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

  Author: Uwe Schulzweida

*/

/*
   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 zaxisID;
  int toID = -1, saoID = -1, thoID = -1;
  char varname[CDI_MAX_NAME], stdname[CDI_MAX_NAME];
  double pin = -1;

  cdo_initialize(process);

  if (cdo_operator_argc() == 1) pin = parameter_to_double(cdo_operator_argv(0));

  const auto streamID1 = cdo_open_read(0);
  const auto vlistID1 = cdo_stream_inq_vlist(streamID1);

  const auto nvars = vlistNvars(vlistID1);

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

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

          // clang-format off
          if      (cdo_cmpstr(varname, "to")) code = 20;
          else if (cdo_cmpstr(varname, "sao")) code = 5;
          else if (cdo_cmpstr(varname, "tho")) code = 2;
          else if (cdo_cmpstr(varname, "s")) code = 5;
          else if (cdo_cmpstr(varname, "t")) code = 2;
          else if (cdo_cmpstr(stdname, "sea_water_salinity")) code = 5;
          else if (cdo_cmpstr(stdname, "sea_water_potential_temperature")) code = 2;
          // clang-format on
        }

      // clang-format off
      if      (code == 20) toID = varID;
      else if (code == 5) saoID = varID;
      else if (code == 2) thoID = varID;
      // clang-format on
    }

  if (saoID == -1) cdo_abort("Sea water salinity not found!");
  if (toID == -1 && thoID != -1)
    {
      cdo_print("Use the CDO operator 'adisit' to convert potential temperature to In-situ temperature.");
      cdo_print("Here is an example:");
      cdo_print("   cdo rhopot -adisit %s %s", cdo_get_stream_name(0), cdo_get_stream_name(1));
    }
  if (toID == -1) cdo_abort("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) cdo_abort("temperature and salinity have different number of levels!");
  const auto nlevel = nlevel1;

  Varray<double> pressure(nlevel);
  cdo_zaxis_inq_levels(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)
    {
      cdo_print("Level Pressure");
      for (int i = 0; i < nlevel; ++i) cdo_print("%5d  %g", i + 1, pressure[i]);
    }

  FieldVector to(nlevel), sao(nlevel), rho(nlevel);
  for (int 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();
  vlistDefNtsteps(vlistID2, vlistNtsteps(vlistID1));

  const auto varID2 = vlistDefVar(vlistID2, gridID, zaxisID, TIME_VARYING);
  vlistDefVarParam(vlistID2, varID2, cdiEncodeParam(18, 255, 255));
  cdiDefKeyString(vlistID2, varID2, CDI_KEY_NAME, "rhopoto");
  cdiDefKeyString(vlistID2, varID2, CDI_KEY_LONGNAME, "Sea water potential density");
  cdiDefKeyString(vlistID2, varID2, CDI_KEY_STDNAME, "sea_water_potential_density");
  cdiDefKeyString(vlistID2, varID2, CDI_KEY_UNITS, "kg m-3");
  vlistDefVarMissval(vlistID2, varID2, rho[0].missval);
  vlistDefVarDatatype(vlistID2, varID2, datatype);

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

  const auto streamID2 = cdo_open_write(1);
  cdo_def_vlist(streamID2, vlistID2);

  int tsID = 0;
  while (true)
    {
      const auto nrecs = cdo_stream_inq_timestep(streamID1, tsID);
      if (nrecs == 0) break;

      cdo_taxis_copy_timestep(taxisID2, taxisID1);
      cdo_def_timestep(streamID2, tsID);

      for (int recID = 0; recID < nrecs; ++recID)
        {
          int varID, levelID;
          cdo_inq_record(streamID1, &varID, &levelID);
          if (varID == toID) cdo_read_record(streamID1, to[levelID].vec_d.data(), &to[levelID].nmiss);
          if (varID == saoID) cdo_read_record(streamID1, sao[levelID].vec_d.data(), &sao[levelID].nmiss);
        }

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

      for (int levelID = 0; levelID < nlevel; ++levelID)
        {
          cdo_def_record(streamID2, 0, levelID);
          cdo_write_record(streamID2, rho[levelID].vec_d.data(), field_num_miss(rho[levelID]));
        }

      tsID++;
    }

  cdo_stream_close(streamID2);
  cdo_stream_close(streamID1);

  vlistDestroy(vlistID2);

  cdo_finish();

  return nullptr;
}
