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

# Copyright 2013 Cloudbase Solutions Srl
# 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.

"""
Management class for migration / resize operations.
"""
import os

from nova.openstack.common import excutils
from nova.openstack.common.gettextutils import _
from nova.openstack.common import log as logging
from nova.virt.hyperv import imagecache
from nova.virt.hyperv import utilsfactory
from nova.virt.hyperv import vmops
from nova.virt.hyperv import vmutils
from nova.virt.hyperv import volumeops

LOG = logging.getLogger(__name__)


class MigrationOps(object):
    def __init__(self):
        self._hostutils = utilsfactory.get_hostutils()
        self._vmutils = utilsfactory.get_vmutils()
        self._vhdutils = utilsfactory.get_vhdutils()
        self._pathutils = utilsfactory.get_pathutils()
        self._volumeops = volumeops.VolumeOps()
        self._vmops = vmops.VMOps()
        self._imagecache = imagecache.ImageCache()

    def _migrate_disk_files(self, instance_name, disk_files, dest):
        same_host = False
        if dest in self._hostutils.get_local_ips():
            same_host = True
            LOG.debug(_("Migration target is the source host"))
        else:
            LOG.debug(_("Migration target host: %s") % dest)

        instance_path = self._pathutils.get_instance_dir(instance_name)
        revert_path = self._pathutils.get_instance_migr_revert_dir(
            instance_name, remove_dir=True)
        dest_path = None

        try:
            if same_host:
                # Since source and target are the same, we copy the files to
                # a temporary location before moving them into place
                dest_path = '%s_tmp' % instance_path
                if self._pathutils.exists(dest_path):
                    self._pathutils.rmtree(dest_path)
                self._pathutils.makedirs(dest_path)
            else:
                dest_path = self._pathutils.get_instance_dir(
                    instance_name, dest, remove_dir=True)
            for disk_file in disk_files:
                # Skip the config drive as the instance is already configured
                if os.path.basename(disk_file).lower() != 'configdrive.vhd':
                    LOG.debug(_('Copying disk "%(disk_file)s" to '
                                '"%(dest_path)s"'),
                              {'disk_file': disk_file, 'dest_path': dest_path})
                    self._pathutils.copy(disk_file, dest_path)

            self._pathutils.rename(instance_path, revert_path)

            if same_host:
                self._pathutils.rename(dest_path, instance_path)
        except Exception:
            with excutils.save_and_reraise_exception():
                self._cleanup_failed_disk_migration(instance_path, revert_path,
                                                    dest_path)

    def _cleanup_failed_disk_migration(self, instance_path,
                                       revert_path, dest_path):
        try:
            if dest_path and self._pathutils.exists(dest_path):
                self._pathutils.rmtree(dest_path)
            if self._pathutils.exists(revert_path):
                self._pathutils.rename(revert_path, instance_path)
        except Exception as ex:
            # Log and ignore this exception
            LOG.exception(ex)
            LOG.error(_("Cannot cleanup migration files"))

    def _check_target_instance_type(self, instance, instance_type):
        new_root_gb = instance_type['root_gb']
        curr_root_gb = instance['root_gb']

        if new_root_gb < curr_root_gb:
            raise vmutils.VHDResizeException(
                _("Cannot resize the root disk to a smaller size. Current "
                  "size: %(curr_root_gb)s GB. Requested size: "
                  "%(new_root_gb)s GB") %
                {'curr_root_gb': curr_root_gb, 'new_root_gb': new_root_gb})

    def migrate_disk_and_power_off(self, context, instance, dest,
                                   instance_type, network_info,
                                   block_device_info=None):
        LOG.debug(_("migrate_disk_and_power_off called"), instance=instance)

        self._check_target_instance_type(instance, instance_type)

        self._vmops.power_off(instance)

        instance_name = instance["name"]

        (disk_files,
         volume_drives) = self._vmutils.get_vm_storage_paths(instance_name)

        if disk_files:
            self._migrate_disk_files(instance_name, disk_files, dest)

        self._vmops.destroy(instance, destroy_disks=False)

        # disk_info is not used
        return ""

    def confirm_migration(self, migration, instance, network_info):
        LOG.debug(_("confirm_migration called"), instance=instance)

        self._pathutils.get_instance_migr_revert_dir(instance['name'],
                                                     remove_dir=True)

    def _revert_migration_files(self, instance_name):
        instance_path = self._pathutils.get_instance_dir(
            instance_name, create_dir=False, remove_dir=True)

        revert_path = self._pathutils.get_instance_migr_revert_dir(
            instance_name)
        self._pathutils.rename(revert_path, instance_path)

    def finish_revert_migration(self, instance, network_info,
                                block_device_info=None, power_on=True):
        LOG.debug(_("finish_revert_migration called"), instance=instance)

        instance_name = instance['name']
        self._revert_migration_files(instance_name)

        if self._volumeops.ebs_root_in_block_devices(block_device_info):
            root_vhd_path = None
        else:
            root_vhd_path = self._pathutils.lookup_root_vhd_path(instance_name)

        eph_vhd_path = self._pathutils.lookup_ephemeral_vhd_path(instance_name)

        self._vmops.create_instance(instance, network_info, block_device_info,
                                    root_vhd_path, eph_vhd_path)

        if power_on:
            self._vmops.power_on(instance)

    def _merge_base_vhd(self, diff_vhd_path, base_vhd_path):
        base_vhd_copy_path = os.path.join(os.path.dirname(diff_vhd_path),
                                          os.path.basename(base_vhd_path))
        try:
            LOG.debug(_('Copying base disk %(base_vhd_path)s to '
                        '%(base_vhd_copy_path)s'),
                      {'base_vhd_path': base_vhd_path,
                       'base_vhd_copy_path': base_vhd_copy_path})
            self._pathutils.copyfile(base_vhd_path, base_vhd_copy_path)

