odm/include/ncsimple.h

#pragma once
#include "nczarrcommon.h"
#include <netcdf.h>
#include <variant>

class NCSimpleTypes: public NcZarrTypes
{
 protected:
 template<class VType> class ReadedData
 {
  using Vec = std::vector<size_t>;

  private:
  std::unique_ptr<VType[]> data;

  public:
  ReadedData() = default;

  ReadedData(std::unique_ptr<VType[]>&& d): data(std::move(d)) {}

  VType operator()(size_t lini) const { return data[lini]; }
 };
};

class NCSimpleFunctions: public NCSimpleTypes
{
 int ncid;

 RetVal<std::vector<Attribute>> ReadAtts(int vid) const;

 protected:
 NCSimpleFunctions(): ncid(0) {}

 template<class VType> RetVal<ReadedData<VType>> Read(const MString& var, const size_t* start, const size_t* count) const
 {
  static const MString pref = "NCSimpleFunctions::Read";

  size_t       ind = FindInd(var, vars);
  const size_t N   = vars[ind].NDim();

  std::unique_ptr<VType[]> cdata;

  size_t dsize = 1;
  for(size_t i = 0; i < N; i++) dsize *= count[i];
  cdata.reset(new VType[dsize]);

  int vid;
  int res = nc_inq_varid(ncid, var.Buf(), &vid);
  if(res != NC_NOERR) return Error(pref, MString("nc_inq_varid error: ") + nc_strerror(res));

  if constexpr(std::is_same_v<VType, float>)
   res = nc_get_vara_float(ncid, vid, start, count, cdata.get());
  else if constexpr(std::is_same_v<VType, double>)
   res = nc_get_vara_double(ncid, vid, start, count, cdata.get());
  else if constexpr(std::is_same_v<VType, int>)
   res = nc_get_vara_int(ncid, vid, start, count, cdata.get());
  else if constexpr(std::is_same_v<VType, long>)
   res = nc_get_vara_long(ncid, vid, start, count, cdata.get());
  else if constexpr(std::is_same_v<VType, long long>)
   res = nc_get_vara_longlong(ncid, vid, start, count, cdata.get());
  else if constexpr(std::is_same_v<VType, short>)
   res = nc_get_vara_short(ncid, vid, start, count, cdata.get());
  else if constexpr(std::is_same_v<VType, signed char>)
   res = nc_get_vara_schar(ncid, vid, start, count, cdata.get());
  else if constexpr(std::is_same_v<VType, unsigned int>)
   res = nc_get_vara_uint(ncid, vid, start, count, cdata.get());
  else if constexpr(std::is_same_v<VType, unsigned long long>)
   res = nc_get_vara_ulonglong(ncid, vid, start, count, cdata.get());
  else if constexpr(std::is_same_v<VType, unsigned short>)
   res = nc_get_vara_ushort(ncid, vid, start, count, cdata.get());
  else if constexpr(std::is_same_v<VType, unsigned char>)
   res = nc_get_vara_ubyte(ncid, vid, start, count, cdata.get());
  else
   return Error(pref, "Unsupported variable type");

  if(res != NC_NOERR) return Error(pref, MString("nc_get_vara error: ") + nc_strerror(res));

  return ReadedData<VType>(std::move(cdata));
 }

 public:
 ~NCSimpleFunctions() { nc_close(ncid); }

 Error Open(const MString& filename);
};

using NCSimple = NcZarrRead<NCSimpleFunctions>;