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

//! CLI argument parsing.
//!
//! Code in this module must not instantiate any complex VM objects!
//!
//! In other words, this module is only responsible for marshalling raw CLI
//! strings into typed Rust structs/enums, and should consist of entirely _pure
//! functions_.
//!
//! e.g: instead of opening a `File` directly, parse the specified file path
//! into a `PathBuf`, and allow later parts of the init flow to handle opening
//! the file.

// NOTE: This module itself is not pub, but the Options struct below is
//       re-exported as pub in main to make this lint fire. It won't fire on
//       anything else on this file though.
#![warn(missing_docs)]

use anyhow::Context;
use clap::Parser;
use clap::ValueEnum;
use hvlite_defs::config::DeviceVtl;
use hvlite_defs::config::Hypervisor;
use hvlite_defs::config::PcatBootDevice;
use hvlite_defs::config::VirtioBus;
use hvlite_defs::config::Vtl2BaseAddressType;
use hvlite_defs::config::X2ApicConfig;
use hvlite_defs::config::DEFAULT_PCAT_BOOT_ORDER;
use std::ffi::OsString;
use std::path::PathBuf;
use std::str::FromStr;
use thiserror::Error;

/// OpenVMM virtual machine monitor.
///
/// This is not yet a stable interface and may change radically between
/// versions.
#[derive(Parser)]
pub struct Options {
    /// processor count
    #[clap(short = 'p', long, value_name = "COUNT", default_value = "1")]
    pub processors: u32,

    /// guest RAM size
    #[clap(
        short = 'm',
        long,
        value_name = "SIZE",
        default_value = "1GB",
        value_parser = parse_memory
    )]
    pub memory: u64,

    /// use shared memory segment
    #[clap(short = 'M', long)]
    pub shared_memory: bool,

    /// prefetch guest RAM
    #[clap(long)]
    pub prefetch: bool,

    /// start in paused state
    #[clap(short = 'P', long)]
    pub paused: bool,

    /// kernel image (when using linux direct boot)
    #[clap(short = 'k', long, value_name = "FILE", default_value = default_value_from_arch_env("OPENVMM_LINUX_DIRECT_KERNEL"))]
    pub kernel: OptionalPathBuf,

    /// initrd image (when using linux direct boot)
    #[clap(short = 'r', long, value_name = "FILE", default_value = default_value_from_arch_env("OPENVMM_LINUX_DIRECT_INITRD"))]
    pub initrd: OptionalPathBuf,

    /// extra kernel command line args
    #[clap(short = 'c', long, value_name = "STRING")]
    pub cmdline: Vec<String>,

    /// enable HV#1 capabilities
    #[clap(long)]
    pub hv: bool,

    /// enable vtl2 - only supported in WHP and simulated without hypervisor support currently
    ///
    /// Currently implies --get.
    #[clap(long, requires("hv"))]
    pub vtl2: bool,

    /// Add GET and related devices for using the OpenHCL paravisor to the
    /// highest enabled VTL.
    #[clap(long, requires("hv"))]
    pub get: bool,

    /// disable the VTL0 alias map presented to VTL2 by default
    #[clap(long, requires("vtl2"))]
    pub no_alias_map: bool,

    /// The vtl2 paravisor has an APIC emulator, so do not emulate lower VTL
    /// APICs on the host.
    #[clap(long, requires("vtl2"))]
    pub vtl2_emulates_apic: bool,

    /// enable isolation emulation
    #[clap(long, requires("vtl2"))]
    pub isolation: Option<IsolationCli>,

    /// the hybrid vsock listener path
    #[clap(long, value_name = "PATH")]
    pub vsock_path: Option<String>,

    /// the VTL2 hybrid vsock listener path
    #[clap(long, value_name = "PATH", requires("vtl2"))]
    pub vtl2_vsock_path: Option<String>,

    /// the late map vtl0 ram access policy when vtl2 is enabled
    #[clap(long, requires("vtl2"), default_value = "halt")]
    pub late_map_vtl0_policy: Vtl0LateMapPolicyCli,

    /// disable in-hypervisor enlightenment implementation (where possible)
    #[clap(long)]
    pub no_enlightenments: bool,

    /// disable the in-hypervisor APIC and use the user-mode one (where possible)
    #[clap(long)]
    pub user_mode_apic: bool,

    /// attach a disk (can be passed multiple times)
    #[clap(long_help = r#"
e.g: --disk memdiff:file:/path/to/disk.vhd

syntax: \<path\> | kind:<arg>[,flag,opt=arg,...]

