// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

mod hvc;
pub mod powershell;
pub mod vm;

use vmsocket::VmAddress;
use vmsocket::VmSocket;

use crate::Disk;
use crate::Drive;
use crate::Firmware;
use crate::IsolationType;
use crate::ModifyFn;
use crate::NoPetriVmInspector;
use crate::OpenHclServicingFlags;
use crate::OpenvmmLogConfig;
use crate::PetriHaltReasonDetail;
use crate::PetriVmConfig;
use crate::PetriVmResources;
use crate::PetriVmRuntime;
use crate::PetriVmRuntimeConfig;
use crate::PetriVmmBackend;
use crate::ShutdownKind;
use crate::UefiConfig;
use crate::VmbusStorageController;
use crate::VmmQuirks;
use crate::hyperv::powershell::HyperVNewCustomVMArgs;
use crate::kmsg_log_task;
use crate::openhcl_diag::OpenHclDiagHandler;
use crate::vm::PetriVmProperties;
use crate::vm::append_cmdline;
use anyhow::Context;
use async_trait::async_trait;
use disk_backend::sync_wrapper::BlockingDisk;
use disk_vhdmp::VhdmpDisk;
use get_resources::ged::FirmwareEvent;
use guid::Guid;
use pal_async::DefaultDriver;
use pal_async::pipe::PolledPipe;
use pal_async::socket::PolledSocket;
use pal_async::task::Spawn;
use pal_async::task::Task;
use pal_async::timer::PolledTimer;
use petri_artifacts_common::tags::GuestQuirksInner;
use petri_artifacts_common::tags::MachineArch;
use petri_artifacts_common::tags::OsFlavor;
use petri_artifacts_core::ArtifactResolver;
use petri_artifacts_core::ResolvedArtifact;
use pipette_client::PipetteClient;
pub use powershell::request_physical_nvme;
use std::collections::HashMap;
use std::io::ErrorKind;
use std::io::Write;
use std::path::Path;
use std::path::PathBuf;
use std::sync::Arc;
use std::time::Duration;
use tempfile::TempDir;
use tempfile::TempPath;
use vm::HyperVVM;
use vtl2_settings_proto::Vtl2Settings;

const IGVM_FILE_NAME: &str = "igvm.bin";

/// The Hyper-V Petri backend
#[derive(Debug)]
pub struct HyperVPetriBackend {}

/// Resources needed at runtime for a Hyper-V Petri VM
pub struct HyperVPetriRuntime {
    vm: HyperVVM,
    log_tasks: Vec<Task<anyhow::Result<()>>>,
    temp_dir: TempDir,
    output_dir: PathBuf,
    driver: DefaultDriver,
    properties: PetriVmProperties,
}

#[async_trait]
impl PetriVmmBackend for HyperVPetriBackend {
    type VmmConfig = ();
    type VmRuntime = HyperVPetriRuntime;

    fn check_compat(firmware: &Firmware, arch: MachineArch) -> bool {
        arch == MachineArch::host()
            && !firmware.is_linux_direct()
            && !(firmware.is_pcat() && arch == MachineArch::Aarch64)
    }

    fn quirks(firmware: &Firmware) -> (GuestQuirksInner, VmmQuirks) {
        (firmware.quirks().hyperv, VmmQuirks::default())
    }

    fn default_servicing_flags() -> OpenHclServicingFlags {
        OpenHclServicingFlags {
            enable_nvme_keepalive: false, // TODO: Support NVMe KA in the Hyper-V Petri Backend
            enable_mana_keepalive: false,
            override_version_checks: true, // TODO: figure out why our tests don't pass the version check
            stop_timeout_hint_secs: None,
        }
    }

    fn create_guest_dump_disk() -> anyhow::Result<
        Option<(
            Arc<TempPath>,
            Box<dyn FnOnce() -> anyhow::Result<Box<dyn fatfs::ReadWriteSeek>>>,
        )>,
    > {
        // Make a 16 GiB dynamic VHD for guest crash dumps.
        let crash_disk = tempfile::Builder::new()
            .suffix(".vhdx")
            .make(|path| disk_vhdmp::Vhd::create_dynamic(path, 16 * 1024, true))
            .context("error creating crash dump vhdx")?;
        let (crash_disk, crash_disk_path) = crash_disk.into_parts();
        crash_disk
            .attach_for_raw_access(false)
            .context("error attaching crash dump vhdx")?;
        let mut crash_disk = BlockingDisk::new(
            disk_backend::Disk::new(
                VhdmpDisk::new(crash_disk, false).context("failed opening vhdmp")?,
            )
            .unwrap(),
        );

