use {
    crate::{
        async_engine::{Phase, SpawnedFuture},
        backend::{
            AxisSource, Backend, BackendDrmDevice, BackendEvent, Connector, ConnectorEvent,
            ConnectorId, ConnectorKernelId, DrmDeviceId, DrmEvent, InputDevice,
            InputDeviceAccelProfile, InputDeviceCapability, InputDeviceId, InputEvent, KeyState,
            Mode, MonitorInfo, ScrollAxis, TransformMatrix, AXIS_120,
        },
        fixed::Fixed,
        format::XRGB8888,
        gfx_api::{GfxContext, GfxError, GfxFramebuffer, GfxTexture},
        renderer::RenderResult,
        state::State,
        time::now_usec,
        utils::{
            clonecell::CloneCell, copyhashmap::CopyHashMap, errorfmt::ErrorFmt, numcell::NumCell,
            queue::AsyncQueue, syncqueue::SyncQueue,
        },
        video::{
            drm::{ConnectorType, Drm, DrmError, DrmVersion},
            gbm::{GbmBo, GbmDevice, GbmError, GBM_BO_USE_RENDERING},
        },
        wire_xcon::{
            ChangeProperty, ChangeWindowAttributes, ConfigureNotify, CreateCursor, CreatePixmap,
            CreateWindow, CreateWindowValues, DestroyNotify, Dri3Open, Dri3PixmapFromBuffers,
            Dri3QueryVersion, Extension, FreePixmap, MapWindow, PresentCompleteNotify,
            PresentIdleNotify, PresentPixmap, PresentQueryVersion, PresentSelectInput,
            XiButtonPress, XiButtonRelease, XiDeviceInfo, XiEnter, XiEventMask,
            XiGetDeviceButtonMapping, XiGrabDevice, XiHierarchy, XiKeyPress, XiKeyRelease,
            XiMotion, XiQueryDevice, XiQueryVersion, XiSelectEvents, XiUngrabDevice,
            XkbPerClientFlags, XkbUseExtension,
        },
        xcon::{
            consts::{
                ATOM_STRING, ATOM_WM_CLASS, EVENT_MASK_EXPOSURE, EVENT_MASK_STRUCTURE_NOTIFY,
                EVENT_MASK_VISIBILITY_CHANGE, GRAB_MODE_ASYNC, GRAB_STATUS_SUCCESS,
                INPUT_DEVICE_ALL, INPUT_DEVICE_ALL_MASTER, INPUT_DEVICE_TYPE_MASTER_KEYBOARD,
                INPUT_HIERARCHY_MASK_MASTER_ADDED, INPUT_HIERARCHY_MASK_MASTER_REMOVED,
                PRESENT_EVENT_MASK_COMPLETE_NOTIFY, PRESENT_EVENT_MASK_IDLE_NOTIFY,
                PROP_MODE_REPLACE, WINDOW_CLASS_INPUT_OUTPUT, XI_EVENT_MASK_BUTTON_PRESS,
                XI_EVENT_MASK_BUTTON_RELEASE, XI_EVENT_MASK_ENTER, XI_EVENT_MASK_FOCUS_IN,
                XI_EVENT_MASK_FOCUS_OUT, XI_EVENT_MASK_HIERARCHY, XI_EVENT_MASK_KEY_PRESS,
                XI_EVENT_MASK_KEY_RELEASE, XI_EVENT_MASK_LEAVE, XI_EVENT_MASK_MOTION,
                XI_EVENT_MASK_TOUCH_BEGIN, XI_EVENT_MASK_TOUCH_END, XI_EVENT_MASK_TOUCH_UPDATE,
                XKB_PER_CLIENT_FLAG_DETECTABLE_AUTO_REPEAT,
            },
            Event, XEvent, Xcon, XconError,
        },
    },
    jay_config::video::GfxApi,
    std::{
        any::Any,
        borrow::Cow,
        cell::{Cell, RefCell},
        collections::VecDeque,
        error::Error,
        future::pending,
        rc::Rc,
    },
    thiserror::Error,
    uapi::{c::dev_t, Errno},
};

