niri/src/layout/mod.rs

//! Window layout logic.
//!
//! Niri implements scrollable tiling with workspaces. There's one primary output, and potentially
//! multiple other outputs.
//!
//! Our layout has the following invariants:
//!
//! 1. Disconnecting and reconnecting the same output must not change the layout.
//!    * This includes both secondary outputs and the primary output.
//! 2. Connecting an output must not change the layout for any workspaces that were never on that
//!    output.
//!
//! Therefore, we implement the following logic: every workspace keeps track of which output it
//! originated on. When an output disconnects, its workspace (or workspaces, in case of the primary
//! output disconnecting) are appended to the (potentially new) primary output, but remember their
//! original output. Then, if the original output connects again, all workspaces originally from
//! there move back to that output.
//!
//! In order to avoid surprising behavior, if the user creates or moves any new windows onto a
//! workspace, it forgets its original output, and its current output becomes its original output.
//! Imagine a scenario: the user works with a laptop and a monitor at home, then takes their laptop
//! with them, disconnecting the monitor, and keeps working as normal, using the second monitor's
//! workspace just like any other. Then they come back, reconnect the second monitor, and now we
//! don't want an unassuming workspace to end up on it.
//!
//! ## Workspaces-only-on-primary considerations
//!
//! If this logic results in more than one workspace present on a secondary output, then as a
//! compromise we only keep the first workspace there, and move the rest to the primary output,
//! making the primary output their original output.

use std::cmp::min;
use std::mem;
use std::rc::Rc;
use std::time::Duration;

use niri_config::{CenterFocusedColumn, Config, FloatOrInt, Struts, Workspace as WorkspaceConfig};
use niri_ipc::SizeChange;
use smithay::backend::renderer::element::surface::WaylandSurfaceRenderElement;
use smithay::backend::renderer::element::Id;
use smithay::backend::renderer::gles::{GlesRenderer, GlesTexture};
use smithay::output::{self, Output};
use smithay::reexports::wayland_server::protocol::wl_surface::WlSurface;
use smithay::utils::{Logical, Point, Scale, Serial, Size, Transform};

pub use self::monitor::MonitorRenderElement;
use self::monitor::{Monitor, WorkspaceSwitch};
use self::workspace::{compute_working_area, Column, ColumnWidth, OutputId, Workspace};
use crate::niri_render_elements;
use crate::render_helpers::renderer::NiriRenderer;
use crate::render_helpers::snapshot::RenderSnapshot;
use crate::render_helpers::solid_color::{SolidColorBuffer, SolidColorRenderElement};
use crate::render_helpers::texture::TextureBuffer;
use crate::render_helpers::{BakedBuffer, RenderTarget, SplitElements};
use crate::utils::{output_size, round_logical_in_physical_max1, ResizeEdge};
use crate::window::ResolvedWindowRules;

pub mod closing_window;
pub mod focus_ring;
pub mod monitor;
pub mod opening_window;
pub mod tile;
pub mod workspace;

/// Size changes up to this many pixels don't animate.
pub const RESIZE_ANIMATION_THRESHOLD: f64 = 10.;

niri_render_elements! {
    LayoutElementRenderElement<R> => {
        Wayland = WaylandSurfaceRenderElement<R>,
        SolidColor = SolidColorRenderElement,
    }
}

pub type LayoutElementRenderSnapshot =
    RenderSnapshot<BakedBuffer<TextureBuffer<GlesTexture>>, BakedBuffer<SolidColorBuffer>>;

#[derive(Debug, Clone, Copy)]
pub struct InteractiveResizeData {
    pub edges: ResizeEdge,
}

pub trait LayoutElement {
    /// Type that can be used as a unique ID of this element.
    type Id: PartialEq + std::fmt::Debug;

    /// Unique ID of this element.
    fn id(&self) -> &Self::Id;

    /// Visual size of the element.
    ///
    /// This is what the user would consider the size, i.e. excluding CSD shadows and whatnot.
    /// Corresponds to the Wayland window geometry size.
    fn size(&self) -> Size<i32, Logical>;

    /// Returns the location of the element's buffer relative to the element's visual geometry.
    ///
    /// I.e. if the element has CSD shadows, its buffer location will have negative coordinates.
    fn buf_loc(&self) -> Point<i32, Logical>;

    /// Checks whether a point is in the element's input region.
    ///
    /// The point is relative to the element's visual geometry.
    fn is_in_input_region(&self, point: Point<f64, Logical>) -> bool;