valid disk kinds:
    `mem:<len>`                    memory backed disk
        <len>: length of ramdisk, e.g.: `1G`
    `memdiff:<disk>`               memory backed diff disk
        <disk>: lower disk, e.g.: `file:base.img`
    `file:\<path\>`                  file-backed disk
        \<path\>: path to file

flags:
    `ro`                           open disk as read-only
    `dvd`                          specifies that device is cd/dvd and it is read_only
    `vtl2`                         assign this disk to VTL2
    `uh`                           relay this disk to VTL0 through Underhill
"#)]
    #[clap(long, value_name = "FILE")]
    pub disk: Vec<DiskCli>,

    /// attach a disk via an NVMe controller
    #[clap(long_help = r#"
e.g: --nvme memdiff:file:/path/to/disk.vhd

syntax: \<path\> | kind:<arg>[,flag,opt=arg,...]

valid disk kinds:
    `mem:<len>`                    memory backed disk
        <len>: length of ramdisk, e.g.: `1G`
    `memdiff:<disk>`               memory backed diff disk
        <disk>: lower disk, e.g.: `file:base.img`
    `file:\<path\>`                  file-backed disk
        \<path\>: path to file

flags:
    `ro`                           open disk as read-only
    `vtl2`                         assign this disk to VTL2
"#)]
    #[clap(long)]
    pub nvme: Vec<DiskCli>,

    /// number of sub-channels for the SCSI controller
    #[clap(long, value_name = "COUNT", default_value = "0")]
    pub scsi_sub_channels: u16,

    /// expose a virtual NIC
    #[clap(long)]
    pub nic: bool,

    /// expose a virtual NIC with the given backend (consomme | dio | tap | none)
    ///
    /// Prefix with `uh:` to add this NIC via Mana emulation through Underhill,
    /// or `vtl2:` to assign this NIC to VTL2.
    #[clap(long)]
    pub net: Vec<NicConfigCli>,

    /// expose a virtual NIC using the Windows kernel-mode vmswitch.
    ///
    /// Specify the switch ID or "default" for the default switch.
    #[clap(long, value_name = "SWITCH_ID")]
    pub kernel_vmnic: Vec<String>,

    /// expose a graphics device
    #[clap(long)]
    pub gfx: bool,

    /// support a graphics device in vtl2
    #[clap(long, requires("vtl2"), conflicts_with("gfx"))]
    pub vtl2_gfx: bool,

    /// listen for vnc connections. implied by gfx.
    #[clap(long)]
    pub vnc: bool,

    /// VNC port number
    #[clap(long, value_name = "PORT", default_value = "5900")]
    pub vnc_port: u16,

    /// set the APIC ID offset, for testing APIC IDs that don't match VP index
    #[cfg(guest_arch = "x86_64")]
    #[clap(long, default_value_t)]
    pub apic_id_offset: u32,

    /// the maximum number of VPs per socket
    #[clap(long)]
    pub vps_per_socket: Option<u32>,

    /// enable or disable SMT (hyperthreading) (auto | force | off)
    #[clap(long, default_value = "auto")]
    pub smt: SmtConfigCli,

    /// configure x2apic (auto | supported | off | on)
    #[cfg(guest_arch = "x86_64")]
    #[clap(long, default_value = "auto", value_parser = parse_x2apic)]
    pub x2apic: X2ApicConfig,

    /// use virtio console
    #[clap(long)]
    pub virtio_console: bool,

    /// use virtio console enumerated via VPCI
    #[clap(long, conflicts_with("virtio_console"))]
    pub virtio_console_pci: bool,

    /// COM1 binding (console | stderr | listen=\<path\> | term[=\<terminal emulator\>] | none)
    #[clap(long, value_name = "SERIAL")]
    pub com1: Option<SerialConfigCli>,

    /// COM2 binding (console | stderr | listen=\<path\> | term[=\<terminal emulator\>] | none)
    #[clap(long, value_name = "SERIAL")]
    pub com2: Option<SerialConfigCli>,

    /// COM3 binding (console | stderr | listen=\<path\> | term[=\<terminal emulator\>] | none)
    #[clap(long, value_name = "SERIAL")]
    pub com3: Option<SerialConfigCli>,

    /// COM4 binding (console | stderr | listen=\<path\> | term[=\<terminal emulator\>] | none)
    #[clap(long, value_name = "SERIAL")]
    pub com4: Option<SerialConfigCli>,

