#!/usr/bin/env python3
#
# Copyright (C) 2021 VyOS maintainers and contributors
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 or later as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

import re
import sys
import argparse

class MalformedRange(Exception):
    pass

def validate_range(value, min=None, max=None):
    try:
        lower, upper = re.match(r'^(\d+)-(\d+)$', value).groups()

        lower, upper = int(lower), int(upper)

        if int(lower) > int(upper):
            raise MalformedRange("the lower bound exceeds the upper bound".format(value))

        if min is not None:
            if lower < min:
                raise MalformedRange("the lower bound must not be less than {}".format(min))

        if max is not None:
            if upper > max:
                raise MalformedRange("the upper bound must not be greater than {}".format(max))

    except (AttributeError, ValueError):
        raise MalformedRange("range syntax error")

parser = argparse.ArgumentParser(description='Range validator.')
parser.add_argument('--min', type=int, action='store')
parser.add_argument('--max', type=int, action='store')
parser.add_argument('value', action='store')

if __name__ == '__main__':
    args = parser.parse_args()

    try:
        validate_range(args.value, min=args.min, max=args.max)
    except MalformedRange as e:
        print("Incorrect range '{}': {}".format(args.value, e))
        sys.exit(1)