// Copyright (c) 2016 The vulkano developers
// Licensed under the Apache License, Version 2.0
// <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT
// license <LICENSE-MIT or https://opensource.org/licenses/MIT>,
// at your option. All files in the project carrying such
// notice may not be copied, modified, or distributed except
// according to those terms.

//! Communication channel with a physical device.
//!
//! The `Device` is one of the most important objects of Vulkan. Creating a `Device` is required
//! before you can create buffers, textures, shaders, etc.
//!
//! Basic example:
//!
//! ```no_run
//! use vulkano::device::Device;
//! use vulkano::device::DeviceExtensions;
//! use vulkano::device::Features;
//! use vulkano::instance::Instance;
//! use vulkano::instance::InstanceExtensions;
//! use vulkano::device::physical::PhysicalDevice;
//! use vulkano::Version;
//!
//! // Creating the instance. See the documentation of the `instance` module.
//! let instance = match Instance::new(None, Version::V1_1, &InstanceExtensions::none(), None) {
//!     Ok(i) => i,
//!     Err(err) => panic!("Couldn't build instance: {:?}", err)
//! };
//!
//! // We just choose the first physical device. In a real application you would choose depending
//! // on the capabilities of the physical device and the user's preferences.
//! let physical_device = PhysicalDevice::enumerate(&instance).next().expect("No physical device");
//!
//! // Here is the device-creating code.
//! let device = {
//!     let queue_family = physical_device.queue_families().next().unwrap();
//!     let features = Features::none();
//!     let ext = DeviceExtensions::none();
//!
//!     match Device::new(physical_device, &features, &ext, Some((queue_family, 1.0))) {
//!         Ok(d) => d,
//!         Err(err) => panic!("Couldn't build device: {:?}", err)
//!     }
//! };
//! ```
//!
//! # Features and extensions
//!
//! Two of the parameters that you pass to `Device::new` are the list of the features and the list
//! of extensions to enable on the newly-created device.
//!
//! > **Note**: Device extensions are the same as instance extensions, except for the device.
//! > Features are similar to extensions, except that they are part of the core Vulkan
//! > specifications instead of being separate documents.
//!
//! Some Vulkan capabilities, such as swapchains (that allow you to render on the screen) or
//! geometry shaders for example, require that you enable a certain feature or extension when you
//! create the device. Contrary to OpenGL, you can't use the functions provided by a feature or an
//! extension if you didn't explicitly enable it when creating the device.
//!
//! Not all physical devices support all possible features and extensions. For example mobile
//! devices tend to not support geometry shaders, because their hardware is not capable of it. You
//! can query what is supported with respectively `PhysicalDevice::supported_features` and
//! `DeviceExtensions::supported_by_device`.
//!
//! > **Note**: The fact that you need to manually enable features at initialization also means
//! > that you don't need to worry about a capability not being supported later on in your code.
//!
//! # Queues
//!
//! Each physical device proposes one or more *queues* that are divided in *queue families*. A
//! queue is a thread of execution to which you can submit commands that the GPU will execute.
//!
//! > **Note**: You can think of a queue like a CPU thread. Each queue executes its commands one
//! > after the other, and queues run concurrently. A GPU behaves similarly to the hyper-threading
//! > technology, in the sense that queues will only run partially in parallel.
//!
//! The Vulkan API requires that you specify the list of queues that you are going to use at the
//! same time as when you create the device. This is done in vulkano by passing an iterator where
//! each element is a tuple containing a queue family and a number between 0.0 and 1.0 indicating
//! the priority of execution of the queue relative to the others.
//!
//! TODO: write better doc here
//!
//! The `Device::new` function returns the newly-created device, but also the list of queues.
//!
//! # Extended example
//!
//! TODO: write

