import os
import pwd

from base64 import b64decode
from copy import deepcopy
from subprocess import check_call, check_output

from charmhelpers.fetch import (
    apt_update,
    apt_upgrade,
    apt_install
)

from charmhelpers.core.host import (
    mkdir,
    service_restart,
    lsb_release
)

from charmhelpers.core.hookenv import (
    config,
    log,
    related_units,
    relation_ids,
    relation_get,
    DEBUG
)

from charmhelpers.contrib.openstack.neutron import neutron_plugin_attribute
from charmhelpers.contrib.openstack import templating, context
from charmhelpers.contrib.openstack.alternatives import install_alternative

from charmhelpers.contrib.openstack.utils import (
    configure_installation_source,
    get_os_codename_install_source,
    os_release
)

from nova_compute_context import (
    CloudComputeContext,
    NovaComputeLibvirtContext,
    NovaComputeCephContext,
    NeutronComputeContext,
    InstanceConsoleContext,
    CEPH_CONF,
    ceph_config_file,
    HostIPContext,
)

CA_CERT_PATH = '/usr/local/share/ca-certificates/keystone_juju_ca_cert.crt'

TEMPLATES = 'templates/'

BASE_PACKAGES = [
    'nova-compute',
    'genisoimage',  # was missing as a package dependency until raring.
]

NOVA_CONF_DIR = "/etc/nova"
QEMU_CONF = '/etc/libvirt/qemu.conf'
LIBVIRTD_CONF = '/etc/libvirt/libvirtd.conf'
LIBVIRT_BIN = '/etc/default/libvirt-bin'
NOVA_CONF = '%s/nova.conf' % NOVA_CONF_DIR

BASE_RESOURCE_MAP = {
    QEMU_CONF: {
        'services': ['libvirt-bin'],
        'contexts': [],
    },
    LIBVIRTD_CONF: {
        'services': ['libvirt-bin'],
        'contexts': [NovaComputeLibvirtContext()],
    },
    LIBVIRT_BIN: {
        'services': ['libvirt-bin'],
        'contexts': [NovaComputeLibvirtContext()],
    },
    NOVA_CONF: {
        'services': ['nova-compute'],
        'contexts': [context.AMQPContext(ssl_dir=NOVA_CONF_DIR),
                     context.SharedDBContext(
                         relation_prefix='nova', ssl_dir=NOVA_CONF_DIR),
                     context.PostgresqlDBContext(),
                     context.ImageServiceContext(),
                     context.OSConfigFlagContext(),
                     CloudComputeContext(),
                     NovaComputeLibvirtContext(),
                     NovaComputeCephContext(),
                     context.SyslogContext(),
                     context.SubordinateConfigContext(
                         interface='nova-ceilometer',
                         service='nova',
                         config_file=NOVA_CONF),
                     InstanceConsoleContext(),
                     HostIPContext()],
    },
}

CEPH_SECRET = '/etc/ceph/secret.xml'

CEPH_RESOURCES = {
    CEPH_SECRET: {
        'contexts': [NovaComputeCephContext()],
        'services': [],
    }
}

QUANTUM_CONF_DIR = "/etc/quantum"
QUANTUM_CONF = '%s/quantum.conf' % QUANTUM_CONF_DIR

QUANTUM_RESOURCES = {
    QUANTUM_CONF: {
        'services': [],
        'contexts': [NeutronComputeContext(),
                     context.AMQPContext(ssl_dir=QUANTUM_CONF_DIR),
                     context.SyslogContext()],
    }
}

NEUTRON_CONF_DIR = "/etc/neutron"
NEUTRON_CONF = '%s/neutron.conf' % NEUTRON_CONF_DIR

NEUTRON_RESOURCES = {
    NEUTRON_CONF: {
        'services': [],
        'contexts': [NeutronComputeContext(),
                     context.AMQPContext(ssl_dir=NEUTRON_CONF_DIR),
                     context.SyslogContext()],
    }
}