            LOG.debug(_("Reconnecting copied base VHD "
                        "%(base_vhd_copy_path)s and diff "
                        "VHD %(diff_vhd_path)s"),
                      {'base_vhd_copy_path': base_vhd_copy_path,
                       'diff_vhd_path': diff_vhd_path})
            self._vhdutils.reconnect_parent_vhd(diff_vhd_path,
                                                base_vhd_copy_path)

            LOG.debug(_("Merging base disk %(base_vhd_copy_path)s and "
                        "diff disk %(diff_vhd_path)s"),
                      {'base_vhd_copy_path': base_vhd_copy_path,
                       'diff_vhd_path': diff_vhd_path})
            self._vhdutils.merge_vhd(diff_vhd_path, base_vhd_copy_path)

            # Replace the differential VHD with the merged one
            self._pathutils.rename(base_vhd_copy_path, diff_vhd_path)
        except Exception:
            with excutils.save_and_reraise_exception():
                if self._pathutils.exists(base_vhd_copy_path):
                    self._pathutils.remove(base_vhd_copy_path)

    def _check_resize_vhd(self, vhd_path, vhd_info, new_size):
        curr_size = vhd_info['MaxInternalSize']
        if new_size < curr_size:
            raise vmutils.VHDResizeException(_("Cannot resize a VHD "
                                               "to a smaller size"))
        elif new_size > curr_size:
            self._resize_vhd(vhd_path, new_size)

    def _resize_vhd(self, vhd_path, new_size):
        if vhd_path.split('.')[-1].lower() == "vhd":
            LOG.debug(_("Getting parent disk info for disk: %s"), vhd_path)
            base_disk_path = self._vhdutils.get_vhd_parent_path(vhd_path)
            if base_disk_path:
                # A differential VHD cannot be resized. This limitation
                # does not apply to the VHDX format.
                self._merge_base_vhd(vhd_path, base_disk_path)
        LOG.debug(_("Resizing disk \"%(vhd_path)s\" to new max "
                    "size %(new_size)s"),
                  {'vhd_path': vhd_path, 'new_size': new_size})
        self._vhdutils.resize_vhd(vhd_path, new_size)

    def _check_base_disk(self, context, instance, diff_vhd_path,
                         src_base_disk_path):
        base_vhd_path = self._imagecache.get_cached_image(context, instance)

        # If the location of the base host differs between source
        # and target hosts we need to reconnect the base disk
        if src_base_disk_path.lower() != base_vhd_path.lower():
            LOG.debug(_("Reconnecting copied base VHD "
                        "%(base_vhd_path)s and diff "
                        "VHD %(diff_vhd_path)s"),
                      {'base_vhd_path': base_vhd_path,
                       'diff_vhd_path': diff_vhd_path})
            self._vhdutils.reconnect_parent_vhd(diff_vhd_path,
                                                base_vhd_path)

    def finish_migration(self, context, migration, instance, disk_info,
                         network_info, image_meta, resize_instance=False,
                         block_device_info=None, power_on=True):
        LOG.debug(_("finish_migration called"), instance=instance)

        instance_name = instance['name']

        if self._volumeops.ebs_root_in_block_devices(block_device_info):
            root_vhd_path = None
        else:
            root_vhd_path = self._pathutils.lookup_root_vhd_path(instance_name)
            if not root_vhd_path:
                raise vmutils.HyperVException(_("Cannot find boot VHD "
                                                "file for instance: %s") %
                                              instance_name)

            root_vhd_info = self._vhdutils.get_vhd_info(root_vhd_path)
            src_base_disk_path = root_vhd_info.get("ParentPath")
            if src_base_disk_path:
                self._check_base_disk(context, instance, root_vhd_path,
                                      src_base_disk_path)

            if resize_instance:
                new_size = instance['root_gb'] * 1024 ** 3
                self._check_resize_vhd(root_vhd_path, root_vhd_info, new_size)

        eph_vhd_path = self._pathutils.lookup_ephemeral_vhd_path(instance_name)
        if resize_instance:
            new_size = instance.get('ephemeral_gb', 0) * 1024 ** 3
            if not eph_vhd_path:
                if new_size:
                    eph_vhd_path = self._vmops.create_ephemeral_vhd(instance)
            else:
                eph_vhd_info = self._vhdutils.get_vhd_info(eph_vhd_path)
                self._check_resize_vhd(eph_vhd_path, eph_vhd_info, new_size)

        self._vmops.create_instance(instance, network_info, block_device_info,
                                    root_vhd_path, eph_vhd_path)
        if power_on:
            self._vmops.power_on(instance)