pub(crate) use self::features::FeaturesFfi;
pub use self::features::{FeatureRestriction, FeatureRestrictionError, Features};
pub use self::properties::Properties;
pub(crate) use self::properties::PropertiesFfi;
pub use crate::autogen::DeviceExtensions;
use crate::check_errors;
use crate::command_buffer::pool::StandardCommandPool;
use crate::descriptor_set::pool::StdDescriptorPool;
use crate::device::physical::PhysicalDevice;
use crate::device::physical::QueueFamily;
pub use crate::extensions::{
    ExtensionRestriction, ExtensionRestrictionError, SupportedExtensionsError,
};
use crate::fns::DeviceFunctions;
use crate::format::Format;
use crate::image::ImageCreateFlags;
use crate::image::ImageFormatProperties;
use crate::image::ImageTiling;
use crate::image::ImageType;
use crate::image::ImageUsage;
use crate::instance::Instance;
use crate::memory::pool::StdMemoryPool;
use crate::Error;
use crate::OomError;
use crate::SynchronizedVulkanObject;
use crate::Version;
use crate::VulkanObject;
use ash::vk::Handle;
use fnv::FnvHasher;
use smallvec::SmallVec;
use std::collections::hash_map::Entry;
use std::collections::HashMap;
use std::error;
use std::ffi::CStr;
use std::ffi::CString;
use std::fmt;
use std::hash::BuildHasherDefault;
use std::hash::Hash;
use std::hash::Hasher;
use std::mem;
use std::mem::MaybeUninit;
use std::ops::Deref;
use std::ptr;
use std::sync::Arc;
use std::sync::Mutex;
use std::sync::MutexGuard;
use std::sync::Weak;

pub(crate) mod extensions;
pub(crate) mod features;
pub mod physical;
pub(crate) mod properties;

/// Represents a Vulkan context.
pub struct Device {
    instance: Arc<Instance>,
    physical_device: usize,
    device: ash::vk::Device,

    // The highest version that is supported for this device.
    // This is the minimum of Instance::max_api_version and PhysicalDevice::api_version.
    api_version: Version,

    fns: DeviceFunctions,
    standard_pool: Mutex<Weak<StdMemoryPool>>,
    standard_descriptor_pool: Mutex<Weak<StdDescriptorPool>>,
    standard_command_pools:
        Mutex<HashMap<u32, Weak<StandardCommandPool>, BuildHasherDefault<FnvHasher>>>,
    features: Features,
    extensions: DeviceExtensions,
    active_queue_families: SmallVec<[u32; 8]>,
    allocation_count: Mutex<u32>,
    fence_pool: Mutex<Vec<ash::vk::Fence>>,
    semaphore_pool: Mutex<Vec<ash::vk::Semaphore>>,
    event_pool: Mutex<Vec<ash::vk::Event>>,
}

// The `StandardCommandPool` type doesn't implement Send/Sync, so we have to manually reimplement
// them for the device itself.
unsafe impl Send for Device {}
unsafe impl Sync for Device {}

impl Device {
    /// Builds a new Vulkan device for the given physical device.
    ///
    /// You must pass two things when creating a logical device:
    ///
    /// - A list of optional Vulkan features that must be enabled on the device. Note that if a
    ///   feature is not enabled at device creation, you can't use it later even it it's supported
    ///   by the physical device.
    ///
    /// - An iterator to a list of queues to create. Each element of the iterator must indicate
    ///   the family whose queue belongs to and a priority between 0.0 and 1.0 to assign to it.
    ///   A queue with a higher value indicates that the commands will execute faster than on a
    ///   queue with a lower value. Note however that no guarantee can be made on the way the
    ///   priority value is handled by the implementation.
    ///
    /// # Panic
    ///
    /// - Panics if one of the queue families doesn't belong to the given device.
    ///
    // TODO: return Arc<Queue> and handle synchronization in the Queue
    // TODO: should take the PhysicalDevice by value
    pub fn new<'a, I>(
        physical_device: PhysicalDevice,
        requested_features: &Features,
        requested_extensions: &DeviceExtensions,
        queue_families: I,
    ) -> Result<(Arc<Device>, QueuesIter), DeviceCreationError>
    where
        I: IntoIterator<Item = (QueueFamily<'a>, f32)>,
    {
        let instance = physical_device.instance();
        let fns_i = instance.fns();
        let api_version = physical_device.api_version();

        // Check if the extensions are correct
        requested_extensions.check_requirements(
            physical_device.supported_extensions(),
            api_version,
            instance.enabled_extensions(),
        )?;

        let mut requested_features = requested_features.clone();

