import os
import netCDF4 as n4

def is_nc_file(filename,workDir):
    """
    Checks if a file exists and is a NetCDF file.

    Args:
        filename: The file name with whole path.

    Returns:
        True if the file exists and is a NetCDF file, False otherwise.
    """
    if not os.path.exists(filename):
        print("Warning: File " + filename + " does not exist")
        return False

    try:
        n4.Dataset(filename)
        return True
    except OSError:
        print("Warning: File " + filename + " is corrupted or unknown file format")
        with open(workDir + "/obs_log.txt","a") as obs_log:
            obs_log.write("Warning: File " + filename + " is corrupted or unknown file format\n")
        return False