// Copyright (c) 2016 The vulkano developers
// Licensed under the Apache License, Version 2.0
// <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT
// license <LICENSE-MIT or http://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.

use smallvec::SmallVec;
use std::sync::Arc;
use std::sync::atomic::AtomicBool;
use std::sync::atomic::Ordering;

use buffer::BufferAccess;
use buffer::BufferUsage;
use buffer::CpuAccessibleBuffer;
use buffer::TypedBufferAccess;
use command_buffer::AutoCommandBuffer;
use command_buffer::AutoCommandBufferBuilder;
use command_buffer::CommandBuffer;
use command_buffer::CommandBufferExecFuture;
use device::Device;
use device::Queue;
use format::AcceptsPixels;
use format::Format;
use format::FormatDesc;
use image::Dimensions;
use image::ImageInner;
use image::ImageLayout;
use image::ImageUsage;
use image::MipmapsCount;
use image::sys::ImageCreationError;
use image::sys::UnsafeImage;
use image::sys::UnsafeImageView;
use image::traits::ImageAccess;
use image::traits::ImageContent;
use image::traits::ImageViewAccess;
use instance::QueueFamily;
use memory::DedicatedAlloc;
use memory::pool::AllocFromRequirementsFilter;
use memory::pool::AllocLayout;
use memory::pool::MappingRequirement;
use memory::pool::MemoryPool;
use memory::pool::MemoryPoolAlloc;
use memory::pool::PotentialDedicatedAllocation;
use memory::pool::StdMemoryPoolAlloc;
use sync::AccessError;
use sync::NowFuture;
use sync::Sharing;

/// Image whose purpose is to be used for read-only purposes. You can write to the image once,
/// but then you must only ever read from it.
// TODO: type (2D, 3D, array, etc.) as template parameter
#[derive(Debug)]
pub struct ImmutableImage<F, A = PotentialDedicatedAllocation<StdMemoryPoolAlloc>> {
    image: UnsafeImage,
    view: UnsafeImageView,
    dimensions: Dimensions,
    memory: A,
    format: F,
    initialized: AtomicBool,
    layout: ImageLayout,
}

// Must not implement Clone, as that would lead to multiple `used` values.
pub struct ImmutableImageInitialization<F, A = PotentialDedicatedAllocation<StdMemoryPoolAlloc>> {
    image: Arc<ImmutableImage<F, A>>,
    used: AtomicBool,
}

impl<F> ImmutableImage<F> {
    #[deprecated(note = "use ImmutableImage::uninitialized instead")]
    #[inline]
    pub fn new<'a, I>(device: Arc<Device>, dimensions: Dimensions, format: F, queue_families: I)
                      -> Result<Arc<ImmutableImage<F>>, ImageCreationError>
        where F: FormatDesc,
              I: IntoIterator<Item = QueueFamily<'a>>
    {
        #[allow(deprecated)]
        ImmutableImage::with_mipmaps(device,
                                     dimensions,
                                     format,
                                     MipmapsCount::One,
                                     queue_families)
    }

    #[deprecated(note = "use ImmutableImage::uninitialized instead")]
    #[inline]
    pub fn with_mipmaps<'a, I, M>(device: Arc<Device>, dimensions: Dimensions, format: F,
                                  mipmaps: M, queue_families: I)
                                  -> Result<Arc<ImmutableImage<F>>, ImageCreationError>
        where F: FormatDesc,
              I: IntoIterator<Item = QueueFamily<'a>>,
              M: Into<MipmapsCount>
    {
        let usage = ImageUsage {
            transfer_source: true, // for blits
            transfer_destination: true,
            sampled: true,
            ..ImageUsage::none()
        };

        let (image, _) = ImmutableImage::uninitialized(device,
                                                       dimensions,
                                                       format,
                                                       mipmaps,
                                                       usage,
                                                       ImageLayout::ShaderReadOnlyOptimal,
                                                       queue_families)?;
        image.initialized.store(true, Ordering::Relaxed); // Allow uninitialized access for backwards compatibility
        Ok(image)
    }

    /// Builds an uninitialized immutable image.
    ///
    /// Returns two things: the image, and a special access that should be used for the initial upload to the image.
    pub fn uninitialized<'a, I, M>(
        device: Arc<Device>, dimensions: Dimensions, format: F, mipmaps: M, usage: ImageUsage,
        layout: ImageLayout, queue_families: I)
        -> Result<(Arc<ImmutableImage<F>>, ImmutableImageInitialization<F>), ImageCreationError>
        where F: FormatDesc,
              I: IntoIterator<Item = QueueFamily<'a>>,
              M: Into<MipmapsCount>
    {
        let queue_families = queue_families
            .into_iter()
            .map(|f| f.id())
            .collect::<SmallVec<[u32; 4]>>();

        let (image, mem_reqs) = unsafe {
            let sharing = if queue_families.len() >= 2 {
                Sharing::Concurrent(queue_families.iter().cloned())
            } else {
                Sharing::Exclusive
            };

