// Modified triangle example to show `SubbufferAllocator`.

use std::{
    error::Error,
    sync::Arc,
    time::{SystemTime, UNIX_EPOCH},
};
use vulkano::{
    buffer::{
        allocator::{SubbufferAllocator, SubbufferAllocatorCreateInfo},
        BufferContents, BufferUsage,
    },
    command_buffer::{
        allocator::StandardCommandBufferAllocator, CommandBufferBeginInfo, CommandBufferLevel,
        CommandBufferUsage, RecordingCommandBuffer, RenderPassBeginInfo,
    },
    device::{
        physical::PhysicalDeviceType, Device, DeviceCreateInfo, DeviceExtensions, QueueCreateInfo,
        QueueFlags,
    },
    image::{view::ImageView, Image, ImageUsage},
    instance::{Instance, InstanceCreateFlags, InstanceCreateInfo},
    memory::allocator::{MemoryTypeFilter, StandardMemoryAllocator},
    pipeline::{
        graphics::{
            color_blend::{ColorBlendAttachmentState, ColorBlendState},
            input_assembly::InputAssemblyState,
            multisample::MultisampleState,
            rasterization::RasterizationState,
            vertex_input::{Vertex, VertexDefinition},
            viewport::{Viewport, ViewportState},
            GraphicsPipelineCreateInfo,
        },
        layout::PipelineDescriptorSetLayoutCreateInfo,
        DynamicState, GraphicsPipeline, PipelineLayout, PipelineShaderStageCreateInfo,
    },
    render_pass::{Framebuffer, FramebufferCreateInfo, RenderPass, Subpass},
    swapchain::{
        acquire_next_image, Surface, Swapchain, SwapchainCreateInfo, SwapchainPresentInfo,
    },
    sync::{self, GpuFuture},
    Validated, VulkanError, VulkanLibrary,
};
use winit::{
    event::{Event, WindowEvent},
    event_loop::{ControlFlow, EventLoop},
    window::WindowBuilder,
};

fn main() -> Result<(), impl Error> {
    let event_loop = EventLoop::new().unwrap();

    let library = VulkanLibrary::new().unwrap();
    let required_extensions = Surface::required_extensions(&event_loop).unwrap();
    let instance = Instance::new(
        library,
        InstanceCreateInfo {
            flags: InstanceCreateFlags::ENUMERATE_PORTABILITY,
            enabled_extensions: required_extensions,
            ..Default::default()
        },
    )
    .unwrap();

    let device_extensions = DeviceExtensions {
        khr_swapchain: true,
        ..DeviceExtensions::empty()
    };
    let (physical_device, queue_family_index) = instance
        .enumerate_physical_devices()
        .unwrap()
        .filter(|p| p.supported_extensions().contains(&device_extensions))
        .filter_map(|p| {
            p.queue_family_properties()
                .iter()
                .enumerate()
                .position(|(i, q)| {
                    q.queue_flags.intersects(QueueFlags::GRAPHICS)
                        && p.presentation_support(i as u32, &event_loop).unwrap()
                })
                .map(|i| (p, i as u32))
        })
        .min_by_key(|(p, _)| match p.properties().device_type {
            PhysicalDeviceType::DiscreteGpu => 0,
            PhysicalDeviceType::IntegratedGpu => 1,
            PhysicalDeviceType::VirtualGpu => 2,
            PhysicalDeviceType::Cpu => 3,
            PhysicalDeviceType::Other => 4,
            _ => 5,
        })
        .unwrap();

    println!(
        "Using device: {} (type: {:?})",
        physical_device.properties().device_name,
        physical_device.properties().device_type,
    );

    let (device, mut queues) = Device::new(
        physical_device,
        DeviceCreateInfo {
            enabled_extensions: device_extensions,
            queue_create_infos: vec![QueueCreateInfo {
                queue_family_index,
                ..Default::default()
            }],
            ..Default::default()
        },
    )
    .unwrap();

    let queue = queues.next().unwrap();

    let window = Arc::new(WindowBuilder::new().build(&event_loop).unwrap());
    let surface = Surface::from_window(instance.clone(), window.clone()).unwrap();

    let (mut swapchain, images) = {
        let surface_capabilities = device
            .physical_device()
            .surface_capabilities(&surface, Default::default())
            .unwrap();
        let image_format = device
            .physical_device()
            .surface_formats(&surface, Default::default())
            .unwrap()[0]
            .0;

        Swapchain::new(
            device.clone(),
            surface,
            SwapchainCreateInfo {
                min_image_count: surface_capabilities.min_image_count.max(2),
                image_format,
                image_extent: window.inner_size().into(),
                image_usage: ImageUsage::COLOR_ATTACHMENT,
                composite_alpha: surface_capabilities
                    .supported_composite_alpha
                    .into_iter()
                    .next()
                    .unwrap(),
                ..Default::default()
            },
        )
        .unwrap()
    };

    let memory_allocator = Arc::new(StandardMemoryAllocator::new_default(device.clone()));

