// 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 instancing example!
//
// This is a simple, modified version of the `triangle.rs` example that demonstrates how we can use
// the "instancing" technique with vulkano to draw many instances of the triangle.

#[macro_use]
extern crate vulkano;
extern crate vulkano_shaders;
extern crate vulkano_win;
extern crate winit;

use std::sync::Arc;
use vulkano::buffer::{BufferUsage, CpuAccessibleBuffer, TypedBufferAccess};
use vulkano::command_buffer::{AutoCommandBufferBuilder, CommandBufferUsage, SubpassContents};
use vulkano::device::physical::{PhysicalDevice, PhysicalDeviceType};
use vulkano::device::{Device, DeviceExtensions, Features};
use vulkano::image::view::ImageView;
use vulkano::image::{ImageUsage, SwapchainImage};
use vulkano::instance::Instance;
use vulkano::pipeline::vertex::BuffersDefinition;
use vulkano::pipeline::viewport::Viewport;
use vulkano::pipeline::GraphicsPipeline;
use vulkano::render_pass::{Framebuffer, FramebufferAbstract, RenderPass, Subpass};
use vulkano::swapchain;
use vulkano::swapchain::{AcquireError, Swapchain, SwapchainCreationError};
use vulkano::sync;
use vulkano::sync::{FlushError, GpuFuture};
use vulkano::Version;
use vulkano_win::VkSurfaceBuild;
use winit::event::{Event, WindowEvent};
use winit::event_loop::{ControlFlow, EventLoop};
use winit::window::{Window, WindowBuilder};

// # Vertex Types
//
// Seeing as we are going to use the `OneVertexOneInstanceDefinition` vertex definition for our
// graphics pipeline, we need to define two vertex types:
//
// 1. `Vertex` is the vertex type that we will use to describe the triangle's geometry.
#[derive(Default, Debug, Clone)]
struct Vertex {
    position: [f32; 2],
}
impl_vertex!(Vertex, position);

// 2. `InstanceData` is the vertex type that describes the unique data per instance.
#[derive(Default, Debug, Clone)]
struct InstanceData {
    position_offset: [f32; 2],
    scale: f32,
}
impl_vertex!(InstanceData, position_offset, scale);

fn main() {
    let required_extensions = vulkano_win::required_extensions();
    let instance = Instance::new(None, Version::V1_1, &required_extensions, None).unwrap();

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

    let device_extensions = DeviceExtensions {
        khr_swapchain: true,
        ..DeviceExtensions::none()
    };
    let (physical_device, queue_family) = PhysicalDevice::enumerate(&instance)
        .filter(|&p| p.supported_extensions().is_superset_of(&device_extensions))
        .filter_map(|p| {
            p.queue_families()
                .find(|&q| q.supports_graphics() && surface.is_supported(q).unwrap_or(false))
                .map(|q| (p, q))
        })
        .min_by_key(|(p, _)| match p.properties().device_type {
            PhysicalDeviceType::DiscreteGpu => 0,
            PhysicalDeviceType::IntegratedGpu => 1,
            PhysicalDeviceType::VirtualGpu => 2,
            PhysicalDeviceType::Cpu => 3,
            PhysicalDeviceType::Other => 4,
        })
        .unwrap();

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

    let (device, mut queues) = Device::new(
        physical_device,
        &Features::none(),
        &physical_device
            .required_extensions()
            .union(&device_extensions),
        [(queue_family, 0.5)].iter().cloned(),
    )
    .unwrap();

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

    let (mut swapchain, images) = {
        let caps = surface.capabilities(physical_device).unwrap();
        let composite_alpha = caps.supported_composite_alpha.iter().next().unwrap();
        let format = caps.supported_formats[0].0;
        let dimensions: [u32; 2] = surface.window().inner_size().into();

        Swapchain::start(device.clone(), surface.clone())
            .num_images(caps.min_image_count)
            .format(format)
            .dimensions(dimensions)
            .usage(ImageUsage::color_attachment())
            .sharing_mode(&queue)
            .composite_alpha(composite_alpha)
            .build()
            .unwrap()
    };

    // We now create a buffer that will store the shape of our triangle.
    // This triangle is identical to the one in the `triangle.rs` example.
    let triangle_vertex_buffer = {
        CpuAccessibleBuffer::from_iter(
            device.clone(),
            BufferUsage::all(),
            false,
            [
                Vertex {
                    position: [-0.5, -0.25],
                },
                Vertex {
                    position: [0.0, 0.5],
                },
                Vertex {
                    position: [0.25, -0.1],
                },
            ]
            .iter()
            .cloned(),
        )
        .unwrap()
    };