        // TODO: The plan regarding `robust_buffer_access` is to check the shaders' code to see
        //       if they can possibly perform out-of-bounds reads and writes. If the user tries
        //       to use a shader that can perform out-of-bounds operations without having
        //       `robust_buffer_access` enabled, an error is returned.
        //
        //       However for the moment this verification isn't performed. In order to be safe,
        //       we always enable the `robust_buffer_access` feature as it is guaranteed to be
        //       supported everywhere.
        //
        //       The only alternative (while waiting for shaders introspection to work) is to
        //       make all shaders depend on `robust_buffer_access`. But since usually the
        //       majority of shaders don't need this feature, it would be very annoying to have
        //       to enable it manually when you don't need it.
        //
        //       Note that if we ever remove this, don't forget to adjust the change in
        //       `Device`'s construction below.
        requested_features.robust_buffer_access = true;

        // Check if the features are correct
        requested_features.check_requirements(
            physical_device.supported_features(),
            api_version,
            requested_extensions,
        )?;

        // device creation
        let (device, queues) = unsafe {
            // each element of `queues` is a `(queue_family, priorities)`
            // each queue family must only have one entry in `queues`
            let mut queues: Vec<(u32, Vec<f32>)> =
                Vec::with_capacity(physical_device.queue_families().len());

            // this variable will contain the queue family ID and queue ID of each requested queue
            let mut output_queues: SmallVec<[(u32, u32); 8]> = SmallVec::new();

            for (queue_family, priority) in queue_families {
                // checking the parameters
                assert_eq!(
                    queue_family.physical_device().internal_object(),
                    physical_device.internal_object()
                );
                if priority < 0.0 || priority > 1.0 {
                    return Err(DeviceCreationError::PriorityOutOfRange);
                }

                // adding to `queues` and `output_queues`
                if let Some(q) = queues.iter_mut().find(|q| q.0 == queue_family.id()) {
                    output_queues.push((queue_family.id(), q.1.len() as u32));
                    q.1.push(priority);
                    if q.1.len() > queue_family.queues_count() {
                        return Err(DeviceCreationError::TooManyQueuesForFamily);
                    }
                    continue;
                }
                queues.push((queue_family.id(), vec![priority]));
                output_queues.push((queue_family.id(), 0));
            }

            // turning `queues` into an array of `vkDeviceQueueCreateInfo` suitable for Vulkan
            let queues = queues
                .iter()
                .map(
                    |&(queue_id, ref priorities)| ash::vk::DeviceQueueCreateInfo {
                        flags: ash::vk::DeviceQueueCreateFlags::empty(),
                        queue_family_index: queue_id,
                        queue_count: priorities.len() as u32,
                        p_queue_priorities: priorities.as_ptr(),
                        ..Default::default()
                    },
                )
                .collect::<SmallVec<[_; 16]>>();

            let mut features_ffi = FeaturesFfi::default();
            features_ffi.make_chain(
                api_version,
                requested_extensions,
                instance.enabled_extensions(),
            );
            features_ffi.write(&requested_features);

            // Device layers were deprecated in Vulkan 1.0.13, and device layer requests should be
            // ignored by the driver. For backwards compatibility, the spec recommends passing the
            // exact instance layers to the device as well. There's no need to support separate
            // requests at device creation time for legacy drivers: the spec claims that "[at] the
            // time of deprecation there were no known device-only layers."
            //
            // Because there's no way to query the list of layers enabled for an instance, we need
            // to save it alongside the instance. (`vkEnumerateDeviceLayerProperties` should get
            // the right list post-1.0.13, but not pre-1.0.13, so we can't use it here.)
            let layers_ptrs = instance
                .enabled_layers()
                .map(|layer| layer.as_ptr())
                .collect::<SmallVec<[_; 16]>>();

            let extensions_strings: Vec<CString> = requested_extensions.into();
            let extensions_ptrs = extensions_strings
                .iter()
                .map(|extension| extension.as_ptr())
                .collect::<SmallVec<[_; 16]>>();

            let has_khr_get_physical_device_properties2 = instance
                .enabled_extensions()
                .khr_get_physical_device_properties2;

            let infos = ash::vk::DeviceCreateInfo {
                p_next: if has_khr_get_physical_device_properties2 {
                    features_ffi.head_as_ref() as *const _ as _
                } else {
                    ptr::null()
                },
                flags: ash::vk::DeviceCreateFlags::empty(),
                queue_create_info_count: queues.len() as u32,
                p_queue_create_infos: queues.as_ptr(),
                enabled_layer_count: layers_ptrs.len() as u32,
                pp_enabled_layer_names: layers_ptrs.as_ptr(),
                enabled_extension_count: extensions_ptrs.len() as u32,
                pp_enabled_extension_names: extensions_ptrs.as_ptr(),
                p_enabled_features: if has_khr_get_physical_device_properties2 {
                    ptr::null()
                } else {
                    &features_ffi.head_as_ref().features
                },
                ..Default::default()
            };

            let mut output = MaybeUninit::uninit();
            check_errors(fns_i.v1_0.create_device(
                physical_device.internal_object(),
                &infos,
                ptr::null(),
                output.as_mut_ptr(),
            ))?;

