/* ----------------------------------------------------------------------
   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 "fix_print.h"

#include "comm.h"
#include "error.h"
#include "input.h"
#include "memory.h"
#include "modify.h"
#include "update.h"
#include "variable.h"

#include <cstring>

using namespace LAMMPS_NS;
using namespace FixConst;

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

FixPrint::FixPrint(LAMMPS *lmp, int narg, char **arg) :
    Fix(lmp, narg, arg), fp(nullptr), text(nullptr), copy(nullptr), work(nullptr),
    var_print(nullptr)
{
  if (narg < 5) utils::missing_cmd_args(FLERR, "fix print", error);
  if (utils::strmatch(arg[3], "^v_")) {
    var_print = utils::strdup(arg[3] + 2);
    nevery = 1;
  } else {
    nevery = utils::inumeric(FLERR, arg[3], false, lmp);
    if (nevery <= 0) error->all(FLERR, "Illegal fix print nevery value {}; must be > 0", nevery);
  }

  text = utils::strdup(arg[4]);
  int n = strlen(text) + 1;
  copy = (char *) memory->smalloc(n * sizeof(char), "fix/print:copy");
  work = (char *) memory->smalloc(n * sizeof(char), "fix/print:work");
  maxcopy = maxwork = n;

  // parse optional args

  fp = nullptr;
  screenflag = 1;
  char *title = nullptr;

  int iarg = 5;
  while (iarg < narg) {
    if ((strcmp(arg[iarg], "file") == 0) || (strcmp(arg[iarg], "append") == 0)) {
      if (iarg + 2 > narg)
        utils::missing_cmd_args(FLERR, std::string("fix print ") + arg[iarg], error);
      if (comm->me == 0) {
        if (strcmp(arg[iarg], "file") == 0)
          fp = fopen(arg[iarg + 1], "w");
        else
          fp = fopen(arg[iarg + 1], "a");
        if (fp == nullptr)
          error->one(FLERR, "Cannot open fix print file {}: {}", arg[iarg + 1],
                     utils::getsyserror());
      }
      iarg += 2;
    } else if (strcmp(arg[iarg], "screen") == 0) {
      if (iarg + 2 > narg) utils::missing_cmd_args(FLERR, "fix print screen", error);
      screenflag = utils::logical(FLERR, arg[iarg + 1], false, lmp);
      iarg += 2;
    } else if (strcmp(arg[iarg], "title") == 0) {
      if (iarg + 2 > narg) utils::missing_cmd_args(FLERR, "fix print title", error);
      delete[] title;
      title = utils::strdup(arg[iarg + 1]);
      iarg += 2;
    } else
      error->all(FLERR, "Unknown fix print keyword: {}", arg[iarg]);
  }

  // print file comment line

  if (fp && (comm->me == 0)) {
    if (title)
      fprintf(fp, "%s\n", title);
    else
      fprintf(fp, "# Fix print output for fix %s\n", id);
  }

  delete[] title;
}

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

FixPrint::~FixPrint()
{
  delete[] text;
  delete[] var_print;
  memory->sfree(copy);
  memory->sfree(work);

  if (fp && (comm->me == 0)) fclose(fp);
}

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

int FixPrint::setmask()
{
  int mask = 0;
  mask |= END_OF_STEP;
  return mask;
}

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

void FixPrint::init()
{
  if (var_print) {
    ivar_print = input->variable->find(var_print);
    if (ivar_print < 0)
      error->all(FLERR, "Variable {} for fix print timestep does not exist", var_print);
    if (!input->variable->equalstyle(ivar_print))
      error->all(FLERR, "Variable {} for fix print timestep is invalid style", var_print);
    next_print = static_cast<bigint>(input->variable->compute_equal(ivar_print));
    if (next_print <= update->ntimestep)
      error->all(FLERR, "Fix print timestep variable {} returned a bad timestep: {}", var_print,
                 next_print);
  } else {
    if (update->ntimestep % nevery)
      next_print = (update->ntimestep / nevery) * nevery + nevery;
    else
      next_print = update->ntimestep;
  }

  // add next_print to all computes that store invocation times
  // since don't know a priori which are invoked via variables by this fix
  // once in end_of_step() can set timestep for ones actually invoked

  modify->addstep_compute_all(next_print);
}

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

void FixPrint::setup(int /* vflag */)
{
  end_of_step();
}

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

void FixPrint::end_of_step()
{
  if (update->ntimestep != next_print) return;

  // make a copy of text to work on
  // substitute for $ variables (no printing)
  // append a newline and print final copy
  // variable evaluation may invoke computes so wrap with clear/add

  modify->clearstep_compute();

  strncpy(copy, text, maxcopy);
  input->substitute(copy, work, maxcopy, maxwork, 0);

  if (var_print) {
    next_print = static_cast<bigint>(input->variable->compute_equal(ivar_print));
    if (next_print <= update->ntimestep)
      error->all(FLERR, "Fix print timestep variable returned a bad timestep: {}", next_print);
  } else {
    next_print = (update->ntimestep / nevery) * nevery + nevery;
  }

  modify->addstep_compute(next_print);

  if (comm->me == 0) {
    if (screenflag) utils::logmesg(lmp, std::string(copy) + "\n");
    if (fp) {
      fmt::print(fp, "{}\n", copy);
      fflush(fp);
    }
  }
}