# 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.
#
# Compute 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 Compute.  If not, see <http://www.gnu.org/licenses/>.

"""Hypervisor session manager."""

import logging
from contextlib import AbstractContextManager
from types import TracebackType
from typing import Any, NamedTuple
from uuid import uuid4

import libvirt
from lxml import etree

from .config import Config
from .exceptions import (
    InstanceNotFoundError,
    SessionError,
    StoragePoolNotFoundError,
)
from .instance import Instance, InstanceConfig, InstanceSchema
from .instance.cloud_init import CloudInit
from .instance.devices import DiskConfig, DiskDriver
from .storage import StoragePool, VolumeConfig
from .utils import diskutils, units


log = logging.getLogger(__name__)

config = Config()


class Capabilities(NamedTuple):
    """Store domain capabilities info."""

    arch: str
    virt_type: str
    emulator: str
    machine: str
    max_vcpus: int
    cpu_vendor: str
    cpu_model: str
    cpu_features: dict
    usable_cpus: list[dict]


class NodeInfo(NamedTuple):
    """
    Store compute node info.

    See https://libvirt.org/html/libvirt-libvirt-host.html#virNodeInfo
    NOTE: memory unit in libvirt docs is wrong! Actual unit is MiB.
    """

    arch: str
    memory: int
    cpus: int
    mhz: int
    nodes: int
    sockets: int
    cores: int
    threads: int


class Session(AbstractContextManager):
    """Hypervisor session context manager."""

    def __init__(self, uri: str | None = None):
        """
        Initialise session with hypervisor.

        :param uri: libvirt connection URI.
        """
        log.debug('Config=%s', config)
        self.LIBVIRT_URI = config['libvirt']['uri']
        self.IMAGES_POOL = config['storage']['images']
        self.VOLUMES_POOL = config['storage']['volumes']
        self._uri = uri or self.LIBVIRT_URI
        self._connection = libvirt.open(self._uri)

    def __enter__(self):
        """Return Session object."""
        return self

    def __exit__(
        self,
        exc_type: type[BaseException] | None,
        exc_value: BaseException | None,
        exc_traceback: TracebackType | None,
    ):
        """Close the connection when leaving the context."""
        self.close()

    @property
    def uri(self) -> str:
        """Libvirt connection URI."""
        return self._uri

    @property
    def connection(self) -> libvirt.virConnect:
        """Libvirt connection object."""
        return self._connection

    def close(self) -> None:
        """Close connection to libvirt daemon."""
        self.connection.close()

    def get_node_info(self) -> NodeInfo:
        """Return information about compute node."""
        info = self.connection.getInfo()
        return NodeInfo(
            arch=info[0],
            memory=info[1],
            cpus=info[2],
            mhz=info[3],
            nodes=info[4],
            sockets=info[5],
            cores=info[6],
            threads=info[7],
        )

    def _cap_get_usable_cpus(self, xml: etree.Element) -> list[dict]:
        x = xml.xpath('/domainCapabilities/cpu/mode[@name="custom"]')[0]
        cpus = []
        for cpu in x.findall('model'):
            if cpu.get('usable') == 'yes':
                cpus.append(  # noqa: PERF401
                    {
                        'vendor': cpu.get('vendor'),
                        'model': cpu.text,
                    }
                )
        return cpus

    def _cap_get_cpu_features(self, xml: etree.Element) -> dict:
        x = xml.xpath('/domainCapabilities/cpu/mode[@name="host-model"]')[0]
        require = []
        disable = []
        for feature in x.findall('feature'):
            policy = feature.get('policy')
            name = feature.get('name')
            if policy == 'require':
                require.append(name)
            if policy == 'disable':
                disable.append(name)
        return {'require': require, 'disable': disable}

    def get_capabilities(self) -> Capabilities:
        """Return capabilities e.g. arch, virt, emulator, etc."""
        prefix = '/domainCapabilities'
        hprefix = f'{prefix}/cpu/mode[@name="host-model"]'
        caps = etree.fromstring(self.connection.getDomainCapabilities())
        return Capabilities(
            arch=caps.xpath(f'{prefix}/arch/text()')[0],
            virt_type=caps.xpath(f'{prefix}/domain/text()')[0],
            emulator=caps.xpath(f'{prefix}/path/text()')[0],
            machine=caps.xpath(f'{prefix}/machine/text()')[0],
            max_vcpus=int(caps.xpath(f'{prefix}/vcpu/@max')[0]),
            cpu_vendor=caps.xpath(f'{hprefix}/vendor/text()')[0],
            cpu_model=caps.xpath(f'{hprefix}/model/text()')[0],
            cpu_features=self._cap_get_cpu_features(caps),
            usable_cpus=self._cap_get_usable_cpus(caps),
        )

    def create_instance(self, **kwargs: Any) -> Instance:
        """
        Create and return new compute instance.

