#include <stdlib.h>

#include <octave/oct.h>
#include <netcdf.h>

/* Read a 2-D arrays variable from a netcdf file.

 Command to compile this extension:

 mkoctfile ncrdvar.cc -lnetcdf

 If the data in the netcdf file is 1-D use a column vector.

 If the data is 2-D the columns size must match that in the netcdf file,
 or the returned data will be scrambled.

 Mark P. Esplin
 Stewart Radiance Laboratory
 Oct 25, 2001
 */

DEFUN_DLD (ncrdvar, args, ,
"Read a 2-D arrays variable from a netcdf file.\n\
Returns [data, status]\n\n\
           \narg1: netcdf file name\narg2: variable name\narg3: number of rows\
           \narg4: number of columns")
{
    int ncid,varid,nc_status;
    size_t start[3],count[3];
    int irow,icol,iadd;
    string fname,varname;

    octave_value_list retval;
    int nargin = args.length();
    if (nargin != 4 || !args(2).is_real_scalar() || !args(3).is_real_scalar() ){
        print_usage ("ncrdvar");
        return retval;
    }

    int nrow = args(2).int_value();
    int ncol = args(3).int_value();

    double TempStore[nrow*ncol];
    Matrix y (nrow,ncol);

    fname = args(0).string_value();
    varname = args(1).string_value();
    retval(0) = "0";

    nc_status = nc_open(fname.c_str(),NC_NOWRITE,&ncid);
    if(nc_status != NC_NOERR){
        retval(1) = "couldn't open file";
        return retval;
    }

    nc_status = nc_inq_varid(ncid, varname.c_str(), &varid);
    if(nc_status != NC_NOERR){
        retval(1) = "variable not defined";
        nc_close(ncid);
        return retval;
    }

    start[0]=0; start[1]=0; start[2]=0;
    count[0]=nrow; count[1]=ncol; count[2]=0;

    nc_status = nc_get_vara_double(ncid, varid, start, count, TempStore);
    if(nc_status != NC_NOERR) {
        retval(1) = "Error reading data";
        nc_close(ncid);
        return retval;
    }

    for(irow=0;irow<nrow;irow++){
        for(icol=0; icol<ncol; icol++){
            iadd = irow*ncol;
            y(irow,icol)=TempStore[icol+iadd];
        }
    }

    retval(0) = y;

    retval(1) = "worked";
    nc_close(ncid);
    return retval;
}