/*
  This file is part of CDO. CDO is a collection of Operators to
  manipulate and analyse Climate model Data.

  Copyright (C) 2003-2020 Uwe Schulzweida, <uwe.schulzweida AT mpimet.mpg.de>
  See COPYING file for copying and redistribution conditions.

  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; version 2 of the License.

  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.
*/

/*
   This module contains the following operators:

      Adisit      adisit          compute insitu from potential temperature
      Adisit      adipot          compute potential from insitu temperature
*/

#include <cdi.h>

#include "cdo_options.h"
#include "cdo_zaxis.h"
#include "process_int.h"
#include "cdo_vlist.h"
#include "param_conversion.h"
#include "util_string.h"

/*
!>
!! transformation from potential to in situ temperature
!! according to Bryden, 1973, "New polynomials for thermal expansion,
!! adiabatic temperature gradient and potential temperature of sea
!! water". Deep Sea Research and Oceanographic Abstracts. 20, 401-408
!! (GILL P.602), which gives the inverse transformation for an
!! approximate value, all terms linear in t are taken after that one
!! newton step.  for the check value 8.4678516 the accuracy is 0.2
!! mikrokelvin.
!!
*/

/* compute insitu temperature from potential temperature */
static inline double
adisit_1(const double tpot, const double sal, const double p)
{
  constexpr double a_a1 = 3.6504E-4, a_a2 = 8.3198E-5, a_a3 = 5.4065E-7, a_a4 = 4.0274E-9, a_b1 = 1.7439E-5, a_b2 = 2.9778E-7,
                   a_c1 = 8.9309E-7, a_c2 = 3.1628E-8, a_c3 = 2.1987E-10, a_d = 4.1057E-9, a_e1 = 1.6056E-10, a_e2 = 5.0484E-12;

  const double qc = p * (a_a1 + p * (a_c1 - a_e1 * p));
  const double qv = p * (a_b1 - a_d * p);
  const double dc = 1. + p * (-a_a2 + p * (a_c2 - a_e2 * p));
  const double dv = a_b2 * p;
  const double qnq = -p * (-a_a3 + p * a_c3);
  const double qn3 = -p * a_a4;

  const double tpo = tpot;
  const double qvs = qv * (sal - 35.) + qc;
  const double dvs = dv * (sal - 35.) + dc;
  double t = (tpo + qvs) / dvs;
  const double fne = -qvs + t * (dvs + t * (qnq + t * qn3)) - tpo;
  const double fst = dvs + t * (2. * qnq + 3. * qn3 * t);
  t = t - fne / fst;

  return t;
}

/* compute potential temperature from insitu temperature */
/* Ref: Gill, p. 602, Section A3.5:Potential Temperature */
static inline double
adipot(const double t, const double s, const double p)
{
  constexpr double a_a1 = 3.6504E-4, a_a2 = 8.3198E-5, a_a3 = 5.4065E-7, a_a4 = 4.0274E-9, a_b1 = 1.7439E-5, a_b2 = 2.9778E-7,
                   a_c1 = 8.9309E-7, a_c2 = 3.1628E-8, a_c3 = 2.1987E-10, a_d = 4.1057E-9, a_e1 = 1.6056E-10, a_e2 = 5.0484E-12;

  const double s_rel = s - 35.0;

  const double aa = (a_a1 + t * (a_a2 - t * (a_a3 - a_a4 * t)));
  const double bb = s_rel * (a_b1 - a_b2 * t);
  const double cc = (a_c1 + t * (-a_c2 + a_c3 * t));
  const double cc1 = a_d * s_rel;
  const double dd = (-a_e1 + a_e2 * t);

  const double tpot = t - p * (aa + bb + p * (cc - cc1 + p * dd));

  return tpot;
}

static void
calc_adisit(size_t gridsize, size_t nlevel, const Varray<double> &pressure, const FieldVector &tho, const FieldVector &sao,
            FieldVector &tis)
{
  // pressure units: hPa
  // tho units:      Celsius
  // sao units:      psu

  for (size_t levelID = 0; levelID < nlevel; ++levelID)
    {
      const auto &thovec = tho[levelID].vec_d;
      const auto &saovec = sao[levelID].vec_d;
      auto &tisvec = tis[levelID].vec_d;
      const auto tho_missval = tho[levelID].missval;
      const auto sao_missval = sao[levelID].missval;
      const auto tis_missval = tis[levelID].missval;
      for (size_t i = 0; i < gridsize; ++i)
        {
          if (DBL_IS_EQUAL(thovec[i], tho_missval) || DBL_IS_EQUAL(saovec[i], sao_missval))
            {
              tisvec[i] = tis_missval;
            }
          else
            {
              tisvec[i] = adisit_1(thovec[i], saovec[i], pressure[levelID]);
            }
        }
    }
}

