/*
  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:

      Invert     invertlat       Invert latitude
      Invert     invertlon       Invert longitude
      Invert     invertlatdes    Invert latitude description
      Invert     invertlondes    Invert longitude description
      Invert     invertlatdata   Invert latitude data
      Invert     invertlondata   Invert longitude data
*/

#include <cdi.h>

#include <utility>

#include "process_int.h"
#include "matrix_view.h"

template <typename T>
static void
invert_lon_data(Varray<T> &v, size_t nlon, size_t nlat)
{
  if (nlat > 0 && nlon > 0)
  {
    Varray<T> vtmp(nlon);
    MatrixView<T> mv(v.data(), nlat, nlon);

    for (size_t ilat = 0; ilat < nlat; ilat++)
    {
      for (size_t ilon = 0; ilon < nlon; ilon++) vtmp[ilon] = mv[ilat][ilon];
      for (size_t ilon = 0; ilon < nlon / 2; ilon++) std::swap(vtmp[ilon], vtmp[nlon - ilon - 1]);
      for (size_t ilon = 0; ilon < nlon; ilon++) mv[ilat][ilon] = vtmp[ilon];
    }
  }
}

static void
invert_lon_data(Field &field)
{
  auto nlon = gridInqXsize(field.grid);
  auto nlat = gridInqYsize(field.grid);
  auto func = [&](auto &v) { invert_lon_data(v, nlon, nlat); };
  field_operation(func, field);
}

template <typename T>
static void
invert_lat_data(Varray<T> &v, size_t nlon, size_t nlat)
{
  if (nlat > 0 && nlon > 0)
  {
    Varray<T> vtmp(nlon);
    MatrixView<T> mv(v.data(), nlat, nlon);

    for (size_t ilat = 0; ilat < nlat / 2; ilat++)
    {
      for (size_t ilon = 0; ilon < nlon; ilon++) vtmp[ilon] = mv[ilat][ilon];
      for (size_t ilon = 0; ilon < nlon; ilon++) mv[ilat][ilon] = mv[nlat - ilat - 1][ilon];
      for (size_t ilon = 0; ilon < nlon; ilon++) mv[nlat - ilat - 1][ilon] = vtmp[ilon];
    }
  }
}

static void
invert_lat_data(Field &field)
{
  auto nlon = gridInqXsize(field.grid);
  auto nlat = gridInqYsize(field.grid);
  auto func = [&](auto &v) { invert_lat_data(v, nlon, nlat); };
  field_operation(func, field);
}

static void
invert_lon_des(int vlistID)
{
  auto numGrids = vlistNumGrids(vlistID);
  for (int index = 0; index < numGrids; ++index)
  {
    auto gridID1 = vlistGrid(vlistID, index);
    auto gridID2 = gridDuplicate(gridID1);

    auto gridtype = gridInqType(gridID1);

    if (!(gridtype == GRID_GENERIC || gridtype == GRID_GAUSSIAN || gridtype == GRID_PROJECTION || gridtype == GRID_LONLAT
          || gridtype == GRID_CURVILINEAR))
      cdo_abort("Unsupported gridtype: %s!", gridNamePtr(gridtype));

    if (gridInqXvals(gridID1, nullptr))
    {
      auto nlon = gridInqXsize(gridID1);
      auto nlat = gridInqYsize(gridID1);
      auto size = (gridtype == GRID_CURVILINEAR) ? nlon * nlat : nlon;