            UnsafeImage::new(device.clone(),
                             usage,
                             format.format(),
                             dimensions.to_image_dimensions(),
                             1,
                             mipmaps,
                             sharing,
                             false,
                             false)?
        };

        let mem = MemoryPool::alloc_from_requirements(&Device::standard_pool(&device),
                                    &mem_reqs,
                                    AllocLayout::Optimal,
                                    MappingRequirement::DoNotMap,
                                    DedicatedAlloc::Image(&image),
                                    |t| if t.is_device_local() {
                                        AllocFromRequirementsFilter::Preferred
                                    } else {
                                        AllocFromRequirementsFilter::Allowed
                                    })?;
        debug_assert!((mem.offset() % mem_reqs.alignment) == 0);
        unsafe {
            image.bind_memory(mem.memory(), mem.offset())?;
        }

        let view = unsafe {
            UnsafeImageView::raw(&image,
                                 dimensions.to_view_type(),
                                 0 .. image.mipmap_levels(),
                                 0 .. image.dimensions().array_layers())?
        };

        let image = Arc::new(ImmutableImage {
                                 image: image,
                                 view: view,
                                 memory: mem,
                                 dimensions: dimensions,
                                 format: format,
                                 initialized: AtomicBool::new(false),
                                 layout: layout,
                             });

        let init = ImmutableImageInitialization {
            image: image.clone(),
            used: AtomicBool::new(false),
        };

        Ok((image, init))
    }

    /// Construct an ImmutableImage from the contents of `iter`.
    ///
    /// TODO: Support mipmaps
    #[inline]
    pub fn from_iter<P, I>(iter: I, dimensions: Dimensions, format: F, queue: Arc<Queue>)
                           -> Result<(Arc<Self>,
                                      CommandBufferExecFuture<NowFuture, AutoCommandBuffer>),
                                     ImageCreationError>
        where P: Send + Sync + Clone + 'static,
              F: FormatDesc + AcceptsPixels<P> + 'static + Send + Sync,
              I: ExactSizeIterator<Item = P>,
              Format: AcceptsPixels<P>
    {
        let source = CpuAccessibleBuffer::from_iter(queue.device().clone(),
                                                    BufferUsage::transfer_source(),
                                                    iter)?;
        ImmutableImage::from_buffer(source, dimensions, format, queue)
    }

    /// Construct an ImmutableImage containing a copy of the data in `source`.
    ///
    /// TODO: Support mipmaps
    pub fn from_buffer<B, P>(source: B, dimensions: Dimensions, format: F, queue: Arc<Queue>)
                             -> Result<(Arc<Self>,
                                        CommandBufferExecFuture<NowFuture, AutoCommandBuffer>),
                                       ImageCreationError>
        where B: BufferAccess + TypedBufferAccess<Content = [P]> + 'static + Clone + Send + Sync,
              P: Send + Sync + Clone + 'static,
              F: FormatDesc + AcceptsPixels<P> + 'static + Send + Sync,
              Format: AcceptsPixels<P>
    {
        let usage = ImageUsage {
            transfer_destination: true,
            sampled: true,
            ..ImageUsage::none()
        };
        let layout = ImageLayout::ShaderReadOnlyOptimal;

        let (buffer, init) =
            ImmutableImage::uninitialized(source.device().clone(),
                                          dimensions,
                                          format,
                                          MipmapsCount::One,
                                          usage,
                                          layout,
                                          source.device().active_queue_families())?;

        let cb = AutoCommandBufferBuilder::new(source.device().clone(), queue.family())?
            .copy_buffer_to_image_dimensions(source,
                                             init,
                                             [0, 0, 0],
                                             dimensions.width_height_depth(),
                                             0,
                                             dimensions.array_layers_with_cube(),
                                             0)
            .unwrap()
            .build()
            .unwrap();

        let future = match cb.execute(queue) {
            Ok(f) => f,
            Err(_) => unreachable!(),
        };

        Ok((buffer, future))
    }
}

impl<F, A> ImmutableImage<F, A> {
    /// Returns the dimensions of the image.
    #[inline]
    pub fn dimensions(&self) -> Dimensions {
        self.dimensions
    }

    /// Returns the number of mipmap levels of the image.
    #[inline]
    pub fn mipmap_levels(&self) -> u32 {
        self.image.mipmap_levels()
    }
}

unsafe impl<F, A> ImageAccess for ImmutableImage<F, A>
    where F: 'static + Send + Sync
{
    #[inline]
    fn inner(&self) -> ImageInner {
        ImageInner {
            image: &self.image,
            first_layer: 0,
            num_layers: self.image.dimensions().array_layers() as usize,
            first_mipmap_level: 0,
            num_mipmap_levels: self.image.mipmap_levels() as usize,
        }
    }

