"""
Module checking the input parameter
"""

from argparse import ArgumentParser, FileType, RawTextHelpFormatter
from .io import test_coordiantes

def arg_parser():
    """
    Argument parser of input line

    Returns:
        ArgumentParser.arguments
    """

    parser = ArgumentParser(
       prog="tws_covariances.sh",
       description="Programm to compute the covariances of given region and return the "
                   "standard deviation of the mean TWS of this region and/or the full "
                   "covariance matrix",
       formatter_class=RawTextHelpFormatter,
    )
    parser.add_argument(
       "-f",
       "--filename",
       required=True,
       type=FileType(),
       help="Filename of the netcdf TWS input file, as downloaded from gravis.gfz-potsdam.de"
    )
    parser.add_argument(
       "-r",
       "--region",
       required=True,
       type=FileType(),
       help="Filename of the ascii file defining the requested region. List of coordinates "
            "lon, lat, each line one coordinate."
            "Coordinates have to be on an even spaced grid. Comment lines have to start with '#'. "
    )
    parser.add_argument(
       "-o",
       "--output",
       required=True,
       type=str,
       help="Filename of the netcdf output file"
    )
    parser.add_argument(
       "-m",
       "--matrix",
       action="store_true",
       help="Return full covariance matrix"
    )
    parser.add_argument(
       "-u",
       "--uncertainty",
       action="store_true",
       help="Return time series of standard deviations for mean TWS time series"
    )
    parser.add_argument(
       "-t",
       "--timeseries",
       action="store_true",
       help="Return mean TWS time series"
    )

    args = parser.parse_args()
    if not args.matrix and not args.uncertainty and not args.timeseries:
        raise RuntimeError("Either covariance matrix (-m) or uncertainties (-u) or timeseries (-t) "
                           "have to be set for the output!")
    test_coordiantes(args.region.name)

    return args