    /// virtio serial binding (console | stderr | listen=\<path\> | term[=\<terminal emulator\>] | none)
    #[clap(long, value_name = "SERIAL")]
    pub virtio_serial: Option<SerialConfigCli>,

    /// vmbus com1 serial binding (console | stderr | listen=\<path\> | term[=\<terminal emulator\>] | none)
    #[structopt(long, value_name = "SERIAL")]
    pub vmbus_com1_serial: Option<SerialConfigCli>,

    /// vmbus com2 serial binding (console | stderr | listen=\<path\> | term[=\<terminal emulator\>] | none)
    #[structopt(long, value_name = "SERIAL")]
    pub vmbus_com2_serial: Option<SerialConfigCli>,

    /// boot UEFI firmware
    #[clap(long, short = 'e')]
    pub uefi: bool,

    /// UEFI firmware file
    #[clap(long, requires("uefi"), conflicts_with("igvm"), value_name = "FILE", default_value = default_value_from_arch_env("OPENVMM_UEFI_FIRMWARE"))]
    pub uefi_firmware: OptionalPathBuf,

    /// enable UEFI debugging on COM1
    #[clap(long, requires("uefi"))]
    pub uefi_debug: bool,

    /// enable memory protections in UEFI
    #[clap(long, requires("uefi"))]
    pub uefi_enable_memory_protections: bool,

    /// set PCAT boot order as comma-separated string of boot device types
    /// (e.g: floppy,hdd,optical,net).
    ///
    /// If less than 4 entries are added, entries are added according to their
    /// default boot order (optical,hdd,net,floppy)
    ///
    /// e.g: passing "floppy,optical" will result in a boot order equivalent to
    /// "floppy,optical,hdd,net".
    ///
    /// Passing duplicate types is an error.
    #[clap(long, requires("pcat"))]
    pub pcat_boot_order: Option<PcatBootOrderCli>,

    /// Boot with PCAT BIOS firmware and piix4 devices
    #[clap(long, conflicts_with("uefi"))]
    pub pcat: bool,

    /// PCAT firmware file
    #[clap(long, requires("pcat"), value_name = "FILE")]
    pub pcat_firmware: Option<PathBuf>,

    /// boot IGVM file
    #[clap(long, conflicts_with("kernel"), value_name = "FILE")]
    pub igvm: Option<PathBuf>,

    /// specify igvm vtl2 relocation type
    /// (absolute=\<addr\>, disable, auto=\<filesize,or memory size\>, vtl2=\<filesize,or memory size\>,)
    #[clap(long, requires("igvm"), default_value = "auto=filesize", value_parser = parse_vtl2_relocation)]
    pub igvm_vtl2_relocation_type: Vtl2BaseAddressType,

    /// add a virtio_9p device (e.g. myfs:C:\)
    #[clap(long, value_name = "tag:root_path", value_parser = parse_fs_arg)]
    pub virtio_9p: Vec<(String, String)>,

    /// output debug info from the 9p server
    #[clap(long)]
    pub virtio_9p_debug: bool,

    /// add a virtio_fs device (e.g. myfs:C:\)
    #[clap(long, value_name = "tag:root_path", value_parser = parse_fs_arg)]
    pub virtio_fs: Vec<(String, String)>,

    /// add a virtio_fs device for sharing memory (e.g. myfs:\SectionDirectoryPath)
    #[clap(long, value_name = "tag:root_path", value_parser = parse_fs_arg)]
    pub virtio_fs_shmem: Vec<(String, String)>,

    /// add a virtio_fs device under either the PCI or MMIO bus, or whatever the hypervisor supports (pci | mmio | auto)
    #[clap(long, value_name = "BUS", default_value = "auto", value_parser = parse_virtio_bus_arg)]
    pub virtio_fs_bus: VirtioBus,

    /// virtio PMEM device
    #[clap(long, value_name = "PATH")]
    pub virtio_pmem: Option<String>,

    /// expose a virtio network with the given backend (dio | vmnic | tap |
    /// none)
    ///
    /// Prefix with `uh:` to add this NIC via Mana emulation through Underhill,
    /// or `vtl2:` to assign this NIC to VTL2.
    #[clap(long)]
    pub virtio_net: Vec<NicConfigCli>,

    /// send log output from the worker process to a file instead of stderr. the file will be overwritten.
    #[clap(long, value_name = "PATH")]
    pub log_file: Option<PathBuf>,

    /// run as a ttrpc server on the specified Unix socket
    #[clap(long, value_name = "SOCKETPATH")]
    pub ttrpc: Option<PathBuf>,

