/*
  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:

      Timselstat    timselrange        Time selection range
      Timselstat    timselmin          Time selection minimum
      Timselstat    timselmax          Time selection maximum
      Timselstat    timselsum          Time selection sum
      Timselstat    timselmean         Time selection mean
      Timselstat    timselavg          Time selection average
      Timselstat    timselvar          Time selection variance
      Timselstat    timselvar1         Time selection variance [Normalize by (n-1)]
      Timselstat    timselstd          Time selection standard deviation
      Timselstat    timselstd1         Time selection standard deviation [Normalize by (n-1)]
*/

#include <cdi.h>

#include "cdo_options.h"
#include "functs.h"
#include "process_int.h"
#include "param_conversion.h"
#include "datetime.h"

static void
addOperators(void)
{
  // clang-format off
  cdoOperatorAdd("timselrange", func_range, 0, nullptr);
  cdoOperatorAdd("timselmin",   func_min,   0, nullptr);
  cdoOperatorAdd("timselmax",   func_max,   0, nullptr);
  cdoOperatorAdd("timselsum",   func_sum,   0, nullptr);
  cdoOperatorAdd("timselmean",  func_mean,  0, nullptr);
  cdoOperatorAdd("timselavg",   func_avg,   0, nullptr);
  cdoOperatorAdd("timselvar",   func_var,   0, nullptr);
  cdoOperatorAdd("timselvar1",  func_var1,  0, nullptr);
  cdoOperatorAdd("timselstd",   func_std,   0, nullptr);
  cdoOperatorAdd("timselstd1",  func_std1,  0, nullptr);
  // clang-format on
}

void *
Timselstat(void *process)
{
  TimeStat timestat_date = TimeStat::MEAN;
  int nrecs = 0;
  int tsID;
  int nsets;

  cdoInitialize(process);

  addOperators();

  const auto operatorID = cdoOperatorID();
  const auto operfunc = cdoOperatorF1(operatorID);

  const bool lrange = operfunc == func_range;
  const bool lmean = operfunc == func_mean || operfunc == func_avg;
  const bool lstd = operfunc == func_std || operfunc == func_std1;
  const bool lvarstd = operfunc == func_std || operfunc == func_var || operfunc == func_std1 || operfunc == func_var1;
  const int divisor = operfunc == func_std1 || operfunc == func_var1;

  operatorInputArg("nsets <noffset <nskip>>");

  const auto nargc = operatorArgc();
  const auto ndates = parameter2int(cdoOperatorArgv(0));
  const auto noffset = (nargc > 1) ? parameter2int(cdoOperatorArgv(1)) : 0;
  const auto nskip = (nargc > 2) ? parameter2int(cdoOperatorArgv(2)) : 0;
  const bool lvars2 = lvarstd || lrange;

  if (Options::cdoVerbose) cdoPrint("nsets = %d, noffset = %d, nskip = %d", ndates, noffset, nskip);

  const auto streamID1 = cdoOpenRead(0);

  const auto vlistID1 = cdoStreamInqVlist(streamID1);
  const auto vlistID2 = vlistDuplicate(vlistID1);

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

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

  const auto maxrecs = vlistNrecs(vlistID1);
  std::vector<RecordInfo> recList(maxrecs);

  DateTimeList dtlist;
  dtlist.setStat(timestat_date);
  dtlist.setCalendar(taxisInqCalendar(taxisID1));

  const auto gridsizemax = vlistGridsizeMax(vlistID1);

  Field field;
  field.resize(gridsizemax);

  FieldVector2D samp1, vars1, vars2;
  fieldsFromVlist(vlistID1, samp1);
  fieldsFromVlist(vlistID1, vars1, FIELD_VEC);
  if (lvars2) fieldsFromVlist(vlistID1, vars2, FIELD_VEC);

  for (tsID = 0; tsID < noffset; tsID++)
    {
      nrecs = cdoStreamInqTimestep(streamID1, tsID);
      if (nrecs == 0) break;

      for (int recID = 0; recID < nrecs; recID++)
        {
          int varID, levelID;
          cdoInqRecord(streamID1, &varID, &levelID);

          if (tsID == 0)
            {
              recList[recID].varID = varID;
              recList[recID].levelID = levelID;
              recList[recID].lconst = vlistInqVarTimetype(vlistID1, varID) == TIME_CONSTANT;
            }
        }
    }

  int otsID = 0;
  if (tsID < noffset)
    {
      cdoWarning("noffset is larger than number of timesteps!");
      goto LABEL_END;
    }

  while (true)
    {
      for (nsets = 0; nsets < ndates; nsets++)
        {
          nrecs = cdoStreamInqTimestep(streamID1, tsID);
          if (nrecs == 0) break;