    #[inline]
    fn initial_layout_requirement(&self) -> ImageLayout {
        self.layout
    }

    #[inline]
    fn final_layout_requirement(&self) -> ImageLayout {
        self.layout
    }

    #[inline]
    fn conflicts_buffer(&self, other: &BufferAccess) -> bool {
        false
    }

    #[inline]
    fn conflicts_image(&self, other: &ImageAccess) -> bool {
        self.conflict_key() == other.conflict_key() // TODO:
    }

    #[inline]
    fn conflict_key(&self) -> u64 {
        self.image.key()
    }

    #[inline]
    fn try_gpu_lock(&self, exclusive_access: bool, expected_layout: ImageLayout)
                    -> Result<(), AccessError> {
        if expected_layout != self.layout && expected_layout != ImageLayout::Undefined {
            return Err(AccessError::UnexpectedImageLayout {
                           requested: expected_layout,
                           allowed: self.layout,
                       });
        }

        if exclusive_access {
            return Err(AccessError::ExclusiveDenied);
        }

        if !self.initialized.load(Ordering::Relaxed) {
            return Err(AccessError::BufferNotInitialized);
        }

        Ok(())
    }

    #[inline]
    unsafe fn increase_gpu_lock(&self) {
    }

    #[inline]
    unsafe fn unlock(&self, new_layout: Option<ImageLayout>) {
        debug_assert!(new_layout.is_none());
    }
}

unsafe impl<P, F, A> ImageContent<P> for ImmutableImage<F, A>
    where F: 'static + Send + Sync
{
    #[inline]
    fn matches_format(&self) -> bool {
        true // FIXME:
    }
}

unsafe impl<F: 'static, A> ImageViewAccess for ImmutableImage<F, A>
    where F: 'static + Send + Sync
{
    #[inline]
    fn parent(&self) -> &ImageAccess {
        self
    }

    #[inline]
    fn dimensions(&self) -> Dimensions {
        self.dimensions
    }

    #[inline]
    fn inner(&self) -> &UnsafeImageView {
        &self.view
    }

    #[inline]
    fn descriptor_set_storage_image_layout(&self) -> ImageLayout {
        self.layout
    }

    #[inline]
    fn descriptor_set_combined_image_sampler_layout(&self) -> ImageLayout {
        self.layout
    }

    #[inline]
    fn descriptor_set_sampled_image_layout(&self) -> ImageLayout {
        self.layout
    }

    #[inline]
    fn descriptor_set_input_attachment_layout(&self) -> ImageLayout {
        self.layout
    }

    #[inline]
    fn identity_swizzle(&self) -> bool {
        true
    }
}

unsafe impl<F, A> ImageAccess for ImmutableImageInitialization<F, A>
    where F: 'static + Send + Sync
{
    #[inline]
    fn inner(&self) -> ImageInner {
        ImageAccess::inner(&self.image)
    }

    #[inline]
    fn initial_layout_requirement(&self) -> ImageLayout {
        ImageLayout::Undefined
    }

    #[inline]
    fn final_layout_requirement(&self) -> ImageLayout {
        self.image.layout
    }

    #[inline]
    fn conflicts_buffer(&self, other: &BufferAccess) -> bool {
        false
    }

    #[inline]
    fn conflicts_image(&self, other: &ImageAccess) -> bool {
        self.conflict_key() == other.conflict_key() // TODO:
    }

    #[inline]
    fn conflict_key(&self) -> u64 {
        self.image.image.key()
    }

    #[inline]
    fn try_gpu_lock(&self, _: bool, expected_layout: ImageLayout) -> Result<(), AccessError> {
        if expected_layout != ImageLayout::Undefined {
            return Err(AccessError::UnexpectedImageLayout {
                           requested: expected_layout,
                           allowed: ImageLayout::Undefined,
                       });
        }

        if self.image.initialized.load(Ordering::Relaxed) {
            return Err(AccessError::AlreadyInUse);
        }

        // FIXME: Mipmapped textures require multiple writes to initialize
        if !self.used.compare_and_swap(false, true, Ordering::Relaxed) {
            Ok(())
        } else {
            Err(AccessError::AlreadyInUse)
        }
    }

    #[inline]
    unsafe fn increase_gpu_lock(&self) {
        debug_assert!(self.used.load(Ordering::Relaxed));
    }

    #[inline]
    unsafe fn unlock(&self, new_layout: Option<ImageLayout>) {
        assert_eq!(new_layout, Some(self.image.layout));
        self.image.initialized.store(true, Ordering::Relaxed);
    }
}