        // Format the VHD with FAT32.
        crate::disk_image::build_fat32_disk_image(
            &mut crash_disk,
            "CRASHDUMP",
            b"crashdump  ",
            &[],
        )
        .context("error writing empty crash disk filesystem")?;

        // Prepare the hook to extract crash dumps after the test.
        let crash_disk_path = Arc::new(crash_disk_path);
        let hook_crash_disk = crash_disk_path.clone();
        let disk_opener = Box::new(move || {
            let mut vhd = Err(anyhow::Error::msg("haven't tried to open the vhd yet"));
            // The VM may not be fully shut down immediately, do some retries
            for _ in 0..5 {
                vhd = VhdmpDisk::options()
                    .read_only(true)
                    .open(hook_crash_disk.as_ref())
                    .context("failed opening vhd");
                if vhd.is_ok() {
                    break;
                } else {
                    std::thread::sleep(Duration::from_secs(3));
                }
            }
            let vhdmp = VhdmpDisk::new(vhd?, true).context("failed opening vhdmp")?;
            Ok(Box::new(BlockingDisk::new(disk_backend::Disk::new(vhdmp).unwrap())) as _)
        });
        Ok(Some((crash_disk_path, disk_opener)))
    }

    fn new(_resolver: &ArtifactResolver<'_>) -> Self {
        HyperVPetriBackend {}
    }

    async fn run(
        self,
        config: PetriVmConfig,
        _modify_vmm_config: Option<ModifyFn<Self::VmmConfig>>,
        resources: &PetriVmResources,
        properties: PetriVmProperties,
    ) -> anyhow::Result<(Self::VmRuntime, PetriVmRuntimeConfig)> {
        let PetriVmResources { driver, log_source } = resources;

        assert!(matches!(
            config.host_log_levels,
            None | Some(OpenvmmLogConfig::TestDefault)
        )); // Custom host log levels not supported in HyperV backend yet.

        let temp_dir = tempfile::tempdir()?;

        let igvm_file = properties
            .is_openhcl
            .then(|| temp_dir.path().join(IGVM_FILE_NAME));

        let mut openhcl_command_line = config.firmware.openhcl_config().map(|c| c.command_line());

        let guest_state_path = petri_disk_to_hyperv(config.vmgs.disk(), &temp_dir).await?;

        let mut log_tasks = Vec::new();

        if let Some(UefiConfig {
            disable_frontpage,
            enable_vpci_boot,
            secure_boot_enabled,
            default_boot_always_attempt,
            efi_diagnostics_log_level,
            ..
        }) = config.firmware.uefi_config()
        {
            // TODO: Disable frontpage for non-OpenHCL Hyper-V VMs
            if *disable_frontpage && properties.is_openhcl {
                append_cmdline(
                    &mut openhcl_command_line,
                    "OPENHCL_DISABLE_UEFI_FRONTPAGE=1",
                );
            }

            // For certain configurations, we need to override the override
            // in new_underhill_vm.
            //
            // TODO: remove this (and OpenHCL override) once host changes
            // are saturated.
            if !properties.is_isolated
                && !*secure_boot_enabled
                && config.tpm.is_none()
                && !*default_boot_always_attempt
            {
                append_cmdline(
                    &mut openhcl_command_line,
                    "HCL_DEFAULT_BOOT_ALWAYS_ATTEMPT=0",
                );
            }

            // Plumb the EFI diagnostics log level via the OpenHCL command
            // line. The corresponding `EfiDiagnosticsLogLevel` WMI property
            // is not available on all hosts (e.g. rs_prerelease), so we
            // rely on the underhill env var fallback instead. This means
            // we currently only support setting the level on OpenHCL-backed
            // VMs; for plain Hyper-V UEFI VMs we fail loudly rather than
            // silently dropping the setting.
            //
            // TODO: switch to the WMI property (which would also cover the
            // non-OpenHCL path) once host changes are saturated.
            let efi_diag_cli = match efi_diagnostics_log_level {
                crate::EfiDiagnosticsLogLevel::Default => None,
                crate::EfiDiagnosticsLogLevel::Info => Some("INFO"),
                crate::EfiDiagnosticsLogLevel::Full => Some("FULL"),
            };
            if let Some(cli) = efi_diag_cli {
                if !properties.is_openhcl {
                    anyhow::bail!(
                        "with_efi_diagnostics_log_level({:?}) is only supported for \
                         OpenHCL-backed Hyper-V UEFI VMs in this code path",
                        efi_diagnostics_log_level
                    );
                }
                append_cmdline(
                    &mut openhcl_command_line,
                    format!("HCL_EFI_DIAGNOSTICS_LOG_LEVEL={cli}"),
                );
            }

            if *enable_vpci_boot {
                todo!("hyperv nvme boot");
            }
        }

