use std::{
    borrow::Cow,
    collections::{BTreeSet, HashMap, HashSet},
    ffi::CStr,
    mem::ManuallyDrop,
    ops::{Deref, DerefMut},
    sync::Arc,
};

use ash::{
    ext, khr,
    prelude::VkResult,
    vk::{self, Handle},
};
use parking_lot::Mutex;
use raw_window_handle::RawDisplayHandle;
use tinyvec::{ArrayVec, array_vec};

use crate::{
    Instance, PhysicalDeviceFeatures, PhysicalDeviceInfo, Result,
    queue::{DeviceQueueInfos, DeviceQueues, Queue},
    sync::{self, BinarySemaphore, TimelineSemaphore},
};

#[derive(Debug, Default)]
pub struct DeviceQueueFamilies {
    pub(crate) families: Vec<(u32, u32)>,
    pub(crate) graphics: (u32, u32),
    pub(crate) present: (u32, u32),
    pub(crate) async_compute: (u32, u32),
    pub(crate) transfer: (u32, u32),
    #[expect(dead_code)]
    pub(crate) properties: Box<[vk::QueueFamilyProperties]>,
}

impl DeviceQueueFamilies {
    pub fn swapchain_family_indices(&self) -> ArrayVec<[u32; 2]> {
        let mut indices = array_vec!([u32; 2] => self.graphics.0);

        if self.present.0 != self.graphics.0 {
            indices.push(self.present.0);
        }

        indices
    }
    pub fn graphics_familty(&self) -> u32 {
        self.graphics.0
    }
    pub fn present_familty(&self) -> u32 {
        self.present.0
    }
    pub fn async_compute_familty(&self) -> u32 {
        self.async_compute.0
    }
    pub fn transfer_familty(&self) -> u32 {
        self.transfer.0
    }

    pub fn family_indices(&self, flags: QueueFlags) -> ArrayVec<[u32; 4]> {
        let mut indices = array_vec!([u32; 4]);
        if flags.contains(QueueFlags::GRAPHICS) {
            indices.push(self.graphics_familty());
        }
        if flags.contains(QueueFlags::PRESENT) {
            indices.push(self.present_familty());
        }
        if flags.contains(QueueFlags::ASYNC_COMPUTE) {
            indices.push(self.async_compute_familty());
        }
        if flags.contains(QueueFlags::TRANSFER) {
            indices.push(self.transfer_familty());
        }

        let unique_len = indices.partition_dedup().0.len();
        indices.drain(unique_len..);

        indices
    }
}

bitflags::bitflags! {
    #[repr(transparent)]
    #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
    pub struct QueueFlags: u32 {
        const GRAPHICS = 1 << 0;
        const ASYNC_COMPUTE = 1 << 1;
        const TRANSFER = 1 << 2;
        const PRESENT = 1 << 3;

        const NONE = 0;
        const PRESENT_GRAPHICS = 1 << 0 | 1 << 2;
    }
}

struct DeviceDrop(ash::Device);
impl Drop for DeviceDrop {
    fn drop(&mut self) {
        unsafe {
            _ = self.0.device_wait_idle();
            self.0.destroy_device(None);
        }
    }
}

struct DeviceExtensions {
    pub(crate) debug_utils: ext::debug_utils::Device,
    pub(crate) swapchain: Option<khr::swapchain::Device>,
    pub(crate) mesh_shader: Option<ext::mesh_shader::Device>,
}

type GpuAllocation = gpu_allocator::vulkan::Allocation;

impl DeviceHandle for GpuAllocation {
    unsafe fn destroy(&mut self, device: &Device) {
        let mut swapped = GpuAllocation::default();
        std::mem::swap(self, &mut swapped);
        _ = device.alloc2.lock().free(swapped);
    }
}

#[derive(Debug, Default, Clone, Copy, PartialEq, Eq, Hash)]
pub enum AllocationStrategy {
    #[default]
    /// Let gpu_allocator manage the memory for this allocation, sub-allocating
    /// from larger blocks as needed.
    AllocatorManaged,
    /// Allocate a dedicated block of memory for this allocation. This is
    /// recommended for long-lived resources or resources with specific memory
    /// requirements.
    Dedicated,
}