      Varray<double> coords(size);

      if (gridtype == GRID_CURVILINEAR)
      {
        gridInqXvals(gridID1, coords.data());
        invert_lon_data(coords, nlon, nlat);
        gridDefXvals(gridID2, coords.data());

        if (gridInqYvals(gridID1, nullptr))
        {
          gridInqYvals(gridID1, coords.data());
          invert_lon_data(coords, nlon, nlat);
          gridDefYvals(gridID2, coords.data());
        }
      }
      else
      {
        gridInqXvals(gridID1, coords.data());
        for (size_t ilon = 0; ilon < nlon / 2; ilon++) std::swap(coords[ilon], coords[nlon - ilon - 1]);
        gridDefXvals(gridID2, coords.data());
      }
    }

    if (gridInqXbounds(gridID1, nullptr))
    {
      auto nlon = gridInqXsize(gridID1);
      auto nlat = gridInqYsize(gridID1);
      auto nv = gridInqNvertex(gridID1);
      auto size = (gridtype == GRID_CURVILINEAR) ? nv * nlon * nlat : nv * nlon;

      Varray<double> bounds(size);

      if (gridtype == GRID_CURVILINEAR)
      {
        gridInqXbounds(gridID1, bounds.data());
        invert_lon_data(bounds, nlon * nv, nlat);
        gridDefXbounds(gridID2, bounds.data());

        if (gridInqYbounds(gridID1, nullptr))
        {
          gridInqYbounds(gridID1, bounds.data());
          invert_lon_data(bounds, nlon * nv, nlat);
          gridDefYbounds(gridID2, bounds.data());
        }
      }
      else
      {
        gridInqXbounds(gridID1, bounds.data());
        for (size_t ilon = 0; ilon < nlon / 2; ilon++)
        {
          std::swap(bounds[nlon * 2 - ilon * 2 - 1], bounds[ilon * 2]);
          std::swap(bounds[nlon * 2 - ilon * 2 - 2], bounds[ilon * 2 + 1]);
        }
        gridDefXbounds(gridID2, bounds.data());
      }
    }

    vlistChangeGrid(vlistID, gridID1, gridID2);
  }
}

static void
invert_lat_coord(int gridID)
{
  auto gridtype = gridInqType(gridID);

  if (gridInqYvals(gridID, nullptr))
  {
    auto nlon = gridInqXsize(gridID);
    auto nlat = gridInqYsize(gridID);
    auto size = (gridtype == GRID_CURVILINEAR) ? nlon * nlat : nlat;

    Varray<double> coords(size);

    if (gridtype == GRID_CURVILINEAR)
    {
      if (gridInqXvals(gridID, nullptr))
      {
        gridInqXvals(gridID, coords.data());
        invert_lat_data(coords, nlon, nlat);
        gridDefXvals(gridID, coords.data());
      }

      gridInqYvals(gridID, coords.data());
      invert_lat_data(coords, nlon, nlat);
      gridDefYvals(gridID, coords.data());
    }
    else
    {
      gridInqYvals(gridID, coords.data());
      for (size_t ilat = 0; ilat < nlat / 2; ilat++) std::swap(coords[ilat], coords[nlat - ilat - 1]);
      gridDefYvals(gridID, coords.data());
    }
  }

  if (gridInqYbounds(gridID, nullptr))
  {
    auto nlon = gridInqXsize(gridID);
    auto nlat = gridInqYsize(gridID);
    auto nv = gridInqNvertex(gridID);
    auto size = (gridtype == GRID_CURVILINEAR) ? nv * nlon * nlat : nv * nlat;

    Varray<double> bounds(size);

    if (gridtype == GRID_CURVILINEAR)
    {
      if (gridInqXbounds(gridID, nullptr))
      {
        gridInqXbounds(gridID, bounds.data());
        invert_lat_data(bounds, nlon * nv, nlat);
        gridDefXbounds(gridID, bounds.data());
      }

      gridInqYbounds(gridID, bounds.data());
      invert_lat_data(bounds, nlon * nv, nlat);
      gridDefYbounds(gridID, bounds.data());
    }
    else
    {
      gridInqYbounds(gridID, bounds.data());
      for (size_t ilat = 0; ilat < nlat / 2; ilat++)
      {
        std::swap(bounds[nlat * 2 - ilat * 2 - 1], bounds[ilat * 2]);
        std::swap(bounds[nlat * 2 - ilat * 2 - 2], bounds[ilat * 2 + 1]);
      }
      gridDefYbounds(gridID, bounds.data());
    }
  }
}