        // Map VMBus storage controllers (SCSI and NVMe).
        let mut storage_controllers = HashMap::new();
        for (
            vsid,
            VmbusStorageController {
                target_vtl,
                controller_type,
                drives,
            },
        ) in config.vmbus_storage_controllers.iter()
        {
            let mut hyperv_drives = HashMap::new();
            for (lun, Drive { disk, is_dvd }) in drives {
                hyperv_drives.insert(
                    *lun,
                    powershell::HyperVDrive {
                        disk: petri_disk_to_hyperv(disk.as_ref(), &temp_dir).await?,
                        is_dvd: *is_dvd,
                    },
                );
            }

            let vmbus_controller_type = match controller_type {
                crate::VmbusStorageType::Scsi => powershell::HyperVVmbusStorageType::Scsi,
                crate::VmbusStorageType::Nvme => {
                    for (nsid, drive) in &hyperv_drives {
                        if drive.is_dvd {
                            anyhow::bail!("NVMe emulator does not support DVD drives");
                        }
                        if drive.disk.is_none() {
                            anyhow::bail!("NVMe drive cannot be empty (NSID {})", nsid);
                        }
                    }
                    powershell::HyperVVmbusStorageType::Nvme
                }
                _ => {
                    todo!(
                        "storage type {:?} not yet supported for hyper-v",
                        controller_type
                    )
                }
            };

            storage_controllers.insert(
                *vsid,
                powershell::HyperVVmbusStorageController {
                    controller_type: vmbus_controller_type,
                    target_vtl: *target_vtl,
                    drives: hyperv_drives,
                },
            );
        }

        // Map IDE
        let mut ide_controllers = HashMap::new();
        if let Some(controllers) = config.firmware.ide_controllers() {
            for (controller_number, controller) in controllers.iter().enumerate() {
                let mut drives = HashMap::new();
                for (lun, drive) in controller.iter().enumerate() {
                    if let Some(Drive { disk, is_dvd }) = drive.as_ref() {
                        drives.insert(
                            lun as u8,
                            powershell::HyperVDrive {
                                disk: petri_disk_to_hyperv(disk.as_ref(), &temp_dir).await?,
                                is_dvd: *is_dvd,
                            },
                        );
                    }
                }
                if !drives.is_empty() {
                    ide_controllers.insert(controller_number as u32, drives);
                }
            }
        }

        let nvme_disk_paths: Vec<PathBuf> = storage_controllers
            .values()
            .filter(|c| matches!(c.controller_type, powershell::HyperVVmbusStorageType::Nvme))
            .flat_map(|c| c.drives.values())
            .filter_map(|drive| drive.disk.clone())
            .collect();

        // Attempt to enable COM3 and use that to get KMSG logs, otherwise
        // fall back to use diag_client.
        let supports_com3 = {
            // Hyper-V VBS VMs don't work with COM3 enabled.
            // Hypervisor support is needed for this to work.
            let is_not_vbs = !matches!(config.firmware.isolation(), Some(IsolationType::Vbs));

            // The Hyper-V serial device for ARM doesn't support additional
            // serial ports yet.
            let is_x86 = matches!(config.arch, MachineArch::X86_64);

            // The registry key to enable additional COM ports is only
            // available in newer builds of Windows.
            let current_winver = windows_version::OsVersion::current();
            tracing::debug!(?current_winver, "host windows version");
            // This is the oldest working build used in CI
            // TODO: determine the actual minimum version
            const COM3_MIN_WINVER: u32 = 27813;
            let is_supported_winver = current_winver.build >= COM3_MIN_WINVER;

            properties.is_openhcl && is_not_vbs && is_x86 && is_supported_winver
        };

        // devnote: The imc_hiv and management_vtl_settings temp files are
        // passed into HyperVVM::new and dropped after the VM is created.
        // In both cases, the data written to the file is read into the VM's
        // configuration when the New-CustomVM powershell cmdlet is called.
        // Once this is done, the files can safely be deleted.