    /// Renders the element at the given visual location.
    ///
    /// The element should be rendered in such a way that its visual geometry ends up at the given
    /// location.
    fn render<R: NiriRenderer>(
        &self,
        renderer: &mut R,
        location: Point<f64, Logical>,
        scale: Scale<f64>,
        alpha: f32,
        target: RenderTarget,
    ) -> SplitElements<LayoutElementRenderElement<R>>;

    /// Renders the non-popup parts of the element.
    fn render_normal<R: NiriRenderer>(
        &self,
        renderer: &mut R,
        location: Point<f64, Logical>,
        scale: Scale<f64>,
        alpha: f32,
        target: RenderTarget,
    ) -> Vec<LayoutElementRenderElement<R>> {
        self.render(renderer, location, scale, alpha, target).normal
    }

    /// Renders the popups of the element.
    fn render_popups<R: NiriRenderer>(
        &self,
        renderer: &mut R,
        location: Point<f64, Logical>,
        scale: Scale<f64>,
        alpha: f32,
        target: RenderTarget,
    ) -> Vec<LayoutElementRenderElement<R>> {
        self.render(renderer, location, scale, alpha, target).popups
    }

    fn request_size(&mut self, size: Size<i32, Logical>, animate: bool);
    fn request_fullscreen(&self, size: Size<i32, Logical>);
    fn min_size(&self) -> Size<i32, Logical>;
    fn max_size(&self) -> Size<i32, Logical>;
    fn is_wl_surface(&self, wl_surface: &WlSurface) -> bool;
    fn has_ssd(&self) -> bool;
    fn set_preferred_scale_transform(&self, scale: output::Scale, transform: Transform);
    fn output_enter(&self, output: &Output);
    fn output_leave(&self, output: &Output);
    fn set_offscreen_element_id(&self, id: Option<Id>);
    fn set_activated(&mut self, active: bool);
    fn set_active_in_column(&mut self, active: bool);
    fn set_bounds(&self, bounds: Size<i32, Logical>);

    fn send_pending_configure(&mut self);

    /// Whether the element is currently fullscreen.
    ///
    /// This will *not* switch immediately after a [`LayoutElement::request_fullscreen()`] call.
    fn is_fullscreen(&self) -> bool;

    /// Whether we're requesting the element to be fullscreen.
    ///
    /// This *will* switch immediately after a [`LayoutElement::request_fullscreen()`] call.
    fn is_pending_fullscreen(&self) -> bool;

    fn rules(&self) -> &ResolvedWindowRules;

    /// Runs periodic clean-up tasks.
    fn refresh(&self);

    fn animation_snapshot(&self) -> Option<&LayoutElementRenderSnapshot>;
    fn take_animation_snapshot(&mut self) -> Option<LayoutElementRenderSnapshot>;

    fn set_interactive_resize(&mut self, data: Option<InteractiveResizeData>);
    fn cancel_interactive_resize(&mut self);
    fn update_interactive_resize(&mut self, serial: Serial);
    fn interactive_resize_data(&self) -> Option<InteractiveResizeData>;
}

#[derive(Debug)]
pub struct Layout<W: LayoutElement> {
    /// Monitors and workspaes in the layout.
    monitor_set: MonitorSet<W>,
    /// Configurable properties of the layout.
    options: Rc<Options>,
}

#[derive(Debug)]
enum MonitorSet<W: LayoutElement> {
    /// At least one output is connected.
    Normal {
        /// Connected monitors.
        monitors: Vec<Monitor<W>>,
        /// Index of the primary monitor.
        primary_idx: usize,
        /// Index of the active monitor.
        active_monitor_idx: usize,
    },
    /// No outputs are connected, and these are the workspaces.
    NoOutputs {
        /// The workspaces.
        workspaces: Vec<Workspace<W>>,
    },
}

#[derive(Debug, Clone, PartialEq)]
pub struct Options {
    /// Padding around windows in logical pixels.
    pub gaps: f64,
    /// Extra padding around the working area in logical pixels.
    pub struts: Struts,
    pub focus_ring: niri_config::FocusRing,
    pub border: niri_config::Border,
    pub center_focused_column: CenterFocusedColumn,
    /// Column widths that `toggle_width()` switches between.
    pub preset_widths: Vec<ColumnWidth>,
    /// Initial width for new columns.
    pub default_width: Option<ColumnWidth>,
    pub animations: niri_config::Animations,
}