#[derive(Debug)]
pub(crate) enum Allocation {
    Owned(DeviceObject<GpuAllocation>),
    Shared(Arc<DeviceObject<GpuAllocation>>),
    Unmanaged,
}

impl Allocation {
    pub(crate) fn allocation(&self) -> Option<&GpuAllocation> {
        match self {
            Allocation::Owned(obj) => Some(obj),
            Allocation::Shared(arc) => Some(arc.as_ref()),
            Allocation::Unmanaged => None,
        }
    }

    pub(crate) fn allocation_mut(&mut self) -> Option<&mut GpuAllocation> {
        match self {
            Allocation::Owned(obj) => Some(obj),
            Allocation::Shared(arc) => Arc::get_mut(arc).map(|alloc| &mut alloc.inner),
            Allocation::Unmanaged => None,
        }
    }
}

pub struct DeviceInner {
    pub(crate) alloc2: Mutex<gpu_allocator::vulkan::Allocator>,
    pub(crate) raw: ash::Device,
    pub(crate) adapter: PhysicalDeviceInfo,
    pub(crate) instance: Instance,
    pub(crate) queues: DeviceQueues,
    pub(crate) sync_threadpool: sync::SyncThreadpool,
    pub(crate) device_extensions: DeviceExtensions,
    pub(crate) enabled_extensions: Vec<&'static CStr>,
    _drop: DeviceDrop,
}

impl core::fmt::Debug for DeviceInner {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("DeviceInner")
            .field("device", &self.raw.handle())
            .finish()
    }
}

#[macro_export]
macro_rules! make_extension {
    ($module:path) => {{
        use $module::{NAME as EXTENSION_NAME, SPEC_VERSION as EXTENSION_VERSION};
        $crate::device::Extension {
            name: EXTENSION_NAME,
            version: EXTENSION_VERSION,
        }
    }};
    ($module:path as $version:expr) => {{
        use $module::*;
        $crate::device::Extension {
            name: NAME,
            version: $version,
        }
    }};
}

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
pub struct Extension<'a> {
    pub name: &'a CStr,
    pub version: u32,
}

impl<'a> std::hash::Hash for Extension<'a> {
    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
        self.name.hash(state);
    }
}

pub(crate) fn get_available_extensions(
    entry: &ash::Entry,
    layers: &[&CStr],
) -> Result<Vec<ash::vk::ExtensionProperties>> {
    unsafe {
        let extensions = core::iter::once(entry.enumerate_instance_extension_properties(None))
            .chain(
                layers
                    .iter()
                    .map(|&layer| entry.enumerate_instance_extension_properties(Some(layer))),
            )
            .filter_map(|result| result.ok())
            .flatten()
            .collect::<Vec<ash::vk::ExtensionProperties>>();

        Ok(extensions)
    }
}

/// returns a tuple of supported-or-enabled extensions and unsupported-and-requested extensions
pub(crate) fn get_extensions<'a>(
    entry: &ash::Entry,
    layers: &[&'a CStr],
    mut extensions: Vec<Extension<'a>>,
    display_handle: Option<RawDisplayHandle>,
) -> Result<(HashSet<Extension<'a>>, HashSet<Extension<'a>>)> {
    let available_extensions = get_available_extensions(entry, layers)?;

    let available_extension_names = available_extensions
        .iter()
        .filter_map(|ext| {
            Some((
                ext.extension_name_as_c_str().ok()?.to_str().ok()?,
                ext.spec_version,
            ))
        })
        .collect::<HashMap<_, _>>();

    tracing::debug!(
        "Available extensions: {:?}",
        available_extension_names.iter().collect::<Vec<_>>()
    );

    let mut wsi_extensions = Vec::new();
    wsi_extensions.push(make_extension!(khr::surface));

