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

//! Code to build storage configuration from command line arguments.

use crate::cli_args::DiskCliKind;
use crate::cli_args::UnderhillDiskSource;
use crate::disk_open;
use crate::VmResources;
use anyhow::Context;
use guid::Guid;
use hvlite_defs::config::Config;
use hvlite_defs::config::DeviceVtl;
use hvlite_defs::config::LoadMode;
use hvlite_defs::config::VpciDeviceConfig;
use ide_resources::GuestMedia;
use ide_resources::IdeDeviceConfig;
use ide_resources::IdePath;
use nvme_resources::NamespaceDefinition;
use nvme_resources::NvmeControllerHandle;
use scsidisk_resources::SimpleScsiDiskHandle;
use scsidisk_resources::SimpleScsiDvdHandle;
use storvsp_resources::ScsiControllerHandle;
use storvsp_resources::ScsiDeviceAndPath;
use storvsp_resources::ScsiPath;
use vm_resource::IntoResource;
use vtl2_settings_proto::storage_controller;
use vtl2_settings_proto::Lun;
use vtl2_settings_proto::StorageController;

pub(super) struct StorageBuilder {
    vtl0_ide_disks: Vec<IdeDeviceConfig>,
    vtl0_scsi_devices: Vec<ScsiDeviceAndPath>,
    vtl2_scsi_devices: Vec<ScsiDeviceAndPath>,
    vtl0_nvme_namespaces: Vec<NamespaceDefinition>,
    vtl2_nvme_namespaces: Vec<NamespaceDefinition>,
    underhill_scsi_luns: Vec<Lun>,
    underhill_nvme_luns: Vec<Lun>,
    openhcl_vtl: Option<DeviceVtl>,
}

#[derive(Copy, Clone)]
pub enum DiskLocation {
    Ide(Option<u8>, Option<u8>),
    Scsi(Option<u8>),
    Nvme(Option<u32>),
}

impl From<UnderhillDiskSource> for DiskLocation {
    fn from(value: UnderhillDiskSource) -> Self {
        match value {
            UnderhillDiskSource::Scsi => Self::Scsi(None),
            UnderhillDiskSource::Nvme => Self::Nvme(None),
        }
    }
}

// Arbitrary but constant instance IDs to maintain the same device IDs
// across reboots.
const NVME_VTL0_INSTANCE_ID: Guid = guid::guid!("008091f6-9688-497d-9091-af347dc9173c");
const NVME_VTL2_INSTANCE_ID: Guid = guid::guid!("f9b90f6f-b129-4596-8171-a23481b8f718");
const SCSI_VTL0_INSTANCE_ID: Guid = guid::guid!("ba6163d9-04a1-4d29-b605-72e2ffb1dc7f");
const SCSI_VTL2_INSTANCE_ID: Guid = guid::guid!("73d3aa59-b82b-4fe7-9e15-e2b0b5575cf8");
const UNDERHILL_VTL0_SCSI_INSTANCE: Guid = guid::guid!("e1c5bd94-d0d6-41d4-a2b0-88095a16ded7");
const UNDERHILL_VTL0_NVME_INSTANCE: Guid = guid::guid!("09a59b81-2bf6-4164-81d7-3a0dc977ba65");

impl StorageBuilder {
    pub fn new(openhcl_vtl: Option<DeviceVtl>) -> Self {
        Self {
            vtl0_ide_disks: Vec::new(),
            vtl0_scsi_devices: Vec::new(),
            vtl2_scsi_devices: Vec::new(),
            vtl0_nvme_namespaces: Vec::new(),
            vtl2_nvme_namespaces: Vec::new(),
            underhill_scsi_luns: Vec::new(),
            underhill_nvme_luns: Vec::new(),
            openhcl_vtl,
        }
    }

    pub fn has_vtl0_nvme(&self) -> bool {
        !self.vtl0_nvme_namespaces.is_empty() || !self.underhill_nvme_luns.is_empty()
    }

    pub fn add(
        &mut self,
        vtl: DeviceVtl,
        underhill: Option<UnderhillDiskSource>,
        target: DiskLocation,
        kind: &DiskCliKind,
        is_dvd: bool,
        read_only: bool,
    ) -> anyhow::Result<()> {
        if let Some(source) = underhill {
            if vtl != DeviceVtl::Vtl0 {
                anyhow::bail!("underhill can only offer devices to vtl0");
            }
            self.add_underhill(source.into(), target, kind, is_dvd, read_only)?;
        } else {
            self.add_inner(vtl, target, kind, is_dvd, read_only)?;
        }
        Ok(())
    }

