// 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.

// Welcome to the triangle example!
//
// This is the only example that is entirely detailed. All the other examples avoid code
// duplication by using helper functions.
//
// This example assumes that you are already more or less familiar with graphics programming and
// that you want to learn Vulkan. This means that for example it won't go into details about what a
// vertex or a shader is.

use std::{collections::HashMap, sync::Arc};
use vulkano::{
    buffer::{Buffer, BufferAllocateInfo, BufferContents, BufferUsage},
    command_buffer::{
        allocator::StandardCommandBufferAllocator, AutoCommandBufferBuilder, CommandBufferUsage,
        RenderPassBeginInfo, SubpassContents,
    },
    device::{
        physical::PhysicalDeviceType, Device, DeviceCreateInfo, DeviceExtensions, QueueCreateInfo,
        QueueFlags,
    },
    image::{view::ImageView, ImageAccess, ImageUsage, SwapchainImage},
    instance::{Instance, InstanceCreateInfo},
    memory::allocator::StandardMemoryAllocator,
    pipeline::{
        graphics::{
            input_assembly::InputAssemblyState,
            vertex_input::Vertex,
            viewport::{Viewport, ViewportState},
        },
        GraphicsPipeline,
    },
    render_pass::{Framebuffer, FramebufferCreateInfo, RenderPass, Subpass},
    swapchain::{
        acquire_next_image, AcquireError, Surface, Swapchain, SwapchainCreateInfo,
        SwapchainCreationError, SwapchainPresentInfo,
    },
    sync::{self, FlushError, GpuFuture},
    VulkanLibrary,
};
use vulkano_win::VkSurfaceBuild;
use winit::{
    event::{ElementState, Event, KeyboardInput, WindowEvent},
    event_loop::{ControlFlow, EventLoop},
    window::{Window, WindowBuilder},
};

/// A struct to contain resources related to a window.
struct WindowSurface {
    surface: Arc<Surface>,
    swapchain: Arc<Swapchain>,
    framebuffers: Vec<Arc<Framebuffer>>,
    recreate_swapchain: bool,
    previous_frame_end: Option<Box<dyn GpuFuture>>,
}

fn main() {
    let library = VulkanLibrary::new().unwrap();
    let required_extensions = vulkano_win::required_extensions(&library);
    let instance = Instance::new(
        library,
        InstanceCreateInfo {
            enabled_extensions: required_extensions,
            enumerate_portability: true,
            ..Default::default()
        },
    )
    .unwrap();
    let event_loop = EventLoop::new();

    // A hashmap that contains all of our created windows and their resources.
    let mut window_surfaces = HashMap::new();

    let surface = WindowBuilder::new()
        .build_vk_surface(&event_loop, instance.clone())
        .unwrap();

    // Use the window's id as a means to access it from the hashmap.
    let window = surface.object().unwrap().downcast_ref::<Window>().unwrap();
    let window_id = window.id();

    // Find the device and a queue.
    // TODO: it is assumed the device, queue, and surface surface_capabilities are the same for all
    // windows.

    let (device, queue, surface_caps) = {
        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.surface_support(i as u32, &surface).unwrap_or(false)
                    })
                    .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 surface_capabilities = device
            .physical_device()
            .surface_capabilities(&surface, Default::default())
            .unwrap();

        (device, queues.next().unwrap(), surface_capabilities)
    };

    // The swapchain and framebuffer images for this particular window.
    let (swapchain, images) = {
        let image_format = Some(
            device
                .physical_device()
                .surface_formats(&surface, Default::default())
                .unwrap()[0]
                .0,
        );
        let window = surface.object().unwrap().downcast_ref::<Window>().unwrap();

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

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

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

    let vertices = [
        Vertex {
            position: [-0.5, -0.25],
        },
        Vertex {
            position: [0.0, 0.5],
        },
        Vertex {
            position: [0.25, -0.1],
        },
    ];
    let vertex_buffer = Buffer::from_iter(
        &memory_allocator,
        BufferAllocateInfo {
            buffer_usage: BufferUsage::VERTEX_BUFFER,
            ..Default::default()
        },
        vertices,
    )
    .unwrap();

    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 vs = vs::load(device.clone()).unwrap();
    let fs = fs::load(device.clone()).unwrap();

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

    let pipeline = GraphicsPipeline::start()
        .vertex_input_state(Vertex::per_vertex())
        .vertex_shader(vs.entry_point("main").unwrap(), ())
        .input_assembly_state(InputAssemblyState::new())
        .viewport_state(ViewportState::viewport_dynamic_scissor_irrelevant())
        .fragment_shader(fs.entry_point("main").unwrap(), ())
        .render_pass(Subpass::from(render_pass.clone(), 0).unwrap())
        .build(device.clone())
        .unwrap();

    let mut viewport = Viewport {
        origin: [0.0, 0.0],
        dimensions: [0.0, 0.0],
        depth_range: 0.0..1.0,
    };