# Maps virt-type config to a compute package(s).
VIRT_TYPES = {
    'kvm': ['nova-compute-kvm'],
    'qemu': ['nova-compute-qemu'],
    'xen': ['nova-compute-xen'],
    'uml': ['nova-compute-uml'],
    'lxc': ['nova-compute-lxc'],
}

# Maps virt-type config to a libvirt URI.
LIBVIRT_URIS = {
    'kvm': 'qemu:///system',
    'qemu': 'qemu:///system',
    'xen': 'xen:///',
    'uml': 'uml:///system',
    'lxc': 'lxc:///',
}


def resource_map():
    '''
    Dynamically generate a map of resources that will be managed for a single
    hook execution.
    '''
    # TODO: Cache this on first call?
    resource_map = deepcopy(BASE_RESOURCE_MAP)
    net_manager = network_manager()
    plugin = neutron_plugin()

    # Network manager gets set late by the cloud-compute interface.
    # FlatDHCPManager only requires some extra packages.
    if (net_manager in ['flatmanager', 'flatdhcpmanager'] and
            config('multi-host').lower() == 'yes'):
        resource_map[NOVA_CONF]['services'].extend(
            ['nova-api', 'nova-network']
        )

    # Neutron/quantum requires additional contexts, as well as new resources
    # depending on the plugin used.
    # NOTE(james-page): only required for ovs plugin right now
    if net_manager in ['neutron', 'quantum']:
        if not relation_ids('neutron-plugin') and plugin == 'ovs':
            if net_manager == 'quantum':
                nm_rsc = QUANTUM_RESOURCES
            if net_manager == 'neutron':
                nm_rsc = NEUTRON_RESOURCES
            resource_map.update(nm_rsc)

            conf = neutron_plugin_attribute(plugin, 'config', net_manager)
            svcs = neutron_plugin_attribute(plugin, 'services', net_manager)
            ctxts = (neutron_plugin_attribute(plugin, 'contexts', net_manager)
                     or [])
            resource_map[conf] = {}
            resource_map[conf]['services'] = svcs
            resource_map[conf]['contexts'] = ctxts
            resource_map[conf]['contexts'].append(NeutronComputeContext())

            # associate the plugin agent with main network manager config(s)
            [resource_map[nmc]['services'].extend(svcs) for nmc in nm_rsc]

        resource_map[NOVA_CONF]['contexts'].append(NeutronComputeContext())

    if relation_ids('ceph'):
        CEPH_RESOURCES[ceph_config_file()] = {
            'contexts': [NovaComputeCephContext()],
            'services': ['nova-compute']
        }
        resource_map.update(CEPH_RESOURCES)

    return resource_map


def restart_map():
    '''
    Constructs a restart map based on charm config settings and relation
    state.
    '''
    return {k: v['services'] for k, v in resource_map().iteritems()}


def services():
    ''' Returns a list of services associate with this charm '''
    _services = []
    for v in restart_map().values():
        _services = _services + v
    return list(set(_services))


def register_configs():
    '''
    Returns an OSTemplateRenderer object with all required configs registered.
    '''
    release = os_release('nova-common')
    configs = templating.OSConfigRenderer(templates_dir=TEMPLATES,
                                          openstack_release=release)

    if relation_ids('ceph'):
        # Add charm ceph configuration to resources and
        # ensure directory actually exists
        mkdir(os.path.dirname(ceph_config_file()))
        mkdir(os.path.dirname(CEPH_CONF))
        # Install ceph config as an alternative for co-location with
        # ceph and ceph-osd charms - nova-compute ceph.conf will be
        # lower priority that both of these but thats OK
        if not os.path.exists(ceph_config_file()):
            # touch file for pre-templated generation
            open(ceph_config_file(), 'w').close()
        install_alternative(os.path.basename(CEPH_CONF),
                            CEPH_CONF, ceph_config_file())

    for cfg, d in resource_map().iteritems():
        configs.register(cfg, d['contexts'])
    return configs