    /// run as a grpc server on the specified Unix socket
    #[clap(long, value_name = "SOCKETPATH", conflicts_with("ttrpc"))]
    pub grpc: Option<PathBuf>,

    /// do not launch child processes
    #[clap(long)]
    pub single_process: bool,

    /// device to assign (can be passed multiple times)
    #[cfg(windows)]
    #[clap(long, value_name = "PATH")]
    pub device: Vec<String>,

    /// instead of showing the frontpage the VM will shutdown instead
    #[clap(long, requires("uefi"))]
    pub disable_frontpage: bool,

    /// add a vtpm device
    #[clap(long)]
    pub tpm: bool,

    /// the mesh worker host name.
    ///
    /// Used internally for debugging and diagnostics.
    #[clap(long, default_value = "control", hide(true))]
    #[allow(clippy::option_option)]
    pub internal_worker: Option<Option<String>>,

    /// redirect the VTL 0 vmbus control plane to a proxy in VTL 2.
    #[clap(long)]
    pub vmbus_redirect: bool,

    /// limit the maximum protocol version allowed by vmbus; used for testing purposes
    #[clap(long, value_parser = vmbus_core::parse_vmbus_version)]
    pub vmbus_max_version: Option<u32>,

    /// path to vmgs file. if no file is provided, fallback to in-memory vmgs implementation
    #[clap(long, value_name = "PATH")]
    pub vmgs_file: Option<PathBuf>,

    /// VGA firmware file
    #[clap(long, requires("pcat"), value_name = "FILE")]
    pub vga_firmware: Option<PathBuf>,

    /// enable secure boot
    #[clap(long)]
    pub secure_boot: bool,

    /// use secure boot template
    #[clap(long)]
    pub secure_boot_template: Option<SecureBootTemplateCli>,

    /// custom uefi nvram json file
    #[clap(long, value_name = "PATH")]
    pub custom_uefi_json: Option<PathBuf>,

    /// the path to a named pipe (Windows) or Unix socket (Linux) to relay to the connected
    /// tty.
    ///
    /// This is a hidden argument used internally.
    #[clap(long, hide(true))]
    pub relay_console_path: Option<PathBuf>,

    /// enable in-hypervisor gdb debugger
    #[clap(long, value_name = "PORT")]
    pub gdb: Option<u16>,

    /// enable emulated MANA devices with the given network backend (see --net)
    #[clap(long)]
    pub mana: Vec<NicConfigCli>,

    /// use a specific hypervisor interface
    #[clap(long, value_parser = parse_hypervisor)]
    pub hypervisor: Option<Hypervisor>,

    /// (dev utility) boot linux using a custom (raw) DSDT table.
    ///
    /// This is a _very_ niche utility, and it's unlikely you'll need to use it.
    ///
    /// e.g: this flag helped bring up certain Hyper-V Generation 1 legacy
    /// devices without needing to port the associated ACPI code into HvLite's
    /// DSDT builder.
    #[clap(long, value_name = "FILE", conflicts_with_all(&["uefi", "pcat", "igvm"]))]
    pub custom_dsdt: Option<PathBuf>,

    /// attach an ide drive (can be passed multiple times)
    ///
    /// Each ide controller has two channels. Each channel can have up to two
    /// attachments.
    ///
    /// If the `s` flag is not passed then the drive will we be attached to the
    /// primary ide channel if space is available. If two attachments have already
    /// been added to the primary channel then the drive will be attached to the
    /// secondary channel.
    #[clap(long_help = r#"
e.g: --ide memdiff:file:/path/to/disk.vhd

syntax: \<path\> | kind:<arg>[,flag,opt=arg,...]

valid disk kinds:
    `mem:<len>`                    memory backed disk
        <len>: length of ramdisk, e.g.: `1G`
    `memdiff:<disk>`               memory backed diff disk
        <disk>: lower disk, e.g.: `file:base.img`
    `file:\<path\>`                  file-backed disk
        \<path\>: path to file

flags:
    `ro`                           open disk as read-only
    `s`                            attach drive to secondary ide channel
    `dvd`                          specifies that device is cd/dvd and it is read_only
"#)]
    #[clap(long, value_name = "FILE")]
    pub ide: Vec<IdeDiskCli>,

    /// attach a floppy drive (should be able to be passed multiple times). VM must be generation 1 (no UEFI)
    ///
    #[clap(long_help = r#"
e.g: --floppy memdiff:/path/to/disk.vfd,ro

syntax: \<path\> | kind:<arg>[,flag,opt=arg,...]