        let imc_hiv = if properties.using_vtl0_pipette
            && matches!(properties.os_flavor, OsFlavor::Windows)
            && !properties.is_isolated
        {
            let mut imc_hive_file = tempfile::NamedTempFile::new().context("creating tempfile")?;
            imc_hive_file
                .write_all(include_bytes!("../../../guest-bootstrap/imc.hiv"))
                .context("failed to write imc hive")?;
            Some(imc_hive_file)
        } else {
            None
        };

        let management_vtl_settings = if let Some(vtl2_settings) = config
            .firmware
            .openhcl_config()
            .and_then(|c| c.vtl2_settings.as_ref())
        {
            let mut vtl2_settings_file =
                tempfile::NamedTempFile::new().context("creating tempfile")?;
            vtl2_settings_file
                .write_all(serde_json::to_string(vtl2_settings)?.as_bytes())
                .context("writing settings to tempfile")?;
            Some(vtl2_settings_file)
        } else {
            None
        };

        let hyperv_args = HyperVNewCustomVMArgs {
            firmware_file: igvm_file.clone(),
            firmware_parameters: openhcl_command_line,
            guest_state_path,
            storage_controllers,
            com_3: supports_com3,
            imc_hiv,
            management_vtl_settings,

            ..HyperVNewCustomVMArgs::from_config(&config, &properties)?
        };

        let vm = HyperVVM::new(hyperv_args, log_source.clone(), driver.clone()).await?;

        if properties.is_openhcl {
            // Copy the IGVM file locally, since it may not be accessible by
            // Hyper-V (e.g., if it is in a WSL filesystem).
            let local_path = igvm_file.as_ref().unwrap();
            fs_err::copy(config.firmware.openhcl_firmware().unwrap(), local_path)
                .context("failed to copy igvm file")?;
            acl_for_vm(local_path, Some(*vm.vmid()), false)
                .context("failed to set ACL for igvm file")?;

            let openhcl_log_file = log_source.log_file("openhcl")?;
            if supports_com3 {
                tracing::debug!("getting kmsg logs from COM3");

                let openhcl_serial_pipe_path = vm.get_vm_com_port_path(3);
                log_tasks.push(driver.spawn(
                    "openhcl-log",
                    hyperv_serial_log_task(
                        driver.clone(),
                        openhcl_serial_pipe_path,
                        openhcl_log_file,
                    ),
                ));
            } else {
                tracing::debug!("getting kmsg logs from diag_client");

                log_tasks.push(driver.spawn(
                    "openhcl-log",
                    kmsg_log_task(
                        openhcl_log_file,
                        diag_client::DiagClient::from_hyperv_id(driver.clone(), *vm.vmid()),
                    ),
                ));
            }
        }

        // Grant the VM access to NVMe VHDs
        for path in &nvme_disk_paths {
            acl_for_vm(path, Some(*vm.vmid()), true).context("failed to set ACL for nvme VHD")?;
        }

        let serial_pipe_path = vm.get_vm_com_port_path(1);
        let serial_log_file = log_source.log_file("guest")?;
        log_tasks.push(driver.spawn(
            "guest-log",
            hyperv_serial_log_task(driver.clone(), serial_pipe_path, serial_log_file),
        ));

        vm.start().await?;

        Ok((
            HyperVPetriRuntime {
                vm,
                log_tasks,
                temp_dir,
                output_dir: log_source.output_dir().to_owned(),
                driver: driver.clone(),
                properties,
            },
            config
                .firmware
                .into_runtime_config(config.vmbus_storage_controllers),
        ))
    }
}

#[async_trait]
impl PetriVmRuntime for HyperVPetriRuntime {
    type VmInspector = NoPetriVmInspector;
    type VmFramebufferAccess = vm::HyperVFramebufferAccess;

    async fn teardown(mut self) -> anyhow::Result<()> {
        futures::future::join_all(self.log_tasks.into_iter().map(|t| t.cancel())).await;
        self.vm.remove().await
    }

    async fn wait_for_halt(&mut self, allow_reset: bool) -> anyhow::Result<PetriHaltReasonDetail> {
        self.vm.wait_for_halt(allow_reset).await
    }