#[derive(Debug, Error)]
pub enum XBackendError {
    #[error("Could not connect to the X server")]
    CannotConnect(#[source] XconError),
    #[error("Could not enable XInput")]
    EnableXinput(#[source] XconError),
    #[error("Could not enable Present")]
    EnablePresent(#[source] XconError),
    #[error("Could not enable XKB")]
    EnableXkb(#[source] XconError),
    #[error("Could not enable DRI3")]
    EnableDri3(#[source] XconError),
    #[error("DriOpen returned an error")]
    DriOpen(#[source] XconError),
    #[error("Could not create a pixmap")]
    CreatePixmap(#[source] XconError),
    #[error("Could not create a cursor")]
    CreateCursor(#[source] XconError),
    #[error("Could not select XInput hierarchy events")]
    SelectHierarchyEvents(#[source] XconError),
    #[error("The drm subsystem returned an error")]
    DrmError(#[from] DrmError),
    #[error("The gbm subsystem returned an error")]
    GbmError(#[from] GbmError),
    #[error("Could not import a dma-buf")]
    ImportBuffer(#[source] XconError),
    #[error("Could not create a graphics API context")]
    CreateEgl(#[source] GfxError),
    #[error("Could not create an graphics API image from a dma-buf")]
    CreateImage(#[source] GfxError),
    #[error("Could not create a framebuffer from a graphics API image")]
    CreateFramebuffer(#[source] GfxError),
    #[error("Could not create a texture from an graphics API image")]
    CreateTexture(#[source] GfxError),
    #[error("Could not select input events")]
    CannotSelectInputEvents(#[source] XconError),
    #[error("Could not select present events")]
    CannotSelectPresentEvents(#[source] XconError),
    #[error("libloading returned an error")]
    Libloading(#[from] libloading::Error),
    #[error("An unspecified X error occurred")]
    XconError(#[from] XconError),
    #[error("Could not create a window")]
    CreateWindow(#[source] XconError),
    #[error("Could not set WM_CLASS")]
    WmClass(#[source] XconError),
    #[error("Could not select window events")]
    WindowEvents(#[source] XconError),
    #[error("Could not map a window")]
    MapWindow(#[source] XconError),
    #[error("Could not query device")]
    QueryDevice(#[source] XconError),
    #[error("Could not fstat the drm device")]
    DrmDeviceFstat(#[source] Errno),
    #[error("Render device does not support XRGB8888 format")]
    XRGB8888,
}

pub async fn create(state: &Rc<State>) -> Result<Rc<XBackend>, XBackendError> {
    let c = match Xcon::connect(state).await {
        Ok(c) => c,
        Err(e) => return Err(XBackendError::CannotConnect(e)),
    };
    if let Err(e) = c
        .call(&XiQueryVersion {
            major_version: 2,
            minor_version: 2,
        })
        .await
    {
        return Err(XBackendError::EnableXinput(e));
    }
    if let Err(e) = c
        .call(&Dri3QueryVersion {
            major_version: 1,
            minor_version: 0,
        })
        .await
    {
        return Err(XBackendError::EnableDri3(e));
    }
    if let Err(e) = c
        .call(&PresentQueryVersion {
            major_version: 1,
            minor_version: 0,
        })
        .await
    {
        return Err(XBackendError::EnablePresent(e));
    }
    if let Err(e) = c
        .call(&XkbUseExtension {
            wanted_major: 1,
            wanted_minor: 0,
        })
        .await
    {
        return Err(XBackendError::EnableXkb(e));
    }
    let root = c.root_window();
    let drm = {
        let res = c
            .call(&Dri3Open {
                drawable: root,
                provider: 0,
            })
            .await;
        match res {
            Ok(r) => Drm::reopen(r.get().device_fd.raw(), false)?,
            Err(e) => return Err(XBackendError::DriOpen(e)),
        }
    };
    let drm_dev = match uapi::fstat(drm.raw()) {
        Ok(s) => s.st_rdev,
        Err(e) => return Err(XBackendError::DrmDeviceFstat(e)),
    };
    let gbm = GbmDevice::new(&drm)?;
    let ctx = match state.create_gfx_context(&drm, None) {
        Ok(r) => r,
        Err(e) => return Err(XBackendError::CreateEgl(e)),
    };
    let cursor = {
        let cp = CreatePixmap {
            depth: 1,
            pid: c.generate_id()?,
            drawable: root,
            width: 1,
            height: 1,
        };
        if let Err(e) = c.call(&cp).await {
            return Err(XBackendError::CreatePixmap(e));
        }
        let cc = CreateCursor {
            cid: c.generate_id()?,
            source: cp.pid,
            mask: cp.pid,
            fore_red: 0,
            fore_green: 0,
            fore_blue: 0,
            back_red: 0,
            back_green: 0,
            back_blue: 0,
            x: 0,
            y: 0,
        };
        if let Err(e) = c.call(&cc).await {
            return Err(XBackendError::CreateCursor(e));
        }
        c.call(&FreePixmap { pixmap: cp.pid });
        cc.cid
    };
    {
        let se = XiSelectEvents {
            window: c.root_window(),
            masks: Cow::Borrowed(&[XiEventMask {
                deviceid: INPUT_DEVICE_ALL,
                mask: &[XI_EVENT_MASK_HIERARCHY],
            }]),
        };
        if let Err(e) = c.call(&se).await {
            return Err(XBackendError::SelectHierarchyEvents(e));
        }
    }

    let data = Rc::new(XBackend {
        state: state.clone(),
        c,
        outputs: Default::default(),
        seats: Default::default(),
        mouse_seats: Default::default(),
        ctx: ctx.clone(),
        gbm,
        cursor,
        root,
        scheduled_present: Default::default(),
        grab_requests: Default::default(),
        render_result: Default::default(),
        drm_device_id: state.drm_dev_ids.next(),
        drm_dev,
    });
    data.add_output().await?;