    // taken from wgpu-hal/src/vulkan/instance.rs:
    //
    // we want to enable all the wsi extensions that are applicable to the
    // platform, even if the user didn't explicitly request them, or
    // supplied a different/no display handle, because we might later want
    // to create a surface for a different windowing system, and enabling
    // all the wsi extensions doesn't have any real downsides.
    // We don't notify the user if some of these extensions aren't available
    // (e.g. because wayland isn't supported on some unix system)
    if cfg!(all(
        unix,
        not(target_os = "android"),
        not(target_os = "macos")
    )) {
        wsi_extensions.push(make_extension!(khr::xlib_surface));
        wsi_extensions.push(make_extension!(khr::xcb_surface));
        wsi_extensions.push(make_extension!(khr::wayland_surface));
    }
    if cfg!(target_os = "windows") {
        wsi_extensions.push(make_extension!(khr::win32_surface));
    }
    if cfg!(target_os = "android") {
        wsi_extensions.push(make_extension!(khr::android_surface));
    }
    if cfg!(target_os = "macos") {
        wsi_extensions.push(make_extension!(ext::metal_surface));
        wsi_extensions.push(make_extension!(khr::portability_enumeration));
    }
    if cfg!(all(
        unix,
        not(target_vendor = "apple"),
        not(target_family = "wasm")
    )) {
        wsi_extensions.push(make_extension!(ext::acquire_drm_display));
        wsi_extensions.push(make_extension!(ext::direct_mode_display));
        wsi_extensions.push(make_extension!(khr::display));
    }

    let is_extension_available = |ext: &mut Extension| -> bool {
        if available_extensions
            .iter()
            .any(|inst_ext| inst_ext.extension_name_as_c_str() == Ok(ext.name))
        {
            true
        } else {
            tracing::warn!(
                "Extension {:?} v{} was requested but is not available",
                ext.name,
                ext.version
            );
            false
        }
    };

    let mut enabled_extensions = extensions
        .extract_if(.., is_extension_available)
        .collect::<Vec<_>>();

    enabled_extensions.extend(wsi_extensions.extract_if(.., is_extension_available));

    // if a display handle is provided, ensure the required WSI extensions are present
    if let Some(display_handle) = display_handle {
        let mut required_extensions = ash_window::enumerate_required_extensions(display_handle)?
            .iter()
            .map(|&p| Extension {
                name: unsafe { CStr::from_ptr(p) },
                version: 0,
            })
            // filter out extensions that are already enabled
            .filter(|ext| {
                !enabled_extensions
                    .iter()
                    .any(|enabled| enabled.name == ext.name)
            })
            .collect::<Vec<_>>();

        // filter out extensions that aren't available, and log a warning for them
        let display_extensions = required_extensions.extract_if(.., is_extension_available);

        enabled_extensions.extend(display_extensions);
        extensions.extend(required_extensions);
    }

    // all extensions remaining in `extensions` at this point are unsupported,
    // and were requested by the user or are required by the display handle
    let unsupported_extensions = HashSet::from_iter(extensions);
    let out_extensions = HashSet::from_iter(enabled_extensions);

    Ok((out_extensions, unsupported_extensions))
}

/// returns a list of enabled, or a tuple of enabled and unsupported but requested layers.
pub(crate) fn get_layers<'a>(
    entry: &ash::Entry,
    wants_layers: Vec<&'a CStr>,
) -> core::result::Result<Vec<&'a CStr>, (Vec<&'a CStr>, Vec<&'a CStr>)> {
    unsafe {
        let Ok(available_layers) = entry.enumerate_instance_layer_properties() else {
            return Err((vec![], wants_layers));
        };

        let Ok(available_layer_names) = available_layers
            .iter()
            .map(|layer| layer.layer_name_as_c_str())
            .collect::<core::result::Result<BTreeSet<_>, _>>()
        else {
            return Err((vec![], wants_layers));
        };

        tracing::debug!(
            "Available layers: {:?}",
            available_layer_names
                .iter()
                .map(|s| s.to_str().unwrap_or("<invalid utf8>"))
                .collect::<Vec<_>>()
        );

        let mut enabled_layers = Vec::new();
        let mut unsupported_layers = Vec::new();

        for layer in wants_layers {
            if available_layer_names.contains(&layer) {
                enabled_layers.push(layer);
            } else {
                unsupported_layers.push(layer);
            }
        }

        if !unsupported_layers.is_empty() {
            Err((enabled_layers, unsupported_layers))
        } else {
            Ok(enabled_layers)
        }
    }
}