impl Default for Options {
    fn default() -> Self {
        Self {
            gaps: 16.,
            struts: Default::default(),
            focus_ring: Default::default(),
            border: Default::default(),
            center_focused_column: Default::default(),
            preset_widths: vec![
                ColumnWidth::Proportion(1. / 3.),
                ColumnWidth::Proportion(0.5),
                ColumnWidth::Proportion(2. / 3.),
            ],
            default_width: None,
            animations: Default::default(),
        }
    }
}

impl Options {
    fn from_config(config: &Config) -> Self {
        let layout = &config.layout;
        let preset_column_widths = &layout.preset_column_widths;

        let preset_widths = if preset_column_widths.is_empty() {
            Options::default().preset_widths
        } else {
            preset_column_widths
                .iter()
                .copied()
                .map(ColumnWidth::from)
                .collect()
        };

        // Missing default_column_width maps to Some(ColumnWidth::Proportion(0.5)),
        // while present, but empty, maps to None.
        let default_width = layout
            .default_column_width
            .as_ref()
            .map(|w| w.0.map(ColumnWidth::from))
            .unwrap_or(Some(ColumnWidth::Proportion(0.5)));

        Self {
            gaps: layout.gaps.0,
            struts: layout.struts,
            focus_ring: layout.focus_ring,
            border: layout.border,
            center_focused_column: layout.center_focused_column,
            preset_widths,
            default_width,
            animations: config.animations.clone(),
        }
    }

    fn adjusted_for_scale(mut self, scale: f64) -> Self {
        let round = |logical: f64| round_logical_in_physical_max1(scale, logical);

        self.gaps = round(self.gaps);
        self.focus_ring.width = FloatOrInt(round(self.focus_ring.width.0));
        self.border.width = FloatOrInt(round(self.border.width.0));

        self
    }
}

impl<W: LayoutElement> Layout<W> {
    pub fn new(config: &Config) -> Self {
        Self::with_options_and_workspaces(config, Options::from_config(config))
    }

    pub fn with_options(options: Options) -> Self {
        Self {
            monitor_set: MonitorSet::NoOutputs { workspaces: vec![] },
            options: Rc::new(options),
        }
    }

    fn with_options_and_workspaces(config: &Config, options: Options) -> Self {
        let opts = Rc::new(options);

        let workspaces = config
            .workspaces
            .iter()
            .map(|ws| Workspace::new_with_config_no_outputs(Some(ws.clone()), opts.clone()))
            .collect();

        Self {
            monitor_set: MonitorSet::NoOutputs { workspaces },
            options: opts,
        }
    }

    pub fn add_output(&mut self, output: Output) {
        let id = OutputId::new(&output);

        self.monitor_set = match mem::take(&mut self.monitor_set) {
            MonitorSet::Normal {
                mut monitors,
                primary_idx,
                active_monitor_idx,
            } => {
                let primary = &mut monitors[primary_idx];

                let mut stopped_primary_ws_switch = false;

                let mut workspaces = vec![];
                for i in (0..primary.workspaces.len()).rev() {
                    if primary.workspaces[i].original_output == id {
                        let ws = primary.workspaces.remove(i);

                        // FIXME: this can be coded in a way that the workspace switch won't be
                        // affected if the removed workspace is invisible. But this is good enough
                        // for now.
                        if primary.workspace_switch.is_some() {
                            primary.workspace_switch = None;
                            stopped_primary_ws_switch = true;
                        }

                        // The user could've closed a window while remaining on this workspace, on
                        // another monitor. However, we will add an empty workspace in the end
                        // instead.
                        if ws.has_windows() || ws.name.is_some() {
                            workspaces.push(ws);
                        }

                        if i <= primary.active_workspace_idx {
                            primary.active_workspace_idx =
                                primary.active_workspace_idx.saturating_sub(1);
                        }
                    }
                }

                // If we stopped a workspace switch, then we might need to clean up workspaces.
                if stopped_primary_ws_switch {
                    primary.clean_up_workspaces();
                }

                workspaces.reverse();

                // Make sure there's always an empty workspace.
                workspaces.push(Workspace::new(output.clone(), self.options.clone()));

                for ws in &mut workspaces {
                    ws.set_output(Some(output.clone()));
                }

                monitors.push(Monitor::new(output, workspaces, self.options.clone()));
                MonitorSet::Normal {
                    monitors,
                    primary_idx,
                    active_monitor_idx,
                }
            }
            MonitorSet::NoOutputs { mut workspaces } => {
                // We know there are no empty workspaces there, so add one.
                workspaces.push(Workspace::new(output.clone(), self.options.clone()));

                for workspace in &mut workspaces {
                    workspace.set_output(Some(output.clone()));
                }

                let monitor = Monitor::new(output, workspaces, self.options.clone());