    Ok(data)
}

impl Backend for XBackend {
    fn run(self: Rc<Self>) -> SpawnedFuture<Result<(), Box<dyn Error>>> {
        let slf = self.clone();
        self.state.eng.spawn(async move {
            slf.run().await?;
            Ok(())
        })
    }

    fn into_any(self: Rc<Self>) -> Rc<dyn Any> {
        self
    }
}

pub struct XBackend {
    state: Rc<State>,
    c: Rc<Xcon>,
    outputs: CopyHashMap<u32, Rc<XOutput>>,
    seats: CopyHashMap<u16, Rc<XSeat>>,
    mouse_seats: CopyHashMap<u16, Rc<XSeat>>,
    ctx: Rc<dyn GfxContext>,
    gbm: GbmDevice,
    cursor: u32,
    root: u32,
    scheduled_present: AsyncQueue<Rc<XOutput>>,
    grab_requests: AsyncQueue<(Rc<XSeat>, bool)>,
    render_result: RefCell<RenderResult>,
    drm_device_id: DrmDeviceId,
    drm_dev: dev_t,
}

impl XBackend {
    async fn run(self: Rc<Self>) -> Result<(), XBackendError> {
        self.query_devices(INPUT_DEVICE_ALL_MASTER).await?;

        let _events = self.state.eng.spawn(self.clone().event_handler());
        let _grab = self.state.eng.spawn(self.clone().grab_handler());
        let _present = self
            .state
            .eng
            .spawn2(Phase::Present, self.clone().present_handler());

        self.state.set_render_ctx(Some(self.ctx.clone()));
        self.state
            .backend_events
            .push(BackendEvent::NewDrmDevice(Rc::new(XDrmDevice {
                backend: self.clone(),
                id: self.drm_device_id,
                dev: self.drm_dev,
            })));
        for (_, output) in self.outputs.lock().iter() {
            self.active_output(output).await;
        }

        self.state
            .backend_events
            .push(BackendEvent::DevicesEnumerated);

        pending().await
    }

    async fn event_handler(self: Rc<Self>) {
        loop {
            let event = self.c.event().await;
            if let Err(e) = self.handle_event(&event).await {
                log::error!(
                    "Fatal error: Could not handle an event from the X server: {}",
                    ErrorFmt(e)
                );
                self.state.ring.stop();
                return;
            }
        }
    }

    async fn present_handler(self: Rc<Self>) {
        loop {
            let output = self.scheduled_present.pop().await;
            self.present(&output).await;
        }
    }

    async fn grab_handler(self: Rc<Self>) {
        loop {
            let (dev, grab) = self.grab_requests.pop().await;
            self.handle_grab_request(&dev, grab).await;
        }
    }

    async fn handle_grab_request(&self, dev: &XSeat, grab: bool) {
        if grab {
            let xg = XiGrabDevice {
                window: self.root,
                time: 0,
                cursor: 0,
                deviceid: dev.kb,
                mode: GRAB_MODE_ASYNC,
                paired_device_mode: GRAB_MODE_ASYNC,
                owner_events: 1,
                mask: &[],
            };
            let res = match self.c.call(&xg).await {
                Ok(r) => r,
                Err(e) => {
                    log::error!("Could not grab device {}: {}", dev.kb, ErrorFmt(e));
                    return;
                }
            };
            let res = res.get();
            if res.status != GRAB_STATUS_SUCCESS {
                log::error!("Could not grab device {}: status = {}", dev.kb, res.status);
            }
        } else {
            let ug = XiUngrabDevice {
                time: 0,
                deviceid: dev.kb,
            };
            if let Err(e) = self.c.call(&ug).await {
                log::error!("Could not ungrab device {}: {}", dev.kb, ErrorFmt(e));
            }
        }
    }

    async fn create_images(
        &self,
        window: u32,
        width: i32,
        height: i32,
    ) -> Result<[XImage; 2], XBackendError> {
        let mut images = [None, None];
        let formats = self.ctx.formats();
        let format = match formats.get(&XRGB8888.drm) {
            Some(f) => f,
            None => return Err(XBackendError::XRGB8888),
        };
        for image in &mut images {
            let bo = self.gbm.create_bo(
                &self.state.dma_buf_ids,
                width,
                height,
                XRGB8888,
                &format.write_modifiers,
                GBM_BO_USE_RENDERING,
            )?;
            let dma = bo.dmabuf();
            let img = match self.ctx.clone().dmabuf_img(dma) {
                Ok(f) => f,
                Err(e) => return Err(XBackendError::CreateImage(e)),
            };
            let fb = match img.clone().to_framebuffer() {
                Ok(f) => f,
                Err(e) => return Err(XBackendError::CreateFramebuffer(e)),
            };
            let tex = match img.to_texture() {
                Ok(f) => f,
                Err(e) => return Err(XBackendError::CreateTexture(e)),
            };
            macro_rules! pp {
                ($num:expr, $field:ident) => {
                    dma.planes.get($num).map(|p| p.$field).unwrap_or(0) as _
                };
            }
            let buffers: Vec<_> = dma.planes.iter().map(|p| p.fd.clone()).collect();
            let pixmap = {
                let pfb = Dri3PixmapFromBuffers {
                    pixmap: self.c.generate_id()?,
                    window,
                    num_buffers: dma.planes.len() as _,
                    width: dma.width as _,
                    height: dma.height as _,
                    stride0: pp!(0, stride),
                    offset0: pp!(0, offset),
                    stride1: pp!(1, stride),
                    offset1: pp!(1, offset),
                    stride2: pp!(2, stride),
                    offset2: pp!(2, offset),
                    stride3: pp!(3, stride),
                    offset3: pp!(3, offset),
                    depth: 24,
                    bpp: 32,
                    modifier: dma.modifier,
                    buffers: buffers.into(),
                };
                if let Err(e) = self.c.call(&pfb).await {
                    return Err(XBackendError::ImportBuffer(e));
                }
                pfb.pixmap
            };
            *image = Some(XImage {
                pixmap: Cell::new(pixmap),
                _bo: bo,
                fb: CloneCell::new(fb),
                tex: CloneCell::new(tex),
                idle: Cell::new(true),
                render_on_idle: Cell::new(false),
                last_serial: Cell::new(0),
            });
        }
        Ok([images[0].take().unwrap(), images[1].take().unwrap()])
    }