static void
invert_lat_des(int vlistID)
{
  auto numGrids = vlistNumGrids(vlistID);
  for (int index = 0; index < numGrids; ++index)
  {
    auto gridID1 = vlistGrid(vlistID, index);
    auto gridID2 = gridDuplicate(gridID1);

    auto gridtype = gridInqType(gridID1);

    if (!(gridtype == GRID_GENERIC || gridtype == GRID_GAUSSIAN || gridtype == GRID_PROJECTION || gridtype == GRID_LONLAT
          || gridtype == GRID_CURVILINEAR))
      cdo_abort("Unsupported gridtype: %s!", gridNamePtr(gridtype));

    invert_lat_coord(gridID2);

    auto projID = gridInqProj(gridID2);
    if (projID != CDI_UNDEFID) invert_lat_coord(projID);

    vlistChangeGrid(vlistID, gridID1, gridID2);
  }
}

class Invert : public Process
{
  enum
  {
    func_fld,
    func_all,
    func_hrd,
    func_lon,
    func_lat
  };

public:
  using Process::Process;
  inline static CdoModule module = {
    .name = "Invert",
    .operators = { { "invertlat", func_all, func_lat, InvertHelp },
                   { "invertlon", func_all, func_lon, InvertHelp },
                   { "invertlatdes", func_hrd, func_lat, InvertHelp },
                   { "invertlondes", func_hrd, func_lon, InvertHelp },
                   { "invertlatdata", func_fld, func_lat, InvertHelp },
                   { "invertlondata", func_fld, func_lon, InvertHelp } },
    .aliases = {},
    .mode = EXPOSED,     // Module mode: 0:intern 1:extern
    .number = CDI_REAL,  // Allowed number type
    .constraints = { 1, 1, NoRestriction },
  };
  inline static RegisterEntry<Invert> registration = RegisterEntry<Invert>(module);

  CdoStreamID streamID1{};
  CdoStreamID streamID2{};

  int taxisID1{ CDI_UNDEFID };
  int taxisID2{ CDI_UNDEFID };

  int operfunc1{};
  int operfunc2{};

  VarList varList1{};

public:
  void
  init() override
  {
    auto operatorID = cdo_operator_id();
    operfunc1 = cdo_operator_f1(operatorID);
    operfunc2 = cdo_operator_f2(operatorID);

    operator_check_argc(0);

    streamID1 = cdo_open_read(0);

    auto vlistID1 = cdo_stream_inq_vlist(streamID1);
    auto vlistID2 = vlistDuplicate(vlistID1);

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

    if (operfunc1 == func_all || operfunc1 == func_hrd)
    {
      if (operfunc2 == func_lat)
        invert_lat_des(vlistID2);
      else
        invert_lon_des(vlistID2);
    }

    streamID2 = cdo_open_write(1);

    cdo_def_vlist(streamID2, vlistID2);

    varList1 = VarList(vlistID1);
  }

  void
  run() override
  {
    Field field;

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

      cdo_taxis_copy_timestep(taxisID2, taxisID1);

      cdo_def_timestep(streamID2, tsID);

      for (int fieldID = 0; fieldID < numFields; ++fieldID)
      {
        auto [varID, levelID] = cdo_inq_field(streamID1);
        field.init(varList1.vars[varID]);
        cdo_read_field(streamID1, field);

        cdo_def_field(streamID2, varID, levelID);

        if (operfunc1 == func_all || operfunc1 == func_fld)
        {
          if (operfunc2 == func_lat)
            invert_lat_data(field);
          else
            invert_lon_data(field);

          cdo_write_field(streamID2, field);
        }
        else { cdo_write_field(streamID2, field); }
      }

      tsID++;
    }
  }

  void
  close() override
  {
    cdo_stream_close(streamID2);
    cdo_stream_close(streamID1);
  }
};