valid disk kinds:
    `mem:<len>`                    memory backed disk
        <len>: length of ramdisk, e.g.: `1G`
    `memdiff:<disk>`               memory backed diff disk
        <disk>: lower disk, e.g.: `file:base.img`
    `file:\<path\>`                  file-backed disk
        \<path\>: path to file

flags:
    `ro`                           open disk as read-only
"#)]
    #[clap(long, value_name = "FILE", requires("pcat"), conflicts_with("uefi"))]
    pub floppy: Vec<FloppyDiskCli>,

    /// enable guest watchdog device
    #[clap(long)]
    pub guest_watchdog: bool,

    /// enable Underhill's guest crash dump device, targeting the specified path
    #[clap(long)]
    pub underhill_dump_path: Option<PathBuf>,

    /// halt the VM when the guest requests a reset, instead of resetting it
    #[clap(long)]
    pub halt_on_reset: bool,

    /// write saved state .proto files to the specified path
    #[clap(long)]
    pub write_saved_state_proto: Option<PathBuf>,

    /// specify the IMC hive file for booting Windows
    #[clap(long)]
    pub imc: Option<PathBuf>,

    /// Expose MCR device
    #[clap(long)]
    pub mcr: bool, // TODO MCR: support closed source CLI flags

    /// expose a battery device
    #[clap(long)]
    pub battery: bool,

    /// set the uefi console mode
    #[clap(long, requires("uefi"))]
    pub uefi_console_mode: Option<UefiConsoleModeCli>,
}

fn parse_fs_arg(opt: &str) -> Result<(String, String), &'static str> {
    let (tag, root_path) = opt.split_once(':').ok_or("invalid value")?;
    Ok((tag.to_owned(), root_path.to_owned()))
}

fn parse_virtio_bus_arg(opt: &str) -> Result<VirtioBus, &'static str> {
    Ok(match opt {
        "auto" => VirtioBus::Auto,
        "mmio" => VirtioBus::Mmio,
        "pci" => VirtioBus::Pci,
        "vpci" => VirtioBus::Vpci,
        _ => return Err("expected one of [auto, mmio, pci, vpci]"),
    })
}

#[derive(clap::ValueEnum, Clone, Copy)]
pub enum SecureBootTemplateCli {
    Windows,
    UefiCa,
}

fn parse_memory(s: &str) -> anyhow::Result<u64> {
    || -> Option<u64> {
        let mut b = s.as_bytes();
        if s.ends_with('B') {
            b = &b[..b.len() - 1]
        }
        if b.is_empty() {
            return None;
        }
        let multi = match b[b.len() - 1] as char {
            'T' => Some(1024 * 1024 * 1024 * 1024),
            'G' => Some(1024 * 1024 * 1024),
            'M' => Some(1024 * 1024),
            'K' => Some(1024),
            _ => None,
        };
        if multi.is_some() {
            b = &b[..b.len() - 1]
        }
        let n: u64 = std::str::from_utf8(b).ok()?.parse().ok()?;
        Some(n * multi.unwrap_or(1))
    }()
    .with_context(|| format!("invalid memory size '{0}'", s))
}

/// Parse a number from a string that could be prefixed with 0x to indicate hex.
fn parse_number(s: &str) -> Result<u64, std::num::ParseIntError> {
    match s.strip_prefix("0x") {
        Some(rest) => u64::from_str_radix(rest, 16),
        None => s.parse::<u64>(),
    }
}

#[derive(Clone)]
pub enum DiskCliKind {
    // mem:<len>
    Memory(u64),
    // memdiff:<kind>
    MemoryDiff(Box<DiskCliKind>),
    // prwrap:<kind>
    PersistentReservationsWrapper(Box<DiskCliKind>),
    // file:<path>
    File(PathBuf),
    // blob:<type>:<url>
    Blob { kind: BlobKind, url: String },
}

