use winit::event::WindowEvent;

#[cfg_attr(rustfmt, rustfmt_skip)]
#[allow(unused)]
pub const OPENGL_TO_WGPU_MATRIX: cgmath::Matrix4<f32> = cgmath::Matrix4::new(
    1.0, 0.0, 0.0, 0.0,
    0.0, -1.0, 0.0, 0.0,
    0.0, 0.0, 0.5, 0.0,
    0.0, 0.0, 0.5, 1.0,
);

#[allow(dead_code)]
pub fn cast_slice<T>(data: &[T]) -> &[u8] {
    use std::mem::size_of;
    use std::slice::from_raw_parts;

    unsafe { from_raw_parts(data.as_ptr() as *const u8, data.len() * size_of::<T>()) }
}

#[allow(dead_code)]
pub enum ShaderStage {
    Vertex,
    Fragment,
    Compute,
}

pub fn load_glsl(code: &str, stage: ShaderStage) -> Vec<u32> {
    let ty = match stage {
        ShaderStage::Vertex => glsl_to_spirv::ShaderType::Vertex,
        ShaderStage::Fragment => glsl_to_spirv::ShaderType::Fragment,
        ShaderStage::Compute => glsl_to_spirv::ShaderType::Compute,
    };

    wgpu::read_spirv(glsl_to_spirv::compile(&code, ty).unwrap()).unwrap()
}

pub trait Example: 'static + Sized {
    fn init(
        sc_desc: &wgpu::SwapChainDescriptor,
        device: &wgpu::Device,
    ) -> (Self, Option<wgpu::CommandBuffer>);
    fn resize(
        &mut self,
        sc_desc: &wgpu::SwapChainDescriptor,
        device: &wgpu::Device,
    ) -> Option<wgpu::CommandBuffer>;
    fn update(&mut self, event: WindowEvent);
    fn render(
        &mut self,
        frame: &wgpu::SwapChainOutput,
        device: &wgpu::Device,
    ) -> wgpu::CommandBuffer;
}

pub fn run<E: Example>(title: &str) {
    use winit::{
        event,
        event_loop::{ControlFlow, EventLoop},
    };

    env_logger::init();
    let event_loop = EventLoop::new();
    log::info!("Initializing the window...");

    #[cfg(not(feature = "gl"))]
    let (window, size, surface) = {
        let mut builder = winit::window::WindowBuilder::new();
        builder = builder.with_title(title);
        #[cfg(windows_OFF)] //TODO
        {
            use winit::platform::windows::WindowBuilderExtWindows;
            builder = builder.with_no_redirection_bitmap(true);
        }
        let window = builder.build(&event_loop).unwrap();
        let size = window.inner_size();
        let surface = wgpu::Surface::create(&window);
        (window, size, surface)
    };

    #[cfg(feature = "gl")]
    let (window, instance, size, surface) = {
        let wb = winit::WindowBuilder::new();
        let cb = wgpu::glutin::ContextBuilder::new().with_vsync(true);
        let context = cb.build_windowed(wb, &event_loop).unwrap();
        context.window().set_title(title);

        let hidpi_factor = context.window().hidpi_factor();
        let size = context
            .window()
            .get_inner_size()
            .unwrap()
            .to_physical(hidpi_factor);

        let (context, window) = unsafe { context.make_current().unwrap().split() };

        let instance = wgpu::Instance::new(context);
        let surface = instance.get_surface();

        (window, instance, size, surface)
    };

    let adapter = wgpu::Adapter::request(
        &wgpu::RequestAdapterOptions {
            power_preference: wgpu::PowerPreference::Default,
        },
        wgpu::BackendBit::PRIMARY,
    )
    .unwrap();

    let (device, queue) = adapter.request_device(&wgpu::DeviceDescriptor {
        extensions: wgpu::Extensions {
            anisotropic_filtering: false,
        },
        limits: wgpu::Limits::default(),
    });

    let mut sc_desc = wgpu::SwapChainDescriptor {
        usage: wgpu::TextureUsage::OUTPUT_ATTACHMENT,
        format: wgpu::TextureFormat::Bgra8UnormSrgb,
        width: size.width,
        height: size.height,
        present_mode: wgpu::PresentMode::Mailbox,
    };
    let mut swap_chain = device.create_swap_chain(&surface, &sc_desc);

    log::info!("Initializing the example...");
    let (mut example, init_command_buf) = E::init(&sc_desc, &device);
    if let Some(command_buf) = init_command_buf {
        queue.submit(&[command_buf]);
    }

    log::info!("Entering render loop...");
    event_loop.run(move |event, _, control_flow| {
        *control_flow = if cfg!(feature = "metal-auto-capture") {
            ControlFlow::Exit
        } else {
            ControlFlow::Poll
        };
        match event {
            event::Event::MainEventsCleared => window.request_redraw(),
            event::Event::WindowEvent {
                event: WindowEvent::Resized(size),
                ..
            } => {
                log::info!("Resizing to {:?}", size);
                sc_desc.width = size.width;
                sc_desc.height = size.height;
                swap_chain = device.create_swap_chain(&surface, &sc_desc);
                let command_buf = example.resize(&sc_desc, &device);
                if let Some(command_buf) = command_buf {
                    queue.submit(&[command_buf]);
                }
            }
            event::Event::WindowEvent { event, .. } => match event {
                WindowEvent::KeyboardInput {
                    input:
                        event::KeyboardInput {
                            virtual_keycode: Some(event::VirtualKeyCode::Escape),
                            state: event::ElementState::Pressed,
                            ..
                        },
                    ..
                }
                | WindowEvent::CloseRequested => {
                    *control_flow = ControlFlow::Exit;
                }
                _ => {
                    example.update(event);
                }
            }
            event::Event::RedrawRequested(_) => {
                let frame = swap_chain
                    .get_next_texture()
                    .expect("Timeout when acquiring next swap chain texture");
                let command_buf = example.render(&frame, &device);
                queue.submit(&[command_buf]);
            }
            _ => {}
        }
    });
}

// This allows treating the framework as a standalone example,
// thus avoiding listing the example names in `Cargo.toml`.
#[allow(dead_code)]
fn main() {}