#[cfg(not(all(target_os = "windows", feature = "d3d")))]
fn main() {
    println!("This example requires the `d3d` feature to be enabled on Windows.");
    println!("Run it with `cargo run --example d3d-window --features d3d`");
}

#[cfg(all(target_os = "windows", feature = "d3d"))]
fn main() -> anyhow::Result<()> {
    // NOTE: Most of code is from https://github.com/microsoft/windows-rs/blob/02db74cf5c4796d970e6d972cdc7bc3967380079/crates/samples/windows/direct3d12/src/main.rs

    use winit::{
        application::ApplicationHandler,
        event::WindowEvent,
        event_loop::{ActiveEventLoop, EventLoop},
        keyboard::{Key, NamedKey},
        window::WindowId,
    };

    let event_loop = EventLoop::new()?;

    struct Application {
        context: Option<window::Context>,
    }

    impl ApplicationHandler for Application {
        fn resumed(&mut self, event_loop: &ActiveEventLoop) {
            assert!(self.context.is_none());
            self.context =
                Some(window::Context::new(event_loop).expect("Failed to create window context"))
        }

        fn window_event(
            &mut self,
            event_loop: &ActiveEventLoop,
            _window_id: WindowId,
            event: WindowEvent,
        ) {
            let context = self.context.as_mut().unwrap();
            let state = &mut context.state;

            match event {
                WindowEvent::KeyboardInput { event, .. } => {
                    match event.logical_key {
                        Key::Named(NamedKey::ArrowLeft) => state.x -= 10.0,
                        Key::Named(NamedKey::ArrowRight) => state.x += 10.0,
                        Key::Named(NamedKey::ArrowUp) => state.y += 10.0,
                        Key::Named(NamedKey::ArrowDown) => state.y -= 10.0,
                        Key::Named(NamedKey::Escape) => event_loop.exit(),
                        _ => return,
                    }
                    context.window.request_redraw();
                }
                WindowEvent::RedrawRequested => context.render(),
                WindowEvent::CloseRequested => event_loop.exit(),
                _ => {}
            }
        }
    }

    let mut application = Application { context: None };

    event_loop
        .run_app(&mut application)
        .expect("Failed to run event loop");

    Ok(())
}

#[cfg(all(target_os = "windows", feature = "d3d"))]
mod window {
    use anyhow::Result;
    use windows::{
        core::Interface,
        Win32::{
            Foundation::HWND,
            Graphics::{
                Direct3D::D3D_FEATURE_LEVEL_11_0,
                Direct3D12::{D3D12CreateDevice, ID3D12Device, D3D12_RESOURCE_STATE_COMMON},
                Dxgi::{
                    Common::{
                        DXGI_FORMAT_R8G8B8A8_UNORM, DXGI_SAMPLE_DESC,
                        DXGI_STANDARD_MULTISAMPLE_QUALITY_PATTERN,
                    },
                    CreateDXGIFactory1, IDXGIAdapter1, IDXGIFactory4, IDXGISwapChain3,
                    DXGI_ADAPTER_FLAG, DXGI_ADAPTER_FLAG_NONE, DXGI_ADAPTER_FLAG_SOFTWARE,
                    DXGI_PRESENT, DXGI_SWAP_CHAIN_DESC1, DXGI_SWAP_EFFECT_FLIP_DISCARD,
                    DXGI_USAGE_RENDER_TARGET_OUTPUT,
                },
            },
        },
    };
    use winit::{
        dpi::{LogicalSize, Size},
        event_loop::ActiveEventLoop,
        window::{Window, WindowAttributes},
    };

    use skia_safe::{
        gpu::{
            d3d::{BackendContext, TextureResourceInfo},
            surfaces, BackendRenderTarget, DirectContext, Protected, SurfaceOrigin,
        },
        paint, Color, ColorType, Paint, Rect, Surface,
    };

    const BUFFER_COUNT: usize = 2;

    pub struct Context {
        pub window: Window,
        swap_chain: IDXGISwapChain3,
        direct_context: DirectContext,
        surfaces: [(Surface, BackendRenderTarget); BUFFER_COUNT],
        pub state: State,
    }

    pub struct State {
        pub x: f32,
        pub y: f32,
    }

    impl Context {
        pub fn new(event_loop: &ActiveEventLoop) -> Result<Self> {
            let mut window_attributes = WindowAttributes::default();
            window_attributes.inner_size = Some(Size::new(LogicalSize::new(800, 800)));
            window_attributes.title = "rust-skia-gl-window".into();

            let window = event_loop
                .create_window(window_attributes)
                .expect("Failed to create window");