#[derive(Copy, Clone)]
pub enum BlobKind {
    Flat,
    Vhd1,
}

impl FromStr for DiskCliKind {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> anyhow::Result<Self> {
        let disk = match s.split_once(':') {
            // convenience support for passing bare paths as file disks
            None => DiskCliKind::File(PathBuf::from(s)),
            Some((kind, arg)) => match kind {
                "mem" => DiskCliKind::Memory(parse_memory(arg)?),
                "memdiff" => DiskCliKind::MemoryDiff(Box::new(arg.parse()?)),
                "prwrap" => DiskCliKind::PersistentReservationsWrapper(Box::new(arg.parse()?)),
                "file" => DiskCliKind::File(PathBuf::from(arg)),
                "blob" => {
                    let (blob_kind, url) = arg.split_once(':').context("expected kind:url")?;
                    let blob_kind = match blob_kind {
                        "flat" => BlobKind::Flat,
                        "vhd1" => BlobKind::Vhd1,
                        _ => anyhow::bail!("unknown blob kind {blob_kind}"),
                    };
                    DiskCliKind::Blob {
                        kind: blob_kind,
                        url: url.to_string(),
                    }
                }
                kind => {
                    // here's a fun edge case: what if the user passes `--disk d:\path\to\disk.img`?
                    //
                    // in this case, we actually want to treat that leading `d:` as part of the
                    // path, rather than as a disk with `kind == 'd'`
                    let path_buf = PathBuf::from(s);
                    if path_buf.has_root() {
                        DiskCliKind::File(path_buf)
                    } else {
                        anyhow::bail!("invalid disk kind {kind}");
                    }
                }
            },
        };
        Ok(disk)
    }
}

// <kind>[,ro]
#[derive(Clone)]
pub struct DiskCli {
    pub vtl: DeviceVtl,
    pub kind: DiskCliKind,
    pub read_only: bool,
    pub is_dvd: bool,
    pub underhill: Option<UnderhillDiskSource>,
}

#[derive(Copy, Clone)]
pub enum UnderhillDiskSource {
    Scsi,
    Nvme,
}

impl FromStr for DiskCli {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> anyhow::Result<Self> {
        let mut opts = s.split(',');
        let kind = opts.next().unwrap().parse()?;

        let mut read_only = false;
        let mut is_dvd = false;
        let mut underhill = None;
        let mut vtl = DeviceVtl::Vtl0;
        for opt in opts {
            let mut s = opt.split('=');
            let opt = s.next().unwrap();
            match opt {
                "ro" => read_only = true,
                "dvd" => {
                    is_dvd = true;
                    read_only = true;
                }
                "vtl2" => {
                    vtl = DeviceVtl::Vtl2;
                }
                "uh" => underhill = Some(UnderhillDiskSource::Scsi),
                "uh-nvme" => underhill = Some(UnderhillDiskSource::Nvme),
                opt => anyhow::bail!("unknown option: '{opt}'"),
            }
        }

        if underhill.is_some() && vtl != DeviceVtl::Vtl0 {
            anyhow::bail!("`uh` is incompatible with `vtl2`");
        }

        Ok(DiskCli {
            vtl,
            kind,
            read_only,
            is_dvd,
            underhill,
        })
    }
}

// <kind>[,ro,s]
#[derive(Clone)]
pub struct IdeDiskCli {
    pub kind: DiskCliKind,
    pub read_only: bool,
    pub channel: Option<u8>,
    pub device: Option<u8>,
    pub is_dvd: bool,
}

impl FromStr for IdeDiskCli {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> anyhow::Result<Self> {
        let mut opts = s.split(',');
        let kind = opts.next().unwrap().parse()?;

        let mut read_only = false;
        let mut channel = None;
        let mut device = None;
        let mut is_dvd = false;
        for opt in opts {
            let mut s = opt.split('=');
            let opt = s.next().unwrap();
            match opt {
                "ro" => read_only = true,
                "p" => channel = Some(0),
                "s" => channel = Some(1),
                "0" => device = Some(0),
                "1" => device = Some(1),
                "dvd" => {
                    is_dvd = true;
                    read_only = true;
                }
                _ => anyhow::bail!("unknown option: '{opt}'"),
            }
        }

        Ok(IdeDiskCli {
            kind,
            read_only,
            channel,
            device,
            is_dvd,
        })
    }
}

// <kind>[,ro]
#[derive(Clone)]
pub struct FloppyDiskCli {
    pub kind: DiskCliKind,
    pub read_only: bool,
}

impl FromStr for FloppyDiskCli {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> anyhow::Result<Self> {
        let mut opts = s.split(',');
        let kind = opts.next().unwrap().parse()?;

        let mut read_only = false;
        for opt in opts {
            let mut s = opt.split('=');
            let opt = s.next().unwrap();
            match opt {
                "ro" => read_only = true,
                _ => anyhow::bail!("unknown option: '{opt}'"),
            }
        }