                MonitorSet::Normal {
                    monitors: vec![monitor],
                    primary_idx: 0,
                    active_monitor_idx: 0,
                }
            }
        }
    }

    pub fn remove_output(&mut self, output: &Output) {
        self.monitor_set = match mem::take(&mut self.monitor_set) {
            MonitorSet::Normal {
                mut monitors,
                mut primary_idx,
                mut active_monitor_idx,
            } => {
                let idx = monitors
                    .iter()
                    .position(|mon| &mon.output == output)
                    .expect("trying to remove non-existing output");
                let monitor = monitors.remove(idx);
                let mut workspaces = monitor.workspaces;

                for ws in &mut workspaces {
                    ws.set_output(None);
                }

                // Get rid of empty workspaces.
                workspaces.retain(|ws| ws.has_windows() || ws.name.is_some());

                if monitors.is_empty() {
                    // Removed the last monitor.
                    MonitorSet::NoOutputs { workspaces }
                } else {
                    if primary_idx >= idx {
                        // Update primary_idx to either still point at the same monitor, or at some
                        // other monitor if the primary has been removed.
                        primary_idx = primary_idx.saturating_sub(1);
                    }
                    if active_monitor_idx >= idx {
                        // Update active_monitor_idx to either still point at the same monitor, or
                        // at some other monitor if the active monitor has
                        // been removed.
                        active_monitor_idx = active_monitor_idx.saturating_sub(1);
                    }

                    let primary = &mut monitors[primary_idx];
                    for ws in &mut workspaces {
                        ws.set_output(Some(primary.output.clone()));
                    }

                    let empty_was_focused =
                        primary.active_workspace_idx == primary.workspaces.len() - 1;

                    // Push the workspaces from the removed monitor in the end, right before the
                    // last, empty, workspace.
                    let empty = primary.workspaces.remove(primary.workspaces.len() - 1);
                    primary.workspaces.extend(workspaces);
                    primary.workspaces.push(empty);

                    // If the empty workspace was focused on the primary monitor, keep it focused.
                    if empty_was_focused {
                        primary.active_workspace_idx = primary.workspaces.len() - 1;
                    }

                    MonitorSet::Normal {
                        monitors,
                        primary_idx,
                        active_monitor_idx,
                    }
                }
            }
            MonitorSet::NoOutputs { .. } => {
                panic!("tried to remove output when there were already none")
            }
        }
    }

    pub fn add_window_by_idx(
        &mut self,
        monitor_idx: usize,
        workspace_idx: usize,
        window: W,
        activate: bool,
        width: ColumnWidth,
        is_full_width: bool,
    ) {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        else {
            panic!()
        };

        monitors[monitor_idx].add_window(workspace_idx, window, activate, width, is_full_width);

        if activate {
            *active_monitor_idx = monitor_idx;
        }
    }

    /// Adds a new window to the layout on a specific workspace.
    pub fn add_window_to_named_workspace(
        &mut self,
        workspace_name: &str,
        window: W,
        width: Option<ColumnWidth>,
        is_full_width: bool,
    ) -> Option<&Output> {
        let mut width = width.unwrap_or_else(|| ColumnWidth::Fixed(f64::from(window.size().w)));
        if let ColumnWidth::Fixed(w) = &mut width {
            let rules = window.rules();
            let border_config = rules.border.resolve_against(self.options.border);
            if !border_config.off {
                *w += border_config.width.0 * 2.;
            }
        }

        match &mut self.monitor_set {
            MonitorSet::Normal {
                monitors,
                active_monitor_idx,
                ..
            } => {
                let (mon_idx, mon, ws_idx) = monitors
                    .iter_mut()
                    .enumerate()
                    .find_map(|(mon_idx, mon)| {
                        mon.find_named_workspace_index(workspace_name)
                            .map(move |ws_idx| (mon_idx, mon, ws_idx))
                    })
                    .unwrap();

                // Don't steal focus from an active fullscreen window.
                let mut activate = true;
                let ws = &mon.workspaces[ws_idx];
                if mon_idx == *active_monitor_idx
                    && !ws.columns.is_empty()
                    && ws.columns[ws.active_column_idx].is_fullscreen
                {
                    activate = false;
                }