    async fn add_output(self: &Rc<Self>) -> Result<(), XBackendError> {
        const WIDTH: i32 = 800;
        const HEIGHT: i32 = 600;
        let window_id = {
            let cw = CreateWindow {
                depth: 0,
                wid: self.c.generate_id()?,
                parent: self.root,
                x: 0,
                y: 0,
                width: WIDTH as _,
                height: HEIGHT as _,
                border_width: 0,
                class: WINDOW_CLASS_INPUT_OUTPUT,
                visual: 0,
                values: Default::default(),
            };
            if let Err(e) = self.c.call(&cw).await {
                return Err(XBackendError::CreateWindow(e));
            }
            cw.wid
        };
        let images = self.create_images(window_id, WIDTH, HEIGHT).await?;
        let output = Rc::new(XOutput {
            id: self.state.connector_ids.next(),
            backend: self.clone(),
            window: window_id,
            events: Default::default(),
            width: Cell::new(0),
            height: Cell::new(0),
            serial: Default::default(),
            next_msc: Cell::new(0),
            next_image: Default::default(),
            cb: CloneCell::new(None),
            images,
        });
        {
            let class = "jay\0jay\0";
            let cp = ChangeProperty {
                mode: PROP_MODE_REPLACE,
                window: window_id,
                property: ATOM_WM_CLASS,
                ty: ATOM_STRING,
                format: 8,
                data: class.as_bytes(),
            };
            if let Err(e) = self.c.call(&cp).await {
                return Err(XBackendError::WmClass(e));
            };
        }
        {
            let cwa = ChangeWindowAttributes {
                window: window_id,
                values: CreateWindowValues {
                    event_mask: Some(
                        EVENT_MASK_EXPOSURE
                            | EVENT_MASK_STRUCTURE_NOTIFY
                            | EVENT_MASK_VISIBILITY_CHANGE,
                    ),
                    cursor: Some(self.cursor),
                    ..Default::default()
                },
            };
            if let Err(e) = self.c.call(&cwa).await {
                return Err(XBackendError::WindowEvents(e));
            }
        }
        if let Err(e) = self.c.call(&MapWindow { window: window_id }).await {
            return Err(XBackendError::MapWindow(e));
        }
        {
            let mask = 0
                | XI_EVENT_MASK_MOTION
                | XI_EVENT_MASK_BUTTON_PRESS
                | XI_EVENT_MASK_BUTTON_RELEASE
                | XI_EVENT_MASK_KEY_PRESS
                | XI_EVENT_MASK_KEY_RELEASE
                | XI_EVENT_MASK_ENTER
                | XI_EVENT_MASK_LEAVE
                | XI_EVENT_MASK_FOCUS_IN
                | XI_EVENT_MASK_FOCUS_OUT
                | XI_EVENT_MASK_TOUCH_BEGIN
                | XI_EVENT_MASK_TOUCH_UPDATE
                | XI_EVENT_MASK_TOUCH_END;
            let mask = [XiEventMask {
                deviceid: INPUT_DEVICE_ALL_MASTER,
                mask: &[mask],
            }];
            let xs = XiSelectEvents {
                window: window_id,
                masks: Cow::Borrowed(&mask[..]),
            };
            if let Err(e) = self.c.call(&xs).await {
                return Err(XBackendError::CannotSelectInputEvents(e));
            }
        }
        {
            let mask = 0 | PRESENT_EVENT_MASK_IDLE_NOTIFY | PRESENT_EVENT_MASK_COMPLETE_NOTIFY;
            let si = PresentSelectInput {
                eid: self.c.generate_id()?,
                window: window_id,
                event_mask: mask,
            };
            if let Err(e) = self.c.call(&si).await {
                return Err(XBackendError::CannotSelectPresentEvents(e));
            }
        }
        self.outputs.set(window_id, output.clone());
        Ok(())
    }

    async fn active_output(&self, output: &Rc<XOutput>) {
        self.state
            .backend_events
            .push(BackendEvent::NewConnector(output.clone()));
        output.events.push(ConnectorEvent::Connected(MonitorInfo {
            modes: vec![],
            manufacturer: "X.Org Foundation".to_string(),
            product: format!("X-Window-{}", output.window),
            serial_number: output.window.to_string(),
            initial_mode: Mode {
                width: output.width.get(),
                height: output.height.get(),
                refresh_rate_millihz: 60_000, // TODO
            },
            width_mm: output.width.get(),
            height_mm: output.height.get(),
            non_desktop: false,
        }));
        output.changed();
        self.present(output).await;
    }