        Ok(FloppyDiskCli { kind, read_only })
    }
}

// (console | stderr | listen=\<path\> | none)
#[derive(Clone)]
pub enum SerialConfigCli {
    None,
    Console,
    NewConsole(Option<PathBuf>),
    Stderr,
    Pipe(PathBuf),
}

impl FromStr for SerialConfigCli {
    type Err = String;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let ret = match s {
            "none" => SerialConfigCli::None,
            "console" => SerialConfigCli::Console,
            "stderr" => SerialConfigCli::Stderr,
            "term" => SerialConfigCli::NewConsole(None),
            s if s.starts_with("term=") => {
                SerialConfigCli::NewConsole(Some(PathBuf::from(s.strip_prefix("term=").unwrap())))
            }
            s if s.starts_with("listen=") => {
                SerialConfigCli::Pipe(PathBuf::from(s.strip_prefix("listen=").unwrap()))
            }
            _ => return Err("invalid serial configuration".into()),
        };

        Ok(ret)
    }
}

#[derive(Clone)]
pub enum EndpointConfigCli {
    None,
    Consomme { cidr: Option<String> },
    Dio { id: Option<String> },
    Tap { name: String },
}

impl FromStr for EndpointConfigCli {
    type Err = String;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let ret = match s.split(':').collect::<Vec<_>>().as_slice() {
            ["none"] => EndpointConfigCli::None,
            ["consomme", s @ ..] => EndpointConfigCli::Consomme {
                cidr: s.first().map(|&s| s.to_owned()),
            },
            ["dio", s @ ..] => EndpointConfigCli::Dio {
                id: s.first().map(|s| (*s).to_owned()),
            },
            ["tap", name] => EndpointConfigCli::Tap {
                name: (*name).to_owned(),
            },
            _ => return Err("invalid network backend".into()),
        };

        Ok(ret)
    }
}

#[derive(Clone)]
pub struct NicConfigCli {
    pub vtl: DeviceVtl,
    pub endpoint: EndpointConfigCli,
    pub max_queues: Option<u16>,
    pub underhill: bool,
}

impl FromStr for NicConfigCli {
    type Err = String;

    fn from_str(mut s: &str) -> Result<Self, Self::Err> {
        let mut vtl = DeviceVtl::Vtl0;
        let mut max_queues = None;
        let mut underhill = false;
        while let Some((opt, rest)) = s.split_once(':') {
            if let Some((opt, val)) = opt.split_once('=') {
                match opt {
                    "queues" => {
                        max_queues = Some(val.parse().map_err(|_| "failed to parse queue count")?);
                    }
                    _ => break,
                }
            } else {
                match opt {
                    "vtl2" => {
                        vtl = DeviceVtl::Vtl2;
                    }
                    "uh" => underhill = true,
                    _ => break,
                }
            }
            s = rest;
        }

        if underhill && vtl != DeviceVtl::Vtl0 {
            return Err("`uh` is incompatible with `vtl2`".into());
        }

        let endpoint = s.parse()?;
        Ok(NicConfigCli {
            vtl,
            endpoint,
            max_queues,
            underhill,
        })
    }
}

#[derive(Debug, Error)]
#[error("unknown hypervisor: {0}")]
pub struct UnknownHypervisor(String);

fn parse_hypervisor(s: &str) -> Result<Hypervisor, UnknownHypervisor> {
    match s {
        "kvm" => Ok(Hypervisor::Kvm),
        "mshv" => Ok(Hypervisor::MsHv),
        "whp" => Ok(Hypervisor::Whp),
        _ => Err(UnknownHypervisor(s.to_owned())),
    }
}

#[derive(Debug, Error)]
#[error("unknown VTL2 relocation type: {0}")]
pub struct UnknownVtl2RelocationType(String);

fn parse_vtl2_relocation(s: &str) -> Result<Vtl2BaseAddressType, UnknownVtl2RelocationType> {
    match s {
        "disable" => Ok(Vtl2BaseAddressType::File),
        s if s.starts_with("auto=") => {
            let s = s.strip_prefix("auto=").unwrap_or_default();
            let size = if s == "filesize" {
                None
            } else {
                let size = parse_memory(s).map_err(|e| {
                    UnknownVtl2RelocationType(format!(
                        "unable to parse memory size from {} for 'auto=' type, {e}",
                        e
                    ))
                })?;
                Some(size)
            };
            Ok(Vtl2BaseAddressType::MemoryLayout { size })
        }
        s if s.starts_with("absolute=") => {
            let s = s.strip_prefix("absolute=");
            let addr = parse_number(s.unwrap_or_default()).map_err(|e| {
                UnknownVtl2RelocationType(format!(
                    "unable to parse number from {} for 'absolute=' type",
                    e
                ))
            })?;
            Ok(Vtl2BaseAddressType::Absolute(addr))
        }
        s if s.starts_with("vtl2=") => {
            let s = s.strip_prefix("vtl2=").unwrap_or_default();
            let size = if s == "filesize" {
                None
            } else {
                let size = parse_memory(s).map_err(|e| {
                    UnknownVtl2RelocationType(format!(
                        "unable to parse memory size from {} for 'vtl2=' type, {e}",
                        e
                    ))
                })?;
                Some(size)
            };
            Ok(Vtl2BaseAddressType::Vtl2Allocate { size })
        }
        _ => Err(UnknownVtl2RelocationType(s.to_owned())),
    }
}