    /// Returns the "sub device path" for assigning this into Underhill, or
    /// `None` if Underhill can't use this device as a source.
    fn add_inner(
        &mut self,
        vtl: DeviceVtl,
        target: DiskLocation,
        kind: &DiskCliKind,
        is_dvd: bool,
        read_only: bool,
    ) -> anyhow::Result<Option<u32>> {
        let disk = disk_open(kind, read_only || is_dvd)?;
        let location = match target {
            DiskLocation::Ide(channel, device) => {
                let guest_media = if is_dvd {
                    GuestMedia::Dvd(
                        SimpleScsiDvdHandle {
                            media: Some(disk),
                            requests: None,
                        }
                        .into_resource(),
                    )
                } else {
                    GuestMedia::Disk {
                        disk_type: disk,
                        read_only,
                        disk_parameters: None,
                    }
                };

                let check = |c: u8, d: u8| {
                    channel.unwrap_or(c) == c
                        && device.unwrap_or(d) == d
                        && !self
                            .vtl0_ide_disks
                            .iter()
                            .any(|cfg| cfg.path.channel == c && cfg.path.drive == d)
                };

                let (channel, device) = (0..=1)
                    .flat_map(|c| std::iter::repeat(c).zip(0..=1))
                    .find(|&(c, d)| check(c, d))
                    .context("no free ide slots")?;

                if vtl != DeviceVtl::Vtl0 {
                    anyhow::bail!("ide only supported for VTL0");
                }
                self.vtl0_ide_disks.push(IdeDeviceConfig {
                    path: IdePath {
                        channel,
                        drive: device,
                    },
                    guest_media,
                });
                None
            }
            DiskLocation::Scsi(lun) => {
                let device = if is_dvd {
                    SimpleScsiDvdHandle {
                        media: Some(disk),
                        requests: None,
                    }
                    .into_resource()
                } else {
                    SimpleScsiDiskHandle {
                        disk,
                        read_only,
                        parameters: Default::default(),
                    }
                    .into_resource()
                };
                let devices = match vtl {
                    DeviceVtl::Vtl0 => &mut self.vtl0_scsi_devices,
                    DeviceVtl::Vtl1 => anyhow::bail!("vtl1 unsupported"),
                    DeviceVtl::Vtl2 => &mut self.vtl2_scsi_devices,
                };
                let lun = lun.unwrap_or(devices.len() as u8);
                devices.push(ScsiDeviceAndPath {
                    path: ScsiPath {
                        path: 0,
                        target: 0,
                        lun,
                    },
                    device,
                });
                Some(lun.into())
            }
            DiskLocation::Nvme(nsid) => {
                let namespaces = match vtl {
                    DeviceVtl::Vtl0 => &mut self.vtl0_nvme_namespaces,
                    DeviceVtl::Vtl1 => anyhow::bail!("vtl1 unsupported"),
                    DeviceVtl::Vtl2 => &mut self.vtl2_nvme_namespaces,
                };
                if is_dvd {
                    anyhow::bail!("dvd not supported with nvme");
                }
                let nsid = nsid.unwrap_or(namespaces.len() as u32 + 1);
                namespaces.push(NamespaceDefinition {
                    nsid,
                    disk,
                    read_only,
                });
                Some(nsid)
            }
        };
        Ok(location)
    }

    fn add_underhill(
        &mut self,
        source: DiskLocation,
        target: DiskLocation,
        kind: &DiskCliKind,
        is_dvd: bool,
        read_only: bool,
    ) -> anyhow::Result<()> {
        let vtl = self.openhcl_vtl.context("openhcl not configured")?;
        let sub_device_path = self
            .add_inner(vtl, source, kind, is_dvd, read_only)?
            .context("source device not supported by underhill")?;

        let (device_type, device_path) = match source {
            DiskLocation::Ide(_, _) => anyhow::bail!("ide source not supported for Underhill"),
            DiskLocation::Scsi(_) => (
                vtl2_settings_proto::physical_device::DeviceType::Vscsi,
                if vtl == DeviceVtl::Vtl2 {
                    SCSI_VTL2_INSTANCE_ID
                } else {
                    SCSI_VTL0_INSTANCE_ID
                },
            ),
            DiskLocation::Nvme(_) => (
                vtl2_settings_proto::physical_device::DeviceType::Nvme,
                if vtl == DeviceVtl::Vtl2 {
                    NVME_VTL2_INSTANCE_ID
                } else {
                    NVME_VTL0_INSTANCE_ID
                },
            ),
        };

        let (luns, location) = match target {
            // TODO: once hvlite supports VTL2 with PCAT VTL0, remove this restriction.
            DiskLocation::Ide(_, _) => {
                anyhow::bail!("ide target currently not supported for Underhill (no PCAT support)")
            }
            DiskLocation::Scsi(lun) => {
                let lun = lun.unwrap_or(self.underhill_scsi_luns.len() as u8);
                (&mut self.underhill_scsi_luns, lun.into())
            }
            DiskLocation::Nvme(nsid) => {
                let nsid = nsid.unwrap_or(self.underhill_nvme_luns.len() as u32 + 1);
                (&mut self.underhill_nvme_luns, nsid)
            }
        };

        luns.push(Lun {
            location,
            device_id: Guid::new_random().to_string(),
            vendor_id: "OpenVMM".to_string(),
            product_id: "Disk".to_string(),
            product_revision_level: "1.0".to_string(),
            serial_number: "0".to_string(),
            model_number: "1".to_string(),
            physical_devices: Some(vtl2_settings_proto::PhysicalDevices {
                r#type: vtl2_settings_proto::physical_devices::BackingType::Single.into(),
                device: Some(vtl2_settings_proto::PhysicalDevice {
                    device_type: device_type.into(),
                    device_path: device_path.to_string(),
                    sub_device_path,
                }),
                devices: Vec::new(),
            }),
            is_dvd,
            ..Default::default()
        });

