# Copyright (c) 2014 Hitachi Data Systems, 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.

"""
Volume driver for HDS HNAS NFS storage.
"""

import os
import time

from oslo.config import cfg
from xml.etree import ElementTree as ETree

from cinder import exception
from cinder.image import image_utils
from cinder.openstack.common import excutils
from cinder.openstack.common import log as logging
from cinder.openstack.common import processutils
from cinder.openstack.common import units
from cinder.volume.drivers.hds.hnas_backend import HnasBackend
from cinder.volume.drivers import nfs


HDS_HNAS_NFS_VERSION = '1.0.0'

LOG = logging.getLogger(__name__)

NFS_OPTS = [
    cfg.StrOpt('hds_hnas_nfs_config_file',
               default='/opt/hds/hnas/cinder_nfs_conf.xml',
               help='configuration file for HDS NFS cinder plugin'), ]

CONF = cfg.CONF
CONF.register_opts(NFS_OPTS)

HNAS_DEFAULT_CONFIG = {'hnas_cmd': 'ssc'}


def _xml_read(root, element, check=None):
    """Read an xml element.

    :param root: XML object
    :param element: string desired tag
    :param check: string if present, throw exception if element missing
    """

    try:
        val = root.findtext(element)
        LOG.info(_("%(element)s: %(val)s")
                 % {'element': element,
                    'val': val})
        if val:
            return val.strip()
        if check:
            raise exception.ParameterNotFound(param=element)
        return None
    except ETree.ParseError:
        if check:
            with excutils.save_and_reraise_exception():
                LOG.error(_("XML exception reading parameter: %s") % element)
        else:
            LOG.info(_("XML exception reading parameter: %s") % element)
            return None


def _read_config(xml_config_file):
    """Read hds driver specific xml config file.

    :param xml_config_file: string filename containing XML configuration
    """

    try:
        root = ETree.parse(xml_config_file).getroot()
    except Exception:
        raise exception.NotFound(message='config file not found: '
                                 + xml_config_file)

    # mandatory parameters
    config = {}
    arg_prereqs = ['mgmt_ip0', 'username', 'password']
    for req in arg_prereqs:
        config[req] = _xml_read(root, req, 'check')

    # optional parameters
    config['hnas_cmd'] = _xml_read(root, 'hnas_cmd') or\
        HNAS_DEFAULT_CONFIG['hnas_cmd']

    config['hdp'] = {}
    config['services'] = {}

    # min one needed
    for svc in ['svc_0', 'svc_1', 'svc_2', 'svc_3']:
        if _xml_read(root, svc) is None:
            continue
        service = {'label': svc}

        # none optional
        for arg in ['volume_type', 'hdp']:
            service[arg] = _xml_read(root, svc + '/' + arg, 'check')
        config['services'][service['volume_type']] = service
        config['hdp'][service['hdp']] = service['hdp']

    # at least one service required!
    if config['services'].keys() is None:
        raise exception.ParameterNotFound(param="No service found")

    return config


def factory_bend():
    """Factory over-ride in self-tests."""

    return HnasBackend()


class HDSNFSDriver(nfs.NfsDriver):
    """Base class for Hitachi NFS driver.
      Executes commands relating to Volumes.
    """

    def __init__(self, *args, **kwargs):
        # NOTE(vish): db is set by Manager
        self._execute = None
        self.context = None
        self.configuration = kwargs.get('configuration', None)

        if self.configuration:
            self.configuration.append_config_values(NFS_OPTS)
            self.config = _read_config(
                self.configuration.hds_hnas_nfs_config_file)

        super(HDSNFSDriver, self).__init__(*args, **kwargs)
        self.bend = factory_bend()
        (self.arid, self.nfs_name, self.lumax) = self._array_info_get()

    def _array_info_get(self):
        """Get array parameters."""

        out = self.bend.get_version(self.config['hnas_cmd'],
                                    HDS_HNAS_NFS_VERSION,
                                    self.config['mgmt_ip0'],
                                    self.config['username'],
                                    self.config['password'])

        inf = out.split()
        return inf[1], 'nfs_' + inf[1], inf[6]

    def _id_to_vol(self, volume_id):
        """Given the volume id, retrieve the volume object from database.

        :param volume_id: string volume id
        """

        vol = self.db.volume_get(self.context, volume_id)

        return vol

    def _get_service(self, volume):
        """Get the available service parameters for a given volume using
           its type.

        :param volume: dictionary volume reference
        """

        label = None
        if volume['volume_type']:
            label = volume['volume_type']['name']
        label = label or 'default'
        if label not in self.config['services'].keys():
            # default works if no match is found
            label = 'default'
        if label in self.config['services'].keys():
            svc = self.config['services'][label]
            LOG.info("Get service: %s->%s" % (label, svc['fslabel']))
            service = (svc['hdp'], svc['path'], svc['fslabel'])
        else:
            LOG.info(_("Available services: %s")
                     % self.config['services'].keys())
            LOG.error(_("No configuration found for service: %s") % label)
            raise exception.ParameterNotFound(param=label)

        return service

    def set_execute(self, execute):
        self._execute = execute

    def extend_volume(self, volume, new_size):
        """Extend an existing volume.

