#!/usr/bin/env python
import sys,argparse

version_info=\
"""
Frobnicator  - version 0.1
Copyright (C) 2016 Assaf Gordon <assafgordon@gmail.com>
License: MIT
"""

def parse_command_line():
    # Define parameters
    parser = argparse.ArgumentParser(
        formatter_class=argparse.RawDescriptionHelpFormatter,
        description="This is a frobnicator",
        version=version_info,
        epilog="""

This script frobnicates an input file.
Example:

    $ %(prog)s -v FOO

        """)


    # Option parameters
    parser.add_argument("-V", "--verbose",  help="be verbose",
                        action="store_true")

    # an on/off feature, default 'on'.
    parser.add_argument('--feature', dest='feature', action='store_true',
                        help="enable feature (default)")
    parser.add_argument('--no-feature', dest='feature', action='store_false',
                        help="disable feature")
    parser.set_defaults(feature=True)

    # A numeric optional parameter, not required (could be None)
    parser.add_argument("-L", "--limit", metavar="N", type=int,
                        help="Limit to N events (defaul: no limit)")

    # Positional parameter
    parser.add_argument('filename', metavar='FILE', help='file to process');
    args = parser.parse_args()

    # Ensure optional numeric param is either undefined, or above 0
    if (args.limit is not None) and args.limit<1:
        sys.exit("invalid limit (--limit %d)" % args.limit)

    return args


if __name__ == "__main__":
    args = parse_command_line()

    if args.verbose:
        print "File to process:", args.filename