            let hwnd = HWND(u64::from(window.id()) as *mut _);
            let (width, height) = window.inner_size().into();

            let factory: IDXGIFactory4 = unsafe { CreateDXGIFactory1() }?;
            let (adapter, device) = get_hardware_adapter_and_device(&factory)?;
            let queue = unsafe { device.CreateCommandQueue(&Default::default()) }?;

            let backend_context = BackendContext {
                adapter,
                device,
                queue,
                memory_allocator: None,
                protected_context: Protected::No,
            };
            let mut direct_context =
                unsafe { DirectContext::new_d3d(&backend_context, None) }.unwrap();

            let swap_chain: IDXGISwapChain3 = unsafe {
                factory.CreateSwapChainForHwnd(
                    &backend_context.queue,
                    hwnd,
                    &DXGI_SWAP_CHAIN_DESC1 {
                        Width: width,
                        Height: height,
                        Format: DXGI_FORMAT_R8G8B8A8_UNORM,
                        BufferUsage: DXGI_USAGE_RENDER_TARGET_OUTPUT,
                        BufferCount: BUFFER_COUNT as _,
                        SwapEffect: DXGI_SWAP_EFFECT_FLIP_DISCARD,
                        SampleDesc: DXGI_SAMPLE_DESC {
                            Count: 1,
                            Quality: 0,
                        },
                        ..Default::default()
                    },
                    None,
                    None,
                )
            }?
            .cast()?;

            let surfaces: [_; BUFFER_COUNT] = std::array::from_fn(|i| {
                let resource = unsafe { swap_chain.GetBuffer(i as u32).unwrap() };

                let backend_render_target = BackendRenderTarget::new_d3d(
                    window.inner_size().into(),
                    &TextureResourceInfo {
                        resource,
                        alloc: None,
                        resource_state: D3D12_RESOURCE_STATE_COMMON,
                        format: DXGI_FORMAT_R8G8B8A8_UNORM,
                        sample_count: 1,
                        level_count: 0,
                        sample_quality_pattern: DXGI_STANDARD_MULTISAMPLE_QUALITY_PATTERN,
                        protected: Protected::No,
                    },
                );

                let surface = surfaces::wrap_backend_render_target(
                    &mut direct_context,
                    &backend_render_target,
                    SurfaceOrigin::BottomLeft,
                    ColorType::RGBA8888,
                    None,
                    None,
                )
                .unwrap();

                (surface, backend_render_target)
            });

            fn get_hardware_adapter_and_device(
                factory: &IDXGIFactory4,
            ) -> windows::core::Result<(IDXGIAdapter1, ID3D12Device)> {
                for i in 0.. {
                    let adapter = unsafe { factory.EnumAdapters1(i) }?;

                    let adapter_desc = unsafe { adapter.GetDesc1() }?;

                    if (DXGI_ADAPTER_FLAG(adapter_desc.Flags as _) & DXGI_ADAPTER_FLAG_SOFTWARE)
                        != DXGI_ADAPTER_FLAG_NONE
                    {
                        continue; // Don't select the Basic Render Driver adapter.
                    }

                    let mut device = None;
                    if unsafe { D3D12CreateDevice(&adapter, D3D_FEATURE_LEVEL_11_0, &mut device) }
                        .is_ok()
                    {
                        return Ok((adapter, device.unwrap()));
                    }
                }
                unreachable!()
            }

            println!("Skia initialized with {} surfaces.", surfaces.len());
            println!("Use Arrow Keys to move the rectangle.");

            let state = State { x: 100.0, y: 100.0 };

            Ok(Self {
                window,
                state,
                swap_chain,
                direct_context,
                surfaces,
            })
        }

        pub fn render(&mut self) {
            let index = unsafe { self.swap_chain.GetCurrentBackBufferIndex() };
            let (surface, _) = &mut self.surfaces[index as usize];
            let canvas = surface.canvas();

            canvas.clear(Color::BLUE);

            let mut paint = Paint::default();
            paint.set_color(Color::RED);
            paint.set_style(paint::Style::StrokeAndFill);
            paint.set_anti_alias(true);
            paint.set_stroke_width(10.0);

            canvas.draw_rect(
                Rect::from_xywh(self.state.x, self.state.y, 200.0, 200.0),
                &paint,
            );

            self.direct_context.flush_and_submit_surface(surface, None);

            unsafe { self.swap_chain.Present(1, DXGI_PRESENT::default()) }.unwrap();

            // NOTE: If you get some error when you render, you can check it with:
            // unsafe {
            //     device.GetDeviceRemovedReason().ok().unwrap();
            // }
        }
    }
}