    async fn wait_for_agent(&mut self, set_high_vtl: bool) -> anyhow::Result<PipetteClient> {
        let driver = self.driver.clone();
        let client_core = async move |vm: &HyperVVM| {
            let socket = VmSocket::new().context("failed to create AF_HYPERV socket")?;
            // Extend the default timeout of 2 seconds, as tests are often run
            // in parallel on a host, causing very heavy load on the overall
            // system.
            //
            // TODO: Until #2470 is fixed, extend the timeout even longer to 10
            // seconds to workaround a Windows vmbus bug.
            socket
                .set_connect_timeout(Duration::from_secs(10))
                .context("failed to set connect timeout")?;
            socket
                .set_high_vtl(set_high_vtl)
                .context("failed to set socket for VTL0")?;

            let mut socket = PolledSocket::new(&driver, socket)
                .context("failed to create polled client socket")?
                .convert();
            socket
                .connect(
                    &VmAddress::hyperv_vsock(*vm.vmid(), pipette_client::PIPETTE_VSOCK_PORT).into(),
                )
                .await
                .context("failed to connect")
                .map(|()| socket)
        };

        let driver = self.driver.clone();
        let output_dir = self.output_dir.clone();
        self.vm
            .wait_for_off_or_internal(async move |vm: &HyperVVM| {
                tracing::debug!(set_high_vtl, "attempting to connect to pipette server");
                match client_core(vm).await {
                    Ok(socket) => {
                        tracing::info!(set_high_vtl, "handshaking with pipette");
                        let c = PipetteClient::new(&driver, socket, &output_dir)
                            .await
                            .context("failed to handshake with pipette");
                        tracing::info!(set_high_vtl, "completed pipette handshake");
                        Ok(Some(c?))
                    }
                    Err(err) => {
                        tracing::debug!(
                            err = err.as_ref() as &dyn std::error::Error,
                            "failed to connect to pipette server, retrying",
                        );
                        Ok(None)
                    }
                }
            })
            .await
    }

    fn openhcl_diag(&self) -> Option<OpenHclDiagHandler> {
        self.properties.is_openhcl.then(|| {
            OpenHclDiagHandler::new(diag_client::DiagClient::from_hyperv_id(
                self.driver.clone(),
                *self.vm.vmid(),
            ))
        })
    }

    async fn wait_for_boot_event(&mut self) -> anyhow::Result<FirmwareEvent> {
        self.vm.wait_for_boot_event().await
    }

    async fn wait_for_enlightened_shutdown_ready(&mut self) -> anyhow::Result<()> {
        self.vm.wait_for_enlightened_shutdown_ready().await
    }

    async fn send_enlightened_shutdown(&mut self, kind: ShutdownKind) -> anyhow::Result<()> {
        match kind {
            ShutdownKind::Shutdown => self.vm.stop().await?,
            ShutdownKind::Reboot => self.vm.restart().await?,
        }

        Ok(())
    }

    async fn restart_openhcl(
        &mut self,
        new_openhcl: &ResolvedArtifact,
        flags: OpenHclServicingFlags,
    ) -> anyhow::Result<()> {
        // Overwrite the IGVM file currently in use by the VM. Hyper-V does not
        // support changing the firmware file path while the VM is running, but
        // it will pick up changes to the currently configured file when OpenHCL
        // is restarted.
        fs_err::copy(new_openhcl.get(), self.temp_dir.path().join(IGVM_FILE_NAME))
            .context("failed to replace igvm file")?;

        self.vm.restart_openhcl(flags).await
    }

    async fn save_openhcl(
        &mut self,
        _new_openhcl: &ResolvedArtifact,
        _flags: OpenHclServicingFlags,
    ) -> anyhow::Result<()> {
        anyhow::bail!("saving OpenHCL firmware separately is not yet supported on Hyper-V");
    }

    async fn restore_openhcl(&mut self) -> anyhow::Result<()> {
        anyhow::bail!("restoring OpenHCL firmware separately is not yet supported on Hyper-V");
    }

    async fn update_command_line(&mut self, _command_line: &str) -> anyhow::Result<()> {
        anyhow::bail!("updating command line is not yet supported on Hyper-V");
    }

    fn take_framebuffer_access(&mut self) -> Option<vm::HyperVFramebufferAccess> {
        (!self.properties.is_isolated).then(|| self.vm.get_framebuffer_access())
    }

    async fn reset(&mut self) -> anyhow::Result<()> {
        self.vm.reset().await
    }

