/*
  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:

      Rhopot      rhopot          potential density
*/

#include <algorithm>
#include <cdi.h>

#include "cdo_options.h"
#include "process_int.h"
#include "cdo_vlist.h"
#include "param_conversion.h"
#include <mpim_grid.h>
#include "util_string.h"
#include "cdo_zaxis.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 density from insitu temperature */
static double
potrho_1(const double t, const double sal, const double p)
{
  // clang-format off
  constexpr double r_a0 = 999.842594, r_a1 = 6.793952e-2, r_a2 = -9.095290e-3,
         r_a3 = 1.001685e-4, r_a4 = -1.120083e-6, r_a5 = 6.536332e-9,
         r_b0 = 8.24493e-1, r_b1 = -4.0899e-3, r_b2 = 7.6438e-5,
         r_b3 = -8.2467e-7, r_b4 = 5.3875e-9,
         r_c0 = -5.72466e-3, r_c1 = 1.0227e-4, r_c2 = -1.6546e-6,
         r_d0 = 4.8314e-4,
         r_e0 = 19652.21, r_e1 = 148.4206, r_e2 = -2.327105,
         r_e3 = 1.360477e-2, r_e4 = -5.155288e-5,
         r_f0 = 54.6746, r_f1 = -0.603459, r_f2 = 1.09987e-2,
         r_f3 = -6.1670e-5,
         r_g0 = 7.944e-2, r_g1 = 1.6483e-2, r_g2 = -5.3009e-4,
         r_h0 = 3.239908, r_h1 = 1.43713e-3, r_h2 = 1.16092e-4,
         r_h3 = -5.77905e-7,
         r_ai0 = 2.2838e-3, r_ai1 = -1.0981e-5, r_ai2 = -1.6078e-6,
         r_aj0 = 1.91075e-4,
         r_ak0 = 8.50935e-5, r_ak1 = -6.12293e-6, r_ak2 = 5.2787e-8,
         r_am0 = -9.9348e-7, r_am1 = 2.0816e-8, r_am2 = 9.1697e-10;

  double s = std::max(sal, 0.0);
  double s3h = std::sqrt(s*s*s);

  double rho = (r_a0 + t * (r_a1 + t * (r_a2 + t * (r_a3 + t * (r_a4 + t * r_a5))))
            + s * (r_b0 + t * (r_b1 + t * (r_b2 + t * (r_b3 + t * r_b4))))    
            + r_d0 * s*s                 
            + s3h * (r_c0 + t * (r_c1 + r_c2 * t)))                           
           / (1.                                                            
             - p / (p * (r_h0 + t * (r_h1 + t * (r_h2 + t * r_h3))            
                         + s * (r_ai0 + t * (r_ai1 + r_ai2 * t))              
                         + r_aj0 * s3h                                        
                         + (r_ak0 + t * (r_ak1 + t * r_ak2)                   
                         + s * (r_am0 + t * (r_am1 + t * r_am2))) * p)        
                    + r_e0 + t * (r_e1 + t * (r_e2 + t * (r_e3 + t * r_e4)))  
                    + s * (r_f0 + t * (r_f1 + t * (r_f2 + t * r_f3)))         
                    + s3h * (r_g0 + t * (r_g1 + r_g2 * t))));
  // clang-format on
  return rho;
}

/*
#define N 4
int main (int argc, char *argv[])
{
  int i;
  {
    double p    = 0;
    double t[N] = {22, 25, 28, 31};
    double s[N] = {35, 35, 35, 35};
    double x[N] = {24.219, 23.343, 22.397, 21.384};
    double r[N];

    potrho_1d(t, s, p, r, N);

    for ( i = 0; i < N; ++i )
      printf("%d %5g %3g %8g %8g %8g %10.3f\n", i, p, s[i], t[i], x[i], r[i],
r[i]-x[i]);
  }

