use std::fs::File;
use std::io::Read;
use std::mem;
use std::path::PathBuf;
use std::sync::Arc;

use rusttype::{point, Font, Scale};
use structopt::StructOpt;
use vulkano::buffer::{BufferUsage, CpuAccessibleBuffer};
use vulkano::command_buffer::{AutoCommandBufferBuilder, DynamicState};
use vulkano::device::Device;
use vulkano::framebuffer::{Framebuffer, RenderPassAbstract, Subpass};
use vulkano::instance::Instance;
use vulkano::pipeline::viewport::Viewport;
use vulkano::pipeline::GraphicsPipeline;
use vulkano::swapchain::{
    self, AcquireError, PresentMode, SurfaceTransform, Swapchain, SwapchainCreationError,
};
use vulkano::sync::{now, GpuFuture};
use vulkano::{impl_vertex, single_pass_renderpass};
use vulkano_glyph::GlyphBrush;
use vulkano_win::VkSurfaceBuild;

#[derive(StructOpt)]
struct Args {
    #[structopt(name = "FONT", help = "A .ttf font file to draw", parse(from_os_str))]
    font: PathBuf,
}

fn init_triangle(
    device: Arc<Device>,
    subpass: Subpass<Arc<RenderPassAbstract + Send + Sync>>,
) -> impl FnMut(AutoCommandBufferBuilder, &DynamicState) -> AutoCommandBufferBuilder {
    #[derive(Debug, Clone)]
    struct Vertex {
        position: [f32; 2],
    }
    impl_vertex!(Vertex, position);

    let vertex_buffer = {
        CpuAccessibleBuffer::from_iter(
            device.clone(),
            BufferUsage::all(),
            [
                Vertex {
                    position: [-0.5, -0.25],
                },
                Vertex {
                    position: [0.0, 0.5],
                },
                Vertex {
                    position: [0.25, -0.1],
                },
            ]
            .iter()
            .cloned(),
        )
        .expect("failed to create buffer")
    };

    mod vs {
        vulkano_shaders::shader! {
        ty: "vertex",
        src: "
#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: "
#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()).expect("failed to create shader module");
    let fs = fs::Shader::load(device.clone()).expect("failed to create shader module");

    let pipeline = Arc::new(
        GraphicsPipeline::start()
            .vertex_input_single_buffer::<Vertex>()
            .vertex_shader(vs.main_entry_point(), ())
            .triangle_list()
            .viewports_dynamic_scissors_irrelevant(1)
            .fragment_shader(fs.main_entry_point(), ())
            .render_pass(subpass)
            .build(device.clone())
            .unwrap(),
    );

    move |cmd, state| {
        cmd.draw(pipeline.clone(), state, vertex_buffer.clone(), (), ())
            .unwrap()
    }
}

fn main() {
    env_logger::init();

    let args = Args::from_args();

    let instance = {
        let extensions = vulkano_win::required_extensions();
        Instance::new(None, &extensions, None).expect("failed to create Vulkan instance")
    };

    let physical = vulkano::instance::PhysicalDevice::enumerate(&instance)
        .next()
        .expect("no device available");
    println!(
        "Using device: {} (type: {:?})",
        physical.name(),
        physical.ty()
    );

    let mut events_loop = winit::EventsLoop::new();
    let surface = winit::WindowBuilder::new()
        .with_dimensions(winit::dpi::LogicalSize::new(1000.0, 1000.0))
        .build_vk_surface(&events_loop, instance.clone())
        .unwrap();

    let queue = physical
        .queue_families()
        .find(|&q| q.supports_graphics() && surface.is_supported(q).unwrap_or(false))
        .expect("couldn't find a graphical queue family");

    let (device, mut queues) = {
        let device_ext = vulkano::device::DeviceExtensions {
            khr_swapchain: true,
            ..vulkano::device::DeviceExtensions::none()
        };

        Device::new(
            physical,
            physical.supported_features(),
            &device_ext,
            [(queue, 0.5)].iter().cloned(),
        )
        .expect("failed to create device")
    };

    let queue = queues.next().unwrap();
    let mut dimensions;
    let (mut swapchain, mut images) = {
        let caps = surface
            .capabilities(physical)
            .expect("failed to get surface capabilities");

        dimensions = caps.current_extent.unwrap_or([1024, 768]);
        let alpha = caps.supported_composite_alpha.iter().next().unwrap();
        let format = caps.supported_formats[0].0;

        Swapchain::new(
            device.clone(),
            surface.clone(),
            caps.min_image_count,
            format,
            dimensions,
            1,
            caps.supported_usage_flags,
            &queue,
            SurfaceTransform::Identity,
            alpha,
            PresentMode::Fifo,
            true,
            None,
        )
        .expect("failed to create swapchain")
    };