                // Don't activate if on a different workspace.
                if mon.active_workspace_idx != ws_idx {
                    activate = false;
                }

                mon.add_window(ws_idx, window, activate, width, is_full_width);
                Some(&mon.output)
            }
            MonitorSet::NoOutputs { workspaces } => {
                let ws = workspaces
                    .iter_mut()
                    .find(|ws| {
                        ws.name
                            .as_ref()
                            .map_or(false, |name| name.eq_ignore_ascii_case(workspace_name))
                    })
                    .unwrap();
                ws.add_window(window, true, width, is_full_width);
                None
            }
        }
    }

    pub fn add_column_by_idx(
        &mut self,
        monitor_idx: usize,
        workspace_idx: usize,
        column: Column<W>,
        activate: bool,
    ) {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        else {
            panic!()
        };

        monitors[monitor_idx].add_column(workspace_idx, column, activate);

        if activate {
            *active_monitor_idx = monitor_idx;
        }
    }

    /// Adds a new window to the layout.
    ///
    /// Returns an output that the window was added to, if there were any outputs.
    pub fn add_window(
        &mut self,
        window: W,
        width: Option<ColumnWidth>,
        is_full_width: bool,
    ) -> Option<&Output> {
        let mut width = width.unwrap_or_else(|| ColumnWidth::Fixed(f64::from(window.size().w)));
        if let ColumnWidth::Fixed(w) = &mut width {
            let rules = window.rules();
            let border_config = rules.border.resolve_against(self.options.border);
            if !border_config.off {
                *w += border_config.width.0 * 2.;
            }
        }

        match &mut self.monitor_set {
            MonitorSet::Normal {
                monitors,
                active_monitor_idx,
                ..
            } => {
                let mon = &mut monitors[*active_monitor_idx];

                // Don't steal focus from an active fullscreen window.
                let mut activate = true;
                let ws = &mon.workspaces[mon.active_workspace_idx];
                if !ws.columns.is_empty() && ws.columns[ws.active_column_idx].is_fullscreen {
                    activate = false;
                }

                mon.add_window(
                    mon.active_workspace_idx,
                    window,
                    activate,
                    width,
                    is_full_width,
                );
                Some(&mon.output)
            }
            MonitorSet::NoOutputs { workspaces } => {
                let ws = if let Some(ws) = workspaces.get_mut(0) {
                    ws
                } else {
                    workspaces.push(Workspace::new_no_outputs(self.options.clone()));
                    &mut workspaces[0]
                };
                ws.add_window(window, true, width, is_full_width);
                None
            }
        }
    }

    /// Adds a new window to the layout immediately to the right of another window.
    ///
    /// If that another window was active, activates the new window.
    ///
    /// Returns an output that the window was added to, if there were any outputs.
    pub fn add_window_right_of(
        &mut self,
        right_of: &W::Id,
        window: W,
        width: Option<ColumnWidth>,
        is_full_width: bool,
    ) -> Option<&Output> {
        let mut width = width.unwrap_or_else(|| ColumnWidth::Fixed(f64::from(window.size().w)));
        if let ColumnWidth::Fixed(w) = &mut width {
            let rules = window.rules();
            let border_config = rules.border.resolve_against(self.options.border);
            if !border_config.off {
                *w += border_config.width.0 * 2.;
            }
        }

        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                let mon = monitors
                    .iter_mut()
                    .find(|mon| mon.workspaces.iter().any(|ws| ws.has_window(right_of)))
                    .unwrap();

                mon.add_window_right_of(right_of, window, width, is_full_width);
                Some(&mon.output)
            }
            MonitorSet::NoOutputs { workspaces } => {
                let ws = workspaces
                    .iter_mut()
                    .find(|ws| ws.has_window(right_of))
                    .unwrap();
                ws.add_window_right_of(right_of, window, width, is_full_width);
                None
            }
        }
    }

    /// Adds a new window to the layout on a specific output.
    pub fn add_window_on_output(
        &mut self,
        output: &Output,
        window: W,
        width: Option<ColumnWidth>,
        is_full_width: bool,
    ) {
        let mut width = width.unwrap_or_else(|| ColumnWidth::Fixed(f64::from(window.size().w)));
        if let ColumnWidth::Fixed(w) = &mut width {
            let rules = window.rules();
            let border_config = rules.border.resolve_against(self.options.border);
            if !border_config.off {
                *w += border_config.width.0 * 2.;
            }
        }

        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        else {
            panic!()
        };

        let (mon_idx, mon) = monitors
            .iter_mut()
            .enumerate()
            .find(|(_, mon)| mon.output == *output)
            .unwrap();