    // Now we create another buffer that will store the unique data per instance.
    // For this example, we'll have the instances form a 10x10 grid that slowly gets larger.
    let instance_data_buffer = {
        let rows = 10;
        let cols = 10;
        let n_instances = rows * cols;
        let mut data = Vec::new();
        for c in 0..cols {
            for r in 0..rows {
                let half_cell_w = 0.5 / cols as f32;
                let half_cell_h = 0.5 / rows as f32;
                let x = half_cell_w + (c as f32 / cols as f32) * 2.0 - 1.0;
                let y = half_cell_h + (r as f32 / rows as f32) * 2.0 - 1.0;
                let position_offset = [x, y];
                let scale = (2.0 / rows as f32) * (c * rows + r) as f32 / n_instances as f32;
                data.push(InstanceData {
                    position_offset,
                    scale,
                });
            }
        }
        CpuAccessibleBuffer::from_iter(
            device.clone(),
            BufferUsage::all(),
            false,
            data.iter().cloned(),
        )
        .unwrap()
    };

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

                // The triangle vertex positions.
                layout(location = 0) in vec2 position;

                // The per-instance data.
                layout(location = 1) in vec2 position_offset;
                layout(location = 2) in float scale;

                void main() {
                    // Apply the scale and offset for the instance.
                    gl_Position = vec4(position * scale + position_offset, 0.0, 1.0);
                }
            "
        }
    }

    mod fs {
        vulkano_shaders::shader! {
            ty: "fragment",
            src: "
                #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::Shader::load(device.clone()).unwrap();
    let fs = fs::Shader::load(device.clone()).unwrap();

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

    let pipeline = Arc::new(
        GraphicsPipeline::start()
            // Use the `BuffersDefinition` to describe to vulkano how the two vertex types
            // are expected to be used.
            .vertex_input(
                BuffersDefinition::new()
                    .vertex::<Vertex>()
                    .instance::<InstanceData>(),
            )
            .vertex_shader(vs.main_entry_point(), ())
            .triangle_list()
            .viewports_dynamic_scissors_irrelevant(1)
            .fragment_shader(fs.main_entry_point(), ())
            .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 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());

    event_loop.run(move |event, _, control_flow| {
        match event {
            Event::WindowEvent {
                event: WindowEvent::CloseRequested,
                ..
            } => {
                *control_flow = ControlFlow::Exit;
            }
            Event::WindowEvent {
                event: WindowEvent::Resized(_),
                ..
            } => {
                recreate_swapchain = true;
            }
            Event::RedrawEventsCleared => {
                previous_frame_end.as_mut().unwrap().cleanup_finished();

                if recreate_swapchain {
                    let dimensions: [u32; 2] = surface.window().inner_size().into();
                    let (new_swapchain, new_images) =
                        match swapchain.recreate().dimensions(dimensions).build() {
                            Ok(r) => r,
                            Err(SwapchainCreationError::UnsupportedDimensions) => 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_num, suboptimal, acquire_future) =
                    match swapchain::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 clear_values = vec![[0.0, 0.0, 1.0, 1.0].into()];

                let mut builder = AutoCommandBufferBuilder::primary(
                    device.clone(),
                    queue.family(),
                    CommandBufferUsage::OneTimeSubmit,
                )
                .unwrap();
                builder
                    .begin_render_pass(
                        framebuffers[image_num].clone(),
                        SubpassContents::Inline,
                        clear_values,
                    )
                    .unwrap()
                    .set_viewport(0, [viewport.clone()])
                    .bind_pipeline_graphics(pipeline.clone())
                    // We pass both our lists of vertices here.
                    .bind_vertex_buffers(
                        0,
                        (triangle_vertex_buffer.clone(), instance_data_buffer.clone()),
                    )
                    .draw(
                        triangle_vertex_buffer.len() as u32,
                        instance_data_buffer.len() as u32,
                        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(), swapchain.clone(), image_num)
                    .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());
                    }
                }
            }
            _ => (),
        }
    });
}

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

    images
        .iter()
        .map(|image| {
            let view = ImageView::new(image.clone()).unwrap();
            Arc::new(
                Framebuffer::start(render_pass.clone())
                    .add(view)
                    .unwrap()
                    .build()
                    .unwrap(),
            ) as Arc<dyn FramebufferAbstract>
        })
        .collect::<Vec<_>>()
}
