#
# Copyright 2012 Canonical Ltd.
#
# Authors:
#  James Page <james.page@ubuntu.com>
#  Paul Collins <paul.collins@canonical.com>
#

import socket
import re
from charmhelpers.core.hookenv import (
    unit_get,
    cached,
    config,
    status_set,
    network_get_primary_address,
    log,
    DEBUG,
)
from charmhelpers.fetch import (
    apt_install,
    filter_installed_packages,
)

from charmhelpers.core.host import (
    lsb_release,
    CompareHostReleases,
)

from charmhelpers.contrib.network.ip import (
    get_address_in_network,
    get_ipv6_addr,
)

try:
    import dns.resolver
except ImportError:
    apt_install(filter_installed_packages(['python-dnspython']),
                fatal=True)
    import dns.resolver


def enable_pocket(pocket):
    apt_sources = "/etc/apt/sources.list"
    with open(apt_sources, "r") as sources:
        lines = sources.readlines()
    with open(apt_sources, "w") as sources:
        for line in lines:
            if pocket in line:
                sources.write(re.sub('^# deb', 'deb', line))
            else:
                sources.write(line)


@cached
def get_unit_hostname():
    return socket.gethostname()


@cached
def get_host_ip(hostname=None):
    if config('prefer-ipv6'):
        return get_ipv6_addr()[0]

    hostname = hostname or unit_get('private-address')
    try:
        # Test to see if already an IPv4 address
        socket.inet_aton(hostname)
        return hostname
    except socket.error:
        # This may throw an NXDOMAIN exception; in which case
        # things are badly broken so just let it kill the hook
        answers = dns.resolver.query(hostname, 'A')
        if answers:
            return answers[0].address


@cached
def get_public_addr():
    if config('ceph-public-network'):
        return get_network_addrs('ceph-public-network')[0]

    try:
        return network_get_primary_address('public')
    except NotImplementedError:
        log("network-get not supported", DEBUG)

    return get_host_ip()


@cached
def get_cluster_addr():
    if config('ceph-cluster-network'):
        return get_network_addrs('ceph-cluster-network')[0]

    try:
        return network_get_primary_address('cluster')
    except NotImplementedError:
        log("network-get not supported", DEBUG)

    return get_host_ip()


def get_networks(config_opt='ceph-public-network'):
    """Get all configured networks from provided config option.

    If public network(s) are provided, go through them and return those for
    which we have an address configured.
    """
    networks = config(config_opt)
    if networks:
        networks = networks.split()
        return [n for n in networks if get_address_in_network(n)]

    return []


def get_network_addrs(config_opt):
    """Get all configured public networks addresses.

    If public network(s) are provided, go through them and return the
    addresses we have configured on any of those networks.
    """
    addrs = []
    networks = config(config_opt)
    if networks:
        networks = networks.split()
        addrs = [get_address_in_network(n) for n in networks]
        addrs = [a for a in addrs if a]

    if not addrs:
        if networks:
            msg = ("Could not find an address on any of '%s' - resolve this "
                   "error to retry" % (networks))
            status_set('blocked', msg)
            raise Exception(msg)
        else:
            return [get_host_ip()]

    return addrs


def assert_charm_supports_ipv6():
    """Check whether we are able to support charms ipv6."""
    _release = lsb_release()['DISTRIB_CODENAME'].lower()
    if CompareHostReleases(_release) < "trusty":
        raise Exception("IPv6 is not supported in the charms for Ubuntu "
                        "versions less than Trusty 14.04")