        // Don't steal focus from an active fullscreen window.
        let mut activate = true;
        let ws = &mon.workspaces[mon.active_workspace_idx];
        if mon_idx == *active_monitor_idx
            && !ws.columns.is_empty()
            && ws.columns[ws.active_column_idx].is_fullscreen
        {
            activate = false;
        }

        mon.add_window(
            mon.active_workspace_idx,
            window,
            activate,
            width,
            is_full_width,
        );
    }

    pub fn remove_window(&mut self, window: &W::Id) -> Option<W> {
        let mut rv = None;

        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for (idx, ws) in mon.workspaces.iter_mut().enumerate() {
                        if ws.has_window(window) {
                            rv = Some(ws.remove_window(window));

                            // Clean up empty workspaces that are not active and not last.
                            if !ws.has_windows()
                                && idx != mon.active_workspace_idx
                                && idx != mon.workspaces.len() - 1
                                && mon.workspace_switch.is_none()
                                && mon.workspaces[idx].name.is_none()
                            {
                                mon.workspaces.remove(idx);

                                if idx < mon.active_workspace_idx {
                                    mon.active_workspace_idx -= 1;
                                }
                            }

                            break;
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for (idx, ws) in workspaces.iter_mut().enumerate() {
                    if ws.has_window(window) {
                        rv = Some(ws.remove_window(window));

                        // Clean up empty workspaces.
                        if !ws.has_windows() && workspaces[idx].name.is_none() {
                            workspaces.remove(idx);
                        }

                        break;
                    }
                }
            }
        }

        rv
    }

    pub fn update_window(&mut self, window: &W::Id, serial: Option<Serial>) {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        if ws.has_window(window) {
                            ws.update_window(window, serial);
                            return;
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    if ws.has_window(window) {
                        ws.update_window(window, serial);
                        return;
                    }
                }
            }
        }
    }

    pub fn find_window_and_output(&self, wl_surface: &WlSurface) -> Option<(&W, &Output)> {
        if let MonitorSet::Normal { monitors, .. } = &self.monitor_set {
            for mon in monitors {
                for ws in &mon.workspaces {
                    if let Some(window) = ws.find_wl_surface(wl_surface) {
                        return Some((window, &mon.output));
                    }
                }
            }
        }

        None
    }

    pub fn find_workspace_by_name(&self, workspace_name: &str) -> Option<(usize, &Workspace<W>)> {
        match &self.monitor_set {
            MonitorSet::Normal { ref monitors, .. } => {
                for mon in monitors {
                    if let Some((index, workspace)) =
                        mon.workspaces.iter().enumerate().find(|(_, w)| {
                            w.name
                                .as_ref()
                                .map_or(false, |name| name.eq_ignore_ascii_case(workspace_name))
                        })
                    {
                        return Some((index, workspace));
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces } => {
                if let Some((index, workspace)) = workspaces.iter().enumerate().find(|(_, w)| {
                    w.name
                        .as_ref()
                        .map_or(false, |name| name.eq_ignore_ascii_case(workspace_name))
                }) {
                    return Some((index, workspace));
                }
            }
        }

        None
    }

    pub fn unname_workspace(&mut self, workspace_name: &str) {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    if mon.unname_workspace(workspace_name) {
                        if mon.workspace_switch.is_none() {
                            mon.clean_up_workspaces();
                        }
                        return;
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces } => {
                for (idx, ws) in workspaces.iter_mut().enumerate() {
                    if ws
                        .name
                        .as_ref()
                        .map_or(false, |name| name.eq_ignore_ascii_case(workspace_name))
                    {
                        ws.unname();

                        // Clean up empty workspaces.
                        if !ws.has_windows() {
                            workspaces.remove(idx);
                        }

                        return;
                    }
                }
            }
        }
    }

    pub fn find_window_and_output_mut(
        &mut self,
        wl_surface: &WlSurface,
    ) -> Option<(&mut W, Option<&Output>)> {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        if let Some(window) = ws.find_wl_surface_mut(wl_surface) {
                            return Some((window, Some(&mon.output)));
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces } => {
                for ws in workspaces {
                    if let Some(window) = ws.find_wl_surface_mut(wl_surface) {
                        return Some((window, None));
                    }
                }
            }
        }

        None
    }

    pub fn window_loc(&self, window: &W::Id) -> Option<Point<f64, Logical>> {
        match &self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mon.workspaces {
                        for col in &ws.columns {
                            if let Some(idx) = col.position(window) {
                                return Some(col.window_loc(idx));
                            }
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    for col in &ws.columns {
                        if let Some(idx) = col.position(window) {
                            return Some(col.window_loc(idx));
                        }
                    }
                }
            }
        }