        :param volume: dictionary volume reference
        :param new_size: int size in GB to extend
        """

        nfs_mount = self._get_provider_location(volume['id'])
        path = self._get_volume_path(nfs_mount, volume['name'])

        # Resize the image file on share to new size.
        LOG.debug('Checking file for resize')

        if self._is_file_size_equal(path, new_size):
            return
        else:
            LOG.info(_('Resizing file to %sG'), new_size)
            image_utils.resize_image(path, new_size)
            if self._is_file_size_equal(path, new_size):
                LOG.info(_("LUN %(id)s extended to %(size)s GB.")
                         % {'id': volume['id'], 'size': new_size})
                return
            else:
                raise exception.InvalidResults(
                    _('Resizing image file failed.'))

    def _is_file_size_equal(self, path, size):
        """Checks if file size at path is equal to size."""

        data = image_utils.qemu_img_info(path)
        virt_size = data.virtual_size / units.Gi

        if virt_size == size:
            return True
        else:
            return False

    def create_volume_from_snapshot(self, volume, snapshot):
        """Creates a volume from a snapshot."""

        LOG.debug('create_volume_from %s', volume)
        vol_size = volume['size']
        snap_size = snapshot['volume_size']

        if vol_size != snap_size:
            msg = _('Cannot create volume of size %(vol_size)s from '
                    'snapshot of size %(snap_size)s')
            msg_fmt = {'vol_size': vol_size, 'snap_size': snap_size}
            raise exception.CinderException(msg % msg_fmt)

        self._clone_volume(snapshot['name'],
                           volume['name'],
                           snapshot['volume_id'])
        share = self._get_volume_location(snapshot['volume_id'])

        return {'provider_location': share}

    def create_snapshot(self, snapshot):
        """Create a snapshot.

        :param snapshot: dictionary snapshot reference
        """

        self._clone_volume(snapshot['volume_name'],
                           snapshot['name'],
                           snapshot['volume_id'])
        share = self._get_volume_location(snapshot['volume_id'])
        LOG.debug('Share: %s', share)

        # returns the mount point (not path)
        return {'provider_location': share}

    def delete_snapshot(self, snapshot):
        """Deletes a snapshot.

        :param snapshot: dictionary snapshot reference
        """

        nfs_mount = self._get_provider_location(snapshot['volume_id'])

        if self._volume_not_present(nfs_mount, snapshot['name']):
            return True

        self._execute('rm', self._get_volume_path(nfs_mount, snapshot['name']),
                      run_as_root=True)

    def _get_volume_location(self, volume_id):
        """Returns NFS mount address as <nfs_ip_address>:<nfs_mount_dir>.

        :param volume_id: string volume id
        """

        nfs_server_ip = self._get_host_ip(volume_id)
        export_path = self._get_export_path(volume_id)

        return nfs_server_ip + ':' + export_path

    def _get_provider_location(self, volume_id):
        """Returns provider location for given volume.

        :param volume_id: string volume id
        """

        volume = self.db.volume_get(self.context, volume_id)

        # same format as _get_volume_location
        return volume.provider_location

    def _get_host_ip(self, volume_id):
        """Returns IP address for the given volume.

        :param volume_id: string volume id
        """

        return self._get_provider_location(volume_id).split(':')[0]

    def _get_export_path(self, volume_id):
        """Returns NFS export path for the given volume.

        :param volume_id: string volume id
        """

        return self._get_provider_location(volume_id).split(':')[1]

    def _volume_not_present(self, nfs_mount, volume_name):
        """Check if volume exists.

        :param volume_name: string volume name
        """

        try:
            self._try_execute('ls', self._get_volume_path(nfs_mount,
                                                          volume_name))
        except processutils.ProcessExecutionError:
            # If the volume isn't present
            return True

        return False

    def _try_execute(self, *command, **kwargs):
        # NOTE(vish): Volume commands can partially fail due to timing, but
        #             running them a second time on failure will usually
        #             recover nicely.
        tries = 0
        while True:
            try:
                self._execute(*command, **kwargs)
                return True
            except processutils.ProcessExecutionError:
                tries += 1
                if tries >= self.configuration.num_shell_tries:
                    raise
                LOG.exception(_("Recovering from a failed execute.  "
                                "Try number %s"), tries)
                time.sleep(tries ** 2)

    def _get_volume_path(self, nfs_share, volume_name):
        """Get volume path (local fs path) for given volume name on given nfs
        share.

