# This file is part of Compute
#
# Compute is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Ansible 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Ansible.  If not, see <http://www.gnu.org/licenses/>.

"""Manage storage volumes."""

from dataclasses import dataclass
from pathlib import Path
from time import time
from typing import Union

import libvirt
from lxml import etree
from lxml.builder import E

from compute.common import DeviceConfig, EntityConfig
from compute.utils import units


@dataclass
class VolumeConfig(EntityConfig):
    """
    Storage volume XML config builder.

    Generate XML config for creating a volume in a libvirt
    storage pool.
    """

    name: str
    path: str
    capacity: int

    def to_xml(self) -> str:
        """Return XML config for libvirt."""
        unixtime = str(int(time()))
        xml = E.volume(type='file')
        xml.append(E.name(self.name))
        xml.append(E.key(self.path))
        xml.append(E.source())
        xml.append(E.capacity(str(self.capacity), unit='bytes'))
        xml.append(E.allocation('0'))
        xml.append(
            E.target(
                E.path(self.path),
                E.format(type='qcow2'),
                E.timestamps(
                    E.atime(unixtime), E.mtime(unixtime), E.ctime(unixtime)
                ),
                E.compat('1.1'),
                E.features(E.lazy_refcounts()),
            )
        )
        return etree.tostring(xml, encoding='unicode', pretty_print=True)


@dataclass
class DiskConfig(DeviceConfig):
    """
    Disk XML config builder.

    Generate XML config for attaching or detaching storage volumes
    to compute instances.
    """

    disk_type: str
    source: str | Path
    target: str
    readonly: bool = False

    def to_xml(self) -> str:
        """Return XML config for libvirt."""
        xml = E.disk(type=self.disk_type, device='disk')
        xml.append(E.driver(name='qemu', type='qcow2', cache='writethrough'))
        if self.disk_type == 'file':
            xml.append(E.source(file=str(self.source)))
        xml.append(E.target(dev=self.target, bus='virtio'))
        if self.readonly:
            xml.append(E.readonly())
        return etree.tostring(xml, encoding='unicode', pretty_print=True)

    @classmethod
    def from_xml(cls, xml: Union[str, etree.Element]) -> 'DiskConfig':  # noqa: UP007
        """
        Return :class:`DiskConfig` instance using existing XML config.

        :param xml: Disk device XML configuration as :class:`str` or lxml
            :class:`etree.Element` object.
        """
        if isinstance(xml, str):
            xml = etree.fromstring(xml)
        disk_params = {
            'disk_type': xml.get('type'),
            'source': xml.find('source').get('file'),
            'target': xml.find('target').get('dev'),
            'readonly': False if xml.find('readonly') is None else True,  # noqa: SIM211
        }
        for param in disk_params:
            if disk_params[param] is None:
                msg = f"Bad XML config: parameter '{param}' is not defined"
                raise ValueError(msg)
        return cls(**disk_params)


class Volume:
    """Storage volume manipulating class."""

    def __init__(
        self, pool: libvirt.virStoragePool, vol: libvirt.virStorageVol
    ):
        """
        Initialise Volume.

        :param pool: libvirt virStoragePool object
        :param vol: libvirt virStorageVol object
        """
        self.pool = pool
        self.pool_name = pool.name()
        self.vol = vol
        self.name = vol.name()
        self.path = Path(vol.path())

    def dump_xml(self) -> str:
        """Return volume XML description as string."""
        return self.vol.XMLDesc()

    def clone(self, vol_conf: VolumeConfig) -> None:
        """
        Make a copy of volume to the same storage pool.

        :param vol_info VolumeInfo: New storage volume dataclass object
        """
        self.pool.createXMLFrom(
            vol_conf.to_xml(),
            self.vol,
            flags=libvirt.VIR_STORAGE_VOL_CREATE_PREALLOC_METADATA,
        )

    def resize(self, capacity: int, unit: units.DataUnit) -> None:
        """
        Resize volume.

        :param capacity int: Volume new capacity.
        :param unit DataUnit: Data unit. Internally converts into bytes.
        """
        # TODO @ge: Check actual volume size before resize
        self.vol.resize(units.to_bytes(capacity, unit=unit))

    def delete(self) -> None:
        """Delete volume from storage pool."""
        self.vol.delete()