            (output.assume_init(), output_queues)
        };

        // loading the function pointers of the newly-created device
        let fns = DeviceFunctions::load(|name| unsafe {
            mem::transmute(fns_i.v1_0.get_device_proc_addr(device, name.as_ptr()))
        });

        let mut active_queue_families: SmallVec<[u32; 8]> = SmallVec::new();
        for (queue_family, _) in queues.iter() {
            if let None = active_queue_families
                .iter()
                .find(|&&qf| qf == *queue_family)
            {
                active_queue_families.push(*queue_family);
            }
        }

        let device = Arc::new(Device {
            instance: physical_device.instance().clone(),
            physical_device: physical_device.index(),
            device: device,
            api_version,
            fns,
            standard_pool: Mutex::new(Weak::new()),
            standard_descriptor_pool: Mutex::new(Weak::new()),
            standard_command_pools: Mutex::new(Default::default()),
            features: Features {
                // Always enabled ; see above
                robust_buffer_access: true,
                ..requested_features.clone()
            },
            extensions: requested_extensions.clone(),
            active_queue_families,
            allocation_count: Mutex::new(0),
            fence_pool: Mutex::new(Vec::new()),
            semaphore_pool: Mutex::new(Vec::new()),
            event_pool: Mutex::new(Vec::new()),
        });

        // Iterator for the produced queues.
        let queues = QueuesIter {
            next_queue: 0,
            device: device.clone(),
            families_and_ids: queues,
        };

        Ok((device, queues))
    }

    /// Returns the Vulkan version supported by the device.
    ///
    /// This is the lower of the
    /// [physical device's supported version](crate::instance::PhysicalDevice::api_version) and
    /// the instance's [`max_api_version`](crate::instance::Instance::max_api_version).
    #[inline]
    pub fn api_version(&self) -> Version {
        self.api_version
    }

    /// Grants access to the Vulkan functions of the device.
    #[inline]
    pub fn fns(&self) -> &DeviceFunctions {
        &self.fns
    }

    /// Waits until all work on this device has finished. You should never need to call
    /// this function, but it can be useful for debugging or benchmarking purposes.
    ///
    /// > **Note**: This is the Vulkan equivalent of OpenGL's `glFinish`.
    ///
    /// # Safety
    ///
    /// This function is not thread-safe. You must not submit anything to any of the queue
    /// of the device (either explicitly or implicitly, for example with a future's destructor)
    /// while this function is waiting.
    ///
    pub unsafe fn wait(&self) -> Result<(), OomError> {
        check_errors(self.fns.v1_0.device_wait_idle(self.device))?;
        Ok(())
    }

    /// Returns the instance used to create this device.
    #[inline]
    pub fn instance(&self) -> &Arc<Instance> {
        &self.instance
    }

    /// Returns the physical device that was used to create this device.
    #[inline]
    pub fn physical_device(&self) -> PhysicalDevice {
        PhysicalDevice::from_index(&self.instance, self.physical_device).unwrap()
    }

    /// Returns an iterator to the list of queues families that this device uses.
    ///
    /// > **Note**: Will return `-> impl ExactSizeIterator<Item = QueueFamily>` in the future.
    // TODO: ^
    #[inline]
    pub fn active_queue_families<'a>(
        &'a self,
    ) -> Box<dyn ExactSizeIterator<Item = QueueFamily<'a>> + 'a> {
        let physical_device = self.physical_device();
        Box::new(
            self.active_queue_families
                .iter()
                .map(move |&id| physical_device.queue_family_by_id(id).unwrap()),
        )
    }

    /// Returns the features that have been enabled on the device.
    #[inline]
    pub fn enabled_features(&self) -> &Features {
        &self.features
    }