impl PhysicalDeviceInfo {
    pub fn create_logical_device(
        self,
        instance: &Instance,
        extensions: &[Extension<'static>],
        mut features: PhysicalDeviceFeatures,
        display_handle: Option<RawDisplayHandle>,
    ) -> Result<Device> {
        let queue_infos = DeviceQueueInfos::select_queue_families(instance, &self, display_handle)?;

        let queue_create_infos = queue_infos.into_create_infos();
        let extensions = Self::required_extensions(&self, extensions);

        let create_info = vk::DeviceCreateInfo::default()
            .queue_create_infos(&queue_create_infos)
            .enabled_extension_names(&extensions);
        let create_info = features.push_to_device_create_info(create_info);

        let device = unsafe {
            instance
                .inner
                .raw
                .create_device(self.pdev, &create_info, None)?
        };

        let device_queues = queue_infos.retrieve_queues(&device);

        let enabled_extensions = extensions
            .into_iter()
            .map(|ptr| unsafe { CStr::from_ptr(ptr) })
            .collect::<Vec<_>>();

        let device_extensions = DeviceExtensions {
            debug_utils: ext::debug_utils::Device::new(&instance.inner.raw, &device),
            swapchain: if enabled_extensions.contains(&khr::swapchain::NAME) {
                Some(khr::swapchain::Device::new(&instance.inner.raw, &device))
            } else {
                None
            },
            mesh_shader: if enabled_extensions.contains(&ext::mesh_shader::NAME) {
                Some(ext::mesh_shader::Device::new(&instance.inner.raw, &device))
            } else {
                None
            },
        };

        let alloc2 =
            gpu_allocator::vulkan::Allocator::new(&gpu_allocator::vulkan::AllocatorCreateDesc {
                instance: instance.inner.raw.clone(),
                device: device.clone(),
                physical_device: self.pdev,
                debug_settings: Default::default(),
                buffer_device_address: false,
                allocation_sizes: {
                    const MB: u64 = 1024 * 1024;
                    gpu_allocator::AllocationSizes::new(8 * MB, 64 * MB)
                        .with_max_host_memblock_size(256 * MB)
                        .with_max_device_memblock_size(256 * MB)
                },
            })?;

        let inner = DeviceInner {
            raw: device.clone(),
            alloc2: Mutex::new(alloc2),
            instance: instance.clone(),
            adapter: self,
            queues: device_queues,
            device_extensions,
            enabled_extensions,
            sync_threadpool: sync::SyncThreadpool::new(),
            _drop: DeviceDrop(device),
        };

        let shared = Arc::new(inner);
        Ok(Device {
            pools: Arc::new(DevicePools::new(shared.clone())),
            shared,
        })
    }

    fn required_extensions(&self, requested_extensions: &[Extension<'static>]) -> Vec<*const i8> {
        let mut extensions = vec![khr::swapchain::NAME.as_ptr()];
        for ext in requested_extensions {
            if self
                .properties
                .supported_extensions
                .iter()
                .any(|supported| {
                    supported.extension_name_as_c_str() == Ok(ext.name)
                        && supported.spec_version >= ext.version
                })
            {
                extensions.push(ext.name.as_ptr());
            } else {
                tracing::warn!(
                    "Physical device {:?} does not support required extension {:?}",
                    self.pdev,
                    ext.name
                );
            }
        }
        extensions
    }
}

#[derive(Clone, Debug)]
pub(crate) struct DevicePools {
    pub(crate) fences: Pool<vk::Fence>,
    pub(crate) binary_semaphores: Pool<BinarySemaphore>,
    pub(crate) timeline_semaphores: Pool<TimelineSemaphore>,
}

impl DevicePools {
    pub fn new(device: Arc<DeviceInner>) -> Self {
        Self {
            fences: Pool::new(device.clone()),
            binary_semaphores: Pool::new(device.clone()),
            timeline_semaphores: Pool::new(device),
        }
    }
}