    async fn get_guest_state_file(&self) -> anyhow::Result<Option<PathBuf>> {
        Ok(Some(self.vm.get_guest_state_file().await?))
    }

    async fn set_vtl2_settings(&mut self, settings: &Vtl2Settings) -> anyhow::Result<()> {
        self.vm.set_base_vtl2_settings(settings).await
    }

    async fn set_vmbus_drive(
        &mut self,
        drive: &Drive,
        controller_id: &Guid,
        controller_location: u32,
    ) -> anyhow::Result<()> {
        self.vm
            .set_drive_scsi(
                controller_id,
                controller_location.try_into().context("invalid scsi lun")?,
                petri_disk_to_hyperv(drive.disk.as_ref(), &self.temp_dir)
                    .await?
                    .as_deref(),
                false,
                false,
            )
            .await
    }
}

fn acl_for_vm(path: &Path, id: Option<Guid>, write: bool) -> anyhow::Result<()> {
    let sid_arg = format!(
        "NT VIRTUAL MACHINE\\{name}:{perm}",
        name = if let Some(id) = id {
            format!("{id:X}")
        } else {
            "Virtual Machines".to_string()
        },
        perm = if write { 'M' } else { 'R' }
    );
    let output = std::process::Command::new("icacls.exe")
        .arg(path)
        .arg("/grant")
        .arg(sid_arg)
        .output()
        .context("failed to run icacls")?;
    if !output.status.success() {
        let stderr = String::from_utf8_lossy(&output.stderr);
        anyhow::bail!("icacls failed: {stderr}");
    }
    Ok(())
}

async fn hyperv_serial_log_task(
    driver: DefaultDriver,
    serial_pipe_path: String,
    log_file: crate::PetriLogFile,
) -> anyhow::Result<()> {
    let mut timer = None;
    loop {
        // using `std::fs` here instead of `fs_err` since `raw_os_error` always
        // returns `None` for `fs_err` errors.
        match std::fs::OpenOptions::new()
            .read(true)
            .write(true)
            .open(&serial_pipe_path)
        {
            Ok(file) => {
                let pipe = PolledPipe::new(&driver, file).expect("failed to create pipe");
                // connect/disconnect messages logged internally
                _ = crate::log_task(log_file.clone(), pipe, &serial_pipe_path).await;
            }
            Err(err) => {
                // Log the error if it isn't just that the VM is not running
                // or the pipe is "busy" (which is reported during reset).
                const ERROR_PIPE_BUSY: i32 = 231;
                if !(err.kind() == ErrorKind::NotFound
                    || matches!(err.raw_os_error(), Some(ERROR_PIPE_BUSY)))
                {
                    tracing::warn!("failed to open {serial_pipe_path}: {err:#}",)
                }
                // Wait a bit and try again.
                timer
                    .get_or_insert_with(|| PolledTimer::new(&driver))
                    .sleep(Duration::from_millis(100))
                    .await;
            }
        }
    }
}

async fn make_temp_diff_disk(
    path: impl AsRef<Path>,
    parent_path: impl AsRef<Path>,
) -> anyhow::Result<()> {
    let path = path.as_ref().to_path_buf();
    let parent_path = parent_path.as_ref().to_path_buf();
    tracing::debug!(?path, ?parent_path, "creating differencing vhd");
    blocking::unblock(move || disk_vhdmp::Vhd::create_diff(&path, &parent_path)).await?;
    Ok(())
}

async fn petri_disk_to_hyperv(
    disk: Option<&Disk>,
    temp_dir: &TempDir,
) -> anyhow::Result<Option<PathBuf>> {
    Ok(match disk {
        None => None,
        Some(Disk::Memory(_)) => None, // TODO: Hyper-V memory disk
        Some(Disk::Differencing(parent_path)) => {
            let parent_path = match parent_path {
                crate::DiskPath::Local(path) => path,
                crate::DiskPath::Remote { .. } => {
                    anyhow::bail!(
                        "Hyper-V backend requires local disk files; remote disk artifacts are not supported"
                    )
                }
            };
            let diff_disk_path = temp_dir
                .path()
                .join(parent_path.file_name().context("path has no filename")?);
            make_temp_diff_disk(&diff_disk_path, &parent_path).await?;
            Some(diff_disk_path)
        }
        Some(Disk::Persistent(path)) => Some(path.clone()),
        Some(Disk::Temporary(path)) => Some(path.to_path_buf()),
    })
}
