QGIS/external/mdal/frmts/mdal_netcdf.hpp

/*
 MDAL - Mesh Data Abstraction Library (MIT License)
 Copyright (C) 2018 Peter Petrik (zilolv at gmail dot com)
*/

#ifndef MDAL_NETCDF_HPP
#define MDAL_NETCDF_HPP

#include <string>
#include <vector>
#include <assert.h>
#include <netcdf.h>
#include "mdal_utils.hpp"
#include "mdal.h"

class NetCDFFile
{
  public:
    NetCDFFile(): mNcid( 0 ) {}
    ~NetCDFFile()
    {
      if ( mNcid != 0 ) nc_close( mNcid );
    }

    int handle() const
    {
      return mNcid;
    }

    int openFile( const std::string &fileName )
    {
      int ncid = 0;
      int res = nc_open( fileName.c_str(), NC_NOWRITE, &mNcid );
      if ( res != NC_NOERR )
      {
        //qDebug("error: %s", nc_strerror(res));
        throw MDAL_Status::Err_UnknownFormat;
      }
      return ncid;
    }

    bool hasVariable( const std::string &name ) const
    {
      assert( mNcid != 0 );
      int varid;
      return ( nc_inq_varid( mNcid, name.c_str(), &varid ) == NC_NOERR );
    }

    std::vector<int> readIntArr( const std::string &name, size_t dim ) const
    {
      assert( mNcid != 0 );
      int arr_id;
      if ( nc_inq_varid( mNcid, name.c_str(), &arr_id ) != NC_NOERR )
      {
        throw MDAL_Status::Err_UnknownFormat;
      }
      std::vector<int> arr_val( dim );
      if ( nc_get_var_int( mNcid, arr_id, arr_val.data() ) != NC_NOERR )
      {
        throw MDAL_Status::Err_UnknownFormat;
      }
      return arr_val;
    }


    std::vector<double> readDoubleArr( const std::string &name, size_t dim ) const
    {
      assert( mNcid != 0 );

      int arr_id;
      if ( nc_inq_varid( mNcid, name.c_str(), &arr_id ) != NC_NOERR )
      {
        throw MDAL_Status::Err_UnknownFormat;
      }
      std::vector<double> arr_val( dim );
      if ( nc_get_var_double( mNcid, arr_id, arr_val.data() ) != NC_NOERR )
      {
        throw MDAL_Status::Err_UnknownFormat;
      }
      return arr_val;
    }


    int getAttrInt( const std::string &name, const std::string &attr_name ) const
    {
      assert( mNcid != 0 );

      int arr_id;
      if ( nc_inq_varid( mNcid, name.c_str(), &arr_id ) != NC_NOERR )
      {
        throw MDAL_Status::Err_UnknownFormat;
      }

      int val;
      if ( nc_get_att_int( mNcid, arr_id, attr_name.c_str(), &val ) )
      {
        throw MDAL_Status::Err_UnknownFormat;
      }
      return val;
    }

    std::string getAttrStr( const std::string &name, const std::string &attr_name ) const
    {
      assert( mNcid != 0 );

      int arr_id;
      if ( nc_inq_varid( mNcid, name.c_str(), &arr_id ) ) throw MDAL_Status::Err_UnknownFormat;
      return getAttrStr( attr_name, arr_id );
    }

    std::string getAttrStr( const std::string &name, int varid ) const
    {
      assert( mNcid != 0 );

      size_t attlen = 0;

      if ( nc_inq_attlen( mNcid, varid, name.c_str(), &attlen ) )
      {
        // attribute is missing
        return std::string();
      }

      char *string_attr;
      string_attr = ( char * ) malloc( attlen + 1 );

      if ( nc_get_att_text( mNcid, varid, name.c_str(), string_attr ) ) throw MDAL_Status::Err_UnknownFormat;
      string_attr[attlen] = '\0';

      std::string res( string_attr );
      free( string_attr );

      return res;
    }

    double getFillValue( int varid ) const
    {
      double fill;
      if ( nc_get_att_double( mNcid, varid, "_FillValue", &fill ) )
        fill = std::numeric_limits<double>::quiet_NaN(); // not present/set
      return fill;
    }

    int getVarId( const std::string &name )
    {
      int ncid_val;
      if ( nc_inq_varid( mNcid, name.c_str(), &ncid_val ) != NC_NOERR ) throw MDAL_Status::Err_UnknownFormat;
      return ncid_val;
    }

    void getDimension( const std::string &name, size_t *val, int *ncid_val ) const
    {
      assert( mNcid != 0 );

      if ( nc_inq_dimid( mNcid, name.c_str(), ncid_val ) != NC_NOERR ) throw MDAL_Status::Err_UnknownFormat;
      if ( nc_inq_dimlen( mNcid, *ncid_val, val ) != NC_NOERR ) throw MDAL_Status::Err_UnknownFormat;
    }

    void getDimensionOptional( const std::string &name, size_t *val, int *ncid_val ) const
    {
      assert( mNcid != 0 );

      try
      {
        getDimension( name, val, ncid_val );
      }
      catch ( MDAL_Status )
      {
        *ncid_val = -1;
        *val = 0;
      }
    }
  private:
    int mNcid;

};

#endif // MDAL_NETCDF_HPP