    /// Returns the extensions that have been enabled on the device.
    #[inline]
    pub fn enabled_extensions(&self) -> &DeviceExtensions {
        &self.extensions
    }

    /// Returns the standard memory pool used by default if you don't provide any other pool.
    pub fn standard_pool(me: &Arc<Self>) -> Arc<StdMemoryPool> {
        let mut pool = me.standard_pool.lock().unwrap();

        if let Some(p) = pool.upgrade() {
            return p;
        }

        // The weak pointer is empty, so we create the pool.
        let new_pool = StdMemoryPool::new(me.clone());
        *pool = Arc::downgrade(&new_pool);
        new_pool
    }

    /// Returns the standard descriptor pool used by default if you don't provide any other pool.
    pub fn standard_descriptor_pool(me: &Arc<Self>) -> Arc<StdDescriptorPool> {
        let mut pool = me.standard_descriptor_pool.lock().unwrap();

        if let Some(p) = pool.upgrade() {
            return p;
        }

        // The weak pointer is empty, so we create the pool.
        let new_pool = Arc::new(StdDescriptorPool::new(me.clone()));
        *pool = Arc::downgrade(&new_pool);
        new_pool
    }

    /// Returns the standard command buffer pool used by default if you don't provide any other
    /// pool.
    ///
    /// # Panic
    ///
    /// - Panics if the device and the queue family don't belong to the same physical device.
    ///
    pub fn standard_command_pool(me: &Arc<Self>, queue: QueueFamily) -> Arc<StandardCommandPool> {
        let mut standard_command_pools = me.standard_command_pools.lock().unwrap();

        match standard_command_pools.entry(queue.id()) {
            Entry::Occupied(mut entry) => {
                if let Some(pool) = entry.get().upgrade() {
                    return pool;
                }

                let new_pool = Arc::new(StandardCommandPool::new(me.clone(), queue));
                *entry.get_mut() = Arc::downgrade(&new_pool);
                new_pool
            }
            Entry::Vacant(entry) => {
                let new_pool = Arc::new(StandardCommandPool::new(me.clone(), queue));
                entry.insert(Arc::downgrade(&new_pool));
                new_pool
            }
        }
    }

    /// Used to track the number of allocations on this device.
    ///
    /// To ensure valid usage of the Vulkan API, we cannot call `vkAllocateMemory` when
    /// `maxMemoryAllocationCount` has been exceeded. See the Vulkan specs:
    /// https://www.khronos.org/registry/vulkan/specs/1.0/html/vkspec.html#vkAllocateMemory
    ///
    /// Warning: You should never modify this value, except in `device_memory` module
    pub(crate) fn allocation_count(&self) -> &Mutex<u32> {
        &self.allocation_count
    }

    pub(crate) fn fence_pool(&self) -> &Mutex<Vec<ash::vk::Fence>> {
        &self.fence_pool
    }

    pub(crate) fn semaphore_pool(&self) -> &Mutex<Vec<ash::vk::Semaphore>> {
        &self.semaphore_pool
    }

    pub(crate) fn event_pool(&self) -> &Mutex<Vec<ash::vk::Event>> {
        &self.event_pool
    }

    /// Assigns a human-readable name to `object` for debugging purposes.
    ///
    /// # Panics
    /// * If `object` is not owned by this device.
    pub fn set_object_name<T: VulkanObject + DeviceOwned>(
        &self,
        object: &T,
        name: &CStr,
    ) -> Result<(), OomError> {
        assert!(object.device().internal_object() == self.internal_object());
        unsafe {
            self.set_object_name_raw(T::Object::TYPE, object.internal_object().as_raw(), name)
        }
    }

    /// Assigns a human-readable name to `object` for debugging purposes.
    ///
    /// # Safety
    /// `object` must be a Vulkan handle owned by this device, and its type must be accurately described by `ty`.
    pub unsafe fn set_object_name_raw(
        &self,
        ty: ash::vk::ObjectType,
        object: u64,
        name: &CStr,
    ) -> Result<(), OomError> {
        let info = ash::vk::DebugUtilsObjectNameInfoEXT {
            object_type: ty,
            object_handle: object,
            p_object_name: name.as_ptr(),
            ..Default::default()
        };
        check_errors(
            self.instance
                .fns()
                .ext_debug_utils
                .set_debug_utils_object_name_ext(self.device, &info),
        )?;
        Ok(())
    }