        None
    }

    pub fn update_output_size(&mut self, output: &Output) {
        let _span = tracy_client::span!("Layout::update_output_size");

        let MonitorSet::Normal { monitors, .. } = &mut self.monitor_set else {
            panic!()
        };

        for mon in monitors {
            if &mon.output == output {
                let scale = output.current_scale();
                let transform = output.current_transform();
                let view_size = output_size(output);
                let working_area = compute_working_area(output, self.options.struts);

                for ws in &mut mon.workspaces {
                    ws.set_view_size(scale, transform, view_size, working_area);
                }

                break;
            }
        }
    }

    pub fn activate_window(&mut self, window: &W::Id) {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        else {
            todo!()
        };

        for (monitor_idx, mon) in monitors.iter_mut().enumerate() {
            for (workspace_idx, ws) in mon.workspaces.iter_mut().enumerate() {
                if ws.has_window(window) {
                    *active_monitor_idx = monitor_idx;
                    ws.activate_window(window);

                    // If currently in the middle of a vertical swipe between the target workspace
                    // and some other, don't switch the workspace.
                    match &mon.workspace_switch {
                        Some(WorkspaceSwitch::Gesture(gesture))
                            if gesture.current_idx.floor() == workspace_idx as f64
                                || gesture.current_idx.ceil() == workspace_idx as f64 => {}
                        _ => mon.switch_workspace(workspace_idx, true),
                    }

                    break;
                }
            }
        }
    }

    pub fn activate_output(&mut self, output: &Output) {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        else {
            return;
        };

        let idx = monitors
            .iter()
            .position(|mon| &mon.output == output)
            .unwrap();
        *active_monitor_idx = idx;
    }

    pub fn active_output(&self) -> Option<&Output> {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &self.monitor_set
        else {
            return None;
        };

        Some(&monitors[*active_monitor_idx].output)
    }

    pub fn active_workspace(&self) -> Option<&Workspace<W>> {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &self.monitor_set
        else {
            return None;
        };

        let mon = &monitors[*active_monitor_idx];
        Some(&mon.workspaces[mon.active_workspace_idx])
    }

    pub fn active_window(&self) -> Option<(&W, &Output)> {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &self.monitor_set
        else {
            return None;
        };

        let mon = &monitors[*active_monitor_idx];
        let ws = &mon.workspaces[mon.active_workspace_idx];

        if ws.columns.is_empty() {
            return None;
        }

        let col = &ws.columns[ws.active_column_idx];
        Some((col.tiles[col.active_tile_idx].window(), &mon.output))
    }

    pub fn windows_for_output(&self, output: &Output) -> impl Iterator<Item = &W> + '_ {
        let MonitorSet::Normal { monitors, .. } = &self.monitor_set else {
            panic!()
        };

        let mon = monitors.iter().find(|mon| &mon.output == output).unwrap();
        mon.workspaces.iter().flat_map(|ws| ws.windows())
    }

    pub fn with_windows(&self, mut f: impl FnMut(&W, Option<&Output>)) {
        match &self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mon.workspaces {
                        for win in ws.windows() {
                            f(win, Some(&mon.output));
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces } => {
                for ws in workspaces {
                    for win in ws.windows() {
                        f(win, None);
                    }
                }
            }
        }
    }

    pub fn with_windows_mut(&mut self, mut f: impl FnMut(&mut W, Option<&Output>)) {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        for win in ws.windows_mut() {
                            f(win, Some(&mon.output));
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces } => {
                for ws in workspaces {
                    for win in ws.windows_mut() {
                        f(win, None);
                    }
                }
            }
        }
    }

    fn active_monitor(&mut self) -> Option<&mut Monitor<W>> {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        else {
            return None;
        };

        Some(&mut monitors[*active_monitor_idx])
    }

    pub fn active_monitor_ref(&self) -> Option<&Monitor<W>> {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &self.monitor_set
        else {
            return None;
        };

