"""Make a dummy level2b attr-only dataset.

For every actual level2b file, dump all global attrs out to the same filename
in a different location.  This will give us smaller files that we can carry 
around anywhere (i.e., don't need fjord access) for testing this code.
"""

def make_attr_only_dataset(in_path, out_path):
    """Actually do the work here.
    
    Input:
        in_path: location of actual level2b files to steal attrs from.
        out_path: place we'll write the dummy level2b's to.
    """
    from level2b_utils import find_all_level2b_files, parse_filename
    from netCDF4 import Dataset
    from os.path import basename, exists
    import os
    in_files = find_all_level2b_files(in_path)

    for in_file in in_files:
        # split into dirs by sat to keep dir listing from getting ridiculous
        parsed = parse_filename(in_file)
        full_out_path = out_path+parsed['satname']+'/'
        if not exists(full_out_path):
            os.makedirs(full_out_path)

        out_file = full_out_path+basename(in_file)
        print 'writing file: %s' % basename(out_file)
        in_rootgrp = Dataset(in_file, 'r', format='NETCDF4')
        out_rootgrp = Dataset(out_file, 'w', format='NETCDF4')

        # not sure why we can't just do out_rootgrp.__dict__.update here :(
        for key in in_rootgrp.ncattrs():
            setattr(out_rootgrp, key, getattr(in_rootgrp, key))

        in_rootgrp.close()
        out_rootgrp.close()
    


if __name__ == "__main__":
    """Start cranking away."""
    in_path = '/Users/mhiley/data/avhrr/Satellite_Output/'
    out_path = '/Users/mhiley/temp/'
    make_attr_only_dataset(in_path, out_path)