# vim: tabstop=4 shiftwidth=4 softtabstop=4

# Copyright 2012 OpenStack Foundation.
# All Rights Reserved.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""
Network-related utilities and helper functions.
"""

import logging

LOG = logging.getLogger(__name__)


def parse_host_port(address, default_port=None):
    """
    Interpret a string as a host:port pair.
    An IPv6 address MUST be escaped if accompanied by a port,
    because otherwise ambiguity ensues: 2001:db8:85a3::8a2e:370:7334
    means both [2001:db8:85a3::8a2e:370:7334] and
    [2001:db8:85a3::8a2e:370]:7334.

    >>> parse_host_port('server01:80')
    ('server01', 80)
    >>> parse_host_port('server01')
    ('server01', None)
    >>> parse_host_port('server01', default_port=1234)
    ('server01', 1234)
    >>> parse_host_port('[::1]:80')
    ('::1', 80)
    >>> parse_host_port('[::1]')
    ('::1', None)
    >>> parse_host_port('[::1]', default_port=1234)
    ('::1', 1234)
    >>> parse_host_port('2001:db8:85a3::8a2e:370:7334', default_port=1234)
    ('2001:db8:85a3::8a2e:370:7334', 1234)

    """
    if address[0] == '[':
        # Escaped ipv6
        _host, _port = address[1:].split(']')
        host = _host
        if ':' in _port:
            port = _port.split(':')[1]
        else:
            port = default_port
    else:
        if address.count(':') == 1:
            host, port = address.split(':')
        else:
            # 0 means ipv4, >1 means ipv6.
            # We prohibit unescaped ipv6 addresses with port.
            host = address
            port = default_port

    return (host, None if port is None else int(port))