        :param nfs_share string, example 172.18.194.100:/var/nfs
        :param volume_name string,
            example volume-91ee65ec-c473-4391-8c09-162b00c68a8c
        """

        return os.path.join(self._get_mount_point_for_share(nfs_share),
                            volume_name)

    def create_cloned_volume(self, volume, src_vref):
        """Creates a clone of the specified volume.

        :param volume: dictionary volume reference
        :param src_vref: dictionary src_vref reference
        """

        vol_size = volume['size']
        src_vol_size = src_vref['size']

        if vol_size != src_vol_size:
            msg = _('Cannot create clone of size %(vol_size)s from '
                    'volume of size %(src_vol_size)s')
            msg_fmt = {'vol_size': vol_size, 'src_vol_size': src_vol_size}
            raise exception.CinderException(msg % msg_fmt)

        self._clone_volume(src_vref['name'], volume['name'], src_vref['id'])
        share = self._get_volume_location(src_vref['id'])

        return {'provider_location': share}

    def get_volume_stats(self, refresh=False):
        """Get volume stats.

        if 'refresh' is True, update the stats first.
        """

        _stats = super(HDSNFSDriver, self).get_volume_stats(refresh)
        be_name = self.configuration.safe_get('volume_backend_name')
        _stats["volume_backend_name"] = be_name or 'HDSNFSDriver'
        _stats["vendor_name"] = 'HDS'
        _stats["driver_version"] = HDS_HNAS_NFS_VERSION
        _stats["storage_protocol"] = 'NFS'

        return _stats

    def _get_nfs_info(self):
        out = self.bend.get_nfs_info(self.config['hnas_cmd'],
                                     self.config['mgmt_ip0'],
                                     self.config['username'],
                                     self.config['password'])
        lines = out.split('\n')

        # dict based on NFS exports addresses
        conf = {}
        for line in lines:
            if 'Export' in line:
                inf = line.split()
                (export, path, fslabel, hdp, evs, ip1) = \
                    inf[1], inf[3], inf[5], inf[7], inf[9], inf[11]
                # 9, 10, etc are IP addrs
                key = ip1 + ':' + export
                conf[key] = {}
                conf[key]['path'] = path
                conf[key]['hdp'] = hdp
                conf[key]['fslabel'] = fslabel
                msg = _('nfs_info: %(key)s: %(path)s, HDP: \
                        %(fslabel)s FSID: %(hdp)s')
                LOG.info(msg
                         % {'key': key,
                            'path': path,
                            'fslabel': fslabel,
                            'hdp': hdp})

        return conf

    def do_setup(self, context):
        """Perform internal driver setup."""

        self.context = context
        self._load_shares_config(getattr(self.configuration,
                                         self.driver_prefix +
                                         '_shares_config'))
        LOG.info("Review shares: %s" % self.shares)

        nfs_info = self._get_nfs_info()

        for share in self.shares:
            #export = share.split(':')[1]
            if share in nfs_info.keys():
                LOG.info("share: %s -> %s" % (share, nfs_info[share]['path']))

                for svc in self.config['services'].keys():
                    if share == self.config['services'][svc]['hdp']:
                        self.config['services'][svc]['path'] = \
                            nfs_info[share]['path']
                        # don't overwrite HDP value
                        self.config['services'][svc]['fsid'] = \
                            nfs_info[share]['hdp']
                        self.config['services'][svc]['fslabel'] = \
                            nfs_info[share]['fslabel']
                        LOG.info("Save service info for %s -> %s, %s"
                                 % (svc, nfs_info[share]['hdp'],
                                    nfs_info[share]['path']))
                        break
                if share != self.config['services'][svc]['hdp']:
                    LOG.error("NFS share %s has no service entry: %s -> %s"
                              % (share, svc,
                                 self.config['services'][svc]['hdp']))
                    raise exception.ParameterNotFound(param=svc)
            else:
                LOG.info("share: %s incorrect entry" % share)

    def _clone_volume(self, volume_name, clone_name, volume_id):
        """Clones mounted volume using the HNAS file_clone.

        :param volume_name: string volume name
        :param clone_name: string clone name (or snapshot)
        :param volume_id: string volume id
        """

        export_path = self._get_export_path(volume_id)
        # volume-ID snapshot-ID, /cinder
        LOG.info("Cloning with volume_name %s clone_name %s export_path %s"
                 % (volume_name, clone_name, export_path))

        source_vol = self._id_to_vol(volume_id)
        # sps; added target
        (_hdp, _path, _fslabel) = self._get_service(source_vol)
        target_path = '%s/%s' % (_path, clone_name)
        source_path = '%s/%s' % (_path, volume_name)
        out = self.bend.file_clone(self.config['hnas_cmd'],
                                   self.config['mgmt_ip0'],
                                   self.config['username'],
                                   self.config['password'],
                                   _fslabel, source_path, target_path)

        return out