  {
    double p    = 300;
    double t[N] = {-2.140, -0.186, 1.771, 3.728};
    double s[N] = {35, 35, 35, 35};
    double x[N] = {42.191, 41.941, 41.649, 41.319};
    double r[N];

    potrho_1d(t, s, p, r, N);

    for ( i = 0; i < N; ++i )
      printf("%d %5g %3g %8g %8g %8g %10.3f\n", i, p, s[i], t[i], x[i], r[i],
r[i]-x[i]);
  }

  return 0;
}
*/

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

  for (size_t levelID = 0; levelID < nlevel; ++levelID)
    {
      const auto &tovec = to[levelID].vec_d;
      const auto &saovec = sao[levelID].vec_d;
      auto &rhovec = rho[levelID].vec_d;
      const auto to_missval = to[levelID].missval;
      const auto sao_missval = sao[levelID].missval;
      const auto rho_missval = rho[levelID].missval;
      for (size_t i = 0; i < gridsize; ++i)
        {
          if (DBL_IS_EQUAL(tovec[i], to_missval) || DBL_IS_EQUAL(saovec[i], sao_missval))
            {
              rhovec[i] = rho_missval;
            }
          else
            {
              rhovec[i] = potrho_1(tovec[i], saovec[i], pressure[levelID]);
            }
        }
    }
}

void *
Rhopot(void *process)
{
  int nrecs;
  int varID, levelID;
  int zaxisID;
  int toID = -1, saoID = -1, thoID = -1;
  char varname[CDI_MAX_NAME], stdname[CDI_MAX_NAME];
  double pin = -1;

  cdoInitialize(process);

  if (operatorArgc() == 1) pin = parameter2double(cdoOperatorArgv(0));

  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, "to"))
            code = 20;
          else if (cstrIsEqual(varname, "sao"))
            code = 5;
          else if (cstrIsEqual(varname, "tho"))
            code = 2;
          else if (cstrIsEqual(varname, "s"))
            code = 5;
          else if (cstrIsEqual(varname, "t"))
            code = 2;
          else if (cstrIsEqual(stdname, "sea_water_salinity"))
            code = 5;
          else if (cstrIsEqual(stdname, "sea_water_potential_temperature"))
            code = 2;
        }

      if (code == 20)
        toID = varID;
      else if (code == 5)
        saoID = varID;
      else if (code == 2)
        thoID = varID;
    }

  if (saoID == -1) cdoAbort("Sea water salinity not found!");
  if (toID == -1 && thoID != -1)
    {
      cdoPrint("Use the CDO operator 'adisit' to convert potential temperature to In-situ temperature.");
      cdoPrint("Here is an example:");
      cdoPrint("   cdo rhopot -adisit %s %s", cdoGetStreamName(0), cdoGetStreamName(1));
    }
  if (toID == -1) cdoAbort("In-situ temperature not found!");

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

  zaxisID = vlistInqVarZaxis(vlistID1, saoID);
  const auto nlevel1 = zaxisInqSize(zaxisID);
  zaxisID = vlistInqVarZaxis(vlistID1, toID);
  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 (int i = 0; i < nlevel; ++i) pressure[i] = pin;
  else
    for (int i = 0; i < nlevel; ++i) pressure[i] /= 10;

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

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

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

  const auto vlistID2 = vlistCreate();
  varID = vlistDefVar(vlistID2, gridID, zaxisID, TIME_VARYING);
  vlistDefVarParam(vlistID2, varID, cdiEncodeParam(18, 255, 255));
  cdiDefKeyString(vlistID2, varID, CDI_KEY_NAME, "rhopoto");
  cdiDefKeyString(vlistID2, varID, CDI_KEY_LONGNAME, "Sea water potential density");
  cdiDefKeyString(vlistID2, varID, CDI_KEY_STDNAME, "sea_water_potential_density");
  cdiDefKeyString(vlistID2, varID, CDI_KEY_UNITS, "kg m-3");
  vlistDefVarMissval(vlistID2, varID, rho[0].missval);
  vlistDefVarDatatype(vlistID2, varID, 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 == toID) cdoReadRecord(streamID1, to[levelID].vec_d.data(), &to[levelID].nmiss);
          if (varID == saoID) cdoReadRecord(streamID1, sao[levelID].vec_d.data(), &sao[levelID].nmiss);
        }

      calc_rhopot(gridsize, nlevel, pressure, to, sao, rho);

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

      tsID++;
    }

  cdoStreamClose(streamID2);
  cdoStreamClose(streamID1);

  vlistDestroy(vlistID2);

  cdoFinish();

  return nullptr;
}