          dtlist.taxisInqTimestep(taxisID1, nsets);

          for (int recID = 0; recID < nrecs; recID++)
            {
              int varID, levelID;
              cdoInqRecord(streamID1, &varID, &levelID);

              if (tsID == 0)
                {
                  recList[recID].varID = varID;
                  recList[recID].levelID = levelID;
                  recList[recID].lconst = vlistInqVarTimetype(vlistID1, varID) == TIME_CONSTANT;
                }

              auto &rsamp1 = samp1[varID][levelID];
              auto &rvars1 = vars1[varID][levelID];

              const auto fieldsize = rvars1.size;

              if (nsets == 0)
                {
                  cdoReadRecord(streamID1, rvars1.vec_d.data(), &rvars1.nmiss);
                  if (lrange)
                    {
                      vars2[varID][levelID].nmiss = rvars1.nmiss;
                      vars2[varID][levelID].vec_d = rvars1.vec_d;
                    }

                  if (rvars1.nmiss || !rsamp1.empty())
                    {
                      if (rsamp1.empty()) rsamp1.resize(fieldsize);

                      for (size_t i = 0; i < fieldsize; i++) rsamp1.vec_d[i] = !DBL_IS_EQUAL(rvars1.vec_d[i], rvars1.missval);
                    }
                }
              else
                {
                  cdoReadRecord(streamID1, field.vec_d.data(), &field.nmiss);
                  field.grid = rvars1.grid;
                  field.missval = rvars1.missval;

                  if (field.nmiss || !rsamp1.empty())
                    {
                      if (rsamp1.empty()) rsamp1.resize(fieldsize, nsets);

                      for (size_t i = 0; i < fieldsize; i++)
                        if (!DBL_IS_EQUAL(field.vec_d[i], rvars1.missval)) rsamp1.vec_d[i]++;
                    }

                  if (lvarstd)
                    {
                      vfarsumq(vars2[varID][levelID], field);
                      vfarsum(rvars1, field);
                    }
                  else if (lrange)
                    {
                      vfarmin(vars2[varID][levelID], field);
                      vfarmax(rvars1, field);
                    }
                  else
                    {
                      vfarfun(rvars1, field, operfunc);
                    }
                }
            }

          if (nsets == 0 && lvarstd)
            for (int recID = 0; recID < maxrecs; recID++)
              {
                if (recList[recID].lconst) continue;

                const auto varID = recList[recID].varID;
                const auto levelID = recList[recID].levelID;
                vfarmoq(vars2[varID][levelID], vars1[varID][levelID]);
              }

          tsID++;
        }

      if (nrecs == 0 && nsets == 0) break;

      for (int recID = 0; recID < maxrecs; recID++)
        {
          if (recList[recID].lconst) continue;

          const auto varID = recList[recID].varID;
          const auto levelID = recList[recID].levelID;
          auto &rsamp1 = samp1[varID][levelID];
          auto &rvars1 = vars1[varID][levelID];

          if (lmean)
            {
              if (!rsamp1.empty())
                vfardiv(rvars1, rsamp1);
              else
                vfarcdiv(rvars1, (double) nsets);
            }
          else if (lvarstd)
            {
              auto &rvars2 = vars2[varID][levelID];
              if (!rsamp1.empty())
                {
                  if (lstd)
                    vfarstd(rvars1, rvars2, rsamp1, divisor);
                  else
                    vfarvar(rvars1, rvars2, rsamp1, divisor);
                }
              else
                {
                  if (lstd)
                    vfarcstd(rvars1, rvars2, nsets, divisor);
                  else
                    vfarcvar(rvars1, rvars2, nsets, divisor);
                }
            }
          else if (lrange)
            {
              auto &rvars2 = vars2[varID][levelID];
              vfarsub(rvars1, rvars2);
            }
        }

      dtlist.statTaxisDefTimestep(taxisID2, nsets);
      cdoDefTimestep(streamID2, otsID);

      for (int recID = 0; recID < maxrecs; recID++)
        {
          if (otsID && recList[recID].lconst) continue;

          const auto varID = recList[recID].varID;
          const auto levelID = recList[recID].levelID;
          auto &rvars1 = vars1[varID][levelID];

          cdoDefRecord(streamID2, varID, levelID);
          cdoWriteRecord(streamID2, rvars1.vec_d.data(), rvars1.nmiss);
        }

      if (nrecs == 0) break;
      otsID++;

      for (int i = 0; i < nskip; i++)
        {
          nrecs = cdoStreamInqTimestep(streamID1, tsID);
          if (nrecs == 0) break;
          tsID++;
        }

      if (nrecs == 0) break;
    }

LABEL_END:

  cdoStreamClose(streamID2);
  cdoStreamClose(streamID1);

  cdoFinish();

  return nullptr;
}
