        }
        if (k < nlocal) {
          virial[0] += THIRD * v[0];
          virial[1] += THIRD * v[1];
          virial[2] += THIRD * v[2];
          virial[3] += THIRD * v[3];
          virial[4] += THIRD * v[4];
          virial[5] += THIRD * v[5];
        }
      }
    }

    if (vflag_atom) {
      if (newton_bond || i < nlocal) {
        vatom[i][0] += THIRD * v[0];
        vatom[i][1] += THIRD * v[1];
        vatom[i][2] += THIRD * v[2];
        vatom[i][3] += THIRD * v[3];
        vatom[i][4] += THIRD * v[4];
        vatom[i][5] += THIRD * v[5];
      }
      if (newton_bond || j < nlocal) {
        vatom[j][0] += THIRD * v[0];
        vatom[j][1] += THIRD * v[1];
        vatom[j][2] += THIRD * v[2];
        vatom[j][3] += THIRD * v[3];
        vatom[j][4] += THIRD * v[4];
        vatom[j][5] += THIRD * v[5];
      }
      if (newton_bond || k < nlocal) {
        vatom[k][0] += THIRD * v[0];
        vatom[k][1] += THIRD * v[1];
        vatom[k][2] += THIRD * v[2];
        vatom[k][3] += THIRD * v[3];
        vatom[k][4] += THIRD * v[4];
        vatom[k][5] += THIRD * v[5];
      }
    }
  }

  // per-atom centroid virial

  if (cvflag_atom) {

    // r0 = (r1+r2+r3)/3
    // rij = ri-rj
    // total virial = r10*f1 + r20*f2 + r30*f3
    // del1: r12
    // del2: r32

    if (newton_bond || i < nlocal) {
      double a1[3];

      // a1 = r10 = (2*r12 -   r32)/3
      a1[0] = THIRD * (2 * delx1 - delx2);
      a1[1] = THIRD * (2 * dely1 - dely2);
      a1[2] = THIRD * (2 * delz1 - delz2);

      cvatom[i][0] += a1[0] * f1[0];
      cvatom[i][1] += a1[1] * f1[1];
      cvatom[i][2] += a1[2] * f1[2];
      cvatom[i][3] += a1[0] * f1[1];
      cvatom[i][4] += a1[0] * f1[2];
      cvatom[i][5] += a1[1] * f1[2];
      cvatom[i][6] += a1[1] * f1[0];
      cvatom[i][7] += a1[2] * f1[0];
      cvatom[i][8] += a1[2] * f1[1];
    }

    if (newton_bond || j < nlocal) {
      double a2[3];
      double f2[3];

      // a2 = r20 = ( -r12 -   r32)/3
      a2[0] = THIRD * (-delx1 - delx2);
      a2[1] = THIRD * (-dely1 - dely2);
      a2[2] = THIRD * (-delz1 - delz2);

      f2[0] = -f1[0] - f3[0];
      f2[1] = -f1[1] - f3[1];
      f2[2] = -f1[2] - f3[2];

      cvatom[j][0] += a2[0] * f2[0];
      cvatom[j][1] += a2[1] * f2[1];
      cvatom[j][2] += a2[2] * f2[2];
      cvatom[j][3] += a2[0] * f2[1];
      cvatom[j][4] += a2[0] * f2[2];
      cvatom[j][5] += a2[1] * f2[2];
      cvatom[j][6] += a2[1] * f2[0];
      cvatom[j][7] += a2[2] * f2[0];
      cvatom[j][8] += a2[2] * f2[1];
    }

    if (newton_bond || k < nlocal) {
      double a3[3];

      // a3 = r30 = ( -r12 + 2*r32)/3
      a3[0] = THIRD * (-delx1 + 2 * delx2);
      a3[1] = THIRD * (-dely1 + 2 * dely2);
      a3[2] = THIRD * (-delz1 + 2 * delz2);

      cvatom[k][0] += a3[0] * f3[0];
      cvatom[k][1] += a3[1] * f3[1];
      cvatom[k][2] += a3[2] * f3[2];
      cvatom[k][3] += a3[0] * f3[1];
      cvatom[k][4] += a3[0] * f3[2];
      cvatom[k][5] += a3[1] * f3[2];
      cvatom[k][6] += a3[1] * f3[0];
      cvatom[k][7] += a3[2] * f3[0];
      cvatom[k][8] += a3[2] * f3[1];
    }
  }
}