#[derive(Clone, Debug)]
pub struct Device {
    pub(crate) shared: Arc<DeviceInner>,
    pub(crate) pools: Arc<DevicePools>,
}

impl PartialEq for Device {
    fn eq(&self, other: &Self) -> bool {
        Arc::ptr_eq(&self.shared, &other.shared)
    }
}

impl Eq for Device {}

impl core::ops::Deref for Device {
    type Target = DeviceInner;

    fn deref(&self) -> &Self::Target {
        &self.shared
    }
}

impl DeviceInner {
    pub fn sync_threadpool(&self) -> &sync::SyncThreadpool {
        &self.sync_threadpool
    }
    pub fn dev(&self) -> &ash::Device {
        &self.raw
    }
    pub fn instance(&self) -> &Instance {
        &self.instance
    }
    pub fn queues(&self) -> &DeviceQueues {
        &self.queues
    }
    pub fn phy(&self) -> vk::PhysicalDevice {
        self.adapter.pdev
    }
    pub fn features(&self) -> &crate::PhysicalDeviceFeatures {
        &self.adapter.features
    }
    pub fn properties(&self) -> &crate::PhysicalDeviceProperties {
        &self.adapter.properties
    }
    pub fn physical_device(&self) -> &PhysicalDeviceInfo {
        &self.adapter
    }
    pub fn main_queue(&self) -> &Queue {
        self.queues.graphics()
    }
    pub fn compute_queue(&self) -> &Queue {
        self.queues.compute()
    }
    pub fn transfer_queue(&self) -> &Queue {
        self.queues.transfer()
    }

    pub unsafe fn lock_queues(&self) {
        unsafe {
            self.queues.lock();
        }
    }

    pub unsafe fn unlock_queues(&self) {
        unsafe {
            self.queues.unlock();
        }
    }

    pub fn wait_queue_idle(&self, queue: &Queue) -> VkResult<()> {
        tracing::warn!("locking queue {queue:?} and waiting for idle");

        queue.with_locked(|q| unsafe { self.raw.queue_wait_idle(q.raw) })?;

        tracing::warn!("finished waiting: unlocking queue {queue:?}.");
        Ok(())
    }

    pub fn wait_idle(&self) -> VkResult<()> {
        tracing::warn!("locking all queues and waiting for device to idle");
        unsafe {
            self.lock_queues();
            self.raw.device_wait_idle()?;
            self.unlock_queues();
        }
        tracing::warn!("finished waiting: unlocking all queues.");
        Ok(())
    }

    /// # Safety
    ///
    /// This method inherits the safety contract from [`vkSetDebugUtilsObjectName`]. In particular:
    ///
    /// - `object` must be a valid handle for one of the following:
    ///   - An instance-level object from the same instance as this device.
    ///   - A physical-device-level object that descends from the same physical device as this
    ///     device.
    ///   - A device-level object that descends from this device.
    /// - `object` must be externally synchronized—only the calling thread should access it during
    ///   this call.
    ///
    /// [`vkSetDebugUtilsObjectName`]: https://registry.khronos.org/vulkan/specs/latest/man/html/vkSetDebugUtilsObjectNameEXT.html
    pub unsafe fn debug_name_object<T: vk::Handle>(&self, object: T, name: &str) {
        // avoid heap allocation for short names
        let mut buffer = [0u8; 64];
        let buffer_vec: Vec<u8>;

        let name_bytes = if name.is_empty() {
            &[]
        } else if name.len() < buffer.len() {
            buffer[..name.len()].copy_from_slice(name.as_bytes());
            &buffer[..]
        } else {
            buffer_vec = name
                .as_bytes()
                .iter()
                .cloned()
                .chain(std::iter::once(0))
                .collect();
            &buffer_vec
        };

        let name = CStr::from_bytes_with_nul(name_bytes)
            .expect("there is always a nul terminator because we added one");

        unsafe {
            _ = self
                .device_extensions
                .debug_utils
                .set_debug_utils_object_name(
                    &vk::DebugUtilsObjectNameInfoEXT::default()
                        .object_handle(object)
                        .object_name(name),
                );
        }
    }
}