    async fn query_devices(self: &Rc<Self>, deviceid: u16) -> Result<(), XBackendError> {
        let reply = match self.c.call(&XiQueryDevice { deviceid }).await {
            Ok(r) => r,
            Err(e) => return Err(XBackendError::QueryDevice(e)),
        };
        for dev in reply.get().infos.iter() {
            self.handle_input_device(dev).await;
        }
        Ok(())
    }

    async fn handle_input_device(self: &Rc<Self>, info: &XiDeviceInfo<'_>) {
        if info.ty != INPUT_DEVICE_TYPE_MASTER_KEYBOARD {
            return;
        }
        self.mouse_seats.remove(&info.attachment);
        if let Some(kb) = self.seats.remove(&info.deviceid) {
            kb.removed.set(true);
            kb.kb_changed();
            kb.mouse_changed();
        }
        let pcf = XkbPerClientFlags {
            device_spec: info.deviceid,
            change: XKB_PER_CLIENT_FLAG_DETECTABLE_AUTO_REPEAT,
            value: XKB_PER_CLIENT_FLAG_DETECTABLE_AUTO_REPEAT,
            ctrls_to_change: 0,
            auto_ctrls: 0,
            auto_ctrls_values: 0,
        };
        if let Err(e) = self.c.call(&pcf).await {
            log::warn!(
                "Could not make auto repeat detectable for keyboard {}: {}",
                info.deviceid,
                ErrorFmt(e),
            );
        }
        let seat = Rc::new(XSeat {
            kb_id: self.state.input_device_ids.next(),
            mouse_id: self.state.input_device_ids.next(),
            backend: self.clone(),
            kb: info.deviceid,
            mouse: info.attachment,
            removed: Cell::new(false),
            kb_cb: Default::default(),
            mouse_cb: Default::default(),
            kb_events: RefCell::new(Default::default()),
            mouse_events: RefCell::new(Default::default()),
            button_map: Default::default(),
            kb_name: Rc::new(format!("kb{}", info.deviceid)),
            mouse_name: Rc::new(format!("mouse{}", info.deviceid)),
        });
        seat.update_button_map().await;
        self.seats.set(info.deviceid, seat.clone());
        self.mouse_seats.set(info.attachment, seat.clone());
        self.state
            .backend_events
            .push(BackendEvent::NewInputDevice(Rc::new(XSeatMouse(
                seat.clone(),
            ))));
        self.state
            .backend_events
            .push(BackendEvent::NewInputDevice(Rc::new(XSeatKeyboard(
                seat.clone(),
            ))));
    }

    async fn handle_event(self: &Rc<Self>, event: &Event) -> Result<(), XBackendError> {
        match event.ext() {
            Some(ext) => self.handle_ext_event(ext, event).await,
            _ => self.handle_core_event(event).await,
        }
    }

    async fn handle_ext_event(
        self: &Rc<Self>,
        ext: Extension,
        event: &Event,
    ) -> Result<(), XBackendError> {
        match ext {
            Extension::Present => self.handle_present_event(event),
            Extension::XInputExtension => self.handle_input_event(event).await,
            _ => Ok(()),
        }
    }

    async fn handle_core_event(self: &Rc<Self>, event: &Event) -> Result<(), XBackendError> {
        match event.code() {
            ConfigureNotify::OPCODE => self.handle_configure(event).await,
            DestroyNotify::OPCODE => self.handle_destroy(event),
            _ => Ok(()),
        }
    }

    fn handle_present_event(self: &Rc<Self>, event: &Event) -> Result<(), XBackendError> {
        match event.code() {
            PresentCompleteNotify::OPCODE => self.handle_present_complete(event)?,
            PresentIdleNotify::OPCODE => self.handle_present_idle(event)?,
            _ => {}
        }
        Ok(())
    }

    fn handle_present_complete(self: &Rc<Self>, event: &Event) -> Result<(), XBackendError> {
        let event: PresentCompleteNotify = event.parse()?;
        let window = event.window;
        let output = match self.outputs.get(&window) {
            Some(o) => o,
            _ => return Ok(()),
        };
        output.next_msc.set(event.msc + 1);
        let image = &output.images[output.next_image.get() % output.images.len()];
        if image.idle.get() {
            self.schedule_present(&output);
        } else {
            image.render_on_idle.set(true);
        }
        Ok(())
    }

    fn handle_present_idle(self: &Rc<Self>, event: &Event) -> Result<(), XBackendError> {
        let event: PresentIdleNotify = event.parse()?;
        let output = match self.outputs.get(&event.window) {
            Some(o) => o,
            _ => return Ok(()),
        };
        let mut matched_any = false;
        for image in &output.images {
            if image.last_serial.get() == event.serial {
                matched_any = true;
                image.idle.set(true);
                if image.render_on_idle.replace(false) {
                    self.schedule_present(&output);
                }
            }
        }
        if !matched_any {
            fatal!(
                "idle event did not match any images {}, {}, {}, {:#?}",
                output.serial.get(),
                output.images[0].last_serial.get(),
                output.images[1].last_serial.get(),
                event
            );
        }
        Ok(())
    }

    fn schedule_present(&self, output: &Rc<XOutput>) {
        self.scheduled_present.push(output.clone());
    }