/* ----------------------------------------------------------------------
   tally energy and virial into global and per-atom accumulators
   virial = r1F1 + r2F2 + r3F3 + r4F4
   called by AngleAmoeba for its 4-body angle term
------------------------------------------------------------------------- */

void Angle::ev_tally4(int i, int j, int k, int m, int nlocal, int newton_bond, double eangle,
                      double *f1, double *f2, double *f3, double *f4)
{
  double eanglefourth, v[6];

  if (eflag_either) {
    if (eflag_global) {
      if (newton_bond)
        energy += eangle;
      else {
        eanglefourth = FOURTH * eangle;
        if (i < nlocal) energy += eanglefourth;
        if (j < nlocal) energy += eanglefourth;
        if (k < nlocal) energy += eanglefourth;
        if (m < nlocal) energy += eanglefourth;
      }
    }
    if (eflag_atom) {
      eanglefourth = FOURTH * eangle;
      if (newton_bond || i < nlocal) eatom[i] += eanglefourth;
      if (newton_bond || j < nlocal) eatom[j] += eanglefourth;
      if (newton_bond || k < nlocal) eatom[k] += eanglefourth;
      if (newton_bond || m < nlocal) eatom[m] += eanglefourth;
    }
  }

  if (vflag_either) {
    double **x = atom->x;
    v[0] = x[i][0] * f1[0] + x[j][0] * f2[0] + x[k][0] * f3[0] + x[m][0] * f4[0];
    v[1] = x[i][1] * f1[1] + x[j][1] * f2[1] + x[k][1] * f3[1] + x[m][1] * f4[1];
    v[2] = x[i][2] * f1[2] + x[j][2] * f2[2] + x[k][2] * f3[2] + x[m][2] * f4[2];
    v[3] = x[i][0] * f1[1] + x[j][0] * f2[1] + x[k][0] * f3[1] + x[m][0] * f4[1];
    v[4] = x[i][0] * f1[2] + x[j][0] * f2[2] + x[k][0] * f3[2] + x[m][0] * f4[2];
    v[5] = x[i][1] * f1[2] + x[j][1] * f2[2] + x[k][1] * f3[2] + x[m][1] * f4[2];

    if (vflag_global) {
      if (newton_bond) {
        virial[0] += v[0];
        virial[1] += v[1];
        virial[2] += v[2];
        virial[3] += v[3];
        virial[4] += v[4];
        virial[5] += v[5];
      } else {
        double prefactor = 0.0;
        if (i < nlocal) prefactor += 1.0;
        if (j < nlocal) prefactor += 1.0;
        if (k < nlocal) prefactor += 1.0;
        if (m < nlocal) prefactor += 1.0;
        virial[0] += prefactor * FOURTH * v[0];
        virial[1] += prefactor * FOURTH * v[1];
        virial[2] += prefactor * FOURTH * v[2];
        virial[3] += prefactor * FOURTH * v[3];
        virial[4] += prefactor * FOURTH * v[4];
        virial[5] += prefactor * FOURTH * v[5];
      }
    }

    if (vflag_atom) {
      if (newton_bond || i < nlocal) {
        vatom[i][0] += FOURTH * v[0];
        vatom[i][1] += FOURTH * v[1];
        vatom[i][2] += FOURTH * v[2];
        vatom[i][3] += FOURTH * v[3];
        vatom[i][4] += FOURTH * v[4];
        vatom[i][5] += FOURTH * v[5];
      }
      if (newton_bond || j < nlocal) {
        vatom[j][0] += FOURTH * v[0];
        vatom[j][1] += FOURTH * v[1];
        vatom[j][2] += FOURTH * v[2];
        vatom[j][3] += FOURTH * v[3];
        vatom[j][4] += FOURTH * v[4];
        vatom[j][5] += FOURTH * v[5];
      }
      if (newton_bond || k < nlocal) {
        vatom[k][0] += FOURTH * v[0];
        vatom[k][1] += FOURTH * v[1];
        vatom[k][2] += FOURTH * v[2];
        vatom[k][3] += FOURTH * v[3];
        vatom[k][4] += FOURTH * v[4];
        vatom[k][5] += FOURTH * v[5];
      }
      if (newton_bond || m < nlocal) {
        vatom[m][0] += FOURTH * v[0];
        vatom[m][1] += FOURTH * v[1];
        vatom[m][2] += FOURTH * v[2];
        vatom[m][3] += FOURTH * v[3];
        vatom[m][4] += FOURTH * v[4];
        vatom[m][5] += FOURTH * v[5];
      }
    }
  }
}