def determine_packages():
    packages = [] + BASE_PACKAGES

    net_manager = network_manager()
    if (net_manager in ['flatmanager', 'flatdhcpmanager'] and
            config('multi-host').lower() == 'yes'):
        packages.extend(['nova-api', 'nova-network'])
    elif net_manager in ['quantum', 'neutron']:
        plugin = neutron_plugin()
        pkg_lists = neutron_plugin_attribute(plugin, 'packages', net_manager)
        for pkg_list in pkg_lists:
            packages.extend(pkg_list)

    if relation_ids('ceph'):
        packages.append('ceph-common')

    virt_type = config('virt-type')
    try:
        packages.extend(VIRT_TYPES[virt_type])
    except KeyError:
        log('Unsupported virt-type configured: %s' % virt_type)
        raise

    return packages


def migration_enabled():
    # XXX: confirm juju-core bool behavior is the same.
    return config('enable-live-migration')


def quantum_enabled():
    manager = config('network-manager')
    if not manager:
        return False
    return manager.lower() == 'quantum'


def _network_config():
    '''
    Obtain all relevant network configuration settings from nova-c-c via
    cloud-compute interface.
    '''
    settings = ['network_manager', 'neutron_plugin', 'quantum_plugin']
    net_config = {}
    for rid in relation_ids('cloud-compute'):
        for unit in related_units(rid):
            for setting in settings:
                value = relation_get(setting, rid=rid, unit=unit)
                if value:
                    net_config[setting] = value
    return net_config


def neutron_plugin():
    return (_network_config().get('neutron_plugin') or
            _network_config().get('quantum_plugin'))


def network_manager():
    '''
    Obtain the network manager advertised by nova-c-c, renaming to Quantum
    if required
    '''
    manager = _network_config().get('network_manager')
    if manager:
        manager = manager.lower()
        if manager not in ['quantum', 'neutron']:
            return manager
        if os_release('nova-common') in ['folsom', 'grizzly']:
            return 'quantum'
        else:
            return 'neutron'
    return manager


def public_ssh_key(user='root'):
    home = pwd.getpwnam(user).pw_dir
    try:
        with open(os.path.join(home, '.ssh', 'id_rsa.pub')) as key:
            return key.read().strip()
    except:
        return None


def initialize_ssh_keys(user='root'):
    home_dir = pwd.getpwnam(user).pw_dir
    ssh_dir = os.path.join(home_dir, '.ssh')
    if not os.path.isdir(ssh_dir):
        os.mkdir(ssh_dir)

    priv_key = os.path.join(ssh_dir, 'id_rsa')
    if not os.path.isfile(priv_key):
        log('Generating new ssh key for user %s.' % user)
        cmd = ['ssh-keygen', '-q', '-N', '', '-t', 'rsa', '-b', '2048',
               '-f', priv_key]
        check_output(cmd)

    pub_key = '%s.pub' % priv_key
    if not os.path.isfile(pub_key):
        log('Generating missing ssh public key @ %s.' % pub_key)
        cmd = ['ssh-keygen', '-y', '-f', priv_key]
        p = check_output(cmd).strip()
        with open(pub_key, 'wb') as out:
            out.write(p)
    check_output(['chown', '-R', user, ssh_dir])