    async fn present(&self, output: &Rc<XOutput>) {
        let serial = output.serial.fetch_add(1);

        let image = &output.images[output.next_image.fetch_add(1) % output.images.len()];
        image.idle.set(false);
        image.last_serial.set(serial);

        if let Some(node) = self.state.root.outputs.get(&output.id) {
            let res = self.state.present_output(
                &node,
                &image.fb.get(),
                &image.tex.get(),
                &mut self.render_result.borrow_mut(),
                true,
            );
            if let Err(e) = res {
                log::error!("Could not render screen: {}", ErrorFmt(e));
                return;
            }
        }

        let pp = PresentPixmap {
            window: output.window,
            pixmap: image.pixmap.get(),
            serial,
            valid: 0,
            update: 0,
            x_off: 0,
            y_off: 0,
            target_crtc: 0,
            wait_fence: 0,
            idle_fence: 0,
            options: 0,
            target_msc: output.next_msc.get(),
            divisor: 1,
            remainder: 0,
            notifies: Default::default(),
        };
        if let Err(e) = self.c.call(&pp).await {
            log::error!("Could not present image: {:?}", e);
            return;
        }

        self.state.set_backend_idle(false);
    }

    async fn handle_input_event(self: &Rc<Self>, event: &Event) -> Result<(), XBackendError> {
        match event.code() {
            XiMotion::OPCODE => self.handle_input_motion(event),
            XiEnter::OPCODE => self.handle_input_enter(event),
            XiButtonPress::OPCODE => self.handle_input_button_press(event, KeyState::Pressed),
            XiButtonRelease::OPCODE => self.handle_input_button_press(event, KeyState::Released),
            XiKeyPress::OPCODE => self.handle_input_key_press(event, KeyState::Pressed),
            XiKeyRelease::OPCODE => self.handle_input_key_press(event, KeyState::Released),
            XiHierarchy::OPCODE => self.handle_input_hierarchy(event).await,
            _ => Ok(()),
        }
    }

    fn handle_input_button_press(
        self: &Rc<Self>,
        event: &Event,
        state: KeyState,
    ) -> Result<(), XBackendError> {
        let event: XiButtonPress = event.parse()?;
        if let Some(seat) = self.mouse_seats.get(&event.deviceid) {
            let button = event.detail;
            // let button = seat.button_map.get(&event.detail).unwrap_or(event.detail);
            if matches!(button, 4..=7) {
                if state == KeyState::Pressed {
                    let (axis, val) = match button {
                        4 => (ScrollAxis::Vertical, -1),
                        5 => (ScrollAxis::Vertical, 1),
                        6 => (ScrollAxis::Horizontal, -1),
                        7 => (ScrollAxis::Horizontal, 1),
                        _ => unreachable!(),
                    };
                    seat.mouse_event(InputEvent::AxisSource {
                        source: AxisSource::Wheel,
                    });
                    seat.mouse_event(InputEvent::Axis120 {
                        dist: val * AXIS_120,
                        axis,
                        inverted: false,
                    });
                    seat.mouse_event(InputEvent::AxisFrame {
                        time_usec: now_usec(),
                    });
                }
            } else {
                const BTN_LEFT: u32 = 0x110;
                const BTN_RIGHT: u32 = 0x111;
                const BTN_MIDDLE: u32 = 0x112;
                const BTN_SIDE: u32 = 0x113;
                let button = match button {
                    0 => return Ok(()),
                    1 => BTN_LEFT,
                    2 => BTN_MIDDLE,
                    3 => BTN_RIGHT,
                    n => BTN_SIDE + n - 8,
                };
                seat.mouse_event(InputEvent::Button {
                    time_usec: now_usec(),
                    button,
                    state,
                });
            }
        }
        Ok(())
    }

    fn handle_input_key_press(
        self: &Rc<Self>,
        event: &Event,
        state: KeyState,
    ) -> Result<(), XBackendError> {
        let event: XiKeyPress = event.parse()?;
        if let Some(seat) = self.seats.get(&event.deviceid) {
            seat.kb_event(InputEvent::Key {
                time_usec: now_usec(),
                key: event.detail - 8,
                state,
            });
        }
        Ok(())
    }

    async fn handle_input_hierarchy(self: &Rc<Self>, event: &Event) -> Result<(), XBackendError> {
        let event: XiHierarchy = event.parse()?;
        for info in event.infos.iter() {
            if info.flags & INPUT_HIERARCHY_MASK_MASTER_ADDED != 0 {
                if let Err(e) = self.query_devices(info.deviceid).await {
                    log::error!("Could not query device {}: {}", info.deviceid, ErrorFmt(e));
                }
            } else if info.flags & INPUT_HIERARCHY_MASK_MASTER_REMOVED != 0 {
                self.mouse_seats.remove(&info.attachment);
                if let Some(seat) = self.seats.remove(&info.deviceid) {
                    seat.removed.set(true);
                    seat.kb_changed();
                    seat.mouse_changed();
                }
            }
        }
        Ok(())
    }

