# This file is part of CloudControl.
#
# CloudControl is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# CloudControl is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with CloudControl.  If not, see <http://www.gnu.org/licenses/>.


import logging
from functools import wraps
from xml.etree import cElementTree as et
from StringIO import StringIO

import libvirt
from cloudcontrol.common.client.tags import ttl, refresh


logger = logging.getLogger(__name__)


def _vir_tag(func):
    """Catches libvirt related exception.

    Decorator used for tag declarations that interacts with libvirt.

    """
    @wraps(func)
    def decorated(dom):
        if not dom.hypervisor.handler.virt_connected:
            return
        try:
            return func(dom)
        except libvirt.libvirtError as exc:
            if 'Domain not found' in str(exc):
                # sometimes, libvirt tells us too late when a domain is removed
                # we just ignore the error and remove the domain
                dom.hypervisor.vm_unregister(dom.name)
                return
            logger.exception('Unexpected libvirt error')
            dom.hypervisor.handler.virt_connect_restart()

    return decorated


def uuid(dom):
    """Unique identifier of the domain."""
    return dom.uuid


def status(dom):
    return dom.state


def hv(dom):
    #FIXME: what shoud be the value of this tag ?
    return dom.hypervisor.name


def htype(dom):
    return dom.hypervisor.type


@_vir_tag
def arch(dom):
    """VM CPU architecture."""
    try:
        return dict(i686='x86', x86_64='x64')[et.ElementTree().parse(
            StringIO(dom.lv_dom.XMLDesc(0))).find('os/type').get('arch')]
    except Exception:
        logger.exception('Error while get Architecture tag')


def h(dom):
    """Name of the VM."""
    return dom.name


@_vir_tag
def cpu(dom):
    """Number of CPU of the VM."""
    return dom.lv_dom.info()[3]


@ttl(10)
@refresh(5)
@_vir_tag
def cpuuse(dom):
    """Represent CPU use in percent average on 5 seconds."""
    state, _, _, vcpu, cpu_time = dom.lv_dom.info()
    if state != 1:  # if VM is not running
        return None
    old_cpu_stats = dom.cpu_stats
    dom.cpu_stats = (dom.hypervisor.handler.main.evloop.now(), cpu_time)
    # calculate CPU percentage, code is from virt-manager in domain.py:1210
    return '%.2f' % max(0., min(100., ((cpu_time - old_cpu_stats[1]) * 100.) / (
        (dom.cpu_stats[0] - old_cpu_stats[0]) * 1000. * 1000. * 1000.)))


@_vir_tag
def mem(dom):
    """Memory currently allocated."""
    return dom.lv_dom.info()[2] * 1024


@_vir_tag
def memmax(dom):
    """Maximum memory allocation."""
    return dom.lv_dom.info()[1] * 1024


@_vir_tag
def vncport(dom):
    """VNC port for the VM console access."""
    try:
        port = et.ElementTree().parse(
            StringIO(dom.lv_dom.XMLDesc(0))
        ).find('devices/graphics').get('port')
    except Exception:
        logger.exception('VNCPort')
        raise

    if 0 < int(port) < 65536:
        return port

    return


@ttl(10)
@refresh(10)
@_vir_tag
def disk(dom):
    """Get backend disks."""
    return u' '.join(map(str, xrange(len(dom.disks)))) or None


@ttl(10)
@refresh(10)
@_vir_tag
def nic(dom):
    """VM network interfaces."""
    return u' '.join(map(str, xrange(len(dom.nics)))) or None


@refresh(10)
@_vir_tag
def autostart(dom):
    """Autostart status."""
    return {True: 'yes', False: 'no'}[bool(dom.lv_dom.autostart())]