# vim: tabstop=4 shiftwidth=4 softtabstop=4

#    Copyright (C) 2012 Yahoo! 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.

from devstack import exceptions as excp
from devstack import log as logging
from devstack import settings
from devstack import shell as sh
from devstack import utils

LOG = logging.getLogger('devstack.libvirt')

#http://libvirt.org/uri.html
LIBVIRT_PROTOCOL_MAP = {
    'qemu': "qemu:///system",
    'kvm': "qemu:///system",
    'xen': 'xen:///',
    'uml': 'uml:///system',
    'lxc': 'lxc:///',
}
VIRT_LIB = 'libvirt'

#distros name the libvirt service differently :-(
SV_NAME_MAP = {
    settings.RHEL6: 'libvirtd',
    settings.FEDORA16: 'libvirtd',
    settings.UBUNTU11: 'libvirt-bin',
}

#how libvirt is restarted
LIBVIRT_RESTART_CMD = ['service', '%SERVICE%', 'restart']

#how we check its status
LIBVIRT_STATUS_CMD = ['service', '%SERVICE%', 'status']

#this is just used to check that libvirt will work with
#a given protocol, may not be ideal but does seem to crap
#out if it won't work, so thats good
VIRSH_SANITY_CMD = ['virsh', '-c', '%VIRT_PROTOCOL%', 'uri']

#status is either dead or alive!
_DEAD = 'DEAD'
_ALIVE = 'ALIVE'

#alive wait time, just a sleep we put into so that the service can start up
WAIT_ALIVE_TIME = settings.WAIT_ALIVE_SECS


def _get_virt_lib():
    #late import so that we don't always need this library to be active
    #ie if u aren't using libvirt in the first place
    return utils.import_module(VIRT_LIB)


def _status(distro):
    cmds = list()
    cmds.append({
        'cmd': LIBVIRT_STATUS_CMD,
        'run_as_root': True,
    })
    mp = dict()
    mp['SERVICE'] = SV_NAME_MAP[distro]
    result = utils.execute_template(*cmds,
                                check_exit_code=False,
                                params=mp)
    if not result or not result[0]:
        return _DEAD
    (sysout, stderr) = result[0]
    combined = str(sysout) + str(stderr)
    combined = combined.lower()
    if combined.find("running") != -1 or combined.find('start') != -1:
        return _ALIVE
    else:
        return _DEAD


def _destroy_domain(libvirt, conn, dom_name):
    try:
        dom = conn.lookupByName(dom_name)
        LOG.debug("Destroying domain (%s) (id=%s) running %s" % (dom_name, dom.ID(), dom.OSType()))
        dom.destroy()
        dom.undefine()
    except libvirt.libvirtError, e:
        LOG.warn("Could not clear out libvirt domain (%s) due to [%s]" % (dom_name, e.message))


def restart(distro):
    if _status(distro) != _ALIVE:
        cmds = list()
        cmds.append({
            'cmd': LIBVIRT_RESTART_CMD,
            'run_as_root': True,
        })
        mp = dict()
        mp['SERVICE'] = SV_NAME_MAP[distro]
        utils.execute_template(*cmds, params=mp)
        LOG.info("Restarting the libvirt service, please wait %s seconds until its started." % (WAIT_ALIVE_TIME))
        sh.sleep(WAIT_ALIVE_TIME)


def virt_ok(virt_type, distro):
    virt_protocol = LIBVIRT_PROTOCOL_MAP.get(virt_type)
    if not virt_protocol:
        return False
    try:
        restart(distro)
    except excp.ProcessExecutionError, e:
        LOG.warn("Could not restart libvirt on distro [%s] due to [%s]" % (distro, e.message))
        return False
    try:
        cmds = list()
        cmds.append({
            'cmd': VIRSH_SANITY_CMD,
            'run_as_root': True,
        })
        mp = dict()
        mp['VIRT_PROTOCOL'] = virt_protocol
        utils.execute_template(*cmds, params=mp)
        return True
    except excp.ProcessExecutionError, e:
        LOG.warn("Could check if libvirt was ok for protocol [%s] due to [%s]" % (virt_protocol, e.message))
        return False


def clear_libvirt_domains(distro, virt_type, inst_prefix):
    libvirt = _get_virt_lib()
    if not libvirt:
        LOG.warn("Could not clear out libvirt domains, libvirt not available for python.")
        return
    virt_protocol = LIBVIRT_PROTOCOL_MAP.get(virt_type)
    if not virt_protocol:
        LOG.warn("Could not clear out libvirt domains, no known protocol for virt type %s" % (virt_type))
        return
    with sh.Rooted(True):
        LOG.info("Attempting to clear out leftover libvirt domains using protocol %s" % (virt_protocol))
        try:
            restart(distro)
        except excp.ProcessExecutionError, e:
            LOG.warn("Could not restart libvirt on distro [%s] due to [%s]" % (distro, e.message))
            return
        try:
            conn = libvirt.open(virt_protocol)
        except libvirt.libvirtError, e:
            LOG.warn("Could not connect to libvirt using protocol [%s] due to [%s]" % (virt_protocol, e.message))
            return
        try:
            defined_domains = conn.listDefinedDomains()
            kill_domains = list()
            for domain in defined_domains:
                if domain.startswith(inst_prefix):
                    kill_domains.append(domain)
            if kill_domains:
                LOG.info("Found %s old domains to destroy (%s)" % (len(kill_domains), ", ".join(sorted(kill_domains))))
                for domain in sorted(kill_domains):
                    _destroy_domain(libvirt, conn, domain)
        except libvirt.libvirtError, e:
            LOG.warn("Could not clear out libvirt domains due to [%s]" % (e.message))