    fn handle_input_enter(&self, event: &Event) -> Result<(), XBackendError> {
        let event: XiEnter = event.parse()?;
        if let (Some(win), Some(seat)) = (
            self.outputs.get(&event.event),
            self.mouse_seats.get(&event.deviceid),
        ) {
            seat.mouse_event(InputEvent::ConnectorPosition {
                time_usec: now_usec(),
                connector: win.id,
                x: Fixed::from_1616(event.event_x),
                y: Fixed::from_1616(event.event_y),
            });
        }
        Ok(())
    }

    fn handle_input_motion(&self, event: &Event) -> Result<(), XBackendError> {
        let event: XiMotion = event.parse()?;
        let (win, seat) = match (
            self.outputs.get(&event.event),
            self.mouse_seats.get(&event.deviceid),
        ) {
            (Some(a), Some(b)) => (a, b),
            _ => return Ok(()),
        };
        seat.mouse_event(InputEvent::ConnectorPosition {
            time_usec: now_usec(),
            connector: win.id,
            x: Fixed::from_1616(event.event_x),
            y: Fixed::from_1616(event.event_y),
        });
        Ok(())
    }

    fn handle_destroy(&self, event: &Event) -> Result<(), XBackendError> {
        self.state.ring.stop();
        let event: DestroyNotify = event.parse()?;
        let output = match self.outputs.remove(&event.event) {
            Some(o) => o,
            _ => return Ok(()),
        };
        output.events.push(ConnectorEvent::Disconnected);
        output.events.push(ConnectorEvent::Removed);
        output.changed();
        Ok(())
    }

    async fn handle_configure(&self, event: &Event) -> Result<(), XBackendError> {
        let event: ConfigureNotify = event.parse()?;
        let output = match self.outputs.get(&event.event) {
            Some(o) => o,
            _ => return Ok(()),
        };
        let width = event.width as i32;
        let height = event.height as i32;
        let mut changed = false;
        changed |= output.width.replace(width) != width;
        changed |= output.height.replace(height) != height;
        if changed {
            let images = self.create_images(output.window, width, height).await?;
            for (new, old) in images.iter().zip(output.images.iter()) {
                #[allow(clippy::let_underscore_future)]
                let _ = self.c.call(&FreePixmap {
                    pixmap: old.pixmap.get(),
                });
                old.fb.set(new.fb.get());
                old.tex.set(new.tex.get());
                old.pixmap.set(new.pixmap.get());
            }
            output.events.push(ConnectorEvent::ModeChanged(Mode {
                width,
                height,
                refresh_rate_millihz: 60, // TODO
            }));
            output.changed();
        }
        Ok(())
    }
}

struct XDrmDevice {
    backend: Rc<XBackend>,
    id: DrmDeviceId,
    dev: dev_t,
}

impl BackendDrmDevice for XDrmDevice {
    fn id(&self) -> DrmDeviceId {
        self.id
    }

    fn event(&self) -> Option<DrmEvent> {
        None
    }

    fn on_change(&self, _cb: Rc<dyn Fn()>) {
        // nothing
    }

    fn dev_t(&self) -> dev_t {
        self.dev
    }

    fn make_render_device(&self) {
        log::warn!("make_render_device is not supported by the X backend");
        // nothing
    }

    fn set_gfx_api(&self, _api: GfxApi) {
        log::warn!("set_gfx_api is not supported by the X backend");
        // nothing
    }

    fn gtx_api(&self) -> GfxApi {
        self.backend.ctx.gfx_api()
    }

    fn version(&self) -> Result<DrmVersion, DrmError> {
        self.backend.gbm.drm.version()
    }

    fn set_direct_scanout_enabled(&self, enabled: bool) {
        let _ = enabled;
    }

    fn is_render_device(&self) -> bool {
        true
    }
}

struct XOutput {
    id: ConnectorId,
    backend: Rc<XBackend>,
    window: u32,
    events: SyncQueue<ConnectorEvent>,
    width: Cell<i32>,
    height: Cell<i32>,
    serial: NumCell<u32>,
    next_msc: Cell<u64>,
    next_image: NumCell<usize>,
    images: [XImage; 2],
    cb: CloneCell<Option<Rc<dyn Fn()>>>,
}

struct XImage {
    pixmap: Cell<u32>,
    _bo: GbmBo,
    fb: CloneCell<Rc<dyn GfxFramebuffer>>,
    tex: CloneCell<Rc<dyn GfxTexture>>,
    idle: Cell<bool>,
    render_on_idle: Cell<bool>,
    last_serial: Cell<u32>,
}

impl XOutput {
    fn changed(&self) {
        if let Some(cb) = self.cb.get() {
            cb();
        }
    }
}

impl Connector for XOutput {
    fn id(&self) -> ConnectorId {
        self.id
    }

    fn kernel_id(&self) -> ConnectorKernelId {
        ConnectorKernelId {
            ty: ConnectorType::EmbeddedWindow,
            idx: self.id.raw(),
        }
    }

    fn event(&self) -> Option<ConnectorEvent> {
        self.events.pop()
    }

    fn on_change(&self, cb: Rc<dyn Fn()>) {
        self.cb.set(Some(cb));
    }

    fn damage(&self) {
        // nothing
    }

    fn drm_dev(&self) -> Option<DrmDeviceId> {
        Some(self.backend.drm_device_id)
    }

    fn set_mode(&self, _mode: Mode) {
        log::warn!("X backend doesn't support changing the connector mode");
    }
}