    #[derive(Clone, Copy, BufferContents, Vertex)]
    #[repr(C)]
    struct Vertex {
        #[format(R32G32_SFLOAT)]
        position: [f32; 2],
    }

    // Using a buffer allocator allows multiple buffers to be "in-flight" simultaneously and is
    // suited to highly dynamic data like vertex, index and uniform buffers.
    let buffer_allocator = SubbufferAllocator::new(
        memory_allocator,
        SubbufferAllocatorCreateInfo {
            // We want to use the allocated subbuffers as vertex buffers.
            buffer_usage: BufferUsage::VERTEX_BUFFER,
            memory_type_filter: MemoryTypeFilter::PREFER_DEVICE
                | MemoryTypeFilter::HOST_SEQUENTIAL_WRITE,
            ..Default::default()
        },
    );

    mod vs {
        vulkano_shaders::shader! {
            ty: "vertex",
            src: r"
                #version 450

                layout(location = 0) in vec2 position;

                void main() {
                    gl_Position = vec4(position, 0.0, 1.0);
                }
            ",
        }
    }

    mod fs {
        vulkano_shaders::shader! {
            ty: "fragment",
            src: r"
                #version 450

                layout(location = 0) out vec4 f_color;

                void main() {
                    f_color = vec4(1.0, 0.0, 0.0, 1.0);
                }
            ",
        }
    }

    let render_pass = vulkano::single_pass_renderpass!(
        device.clone(),
        attachments: {
            color: {
                format: swapchain.image_format(),
                samples: 1,
                load_op: Clear,
                store_op: Store,
            },
        },
        pass: {
            color: [color],
            depth_stencil: {},
        },
    )
    .unwrap();

    let pipeline = {
        let vs = vs::load(device.clone())
            .unwrap()
            .entry_point("main")
            .unwrap();
        let fs = fs::load(device.clone())
            .unwrap()
            .entry_point("main")
            .unwrap();
        let vertex_input_state = Vertex::per_vertex().definition(&vs).unwrap();
        let stages = [
            PipelineShaderStageCreateInfo::new(vs),
            PipelineShaderStageCreateInfo::new(fs),
        ];
        let layout = PipelineLayout::new(
            device.clone(),
            PipelineDescriptorSetLayoutCreateInfo::from_stages(&stages)
                .into_pipeline_layout_create_info(device.clone())
                .unwrap(),
        )
        .unwrap();
        let subpass = Subpass::from(render_pass.clone(), 0).unwrap();

        GraphicsPipeline::new(
            device.clone(),
            None,
            GraphicsPipelineCreateInfo {
                stages: stages.into_iter().collect(),
                vertex_input_state: Some(vertex_input_state),
                input_assembly_state: Some(InputAssemblyState::default()),
                viewport_state: Some(ViewportState::default()),
                rasterization_state: Some(RasterizationState::default()),
                multisample_state: Some(MultisampleState::default()),
                color_blend_state: Some(ColorBlendState::with_attachment_states(
                    subpass.num_color_attachments(),
                    ColorBlendAttachmentState::default(),
                )),
                dynamic_state: [DynamicState::Viewport].into_iter().collect(),
                subpass: Some(subpass.into()),
                ..GraphicsPipelineCreateInfo::layout(layout)
            },
        )
        .unwrap()
    };

    let mut viewport = Viewport {
        offset: [0.0, 0.0],
        extent: [0.0, 0.0],
        depth_range: 0.0..=1.0,
    };
    let mut framebuffers = window_size_dependent_setup(&images, render_pass.clone(), &mut viewport);
    let mut recreate_swapchain = false;
    let mut previous_frame_end = Some(sync::now(device.clone()).boxed());

    let command_buffer_allocator = Arc::new(StandardCommandBufferAllocator::new(
        device.clone(),
        Default::default(),
    ));

    event_loop.run(move |event, elwt| {
        elwt.set_control_flow(ControlFlow::Poll);

        match event {
            Event::WindowEvent {
                event: WindowEvent::CloseRequested,
                ..
            } => {
                elwt.exit();
            }
            Event::WindowEvent {
                event: WindowEvent::Resized(_),
                ..
            } => {
                recreate_swapchain = true;
            }
            Event::WindowEvent {
                event: WindowEvent::RedrawRequested,
                ..
            } => {
                let image_extent: [u32; 2] = window.inner_size().into();

                if image_extent.contains(&0) {
                    return;
                }

                previous_frame_end.as_mut().unwrap().cleanup_finished();

                if recreate_swapchain {
                    let (new_swapchain, new_images) = swapchain
                        .recreate(SwapchainCreateInfo {
                            image_extent,
                            ..swapchain.create_info()
                        })
                        .expect("failed to recreate swapchain");