    /// Checks the given combination of image attributes/configuration for compatibility with the physical device.
    ///
    /// Returns a struct with additional capabilities available for this image configuration.
    pub fn image_format_properties(
        &self,
        format: Format,
        ty: ImageType,
        tiling: ImageTiling,
        usage: ImageUsage,
        create_flags: ImageCreateFlags,
    ) -> Result<ImageFormatProperties, String> {
        let fns_i = self.instance().fns();
        let mut output = MaybeUninit::uninit();
        let physical_device = self.physical_device().internal_object();
        unsafe {
            let r = fns_i.v1_0.get_physical_device_image_format_properties(
                physical_device,
                format.into(),
                ty.into(),
                tiling.into(),
                usage.into(),
                create_flags.into(),
                output.as_mut_ptr(),
            );

            match check_errors(r) {
                Ok(_) => Ok(output.assume_init().into()),
                Err(e) => {
                    return Err(String::from(format!(
                        "Image properties not supported. {:#?}",
                        e
                    )))
                }
            }
        }
    }
}

impl fmt::Debug for Device {
    #[inline]
    fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        write!(fmt, "<Vulkan device {:?}>", self.device)
    }
}

unsafe impl VulkanObject for Device {
    type Object = ash::vk::Device;

    #[inline]
    fn internal_object(&self) -> ash::vk::Device {
        self.device
    }
}

impl Drop for Device {
    #[inline]
    fn drop(&mut self) {
        unsafe {
            for &raw_fence in self.fence_pool.lock().unwrap().iter() {
                self.fns
                    .v1_0
                    .destroy_fence(self.device, raw_fence, ptr::null());
            }
            for &raw_sem in self.semaphore_pool.lock().unwrap().iter() {
                self.fns
                    .v1_0
                    .destroy_semaphore(self.device, raw_sem, ptr::null());
            }
            for &raw_event in self.event_pool.lock().unwrap().iter() {
                self.fns
                    .v1_0
                    .destroy_event(self.device, raw_event, ptr::null());
            }
            self.fns.v1_0.destroy_device(self.device, ptr::null());
        }
    }
}

impl PartialEq for Device {
    #[inline]
    fn eq(&self, other: &Self) -> bool {
        self.device == other.device && self.instance == other.instance
    }
}

impl Eq for Device {}

impl Hash for Device {
    #[inline]
    fn hash<H: Hasher>(&self, state: &mut H) {
        self.device.hash(state);
        self.instance.hash(state);
    }
}

/// Implemented on objects that belong to a Vulkan device.
///
/// # Safety
///
/// - `device()` must return the correct device.
///
pub unsafe trait DeviceOwned {
    /// Returns the device that owns `Self`.
    fn device(&self) -> &Arc<Device>;
}

unsafe impl<T> DeviceOwned for T
where
    T: Deref,
    T::Target: DeviceOwned,
{
    #[inline]
    fn device(&self) -> &Arc<Device> {
        (**self).device()
    }
}

/// Iterator that returns the queues produced when creating a device.
pub struct QueuesIter {
    next_queue: usize,
    device: Arc<Device>,
    families_and_ids: SmallVec<[(u32, u32); 8]>,
}

unsafe impl DeviceOwned for QueuesIter {
    fn device(&self) -> &Arc<Device> {
        &self.device
    }
}

impl Iterator for QueuesIter {
    type Item = Arc<Queue>;

    fn next(&mut self) -> Option<Arc<Queue>> {
        unsafe {
            let &(family, id) = match self.families_and_ids.get(self.next_queue) {
                Some(a) => a,
                None => return None,
            };

            self.next_queue += 1;

            let mut output = MaybeUninit::uninit();
            self.device.fns.v1_0.get_device_queue(
                self.device.device,
                family,
                id,
                output.as_mut_ptr(),
            );

            Some(Arc::new(Queue {
                queue: Mutex::new(output.assume_init()),
                device: self.device.clone(),
                family: family,
                id: id,
            }))
        }
    }