struct XSeat {
    kb_id: InputDeviceId,
    mouse_id: InputDeviceId,
    backend: Rc<XBackend>,
    kb: u16,
    mouse: u16,
    removed: Cell<bool>,
    kb_cb: CloneCell<Option<Rc<dyn Fn()>>>,
    mouse_cb: CloneCell<Option<Rc<dyn Fn()>>>,
    kb_events: RefCell<VecDeque<InputEvent>>,
    mouse_events: RefCell<VecDeque<InputEvent>>,
    button_map: CopyHashMap<u32, u32>,
    kb_name: Rc<String>,
    mouse_name: Rc<String>,
}

struct XSeatKeyboard(Rc<XSeat>);

struct XSeatMouse(Rc<XSeat>);

impl XSeat {
    fn kb_changed(&self) {
        if let Some(cb) = self.kb_cb.get() {
            cb();
        }
    }

    fn mouse_changed(&self) {
        if let Some(cb) = self.mouse_cb.get() {
            cb();
        }
    }

    fn mouse_event(&self, event: InputEvent) {
        self.mouse_events.borrow_mut().push_back(event);
        self.mouse_changed();
    }

    fn kb_event(&self, event: InputEvent) {
        self.kb_events.borrow_mut().push_back(event);
        self.kb_changed();
    }

    async fn update_button_map(&self) {
        self.button_map.clear();
        let gdbm = XiGetDeviceButtonMapping {
            device_id: self.mouse as _,
        };
        let reply = match self.backend.c.call(&gdbm).await {
            Ok(r) => r,
            Err(e) => {
                log::error!(
                    "Could not get Xinput button map of device {}: {}",
                    self.mouse,
                    ErrorFmt(e),
                );
                return;
            }
        };
        for (i, map) in reply.get().map.iter().copied().enumerate().rev() {
            self.button_map.set(map as u32, i as u32 + 1);
        }
    }
}

impl InputDevice for XSeatKeyboard {
    fn id(&self) -> InputDeviceId {
        self.0.kb_id
    }

    fn removed(&self) -> bool {
        self.0.removed.get()
    }

    fn event(&self) -> Option<InputEvent> {
        self.0.kb_events.borrow_mut().pop_front()
    }

    fn on_change(&self, cb: Rc<dyn Fn()>) {
        self.0.kb_cb.set(Some(cb));
    }

    fn grab(&self, grab: bool) {
        self.0.backend.grab_requests.push((self.0.clone(), grab));
    }

    fn has_capability(&self, cap: InputDeviceCapability) -> bool {
        match cap {
            InputDeviceCapability::Keyboard => true,
            _ => false,
        }
    }

    fn set_left_handed(&self, left_handed: bool) {
        let _ = left_handed;
    }

    fn set_accel_profile(&self, profile: InputDeviceAccelProfile) {
        let _ = profile;
    }

    fn set_accel_speed(&self, speed: f64) {
        let _ = speed;
    }

    fn set_transform_matrix(&self, matrix: TransformMatrix) {
        let _ = matrix;
    }

    fn name(&self) -> Rc<String> {
        self.0.kb_name.clone()
    }

    fn dev_t(&self) -> Option<dev_t> {
        None
    }

    fn set_tap_enabled(&self, enabled: bool) {
        let _ = enabled;
    }

    fn set_drag_enabled(&self, enabled: bool) {
        let _ = enabled;
    }

    fn set_drag_lock_enabled(&self, enabled: bool) {
        let _ = enabled;
    }

    fn set_natural_scrolling_enabled(&self, enabled: bool) {
        let _ = enabled;
    }
}

impl InputDevice for XSeatMouse {
    fn id(&self) -> InputDeviceId {
        self.0.mouse_id
    }

    fn removed(&self) -> bool {
        self.0.removed.get()
    }

    fn event(&self) -> Option<InputEvent> {
        self.0.mouse_events.borrow_mut().pop_front()
    }

    fn on_change(&self, cb: Rc<dyn Fn()>) {
        self.0.mouse_cb.set(Some(cb));
    }

    fn grab(&self, _grab: bool) {
        log::error!("Cannot grab xorg mouse");
    }

    fn has_capability(&self, cap: InputDeviceCapability) -> bool {
        match cap {
            InputDeviceCapability::Pointer => true,
            _ => false,
        }
    }

    fn set_left_handed(&self, left_handed: bool) {
        let _ = left_handed;
    }

    fn set_accel_profile(&self, profile: InputDeviceAccelProfile) {
        let _ = profile;
    }

    fn set_accel_speed(&self, speed: f64) {
        let _ = speed;
    }

    fn set_transform_matrix(&self, matrix: TransformMatrix) {
        let _ = matrix;
    }

    fn name(&self) -> Rc<String> {
        self.0.mouse_name.clone()
    }

    fn dev_t(&self) -> Option<dev_t> {
        None
    }

    fn set_tap_enabled(&self, enabled: bool) {
        let _ = enabled;
    }

    fn set_drag_enabled(&self, enabled: bool) {
        let _ = enabled;
    }

    fn set_drag_lock_enabled(&self, enabled: bool) {
        let _ = enabled;
    }

    fn set_natural_scrolling_enabled(&self, enabled: bool) {
        let _ = enabled;
    }
}