/* ----------------------------------------------------------------------
   tally energy and virial into global and per-atom accumulators
   called by AngleAmoeba for its 2-body Urey-Bradley H-H bond term
   identical to Bond:ev_tally()
------------------------------------------------------------------------- */

void Angle::ev_tally2(int i, int j, int nlocal, int newton_bond, double ebond, double fbond,
                      double delx, double dely, double delz)
{
  double ebondhalf, v[6];

  if (eflag_either) {
    if (eflag_global) {
      if (newton_bond)
        energy += ebond;
      else {
        ebondhalf = 0.5 * ebond;
        if (i < nlocal) energy += ebondhalf;
        if (j < nlocal) energy += ebondhalf;
      }
    }
    if (eflag_atom) {
      ebondhalf = 0.5 * ebond;
      if (newton_bond || i < nlocal) eatom[i] += ebondhalf;
      if (newton_bond || j < nlocal) eatom[j] += ebondhalf;
    }
  }

  if (vflag_either) {
    v[0] = delx * delx * fbond;
    v[1] = dely * dely * fbond;
    v[2] = delz * delz * fbond;
    v[3] = delx * dely * fbond;
    v[4] = delx * delz * fbond;
    v[5] = dely * delz * fbond;

    if (vflag_global) {
      if (newton_bond) {
        virial[0] += v[0];
        virial[1] += v[1];
        virial[2] += v[2];
        virial[3] += v[3];
        virial[4] += v[4];
        virial[5] += v[5];
      } else {
        if (i < nlocal) {
          virial[0] += 0.5 * v[0];
          virial[1] += 0.5 * v[1];
          virial[2] += 0.5 * v[2];
          virial[3] += 0.5 * v[3];
          virial[4] += 0.5 * v[4];
          virial[5] += 0.5 * v[5];
        }
        if (j < nlocal) {
          virial[0] += 0.5 * v[0];
          virial[1] += 0.5 * v[1];
          virial[2] += 0.5 * v[2];
          virial[3] += 0.5 * v[3];
          virial[4] += 0.5 * v[4];
          virial[5] += 0.5 * v[5];
        }
      }
    }

    if (vflag_atom) {
      if (newton_bond || i < nlocal) {
        vatom[i][0] += 0.5 * v[0];
        vatom[i][1] += 0.5 * v[1];
        vatom[i][2] += 0.5 * v[2];
        vatom[i][3] += 0.5 * v[3];
        vatom[i][4] += 0.5 * v[4];
        vatom[i][5] += 0.5 * v[5];
      }
      if (newton_bond || j < nlocal) {
        vatom[j][0] += 0.5 * v[0];
        vatom[j][1] += 0.5 * v[1];
        vatom[j][2] += 0.5 * v[2];
        vatom[j][3] += 0.5 * v[3];
        vatom[j][4] += 0.5 * v[4];
        vatom[j][5] += 0.5 * v[5];
      }
    }
  }
}

/* ---------------------------------------------------------------------- */

double Angle::memory_usage()
{
  double bytes = (double) comm->nthreads * maxeatom * sizeof(double);
  bytes += (double) comm->nthreads * maxvatom * 6 * sizeof(double);
  bytes += (double) comm->nthreads * maxcvatom * 9 * sizeof(double);
  return bytes;
}

/* -----------------------------------------------------------------------
   reset all type-based angle params via init()
-------------------------------------------------------------------------- */

void Angle::reinit()
{
  if (!reinitflag) error->all(FLERR, "Fix adapt interface to this angle style not supported");

  init();
}