                    swapchain = new_swapchain;
                    framebuffers = window_size_dependent_setup(
                        &new_images,
                        render_pass.clone(),
                        &mut viewport,
                    );
                    recreate_swapchain = false;
                }

                let (image_index, suboptimal, acquire_future) =
                    match acquire_next_image(swapchain.clone(), None).map_err(Validated::unwrap) {
                        Ok(r) => r,
                        Err(VulkanError::OutOfDate) => {
                            recreate_swapchain = true;
                            return;
                        }
                        Err(e) => panic!("failed to acquire next image: {e}"),
                    };

                if suboptimal {
                    recreate_swapchain = true;
                }

                // Rotate once (PI*2) every 5 seconds
                let elapsed = SystemTime::now()
                    .duration_since(UNIX_EPOCH)
                    .unwrap()
                    .as_secs_f64();
                const DURATION: f64 = 5.0;
                let remainder = elapsed.rem_euclid(DURATION);
                let delta = (remainder / DURATION) as f32;
                let angle = delta * std::f32::consts::PI * 2.0;
                const RADIUS: f32 = 0.5;
                // 120Degree offset in radians
                const ANGLE_OFFSET: f32 = (std::f32::consts::PI * 2.0) / 3.0;
                // Calculate vertices
                let data = [
                    Vertex {
                        position: [angle.cos() * RADIUS, angle.sin() * RADIUS],
                    },
                    Vertex {
                        position: [
                            (angle + ANGLE_OFFSET).cos() * RADIUS,
                            (angle + ANGLE_OFFSET).sin() * RADIUS,
                        ],
                    },
                    Vertex {
                        position: [
                            (angle - ANGLE_OFFSET).cos() * RADIUS,
                            (angle - ANGLE_OFFSET).sin() * RADIUS,
                        ],
                    },
                ];
                let num_vertices = data.len() as u32;

                // Allocate a new subbuffer using the buffer allocator.
                let buffer = buffer_allocator.allocate_slice(data.len() as _).unwrap();
                buffer.write().unwrap().copy_from_slice(&data);

                let mut builder = RecordingCommandBuffer::new(
                    command_buffer_allocator.clone(),
                    queue.queue_family_index(),
                    CommandBufferLevel::Primary,
                    CommandBufferBeginInfo {
                        usage: CommandBufferUsage::OneTimeSubmit,
                        ..Default::default()
                    },
                )
                .unwrap();

                builder
                    .begin_render_pass(
                        RenderPassBeginInfo {
                            clear_values: vec![Some([0.0, 0.0, 1.0, 1.0].into())],
                            ..RenderPassBeginInfo::framebuffer(
                                framebuffers[image_index as usize].clone(),
                            )
                        },
                        Default::default(),
                    )
                    .unwrap()
                    .set_viewport(0, [viewport.clone()].into_iter().collect())
                    .unwrap()
                    // Draw our buffer
                    .bind_pipeline_graphics(pipeline.clone())
                    .unwrap()
                    .bind_vertex_buffers(0, buffer)
                    .unwrap();

                unsafe {
                    builder.draw(num_vertices, 1, 0, 0).unwrap();
                }

                builder.end_render_pass(Default::default()).unwrap();

                let command_buffer = builder.end().unwrap();
                let future = previous_frame_end
                    .take()
                    .unwrap()
                    .join(acquire_future)
                    .then_execute(queue.clone(), command_buffer)
                    .unwrap()
                    .then_swapchain_present(
                        queue.clone(),
                        SwapchainPresentInfo::swapchain_image_index(swapchain.clone(), image_index),
                    )
                    .then_signal_fence_and_flush();

                match future.map_err(Validated::unwrap) {
                    Ok(future) => {
                        previous_frame_end = Some(Box::new(future) as Box<_>);
                    }
                    Err(VulkanError::OutOfDate) => {
                        recreate_swapchain = true;
                        previous_frame_end = Some(Box::new(sync::now(device.clone())) as Box<_>);
                    }
                    Err(e) => {
                        println!("failed to flush future: {e}");
                        previous_frame_end = Some(Box::new(sync::now(device.clone())) as Box<_>);
                    }
                }
            }
            Event::AboutToWait => window.request_redraw(),
            _ => (),
        }
    })
}

/// This function is called once during initialization, then again whenever the window is resized.
fn window_size_dependent_setup(
    images: &[Arc<Image>],
    render_pass: Arc<RenderPass>,
    viewport: &mut Viewport,
) -> Vec<Arc<Framebuffer>> {
    let extent = images[0].extent();
    viewport.extent = [extent[0] as f32, extent[1] as f32];

    images
        .iter()
        .map(|image| {
            let view = ImageView::new_default(image.clone()).unwrap();
            Framebuffer::new(
                render_pass.clone(),
                FramebufferCreateInfo {
                    attachments: vec![view],
                    ..Default::default()
                },
            )
            .unwrap()
        })
        .collect::<Vec<_>>()
}