# Copyright 2011, VMware, Inc.
# 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.
#
# Borrowed from nova code base, more utilities will be added/borrowed as and
# when needed.

"""Utilities and helper functions."""

import collections
import datetime
import decimal
import errno
import functools
import hashlib
import multiprocessing
import netaddr
import os
import random
import signal
import socket
import tempfile
import uuid

from eventlet.green import subprocess
from oslo_concurrency import lockutils
from oslo_config import cfg
from oslo_log import log as logging
from oslo_utils import excutils
import six

from neutron.common import constants as n_const

TIME_FORMAT = "%Y-%m-%dT%H:%M:%SZ"
LOG = logging.getLogger(__name__)
SYNCHRONIZED_PREFIX = 'neutron-'

synchronized = lockutils.synchronized_with_prefix(SYNCHRONIZED_PREFIX)


class cache_method_results(object):
    """This decorator is intended for object methods only."""

    def __init__(self, func):
        self.func = func
        functools.update_wrapper(self, func)
        self._first_call = True
        self._not_cached = object()

    def _get_from_cache(self, target_self, *args, **kwargs):
        func_name = "%(module)s.%(class)s.%(func_name)s" % {
            'module': target_self.__module__,
            'class': target_self.__class__.__name__,
            'func_name': self.func.__name__,
        }
        key = (func_name,) + args
        if kwargs:
            key += dict2tuple(kwargs)
        try:
            item = target_self._cache.get(key, self._not_cached)
        except TypeError:
            LOG.debug("Method %(func_name)s cannot be cached due to "
                      "unhashable parameters: args: %(args)s, kwargs: "
                      "%(kwargs)s",
                      {'func_name': func_name,
                       'args': args,
                       'kwargs': kwargs})
            return self.func(target_self, *args, **kwargs)

        if item is self._not_cached:
            item = self.func(target_self, *args, **kwargs)
            target_self._cache.set(key, item, None)

        return item

    def __call__(self, target_self, *args, **kwargs):
        if not hasattr(target_self, '_cache'):
            raise NotImplementedError(
                "Instance of class %(module)s.%(class)s must contain _cache "
                "attribute" % {
                    'module': target_self.__module__,
                    'class': target_self.__class__.__name__})
        if not target_self._cache:
            if self._first_call:
                LOG.debug("Instance of class %(module)s.%(class)s doesn't "
                          "contain attribute _cache therefore results "
                          "cannot be cached for %(func_name)s.",
                          {'module': target_self.__module__,
                           'class': target_self.__class__.__name__,
                           'func_name': self.func.__name__})
                self._first_call = False
            return self.func(target_self, *args, **kwargs)
        return self._get_from_cache(target_self, *args, **kwargs)

    def __get__(self, obj, objtype):
        return functools.partial(self.__call__, obj)


def read_cached_file(filename, cache_info, reload_func=None):
    """Read from a file if it has been modified.

    :param cache_info: dictionary to hold opaque cache.
    :param reload_func: optional function to be called with data when
                        file is reloaded due to a modification.

    :returns: data from file

    """
    mtime = os.path.getmtime(filename)
    if not cache_info or mtime != cache_info.get('mtime'):
        LOG.debug("Reloading cached file %s", filename)
        with open(filename) as fap:
            cache_info['data'] = fap.read()
        cache_info['mtime'] = mtime
        if reload_func:
            reload_func(cache_info['data'])
    return cache_info['data']


def find_config_file(options, config_file):
    """Return the first config file found.

    We search for the paste config file in the following order:
    * If --config-file option is used, use that
    * Search for the configuration files via common cfg directories
    :retval Full path to config file, or None if no config file found
    """
    fix_path = lambda p: os.path.abspath(os.path.expanduser(p))
    if options.get('config_file'):
        if os.path.exists(options['config_file']):
            return fix_path(options['config_file'])

    dir_to_common = os.path.dirname(os.path.abspath(__file__))
    root = os.path.join(dir_to_common, '..', '..', '..', '..')
    # Handle standard directory search for the config file
    config_file_dirs = [fix_path(os.path.join(os.getcwd(), 'etc')),
                        fix_path(os.path.join('~', '.neutron-venv', 'etc',
                                              'neutron')),
                        fix_path('~'),
                        os.path.join(cfg.CONF.state_path, 'etc'),
                        os.path.join(cfg.CONF.state_path, 'etc', 'neutron'),
                        fix_path(os.path.join('~', '.local',
                                              'etc', 'neutron')),
                        '/usr/etc/neutron',
                        '/usr/local/etc/neutron',
                        '/etc/neutron/',
                        '/etc']

    if 'plugin' in options:
        config_file_dirs = [
            os.path.join(x, 'neutron', 'plugins', options['plugin'])
            for x in config_file_dirs
        ]

    if os.path.exists(os.path.join(root, 'plugins')):
        plugins = [fix_path(os.path.join(root, 'plugins', p, 'etc'))
                   for p in os.listdir(os.path.join(root, 'plugins'))]
        plugins = [p for p in plugins if os.path.isdir(p)]
        config_file_dirs.extend(plugins)