static void
calc_adipot(size_t gridsize, size_t nlevel, const Varray<double> &pressure, const FieldVector &t, const FieldVector &s,
            FieldVector &tpot)
{
  // pressure units: hPa
  // t units:        Celsius
  // s units:        psu

  for (size_t levelID = 0; levelID < nlevel; ++levelID)
    {
      const auto &tvec = t[levelID].vec_d;
      const auto &svec = s[levelID].vec_d;
      auto &tpotvec = tpot[levelID].vec_d;
      const auto t_missval = t[levelID].missval;
      const auto s_missval = s[levelID].missval;
      const auto tpot_missval = tpot[levelID].missval;
      for (size_t i = 0; i < gridsize; ++i)
        {
          if (DBL_IS_EQUAL(tvec[i], t_missval) || DBL_IS_EQUAL(svec[i], s_missval))
            {
              tpotvec[i] = tpot_missval;
            }
          else
            {
              tpotvec[i] = adipot(tvec[i], svec[i], pressure[levelID]);
            }
        }
    }
}

void *
Adisit(void *process)
{
  int nrecs;
  int varID, levelID;
  int i;
  int thoID = -1, saoID = -1;
  char varname[CDI_MAX_NAME], stdname[CDI_MAX_NAME];

  cdoInitialize(process);

  const auto ADISIT = cdoOperatorAdd("adisit", 1, 1, "");
  const auto ADIPOT = cdoOperatorAdd("adipot", 1, 1, "");

  const auto operatorID = cdoOperatorID();

  const double pin = (operatorArgc() == 1) ? parameter2double(cdoOperatorArgv(0)) : -1;

  const auto streamID1 = cdoOpenRead(0);
  const auto vlistID1 = cdoStreamInqVlist(streamID1);

  const auto nvars = vlistNvars(vlistID1);

  for (varID = 0; varID < nvars; varID++)
    {
      int code = vlistInqVarCode(vlistID1, varID);
      if (code <= 0)
        {
          vlistInqVarName(vlistID1, varID, varname);
          cstrToLowerCase(varname);

          int length = CDI_MAX_NAME;
          cdiInqKeyString(vlistID1, varID, CDI_KEY_STDNAME, stdname, &length);
          cstrToLowerCase(stdname);

          if (cstrIsEqual(varname, "s") || cstrIsEqual(stdname, "sea_water_salinity"))
            code = 5;
          else if (cstrIsEqual(varname, "t"))
            code = 2;

          if (operatorID == ADISIT)
            {
              if (cstrIsEqual(stdname, "sea_water_potential_temperature")) code = 2;
            }
          else
            {
              if (cstrIsEqual(stdname, "sea_water_temperature")) code = 2;
            }
        }

      if (code == 2 || (code == 20 && operatorID == ADIPOT))
        thoID = varID;
      else if (code == 5)
        saoID = varID;
    }

  if (saoID == -1) cdoAbort("Sea water salinity not found!");
  if (thoID == -1) cdoAbort("%s temperature not found!", (operatorID == ADISIT) ? "Potential" : "Insitu");

  const auto gridID = vlistGrid(vlistID1, 0);
  const auto gridsize = vlist_check_gridsize(vlistID1);

  auto zaxisID = vlistInqVarZaxis(vlistID1, saoID);
  const auto nlevel1 = zaxisInqSize(zaxisID);
  zaxisID = vlistInqVarZaxis(vlistID1, thoID);
  const auto nlevel2 = zaxisInqSize(zaxisID);

  if (nlevel1 != nlevel2) cdoAbort("temperature and salinity have different number of levels!");
  const auto nlevel = nlevel1;

  Varray<double> pressure(nlevel);
  cdoZaxisInqLevels(zaxisID, pressure.data());

  if (pin >= 0)
    for (i = 0; i < nlevel; ++i) pressure[i] = pin;
  else
    for (i = 0; i < nlevel; ++i) pressure[i] /= 10;

  if (Options::cdoVerbose)
    {
      cdoPrint("Level Pressure");
      for (i = 0; i < nlevel; ++i) cdoPrint("%5d  %g", i + 1, pressure[i]);
    }