        :param name: Instance name.
        :type name: str
        :param title: Instance title for humans.
        :type title: str
        :param description: Some information about instance.
        :type description: str
        :param memory: Memory in MiB.
        :type memory: int
        :param max_memory: Maximum memory in MiB.
        :type max_memory: int
        :param vcpus: Number of vCPUs.
        :type vcpus: int
        :param max_vcpus: Maximum vCPUs.
        :type max_vcpus: int
        :param cpu: CPU configuration. See :class:`CPUSchema` for info.
        :type cpu: dict
        :param machine: QEMU emulated machine.
        :type machine: str
        :param emulator: Path to emulator.
        :type emulator: str
        :param arch: CPU architecture to virtualization.
        :type arch: str
        :param boot: Boot settings. See :class:`BootOptionsSchema`.
        :type boot: dict
        :param image: Source disk image name for system disk.
        :type image: str
        :param volumes: List of storage volume configs. For more info
            see :class:`VolumeSchema`.
        :type volumes: list[dict]
        :param network_interfaces: List of virtual network interfaces
            configs. See :class:`NetworkInterfaceSchema` for more info.
        :type network_interfaces: list[dict]
        """
        data = InstanceSchema(**kwargs)
        config = InstanceConfig(data)
        log.info('Define instance XML')
        log.debug(config.to_xml())
        try:
            self.connection.defineXML(config.to_xml())
        except libvirt.libvirtError as e:
            raise SessionError(f'Error defining instance: {e}') from e
        log.info('Getting instance object...')
        instance = self.get_instance(config.name)
        log.info('Start processing volumes...')
        log.info('Connecting to images pool...')
        images_pool = self.get_storage_pool(self.IMAGES_POOL)
        images_pool.refresh()
        log.info('Connecting to volumes pool...')
        volumes_pool = self.get_storage_pool(self.VOLUMES_POOL)
        volumes_pool.refresh()
        disk_targets = []
        for volume in data.volumes:
            log.info('Processing volume=%s', volume)
            log.info('Building volume configuration...')
            capacity = None
            disk_targets.append(volume.target)
            if not volume.source:
                volume_name = f'{uuid4()}.qcow2'
            else:
                volume_name = volume.source
            if volume.device == 'cdrom':
                log.info('Volume %s is CDROM device', volume_name)
            elif volume.source is not None:
                log.info('Using volume %s as source', volume_name)
                volume_source = volume.source
                if volume.capacity:
                    capacity = units.to_bytes(
                        volume.capacity.value, volume.capacity.unit
                    )
            else:
                capacity = units.to_bytes(
                    volume.capacity.value, volume.capacity.unit
                )
                volume_config = VolumeConfig(
                    name=volume_name,
                    path=str(volumes_pool.path.joinpath(volume_name)),
                    capacity=capacity,
                )
                volume_source = volume_config.path
                log.debug('Volume config: %s', volume_config)
                if volume.is_system is True and data.image:
                    log.info(
                        "Volume is marked as 'system', start cloning image..."
                    )
                    log.info('Get image %s', data.image)
                    image = images_pool.get_volume(data.image)
                    log.info('Cloning image into volumes pool...')
                    vol = volumes_pool.clone_volume(image, volume_config)
                else:
                    log.info('Create volume %s', volume_config.name)
                    volumes_pool.create_volume(volume_config)
            if capacity is not None:
                log.info(
                    'Resize cloned volume to specified size: %s',
                    capacity,
                )
                vol.resize(capacity, unit=units.DataUnit.BYTES)
            log.info('Attaching volume to instance...')
            instance.attach_device(
                DiskConfig(
                    type=volume.type,
                    device=volume.device,
                    source=volume_source,
                    target=volume.target,
                    is_readonly=volume.is_readonly,
                    bus=volume.bus,
                    driver=DiskDriver(
                        volume.driver.name,
                        volume.driver.type,
                        volume.driver.cache,
                    ),
                )
            )
        if data.cloud_init:
            log.info('Crating disk for cloud-init...')
            cloud_init = CloudInit()
            cloud_init.user_data = data.cloud_init.user_data
            cloud_init.vendor_data = data.cloud_init.vendor_data
            cloud_init.network_config = data.cloud_init.network_config
            cloud_init.meta_data = data.cloud_init.meta_data
            cloud_init_disk_path = volumes_pool.path.joinpath(
                f'{instance.name}-cloud-init.img'
            )
            cloud_init.create_disk(cloud_init_disk_path)
            log.info('Attaching cloud-init disk to instance...')
            volumes_pool.refresh()
            cloud_init.attach_disk(
                cloud_init_disk_path,
                diskutils.get_disk_target(disk_targets, prefix='vd'),
                instance,
            )
        return instance

    def get_instance(self, name: str) -> Instance:
        """Get compute instance by name."""
        try:
            return Instance(self.connection.lookupByName(name))
        except libvirt.libvirtError as e:
            if e.get_error_code() == libvirt.VIR_ERR_NO_DOMAIN:
                raise InstanceNotFoundError(name) from e
            raise SessionError(e) from e

    def list_instances(self) -> list[Instance]:
        """List all instances."""
        return [Instance(dom) for dom in self.connection.listAllDomains()]

    def get_storage_pool(self, name: str) -> StoragePool:
        """Get storage pool by name."""
        try:
            return StoragePool(self.connection.storagePoolLookupByName(name))
        except libvirt.libvirtError as e:
            if e.get_error_code() == libvirt.VIR_ERR_NO_STORAGE_POOL:
                raise StoragePoolNotFoundError(name) from e
            raise SessionError(e) from e

    def list_storage_pools(self) -> list[StoragePool]:
        """List all strage pools."""
        return [StoragePool(p) for p in self.connection.listStoragePools()]