#[derive(Clone)]
pub struct DeviceOwnedDebugObject<T> {
    pub(crate) device: Device,
    pub(crate) object: T,
    #[cfg(debug_assertions)]
    name: Option<Cow<'static, str>>,
}

impl<T: Eq> Eq for DeviceOwnedDebugObject<T> {}
impl<T: PartialEq> PartialEq for DeviceOwnedDebugObject<T> {
    fn eq(&self, other: &Self) -> bool {
        std::sync::Arc::ptr_eq(&self.device.shared, &other.device.shared)
            && self.object == other.object
    }
}

impl<T: std::fmt::Debug + vk::Handle + Copy> std::fmt::Debug for DeviceOwnedDebugObject<T> {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let mut fmt = f.debug_struct(core::any::type_name::<T>());

        fmt.field_with("device", |f| {
            write!(f, "0x{:x}", self.device.raw.handle().as_raw())
        })
        .field_with("handle", |f| write!(f, "0x{:x}", &self.object.as_raw()));

        #[cfg(debug_assertions)]
        {
            fmt.field("name", &self.name);
        }

        fmt.finish()
    }
}

impl<T> DeviceOwnedDebugObject<T> {
    pub fn new(
        device: crate::Device,
        object: T,
        name: Option<Cow<'static, str>>,
    ) -> ash::prelude::VkResult<Self>
    where
        T: vk::Handle + Copy,
    {
        if let Some(name) = name.as_ref() {
            unsafe {
                device.debug_name_object(object, name);
            }
        }

        Ok(Self {
            device,
            object,
            #[cfg(debug_assertions)]
            name,
        })
    }

    pub fn dev(&self) -> &crate::Device {
        &self.device
    }
    pub fn handle(&self) -> T
    where
        T: Copy,
    {
        self.object
    }
}

#[derive(Debug)]
pub struct DeviceObject<T: DeviceHandle> {
    inner: T,
    device: Device,
    #[cfg(debug_assertions)]
    name: Option<Cow<'static, str>>,
}

impl<T: DeviceHandle> Deref for DeviceObject<T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        &self.inner
    }
}

impl<T: DeviceHandle> DerefMut for DeviceObject<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.inner
    }
}

impl<T: DeviceHandle> DeviceObject<T> {
    pub fn new(inner: T, device: Device, name: Option<Cow<'static, str>>) -> Self
    where
        T: vk::Handle + Clone,
    {
        unsafe {
            if let Some(name) = name.as_ref() {
                device.debug_name_object(inner.clone(), &name);
            }
        }

        Self {
            inner,
            device,
            #[cfg(debug_assertions)]
            name,
        }
    }
    pub fn new_without_name(inner: T, device: Device) -> Self {
        Self {
            inner,
            device,
            #[cfg(debug_assertions)]
            name: None,
        }
    }
    pub fn device(&self) -> &Device {
        &self.device
    }
    pub fn name(&self) -> Option<&str> {
        #[cfg(debug_assertions)]
        {
            self.name.as_deref().map(|cow| cow.as_ref())
        }
        #[cfg(not(debug_assertions))]
        {
            None
        }
    }
}

impl<T: DeviceHandle> Drop for DeviceObject<T> {
    fn drop(&mut self) {
        unsafe {
            self.inner.destroy(&self.device);
        }
    }
}

pub trait DeviceHandle {
    unsafe fn destroy(&mut self, device: &Device);
}

impl DeviceHandle for vk::Semaphore {
    unsafe fn destroy(&mut self, device: &Device) {
        unsafe {
            device.dev().destroy_semaphore(*self, None);
        }
    }
}

impl DeviceHandle for vk::Fence {
    unsafe fn destroy(&mut self, device: &Device) {
        unsafe {
            device.dev().destroy_fence(*self, None);
        }
    }
}

impl DeviceHandle for vk::Buffer {
    unsafe fn destroy(&mut self, device: &Device) {
        unsafe {
            device.dev().destroy_buffer(*self, None);
        }
    }
}

impl DeviceHandle for vk::SwapchainKHR {
    unsafe fn destroy(&mut self, device: &Device) {
        unsafe {
            device
                .device_extensions
                .swapchain
                .as_ref()
                .map(|swapchain| swapchain.destroy_swapchain(*self, None));
        }
    }
}

pub trait DeviceOwned<T> {
    fn device(&self) -> &Device;
    fn handle(&self) -> T;
}

pub trait Pooled: Sized {
    fn create_from_pool(pool: &Pool<Self>) -> Result<Self>;
}