    for cfg_dir in config_file_dirs:
        cfg_file = os.path.join(cfg_dir, config_file)
        if os.path.exists(cfg_file):
            return cfg_file


def ensure_dir(dir_path):
    """Ensure a directory with 755 permissions mode."""
    try:
        os.makedirs(dir_path, 0o755)
    except OSError as e:
        # If the directory already existed, don't raise the error.
        if e.errno != errno.EEXIST:
            raise


def _subprocess_setup():
    # Python installs a SIGPIPE handler by default. This is usually not what
    # non-Python subprocesses expect.
    signal.signal(signal.SIGPIPE, signal.SIG_DFL)


def subprocess_popen(args, stdin=None, stdout=None, stderr=None, shell=False,
                     env=None, preexec_fn=_subprocess_setup, close_fds=True):

    return subprocess.Popen(args, shell=shell, stdin=stdin, stdout=stdout,
                            stderr=stderr, preexec_fn=preexec_fn,
                            close_fds=close_fds, env=env)


def parse_mappings(mapping_list, unique_values=True):
    """Parse a list of mapping strings into a dictionary.

    :param mapping_list: a list of strings of the form '<key>:<value>'
    :param unique_values: values must be unique if True
    :returns: a dict mapping keys to values
    """
    mappings = {}
    for mapping in mapping_list:
        mapping = mapping.strip()
        if not mapping:
            continue
        split_result = mapping.split(':')
        if len(split_result) != 2:
            raise ValueError(_("Invalid mapping: '%s'") % mapping)
        key = split_result[0].strip()
        if not key:
            raise ValueError(_("Missing key in mapping: '%s'") % mapping)
        value = split_result[1].strip()
        if not value:
            raise ValueError(_("Missing value in mapping: '%s'") % mapping)
        if key in mappings:
            raise ValueError(_("Key %(key)s in mapping: '%(mapping)s' not "
                               "unique") % {'key': key, 'mapping': mapping})
        if unique_values and value in mappings.values():
            raise ValueError(_("Value %(value)s in mapping: '%(mapping)s' "
                               "not unique") % {'value': value,
                                                'mapping': mapping})
        mappings[key] = value
    return mappings


def get_hostname():
    return socket.gethostname()


def get_first_host_ip(net, ip_version):
    return str(netaddr.IPAddress(net.first + 1, ip_version))


def compare_elements(a, b):
    """Compare elements if a and b have same elements.

    This method doesn't consider ordering
    """
    if a is None:
        a = []
    if b is None:
        b = []
    return set(a) == set(b)


def safe_sort_key(value):
    """Return value hash or build one for dictionaries."""
    if isinstance(value, collections.Mapping):
        return sorted(value.items())
    return value


def dict2str(dic):
    return ','.join("%s=%s" % (key, val)
                    for key, val in sorted(six.iteritems(dic)))


def str2dict(string):
    res_dict = {}
    for keyvalue in string.split(','):
        (key, value) = keyvalue.split('=', 1)
        res_dict[key] = value
    return res_dict


def dict2tuple(d):
    items = list(d.items())
    items.sort()
    return tuple(items)


def diff_list_of_dict(old_list, new_list):
    new_set = set([dict2str(l) for l in new_list])
    old_set = set([dict2str(l) for l in old_list])
    added = new_set - old_set
    removed = old_set - new_set
    return [str2dict(a) for a in added], [str2dict(r) for r in removed]


def is_extension_supported(plugin, ext_alias):
    return ext_alias in getattr(
        plugin, "supported_extension_aliases", [])


def log_opt_values(log):
    cfg.CONF.log_opt_values(log, logging.DEBUG)


def get_random_mac(base_mac):
    mac = [int(base_mac[0], 16), int(base_mac[1], 16),
           int(base_mac[2], 16), random.randint(0x00, 0xff),
           random.randint(0x00, 0xff), random.randint(0x00, 0xff)]
    if base_mac[3] != '00':
        mac[3] = int(base_mac[3], 16)
    return ':'.join(["%02x" % x for x in mac])


def get_random_string(length):
    """Get a random hex string of the specified length.

    based on Cinder library
      cinder/transfer/api.py
    """
    rndstr = ""
    random.seed(datetime.datetime.now().microsecond)
    while len(rndstr) < length:
        rndstr += hashlib.sha224(str(random.random())).hexdigest()

    return rndstr[0:length]


def get_dhcp_agent_device_id(network_id, host):
    # Split host so as to always use only the hostname and
    # not the domain name. This will guarantee consistentcy
    # whether a local hostname or an fqdn is passed in.
    local_hostname = host.split('.')[0]
    host_uuid = uuid.uuid5(uuid.NAMESPACE_DNS, str(local_hostname))
    return 'dhcp%s-%s' % (host_uuid, network_id)


def cpu_count():
    try:
        return multiprocessing.cpu_count()
    except NotImplementedError:
        return 1


class exception_logger(object):
    """Wrap a function and log raised exception

    :param logger: the logger to log the exception default is LOG.exception

    :returns: origin value if no exception raised; re-raise the exception if
              any occurred