    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 subpass = Subpass::from(
        render_pass.clone() as Arc<RenderPassAbstract + Send + Sync>,
        0,
    )
    .unwrap();

    let mut font_data = Vec::new();
    File::open(args.font)
        .unwrap()
        .read_to_end(&mut font_data)
        .unwrap();
    let font = Font::from_bytes(font_data).unwrap();

    let mut glyph_brush = GlyphBrush::new(&device, subpass.clone()).unwrap();

    let mut framebuffers: Option<Vec<Arc<vulkano::framebuffer::Framebuffer<_, _>>>> = None;
    let mut recreate_swapchain = false;
    let mut previous_frame_end = Box::new(now(device.clone())) as Box<GpuFuture>;

    let section1 = glyph_brush.queue_glyphs(
        font.layout("Hello, world!", Scale::uniform(100.0), point(300.0, 450.0)),
        0,
        [0.0, 0.0, 1.0, 1.0],
    );
    let section2 = glyph_brush.queue_glyphs(
        font.layout("Lower!", Scale::uniform(100.0), point(300.0, 500.0)),
        0,
        [0.0, 1.0, 0.0, 1.0],
    );

    let mut copy_future = glyph_brush
        .cache_sections(&queue, vec![&section1, &section2].iter().cloned())
        .unwrap()
        .map(|f| Box::new(f) as Box<GpuFuture + Send + Sync>);

    let mut draw_triangle = init_triangle(Arc::clone(&device), subpass);

    let mut state = DynamicState {
        line_width: None,
        viewports: Some(vec![Viewport {
            origin: [0.0, 0.0],
            dimensions: [dimensions[0] as f32, dimensions[1] as f32],
            depth_range: 0.0..1.0,
        }]),
        scissors: None,
    };

    loop {
        previous_frame_end.cleanup_finished();

        if recreate_swapchain {
            dimensions = surface
                .capabilities(physical)
                .expect("failed to get surface capabilities")
                .current_extent
                .unwrap();

            let (new_swapchain, new_images) = match swapchain.recreate_with_dimension(dimensions) {
                Ok(r) => r,
                Err(SwapchainCreationError::UnsupportedDimensions) => {
                    continue;
                }
                Err(err) => panic!("{:?}", err),
            };

            mem::replace(&mut swapchain, new_swapchain);
            mem::replace(&mut images, new_images);

            framebuffers = None;

            state = DynamicState {
                line_width: None,
                viewports: Some(vec![Viewport {
                    origin: [0.0, 0.0],
                    dimensions: [dimensions[0] as f32, dimensions[1] as f32],
                    depth_range: 0.0..1.0,
                }]),
                scissors: None,
            };

            recreate_swapchain = false;
        }

        if framebuffers.is_none() {
            let new_framebuffers = Some(
                images
                    .iter()
                    .map(|image| {
                        Arc::new(
                            Framebuffer::start(render_pass.clone())
                                .add(image.clone())
                                .unwrap()
                                .build()
                                .unwrap(),
                        )
                    })
                    .collect::<Vec<_>>(),
            );
            mem::replace(&mut framebuffers, new_framebuffers);
        }

        let copy_future = copy_future
            .take()
            .unwrap_or_else(|| Box::new(now(device.clone())));

        let (image_num, acquire_future) =
            match swapchain::acquire_next_image(swapchain.clone(), None) {
                Ok(r) => r,
                Err(AcquireError::OutOfDate) => {
                    recreate_swapchain = true;
                    continue;
                }
                Err(err) => panic!("{:?}", err),
            };

        let command_buffer =
            AutoCommandBufferBuilder::primary_one_time_submit(device.clone(), queue.family())
                .unwrap()
                .begin_render_pass(
                    framebuffers.as_ref().unwrap()[image_num].clone(),
                    false,
                    vec![[1.0, 1.0, 1.0, 1.0].into()],
                )
                .unwrap();
        let command_buffer = glyph_brush
            .draw(
                command_buffer,
                Some(&section2),
                &state,
                [
                    [1.0, 0.0, 0.0, 0.0],
                    [0.0, 1.0, 0.0, 0.0],
                    [0.0, 0.0, 1.0, 0.0],
                    [0.0, 0.0, 0.0, 1.0],
                ],
                [dimensions[0] as f32, dimensions[1] as f32],
            )
            .unwrap();
        let command_buffer = draw_triangle(command_buffer, &state);
        let command_buffer = glyph_brush
            .draw(
                command_buffer,
                Some(&section1),
                &state,
                [
                    [1.0, 0.0, 0.0, 0.0],
                    [0.0, 1.0, 0.0, 0.0],
                    [0.0, 0.0, 1.0, 0.0],
                    [0.0, 0.0, 0.0, 1.0],
                ],
                [dimensions[0] as f32, dimensions[1] as f32],
            )
            .unwrap();

        let command_buffer = command_buffer.end_render_pass().unwrap().build().unwrap();

        let future = previous_frame_end
            .join(copy_future)
            .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 = Box::new(future) as Box<_>;
            }
            Err(vulkano::sync::FlushError::OutOfDate) => {
                recreate_swapchain = true;
                previous_frame_end = Box::new(vulkano::sync::now(device.clone())) as Box<_>;
            }
            Err(e) => {
                println!("{:?}", e);
                previous_frame_end = Box::new(vulkano::sync::now(device.clone())) as Box<_>;
            }
        }

        let mut done = false;
        events_loop.poll_events(|ev| match ev {
            winit::Event::WindowEvent {
                event: winit::WindowEvent::CloseRequested,
                ..
            } => done = true,
            _ => (),
        });
        if done {
            return;
        }
    }
}