def import_authorized_keys(user='root', prefix=None):
    """Import SSH authorized_keys + known_hosts from a cloud-compute relation.
    Store known_hosts in user's $HOME/.ssh and authorized_keys in a path
    specified using authorized-keys-path config option.
    """
    known_hosts = []
    authorized_keys = []
    if prefix:
        known_hosts_index = relation_get(
            '{}_known_hosts_max_index'.format(prefix))
        if known_hosts_index:
            for index in range(0, int(known_hosts_index)):
                known_hosts.append(relation_get(
                                   '{}_known_hosts_{}'.format(prefix, index)))
        authorized_keys_index = relation_get(
            '{}_authorized_keys_max_index'.format(prefix))
        if authorized_keys_index:
            for index in range(0, int(authorized_keys_index)):
                authorized_keys.append(relation_get(
                    '{}_authorized_keys_{}'.format(prefix, index)))
    else:
        # XXX: Should this be managed via templates + contexts?
        known_hosts_index = relation_get('known_hosts_max_index')
        if known_hosts_index:
            for index in range(0, int(known_hosts_index)):
                known_hosts.append(relation_get(
                    'known_hosts_{}'.format(index)))
        authorized_keys_index = relation_get('authorized_keys_max_index')
        if authorized_keys_index:
            for index in range(0, int(authorized_keys_index)):
                authorized_keys.append(relation_get(
                    'authorized_keys_{}'.format(index)))

    # XXX: Should partial return of known_hosts or authorized_keys
    #      be allowed ?
    if not len(known_hosts) or not len(authorized_keys):
        return
    homedir = pwd.getpwnam(user).pw_dir
    dest_auth_keys = config('authorized-keys-path').format(
        homedir=homedir, username=user)
    dest_known_hosts = os.path.join(homedir, '.ssh/known_hosts')
    log('Saving new known_hosts file to %s and authorized_keys file to: %s.' %
        (dest_known_hosts, dest_auth_keys))

    with open(dest_known_hosts, 'wb') as _hosts:
        for index in range(0, int(known_hosts_index)):
            _hosts.write('{}\n'.format(known_hosts[index]))
    with open(dest_auth_keys, 'wb') as _keys:
        for index in range(0, int(authorized_keys_index)):
            _keys.write('{}\n'.format(authorized_keys[index]))


def do_openstack_upgrade():
    # NOTE(jamespage) horrible hack to make utils forget a cached value
    import charmhelpers.contrib.openstack.utils as utils
    utils.os_rel = None
    new_src = config('openstack-origin')
    new_os_rel = get_os_codename_install_source(new_src)
    log('Performing OpenStack upgrade to %s.' % (new_os_rel))

    configure_installation_source(new_src)
    apt_update(fatal=True)

    dpkg_opts = [
        '--option', 'Dpkg::Options::=--force-confnew',
        '--option', 'Dpkg::Options::=--force-confdef',
    ]

    apt_upgrade(options=dpkg_opts, fatal=True, dist=True)
    apt_install(determine_packages(), fatal=True)

    # Regenerate configs in full for new release
    configs = register_configs()
    configs.write_all()
    [service_restart(s) for s in services()]
    return configs


def import_keystone_ca_cert():
    """If provided, improt the Keystone CA cert that gets forwarded
    to compute nodes via the cloud-compute interface
    """
    ca_cert = relation_get('ca_cert')
    if not ca_cert:
        return
    log('Writing Keystone CA certificate to %s' % CA_CERT_PATH)
    with open(CA_CERT_PATH, 'wb') as out:
        out.write(b64decode(ca_cert))
    check_call(['update-ca-certificates'])


def create_libvirt_secret(secret_file, secret_uuid, key):
    uri = LIBVIRT_URIS[config('virt-type')]
    if secret_uuid in check_output(['virsh', '-c', uri, 'secret-list']):
        log('Libvirt secret already exists for uuid %s.' % secret_uuid,
            level=DEBUG)
        return
    log('Defining new libvirt secret for uuid %s.' % secret_uuid)
    cmd = ['virsh', '-c', uri, 'secret-define', '--file', secret_file]
    check_call(cmd)
    cmd = ['virsh', '-c', uri, 'secret-set-value', '--secret', secret_uuid,
           '--base64', key]
    check_call(cmd)


def enable_shell(user):
    cmd = ['usermod', '-s', '/bin/bash', user]
    check_call(cmd)


def disable_shell(user):
    cmd = ['usermod', '-s', '/bin/false', user]
    check_call(cmd)


def fix_path_ownership(path, user='nova'):
    cmd = ['chown', user, path]
    check_call(cmd)


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