#[derive(Debug, Copy, Clone)]
pub enum SmtConfigCli {
    Auto,
    Force,
    Off,
}

#[derive(Debug, Error)]
#[error("expected auto, force, or off")]
pub struct BadSmtConfig;

impl FromStr for SmtConfigCli {
    type Err = BadSmtConfig;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let r = match s {
            "auto" => Self::Auto,
            "force" => Self::Force,
            "off" => Self::Off,
            _ => return Err(BadSmtConfig),
        };
        Ok(r)
    }
}

#[cfg_attr(not(guest_arch = "x86_64"), allow(dead_code))]
fn parse_x2apic(s: &str) -> Result<X2ApicConfig, &'static str> {
    let r = match s {
        "auto" => X2ApicConfig::Auto,
        "supported" => X2ApicConfig::Supported,
        "off" => X2ApicConfig::Unsupported,
        "on" => X2ApicConfig::Enabled,
        _ => return Err("expected auto, supported, off, or on"),
    };
    Ok(r)
}

#[derive(Debug, Copy, Clone, ValueEnum)]
pub enum Vtl0LateMapPolicyCli {
    Off,
    Log,
    Halt,
    Exception,
}

#[derive(Debug, Copy, Clone, ValueEnum)]
pub enum IsolationCli {
    Vbs,
}

#[derive(Debug, Copy, Clone)]
pub struct PcatBootOrderCli(pub [PcatBootDevice; 4]);

impl FromStr for PcatBootOrderCli {
    type Err = &'static str;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let mut default_order = DEFAULT_PCAT_BOOT_ORDER.map(Some);
        let mut order = Vec::new();

        for item in s.split(',') {
            let device = match item {
                "optical" => PcatBootDevice::Optical,
                "hdd" => PcatBootDevice::HardDrive,
                "net" => PcatBootDevice::Network,
                "floppy" => PcatBootDevice::Floppy,
                _ => return Err("unknown boot device type"),
            };

            let default_pos = default_order
                .iter()
                .position(|x| x == &Some(device))
                .ok_or("cannot pass duplicate boot devices")?;

            order.push(default_order[default_pos].take().unwrap());
        }

        order.extend(default_order.into_iter().flatten());
        assert_eq!(order.len(), 4);

        Ok(Self(order.try_into().unwrap()))
    }
}

#[derive(Copy, Clone, Debug, ValueEnum)]
pub enum UefiConsoleModeCli {
    Default,
    Com1,
    Com2,
    None,
}

/// Read a environment variable that may / may-not have a target-specific
/// prefix. e.g: `default_value_from_arch_env("FOO")` would first try and read
/// from `FOO`, and if that's not found, it will try `X86_64_FOO`.
///
/// Must return an `OsString`, in order to be compatible with `clap`'s
/// default_value code. As such - to encode the absence of the env-var, an empty
/// OsString is returned.
fn default_value_from_arch_env(name: &str) -> OsString {
    let prefix = if cfg!(guest_arch = "x86_64") {
        "X86_64"
    } else if cfg!(guest_arch = "aarch64") {
        "AARCH64"
    } else {
        return Default::default();
    };
    let prefixed = format!("{}_{}", prefix, name);
    std::env::var_os(name)
        .or_else(|| std::env::var_os(prefixed))
        .unwrap_or_default()
}

/// Workaround to use `Option<PathBuf>` alongside [`default_value_from_arch_env`]
#[derive(Clone)]
pub struct OptionalPathBuf(pub Option<PathBuf>);

impl From<&std::ffi::OsStr> for OptionalPathBuf {
    fn from(s: &std::ffi::OsStr) -> Self {
        OptionalPathBuf(if s.is_empty() { None } else { Some(s.into()) })
    }
}