# Copyright 2010 United States Government as represented by the
# Administrator of the National
 Aeronautics and Space Administration.
# All Rights Reserved.
# Copyright (c) 2010 Citrix Systems, Inc.
# Copyright (c) 2011 Piston Cloud Computing, Inc
# Copyright (c) 2012 University Of Minho
# (c) Copyright 2013 Hewlett-Packard Development Company, L.P.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the Licens
e. 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.

"""
Manages information about the host OS and hypervisor.

This class encapsulates a connection to the libvirt
daemon and provides certain higher level APIs around
the raw libvirt API. These APIs are then used by all
the other libvirt related classes
"""

import operator
import os
import socket
import sys
import threading

from eventlet import greenio
from eventlet import greenthread
from eventlet import patcher
from eventlet import tpool
from oslo_config import cfg
from oslo_log import log as logging
from oslo_utils import excutils
from oslo_utils import importutils
from oslo_utils import units
from oslo_utils import versionutils
import six

from nova import context as nova_context
from nova import exception
from nova.i18n import _
from nova.i18n import _LE
from nova.i18n import _LI
from nova.i18n import _LW
from nova import rpc
from nova import utils
from nova.virt import event as virtevent
from nova.virt.libvirt import config as vconfig
from nova.virt.libvirt import guest as libvirt_guest

libvirt = None

LOG = logging.getLogger(__name__)

native_socket = patcher.original('socket')
native_threading = patcher.original("threading")
native_Queue = patcher.original("queue" if six.PY3 else "Queue")

CONF = cfg.CONF
CONF.import_opt('host', 'nova.netconf')
CONF.import_opt('my_ip', 'nova.netconf')


# This list is for libvirt hypervisor drivers that need special handling.
# This is *not* the complete list of supported hypervisor drivers.
HV_DRIVER_QEMU = "QEMU"
HV_DRIVER_XEN = "Xen"


class DomainJobInfo(object):
    """Information about libvirt background jobs

    This class encapsulates information about libvirt
    background jobs. It provides a mapping from either
    the old virDomainGetJobInfo API which returned a
    fixed list of fields, or the modern virDomainGetJobStats
    which returns an extendable dict of fields.
    """

    _have_job_stats = True

    def __init__(self, **kwargs):

        self.type = kwargs.get("type", libvirt.VIR_DOMAIN_JOB_NONE)
        self.time_elapsed = kwargs.get("time_elapsed", 0)
        self.time_remaining = kwargs.get("time_remaining", 0)
        self.downtime = kwargs.get("downtime", 0)
        self.setup_time = kwargs.get("setup_time", 0)
        self.data_total = kwargs.get("data_total", 0)
        self.data_processed = kwargs.get("data_processed", 0)
        self.data_remaining = kwargs.get("data_remaining", 0)
        self.memory_total = kwargs.get("memory_total", 0)
        self.memory_processed = kwargs.get("memory_processed", 0)
        self.memory_remaining = kwargs.get("memory_remaining", 0)
        self.memory_constant = kwargs.get("memory_constant", 0)
        self.memory_normal = kwargs.get("memory_normal", 0)
        self.memory_normal_bytes = kwargs.get("memory_normal_bytes", 0)
        self.memory_bps = kwargs.get("memory_bps", 0)
        self.disk_total = kwargs.get("disk_total", 0)
        self.disk_processed = kwargs.get("disk_processed", 0)
        self.disk_remaining = kwargs.get("disk_remaining", 0)
        self.disk_bps = kwargs.get("disk_bps", 0)
        self.comp_cache = kwargs.get("compression_cache", 0)
        self.comp_bytes = kwargs.get("compression_bytes", 0)
        self.comp_pages = kwargs.get("compression_pages", 0)
        self.comp_cache_misses = kwargs.get("compression_cache_misses", 0)
        self.comp_overflow = kwargs.get("compression_overflow", 0)

    @classmethod
    def _get_job_stats_compat(cls, dom):
        # Make the old virDomainGetJobInfo method look similar to the
        # modern virDomainGetJobStats method
        try:
            info = dom.jobInfo()
        except libvirt.libvirtError as ex:
            # When migration of a transient guest completes, the guest
            # goes away so we'll see NO_DOMAIN error code
            #
            # When migration of a persistent guest completes, the guest
            # merely shuts off, but libvirt unhelpfully raises an
            # OPERATION_INVALID error code
            #
            # Lets pretend both of these mean success
            if ex.get_error_code() in (libvirt.VIR_ERR_NO_DOMAIN,
                                       libvirt.VIR_ERR_OPERATION_INVALID):
                LOG.debug("Domain has shutdown/gone away: %s", ex)
                return cls(type=libvirt.VIR_DOMAIN_JOB_COMPLETED)
            else:
                LOG.debug("Failed to get job info: %s", ex)
                raise

        return cls(
            type=info[0],
            time_elapsed=info[1],
            time_remaining=info[2],
            data_total=info[3],
            data_processed=info[4],
            data_remaining=info[5],
            memory_total=info[6],
            memory_processed=info[7],
            memory_remaining=info[8],
            disk_total=info[9],
            disk_processed=info[10],
            disk_remaining=info[11])

    @classmethod
    def for_domain(cls, dom):
        '''Get job info for the domain

        Query the libvirt job info for the domain (ie progress
        of migration, or snapshot operation)

        Returns: a DomainJobInfo instance
        '''

        if cls._have_job_stats:
            try:
                stats = dom.jobStats()
                return cls(**stats)
            except libvirt.libvirtError as ex:
                if ex.get_error_code() == libvirt.VIR_ERR_NO_SUPPORT:
                    # Remote libvirt doesn't support new API
                    LOG.debug("Missing remote virDomainGetJobStats: %s", ex)
                    cls._have_job_stats = False
                    return cls._get_job_stats_compat(dom)
                elif ex.get_error_code() in (
                        libvirt.VIR_ERR_NO_DOMAIN,
                        libvirt.VIR_ERR_OPERATION_INVALID):
                    # Transient guest finished migration, so it has gone
                    # away completely
                    LOG.debug("Domain has shutdown/gone away: %s", ex)
                    return cls(type=libvirt.VIR_DOMAIN_JOB_COMPLETED)
                else:
                    LOG.debug("Failed to get job stats: %s", ex)
                    raise
            except AttributeError as ex:
                # Local python binding doesn't support new API
                LOG.debug("Missing local virDomainGetJobStats: %s", ex)
                cls._have_job_stats = False
                return cls._get_job_stats_compat(dom)
        else:
            return cls._get_job_stats_compat(dom)


class Host(object):

    def __init__(self, uri, read_only=False,
                 conn_event_handler=None,
                 lifecycle_event_handler=None):

        global libvirt
        if libvirt is None:
            libvirt = importutils.import_module('libvirt')

        self._uri = uri
        self._read_only = read_only
        self._conn_event_handler = conn_event_handler
        self._lifecycle_event_handler = lifecycle_event_handler
        self._skip_list_all_domains = False
        self._caps = None
        self._hostname = None

        self._wrapped_conn = None
        self._wrapped_conn_lock = threading.Lock()
        self._event_queue = None

        self._events_delayed = {}
        # Note(toabctl): During a reboot of a domain, STOPPED and
        #                STARTED