  FieldVector tho(nlevel), sao(nlevel), tis(nlevel);
  for (levelID = 0; levelID < nlevel; ++levelID)
    {
      tho[levelID].resize(gridsize);
      sao[levelID].resize(gridsize);
      tis[levelID].resize(gridsize);
      tho[levelID].missval = vlistInqVarMissval(vlistID1, thoID);
      sao[levelID].missval = vlistInqVarMissval(vlistID1, saoID);
      tis[levelID].missval = tho[levelID].missval;
    }

  int datatype = CDI_DATATYPE_FLT32;
  if (vlistInqVarDatatype(vlistID1, thoID) == CDI_DATATYPE_FLT64 && vlistInqVarDatatype(vlistID1, saoID) == CDI_DATATYPE_FLT64)
    datatype = CDI_DATATYPE_FLT64;

  const auto vlistID2 = vlistCreate();

  const auto tisID2 = vlistDefVar(vlistID2, gridID, zaxisID, TIME_VARYING);
  if (operatorID == ADISIT)
    {
      vlistDefVarParam(vlistID2, tisID2, cdiEncodeParam(20, 255, 255));
      cdiDefKeyString(vlistID2, tisID2, CDI_KEY_NAME, "to");
      cdiDefKeyString(vlistID2, tisID2, CDI_KEY_LONGNAME, "Sea water temperature");
      cdiDefKeyString(vlistID2, tisID2, CDI_KEY_STDNAME, "sea_water_temperature");
    }
  else
    {
      vlistDefVarParam(vlistID2, tisID2, cdiEncodeParam(2, 255, 255));
      cdiDefKeyString(vlistID2, tisID2, CDI_KEY_NAME, "tho");
      cdiDefKeyString(vlistID2, tisID2, CDI_KEY_LONGNAME, "Sea water potential temperature");
      cdiDefKeyString(vlistID2, tisID2, CDI_KEY_STDNAME, "sea_water_potential_temperature");
    }
  cdiDefKeyString(vlistID2, tisID2, CDI_KEY_UNITS, "K");
  vlistDefVarMissval(vlistID2, tisID2, tis[0].missval);
  vlistDefVarDatatype(vlistID2, tisID2, datatype);

  const auto saoID2 = vlistDefVar(vlistID2, gridID, zaxisID, TIME_VARYING);
  vlistDefVarParam(vlistID2, saoID2, cdiEncodeParam(5, 255, 255));
  cdiDefKeyString(vlistID2, saoID2, CDI_KEY_NAME, "s");
  cdiDefKeyString(vlistID2, saoID2, CDI_KEY_LONGNAME, "Sea water salinity");
  cdiDefKeyString(vlistID2, saoID2, CDI_KEY_STDNAME, "sea_water_salinity");
  cdiDefKeyString(vlistID2, saoID2, CDI_KEY_UNITS, "psu");
  vlistDefVarMissval(vlistID2, saoID2, sao[0].missval);
  vlistDefVarDatatype(vlistID2, saoID2, datatype);

  const auto taxisID1 = vlistInqTaxis(vlistID1);
  const auto taxisID2 = taxisDuplicate(taxisID1);
  vlistDefTaxis(vlistID2, taxisID2);

  const auto streamID2 = cdoOpenWrite(1);
  cdoDefVlist(streamID2, vlistID2);

  int tsID = 0;
  while ((nrecs = cdoStreamInqTimestep(streamID1, tsID)))
    {
      taxisCopyTimestep(taxisID2, taxisID1);
      cdoDefTimestep(streamID2, tsID);

      for (int recID = 0; recID < nrecs; ++recID)
        {
          cdoInqRecord(streamID1, &varID, &levelID);
          if (varID == thoID) cdoReadRecord(streamID1, tho[levelID].vec_d.data(), &tho[levelID].nmiss);
          if (varID == saoID) cdoReadRecord(streamID1, sao[levelID].vec_d.data(), &sao[levelID].nmiss);
        }

      if (operatorID == ADISIT)
        calc_adisit(gridsize, nlevel, pressure, tho, sao, tis);
      else
        calc_adipot(gridsize, nlevel, pressure, tho, sao, tis);

      for (levelID = 0; levelID < nlevel; ++levelID)
        {
          cdoDefRecord(streamID2, tisID2, levelID);
          cdoWriteRecord(streamID2, tis[levelID].vec_d.data(), fieldNumMiss(tis[levelID]));

          cdoDefRecord(streamID2, saoID2, levelID);
          cdoWriteRecord(streamID2, sao[levelID].vec_d.data(), fieldNumMiss(sao[levelID]));
        }

      tsID++;
    }

  cdoStreamClose(streamID2);
  cdoStreamClose(streamID1);

  vlistDestroy(vlistID2);

  cdoFinish();

  return nullptr;
}