    #[inline]
    fn size_hint(&self) -> (usize, Option<usize>) {
        let len = self.families_and_ids.len().saturating_sub(self.next_queue);
        (len, Some(len))
    }
}

impl ExactSizeIterator for QueuesIter {}

/// Error that can be returned when creating a device.
#[derive(Copy, Clone, Debug)]
pub enum DeviceCreationError {
    /// Failed to create the device for an implementation-specific reason.
    InitializationFailed,
    /// You have reached the limit to the number of devices that can be created from the same
    /// physical device.
    TooManyObjects,
    /// Failed to connect to the device.
    DeviceLost,
    /// Some of the requested features are unsupported by the physical device.
    FeatureNotPresent,
    /// Some of the requested device extensions are not supported by the physical device.
    ExtensionNotPresent,
    /// Tried to create too many queues for a given family.
    TooManyQueuesForFamily,
    /// The priority of one of the queues is out of the [0.0; 1.0] range.
    PriorityOutOfRange,
    /// There is no memory available on the host (ie. the CPU, RAM, etc.).
    OutOfHostMemory,
    /// There is no memory available on the device (ie. video memory).
    OutOfDeviceMemory,
    /// A restriction for an extension was not met.
    ExtensionRestrictionNotMet(ExtensionRestrictionError),
    /// A restriction for a feature was not met.
    FeatureRestrictionNotMet(FeatureRestrictionError),
}

impl error::Error for DeviceCreationError {}

impl fmt::Display for DeviceCreationError {
    #[inline]
    fn fmt(&self, fmt: &mut fmt::Formatter) -> Result<(), fmt::Error> {
        match *self {
            DeviceCreationError::InitializationFailed => {
                write!(
                    fmt,
                    "failed to create the device for an implementation-specific reason"
                )
            }
            DeviceCreationError::OutOfHostMemory => write!(fmt, "no memory available on the host"),
            DeviceCreationError::OutOfDeviceMemory => {
                write!(fmt, "no memory available on the graphical device")
            }
            DeviceCreationError::DeviceLost => write!(fmt, "failed to connect to the device"),
            DeviceCreationError::TooManyQueuesForFamily => {
                write!(fmt, "tried to create too many queues for a given family")
            }
            DeviceCreationError::FeatureNotPresent => {
                write!(
                    fmt,
                    "some of the requested features are unsupported by the physical device"
                )
            }
            DeviceCreationError::PriorityOutOfRange => {
                write!(
                    fmt,
                    "the priority of one of the queues is out of the [0.0; 1.0] range"
                )
            }
            DeviceCreationError::ExtensionNotPresent => {
                write!(fmt,"some of the requested device extensions are not supported by the physical device")
            }
            DeviceCreationError::TooManyObjects => {
                write!(fmt,"you have reached the limit to the number of devices that can be created from the same physical device")
            }
            DeviceCreationError::ExtensionRestrictionNotMet(err) => err.fmt(fmt),
            DeviceCreationError::FeatureRestrictionNotMet(err) => err.fmt(fmt),
        }
    }
}

impl From<Error> for DeviceCreationError {
    #[inline]
    fn from(err: Error) -> DeviceCreationError {
        match err {
            Error::InitializationFailed => DeviceCreationError::InitializationFailed,
            Error::OutOfHostMemory => DeviceCreationError::OutOfHostMemory,
            Error::OutOfDeviceMemory => DeviceCreationError::OutOfDeviceMemory,
            Error::DeviceLost => DeviceCreationError::DeviceLost,
            Error::ExtensionNotPresent => DeviceCreationError::ExtensionNotPresent,
            Error::FeatureNotPresent => DeviceCreationError::FeatureNotPresent,
            Error::TooManyObjects => DeviceCreationError::TooManyObjects,
            _ => panic!("Unexpected error value: {}", err as i32),
        }
    }
}

impl From<ExtensionRestrictionError> for DeviceCreationError {
    #[inline]
    fn from(err: ExtensionRestrictionError) -> Self {
        Self::ExtensionRestrictionNotMet(err)
    }
}

impl From<FeatureRestrictionError> for DeviceCreationError {
    #[inline]
    fn from(err: FeatureRestrictionError) -> Self {
        Self::FeatureRestrictionNotMet(err)
    }
}

/// Represents a queue where commands can be submitted.
// TODO: should use internal synchronization?
#[derive(Debug)]
pub struct Queue {
    queue: Mutex<ash::vk::Queue>,
    device: Arc<Device>,
    family: u32,
    id: u32, // id within family
}

impl Queue {
    /// Returns the device this queue belongs to.
    #[inline]
    pub fn device(&self) -> &Arc<Device> {
        &self.device
    }