    """
    def __init__(self, logger=None):
        self.logger = logger

    def __call__(self, func):
        if self.logger is None:
            LOG = logging.getLogger(func.__module__)
            self.logger = LOG.exception

        def call(*args, **kwargs):
            try:
                return func(*args, **kwargs)
            except Exception as e:
                with excutils.save_and_reraise_exception():
                    self.logger(e)
        return call


def is_dvr_serviced(device_owner):
    """Check if the port need to be serviced by DVR

    Helper function to check the device owners of the
    ports in the compute and service node to make sure
    if they are required for DVR or any service directly or
    indirectly associated with DVR.
    """
    dvr_serviced_device_owners = (n_const.DEVICE_OWNER_LOADBALANCER,
                                  n_const.DEVICE_OWNER_LOADBALANCERV2,
                                  n_const.DEVICE_OWNER_DHCP)
    return (device_owner.startswith('compute:') or
            device_owner in dvr_serviced_device_owners)


def get_keystone_url(conf):
    if conf.auth_uri:
        auth_uri = conf.auth_uri.rstrip('/')
    else:
        auth_uri = ('%(protocol)s://%(host)s:%(port)s' %
            {'protocol': conf.auth_protocol,
             'host': conf.auth_host,
             'port': conf.auth_port})
    # NOTE(ihrachys): all existing consumers assume version 2.0
    return '%s/v2.0/' % auth_uri


def ip_to_cidr(ip, prefix=None):
    """Convert an ip with no prefix to cidr notation

    :param ip: An ipv4 or ipv6 address.  Convertable to netaddr.IPNetwork.
    :param prefix: Optional prefix.  If None, the default 32 will be used for
        ipv4 and 128 for ipv6.
    """
    net = netaddr.IPNetwork(ip)
    if prefix is not None:
        # Can't pass ip and prefix separately.  Must concatenate strings.
        net = netaddr.IPNetwork(str(net.ip) + '/' + str(prefix))
    return str(net)


def fixed_ip_cidrs(fixed_ips):
    """Create a list of a port's fixed IPs in cidr notation.

    :param fixed_ips: A neutron port's fixed_ips dictionary
    """
    return [ip_to_cidr(fixed_ip['ip_address'], fixed_ip.get('prefixlen'))
            for fixed_ip in fixed_ips]


def is_cidr_host(cidr):
    """Determines if the cidr passed in represents a single host network

    :param cidr: Either an ipv4 or ipv6 cidr.
    :returns: True if the cidr is /32 for ipv4 or /128 for ipv6.
    :raises ValueError: raises if cidr does not contain a '/'.  This disallows
        plain IP addresses specifically to avoid ambiguity.
    """
    if '/' not in str(cidr):
        raise ValueError("cidr doesn't contain a '/'")
    net = netaddr.IPNetwork(cidr)
    if net.version == 4:
        return net.prefixlen == n_const.IPv4_BITS
    return net.prefixlen == n_const.IPv6_BITS


def ip_version_from_int(ip_version_int):
    if ip_version_int == 4:
        return n_const.IPv4
    if ip_version_int == 6:
        return n_const.IPv6
    raise ValueError(_('Illegal IP version number'))


def is_port_trusted(port):
    """Used to determine if port can be trusted not to attack network.

    Trust is currently based on the device_owner field starting with 'network:'
    since we restrict who can use that in the default policy.json file.
    """
    return port['device_owner'].startswith('network:')


class DelayedStringRenderer(object):
    """Takes a callable and its args and calls when __str__ is called

    Useful for when an argument to a logging statement is expensive to
    create. This will prevent the callable from being called if it's
    never converted to a string.
    """

    def __init__(self, function, *args, **kwargs):
        self.function = function
        self.args = args
        self.kwargs = kwargs

    def __str__(self):
        return str(self.function(*self.args, **self.kwargs))


def camelize(s):
    return ''.join(s.replace('_', ' ').title().split())


def round_val(val):
    # we rely on decimal module since it behaves consistently across Python
    # versions (2.x vs. 3.x)
    return int(decimal.Decimal(val).quantize(decimal.Decimal('1'),
                                             rounding=decimal.ROUND_HALF_UP))


def replace_file(file_name, data):
    """Replaces the contents of file_name with data in a safe manner.

    First write to a temp file and then rename. Since POSIX renames are
    atomic, the file is unlikely to be corrupted by competing writes.

    We create the tempfile on the same device to ensure that it can be renamed.
    """

    base_dir = os.path.dirname(os.path.abspath(file_name))
    with tempfile.NamedTemporaryFile('w+',
                                     dir=base_dir,
                                     delete=False) as tmp_file:
        tmp_file.write(data)
    os.chmod(tmp_file.name, 0o644)
    os.rename(tmp_file.name, file_name)