pub struct PoolObject<T: Pooled + vk::Handle + Clone> {
    pub(crate) inner: ManuallyDrop<T>,
    pub(crate) pool: Pool<T>,
    #[cfg(debug_assertions)]
    pub(crate) name: Option<Cow<'static, str>>,
}

impl<T: Pooled + vk::Handle + Clone> PoolObject<T> {
    pub fn name_object(&mut self, name: impl Into<Cow<'static, str>>) {
        #[cfg(debug_assertions)]
        unsafe {
            self.name = Some(name.into());
            self.pool
                .device
                .debug_name_object(T::clone(&self.inner), self.name.as_ref().unwrap());
        }
    }

    pub fn device(&self) -> &Arc<DeviceInner> {
        &self.pool.device
    }
}

impl<T: Pooled + vk::Handle + Clone> Drop for PoolObject<T> {
    fn drop(&mut self) {
        let handle = unsafe { ManuallyDrop::take(&mut self.inner) };
        #[cfg(debug_assertions)]
        if self.name.is_some() {
            unsafe { self.pool.device.debug_name_object(handle.clone(), "") };
        }

        self.pool.push(handle);
    }
}

impl<T: Pooled + vk::Handle + Clone> Deref for PoolObject<T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        &self.inner
    }
}

#[derive(Debug, Clone)]
pub struct Pool<T> {
    pub(crate) pool: Arc<Mutex<Vec<T>>>,
    pub(crate) device: Arc<DeviceInner>,
}

impl<T> Pool<T> {
    pub fn push(&self, item: T) {
        self.pool.lock().push(item);
    }
    pub fn new(device: Arc<DeviceInner>) -> Self {
        Self {
            pool: Arc::new(Mutex::new(Vec::new())),
            device,
        }
    }
    pub fn pop(&self) -> Option<T> {
        self.pool.lock().pop()
    }
}

impl<T: Pooled + vk::Handle + Clone> Pool<T> {
    pub fn get(&self) -> Result<PoolObject<T>> {
        let item = if let Some(item) = self.pool.lock().pop() {
            item
        } else {
            T::create_from_pool(self)?
        };

        Ok(PoolObject {
            inner: ManuallyDrop::new(item),
            pool: self.clone(),
            #[cfg(debug_assertions)]
            name: None,
        })
    }

    pub fn get_named(&self, name: Option<impl Into<Cow<'static, str>>>) -> Result<PoolObject<T>> {
        let mut obj = self.get()?;
        if let Some(name) = name {
            obj.name_object(name);
        }
        Ok(obj)
    }
}

// Macro for helping create and destroy Vulkan objects which are owned by a device.
#[macro_export]
macro_rules! define_device_owned_handle {
    ($(#[$attr:meta])*
        $ty_vis:vis $ty:ident($handle:ty) {
        $($(#[$field_attr:meta])* $field_vis:vis $field_name:ident : $field_ty:ty),*
        $(,)?
    } $(=> |$this:ident| $dtor:stmt)?) => {
        $(#[$attr])*
            $ty_vis struct $ty {
                inner: $crate::device::DeviceOwnedDebugObject<$handle>,
                $(
                    $(#[$field_attr])*
                    $field_vis $field_name: $field_ty,
                )*
            }

        impl $crate::device::DeviceOwned<$handle> for $ty {
            fn device(&self) -> &$crate::device::Device {
                self.inner.dev()
            }
            fn handle(&self) -> $handle {
                self.inner.handle()
            }
        }

        impl $ty {
            #[allow(clippy::too_many_arguments, reason = "This function is generated by a macro")]
            fn construct(
                device: $crate::device::Device,
                handle: $handle,
                name: Option<::std::borrow::Cow<'static, str>>,
                $($field_name: $field_ty,)*
            ) -> ::ash::prelude::VkResult<Self> {
                Ok(Self {
                    inner: $crate::device::DeviceOwnedDebugObject::new(
                        device,
                        handle,
                        name,
                    )?,
                    $($field_name,)*
                })
            }
        }

        $(
            impl Drop for $ty {
                fn drop(&mut self) {
                    #[allow(unused_mut)]
                    let mut $this = self;
                    $dtor
                }
            }
        )?
    };
}