    /// Returns true if this is the same queue as another one.
    #[inline]
    pub fn is_same(&self, other: &Queue) -> bool {
        self.id == other.id
            && self.family == other.family
            && self.device.internal_object() == other.device.internal_object()
    }

    /// Returns the family this queue belongs to.
    #[inline]
    pub fn family(&self) -> QueueFamily {
        self.device
            .physical_device()
            .queue_family_by_id(self.family)
            .unwrap()
    }

    /// Returns the index of this queue within its family.
    #[inline]
    pub fn id_within_family(&self) -> u32 {
        self.id
    }

    /// Waits until all work on this queue has finished.
    ///
    /// Just like `Device::wait()`, you shouldn't have to call this function in a typical program.
    #[inline]
    pub fn wait(&self) -> Result<(), OomError> {
        unsafe {
            let fns = self.device.fns();
            let queue = self.queue.lock().unwrap();
            check_errors(fns.v1_0.queue_wait_idle(*queue))?;
            Ok(())
        }
    }
}

impl PartialEq for Queue {
    fn eq(&self, other: &Self) -> bool {
        self.is_same(other)
    }
}

impl Eq for Queue {}

unsafe impl DeviceOwned for Queue {
    fn device(&self) -> &Arc<Device> {
        &self.device
    }
}

unsafe impl SynchronizedVulkanObject for Queue {
    type Object = ash::vk::Queue;

    #[inline]
    fn internal_object_guard(&self) -> MutexGuard<ash::vk::Queue> {
        self.queue.lock().unwrap()
    }
}

#[cfg(test)]
mod tests {
    use crate::device::physical::PhysicalDevice;
    use crate::device::Device;
    use crate::device::DeviceCreationError;
    use crate::device::DeviceExtensions;
    use crate::device::{FeatureRestriction, FeatureRestrictionError, Features};
    use std::sync::Arc;

    #[test]
    fn one_ref() {
        let (mut device, _) = gfx_dev_and_queue!();
        assert!(Arc::get_mut(&mut device).is_some());
    }

    #[test]
    fn too_many_queues() {
        let instance = instance!();
        let physical = match PhysicalDevice::enumerate(&instance).next() {
            Some(p) => p,
            None => return,
        };

        let family = physical.queue_families().next().unwrap();
        let queues = (0..family.queues_count() + 1).map(|_| (family, 1.0));

        match Device::new(
            physical,
            &Features::none(),
            &DeviceExtensions::none(),
            queues,
        ) {
            Err(DeviceCreationError::TooManyQueuesForFamily) => return, // Success
            _ => panic!(),
        };
    }

    #[test]
    fn unsupposed_features() {
        let instance = instance!();
        let physical = match PhysicalDevice::enumerate(&instance).next() {
            Some(p) => p,
            None => return,
        };

        let family = physical.queue_families().next().unwrap();

        let features = Features::all();
        // In the unlikely situation where the device supports everything, we ignore the test.
        if physical.supported_features().is_superset_of(&features) {
            return;
        }

        match Device::new(
            physical,
            &features,
            &DeviceExtensions::none(),
            Some((family, 1.0)),
        ) {
            Err(DeviceCreationError::FeatureRestrictionNotMet(FeatureRestrictionError {
                restriction: FeatureRestriction::NotSupported,
                ..
            })) => return, // Success
            _ => panic!(),
        };
    }

    #[test]
    fn priority_out_of_range() {
        let instance = instance!();
        let physical = match PhysicalDevice::enumerate(&instance).next() {
            Some(p) => p,
            None => return,
        };

        let family = physical.queue_families().next().unwrap();

        match Device::new(
            physical,
            &Features::none(),
            &DeviceExtensions::none(),
            Some((family, 1.4)),
        ) {
            Err(DeviceCreationError::PriorityOutOfRange) => (), // Success
            _ => panic!(),
        };

        match Device::new(
            physical,
            &Features::none(),
            &DeviceExtensions::none(),
            Some((family, -0.2)),
        ) {
            Err(DeviceCreationError::PriorityOutOfRange) => (), // Success
            _ => panic!(),
        };
    }
}