        Ok(())
    }

    pub fn build_config(
        &mut self,
        config: &mut Config,
        resources: &mut VmResources,
        scsi_sub_channels: u16,
    ) -> anyhow::Result<()> {
        config.ide_disks.append(&mut self.vtl0_ide_disks);

        // Add an empty VTL0 SCSI controller even if there are no configured disks.
        if !self.vtl0_scsi_devices.is_empty() || config.vmbus.is_some() {
            let (send, recv) = mesh::channel();
            config.vmbus_devices.push((
                DeviceVtl::Vtl0,
                ScsiControllerHandle {
                    instance_id: SCSI_VTL0_INSTANCE_ID,
                    max_sub_channel_count: scsi_sub_channels,
                    devices: std::mem::take(&mut self.vtl0_scsi_devices),
                    io_queue_depth: None,
                    requests: Some(recv),
                }
                .into_resource(),
            ));
            resources.scsi_rpc = Some(send);
        }

        if !self.vtl2_scsi_devices.is_empty() {
            if config
                .hypervisor
                .with_vtl2
                .as_ref()
                .is_none_or(|c| c.vtl0_alias_map)
            {
                anyhow::bail!("must specify --vtl2 and --no-alias-map to offer disks to VTL2");
            }
            config.vmbus_devices.push((
                DeviceVtl::Vtl2,
                ScsiControllerHandle {
                    instance_id: SCSI_VTL2_INSTANCE_ID,
                    max_sub_channel_count: scsi_sub_channels,
                    devices: std::mem::take(&mut self.vtl2_scsi_devices),
                    io_queue_depth: None,
                    requests: None,
                }
                .into_resource(),
            ));
        }

        if !self.vtl0_nvme_namespaces.is_empty() {
            config.vpci_devices.push(VpciDeviceConfig {
                vtl: DeviceVtl::Vtl0,
                instance_id: NVME_VTL0_INSTANCE_ID,
                resource: NvmeControllerHandle {
                    subsystem_id: NVME_VTL0_INSTANCE_ID,
                    namespaces: std::mem::take(&mut self.vtl0_nvme_namespaces),
                    max_io_queues: 64,
                    msix_count: 64,
                }
                .into_resource(),
            });

            // Tell UEFI to try to enumerate VPCI devices since there might be
            // an NVMe namespace to boot from.
            if let LoadMode::Uefi {
                enable_vpci_boot: vpci_boot,
                ..
            } = &mut config.load_mode
            {
                *vpci_boot = true;
            }
        }

        if !self.vtl2_nvme_namespaces.is_empty() {
            if config
                .hypervisor
                .with_vtl2
                .as_ref()
                .is_none_or(|c| c.vtl0_alias_map)
            {
                anyhow::bail!("must specify --vtl2 and --no-alias-map to offer disks to VTL2");
            }
            config.vpci_devices.push(VpciDeviceConfig {
                vtl: DeviceVtl::Vtl2,
                instance_id: NVME_VTL2_INSTANCE_ID,
                resource: NvmeControllerHandle {
                    subsystem_id: NVME_VTL2_INSTANCE_ID,
                    namespaces: std::mem::take(&mut self.vtl2_nvme_namespaces),
                    max_io_queues: 64,
                    msix_count: 64,
                }
                .into_resource(),
            });
        }

        Ok(())
    }

    pub fn build_underhill(&self) -> Vec<StorageController> {
        let mut storage_controllers = Vec::new();
        if !self.underhill_scsi_luns.is_empty() {
            let controller = StorageController {
                instance_id: UNDERHILL_VTL0_SCSI_INSTANCE.to_string(),
                protocol: storage_controller::StorageProtocol::Scsi.into(),
                luns: self.underhill_scsi_luns.clone(),
                io_queue_depth: None,
            };
            storage_controllers.push(controller);
        }

        if !self.underhill_nvme_luns.is_empty() {
            let controller = StorageController {
                instance_id: UNDERHILL_VTL0_NVME_INSTANCE.to_string(),
                protocol: storage_controller::StorageProtocol::Nvme.into(),
                luns: self.underhill_nvme_luns.clone(),
                io_queue_depth: None,
            };
            storage_controllers.push(controller);
        }

        storage_controllers
    }
}