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

    window_surfaces.insert(
        window_id,
        WindowSurface {
            surface,
            swapchain,
            recreate_swapchain: false,
            framebuffers: window_size_dependent_setup(&images, render_pass.clone(), &mut viewport),
            previous_frame_end: Some(sync::now(device.clone()).boxed()),
        },
    );

    event_loop.run(move |event, event_loop, control_flow| match event {
        Event::WindowEvent {
            event: WindowEvent::CloseRequested,
            ..
        } => {
            *control_flow = ControlFlow::Exit;
        }
        Event::WindowEvent {
            window_id,
            event: WindowEvent::Resized(_),
            ..
        } => {
            window_surfaces
                .get_mut(&window_id)
                .unwrap()
                .recreate_swapchain = true;
        }
        Event::WindowEvent {
            event:
                WindowEvent::KeyboardInput {
                    input:
                        KeyboardInput {
                            state: ElementState::Pressed,
                            ..
                        },
                    ..
                },
            ..
        } => {
            let surface = WindowBuilder::new()
                .build_vk_surface(event_loop, instance.clone())
                .unwrap();
            let window = surface.object().unwrap().downcast_ref::<Window>().unwrap();
            let window_id = window.id();
            let (swapchain, images) = {
                let composite_alpha = surface_caps
                    .supported_composite_alpha
                    .into_iter()
                    .next()
                    .unwrap();
                let image_format = Some(
                    device
                        .physical_device()
                        .surface_formats(&surface, Default::default())
                        .unwrap()[0]
                        .0,
                );

                Swapchain::new(
                    device.clone(),
                    surface.clone(),
                    SwapchainCreateInfo {
                        min_image_count: surface_caps.min_image_count,
                        image_format,
                        image_extent: window.inner_size().into(),
                        image_usage: ImageUsage::COLOR_ATTACHMENT,
                        composite_alpha,
                        ..Default::default()
                    },
                )
                .unwrap()
            };

            window_surfaces.insert(
                window_id,
                WindowSurface {
                    surface,
                    swapchain,
                    recreate_swapchain: false,
                    framebuffers: window_size_dependent_setup(
                        &images,
                        render_pass.clone(),
                        &mut viewport,
                    ),
                    previous_frame_end: Some(sync::now(device.clone()).boxed()),
                },
            );
        }
        Event::RedrawEventsCleared => {
            window_surfaces.values().for_each(|s| {
                let window = s
                    .surface
                    .object()
                    .unwrap()
                    .downcast_ref::<Window>()
                    .unwrap();
                window.request_redraw()
            });
        }
        Event::RedrawRequested(window_id) => {
            let WindowSurface {
                surface,
                swapchain,
                recreate_swapchain,
                framebuffers,
                previous_frame_end,
            } = window_surfaces.get_mut(&window_id).unwrap();

            let window = surface.object().unwrap().downcast_ref::<Window>().unwrap();
            let dimensions = window.inner_size();
            if dimensions.width == 0 || dimensions.height == 0 {
                return;
            }

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

            if *recreate_swapchain {
                let (new_swapchain, new_images) = match swapchain.recreate(SwapchainCreateInfo {
                    image_extent: dimensions.into(),
                    ..swapchain.create_info()
                }) {
                    Ok(r) => r,
                    Err(SwapchainCreationError::ImageExtentNotSupported { .. }) => return,
                    Err(e) => panic!("failed to recreate swapchain: {e}"),
                };

                *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) {
                    Ok(r) => r,
                    Err(AcquireError::OutOfDate) => {
                        *recreate_swapchain = true;
                        return;
                    }
                    Err(e) => panic!("failed to acquire next image: {e}"),
                };

            if suboptimal {
                *recreate_swapchain = true;
            }

            let mut builder = AutoCommandBufferBuilder::primary(
                &command_buffer_allocator,
                queue.queue_family_index(),
                CommandBufferUsage::OneTimeSubmit,
            )
            .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(),
                        )
                    },
                    SubpassContents::Inline,
                )
                .unwrap()
                .set_viewport(0, [viewport.clone()])
                .bind_pipeline_graphics(pipeline.clone())
                .bind_vertex_buffers(0, vertex_buffer.clone())
                .draw(vertex_buffer.len() as u32, 1, 0, 0)
                .unwrap()
                .end_render_pass()
                .unwrap();
            let command_buffer = builder.build().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 {
                Ok(future) => {
                    *previous_frame_end = Some(future.boxed());
                }
                Err(FlushError::OutOfDate) => {
                    *recreate_swapchain = true;
                    *previous_frame_end = Some(sync::now(device.clone()).boxed());
                }
                Err(e) => {
                    println!("failed to flush future: {e}");
                    *previous_frame_end = Some(sync::now(device.clone()).boxed());
                }
            }
        }
        _ => (),
    });
}

fn window_size_dependent_setup(
    images: &[Arc<SwapchainImage>],
    render_pass: Arc<RenderPass>,
    viewport: &mut Viewport,
) -> Vec<Arc<Framebuffer>> {
    let dimensions = images[0].dimensions().width_height();
    viewport.dimensions = [dimensions[0] as f32, dimensions[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<_>>()
}