        Some(&monitors[*active_monitor_idx])
    }

    pub fn monitor_for_output(&self, output: &Output) -> Option<&Monitor<W>> {
        let MonitorSet::Normal { monitors, .. } = &self.monitor_set else {
            return None;
        };

        monitors.iter().find(|monitor| &monitor.output == output)
    }

    pub fn monitor_for_workspace(&self, workspace_name: &str) -> Option<&Monitor<W>> {
        let MonitorSet::Normal { monitors, .. } = &self.monitor_set else {
            return None;
        };

        monitors.iter().find(|monitor| {
            monitor.workspaces.iter().any(|ws| {
                ws.name
                    .as_ref()
                    .map_or(false, |name| name.eq_ignore_ascii_case(workspace_name))
            })
        })
    }

    pub fn outputs(&self) -> impl Iterator<Item = &Output> + '_ {
        let monitors = if let MonitorSet::Normal { monitors, .. } = &self.monitor_set {
            &monitors[..]
        } else {
            &[][..]
        };

        monitors.iter().map(|mon| &mon.output)
    }

    pub fn move_left(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_left();
    }

    pub fn move_right(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_right();
    }

    pub fn move_column_to_first(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_column_to_first();
    }

    pub fn move_column_to_last(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_column_to_last();
    }

    pub fn move_down(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_down();
    }

    pub fn move_up(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_up();
    }

    pub fn move_down_or_to_workspace_down(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_down_or_to_workspace_down();
    }

    pub fn move_up_or_to_workspace_up(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_up_or_to_workspace_up();
    }

    pub fn consume_or_expel_window_left(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.consume_or_expel_window_left();
    }

    pub fn consume_or_expel_window_right(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.consume_or_expel_window_right();
    }

    pub fn focus_left(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_left();
    }

    pub fn focus_right(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_right();
    }

    pub fn focus_column_first(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_column_first();
    }

    pub fn focus_column_last(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_column_last();
    }

    pub fn focus_column_right_or_first(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_column_right_or_first();
    }

    pub fn focus_column_left_or_last(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_column_left_or_last();
    }

    pub fn focus_column_left_or_output(&mut self, output: &Output) -> bool {
        if let Some(monitor) = self.active_monitor() {
            let workspace = monitor.active_workspace();
            let curr_idx = workspace.active_column_idx;

            if !workspace.columns.is_empty() && curr_idx != 0 {
                monitor.focus_left();
                return false;
            }
        }

        self.focus_output(output);
        true
    }

    pub fn focus_column_right_or_output(&mut self, output: &Output) -> bool {
        if let Some(monitor) = self.active_monitor() {
            let workspace = monitor.active_workspace();
            let curr_idx = workspace.active_column_idx;
            let columns = &workspace.columns;

            if !workspace.columns.is_empty() && curr_idx != columns.len() - 1 {
                monitor.focus_right();
                return false;
            }
        }

        self.focus_output(output);
        true
    }

    pub fn focus_down(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_down();
    }

    pub fn focus_up(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_up();
    }

    pub fn focus_down_or_left(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_down_or_left();
    }

    pub fn focus_down_or_right(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_down_or_right();
    }

    pub fn focus_up_or_left(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_up_or_left();
    }

    pub fn focus_up_or_right(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_up_or_right();
    }

    pub fn focus_window_or_workspace_down(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_window_or_workspace_down();
    }

    pub fn focus_window_or_workspace_up(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.focus_window_or_workspace_up();
    }

    pub fn move_to_workspace_up(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_to_workspace_up();
    }

    pub fn move_to_workspace_down(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_to_workspace_down();
    }

    pub fn move_to_workspace(&mut self, idx: usize) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_to_workspace(idx);
    }

    pub fn move_to_workspace_on_output(&mut self, output: &Output, idx: usize) {
        self.move_to_output(output);
        self.focus_output(output);
        self.move_to_workspace(idx);
    }

    pub fn move_column_to_workspace_up(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_column_to_workspace_up();
    }

    pub fn move_column_to_workspace_down(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_column_to_workspace_down();
    }

    pub fn move_column_to_workspace(&mut self, idx: usize) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_column_to_workspace(idx);
    }

    pub fn move_column_to_workspace_on_output(&mut self, output: &Output, idx: usize) {
        self.move_to_output(output);
        self.focus_output(output);
        self.move_column_to_workspace(idx);
    }

    pub fn switch_workspace_up(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.switch_workspace_up();
    }

    pub fn switch_workspace_down(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.switch_workspace_down();
    }

    pub fn switch_workspace(&mut self, idx: usize) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.switch_workspace(idx, false);
    }

    pub fn switch_workspace_auto_back_and_forth(&mut self, idx: usize) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.switch_workspace_auto_back_and_forth(idx);
    }

    pub fn switch_workspace_previous(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.switch_workspace_previous();
    }

    pub fn consume_into_column(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.consume_into_column();
    }

    pub fn expel_from_column(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.expel_from_column();
    }

    pub fn center_column(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.center_column();
    }

    pub fn focus(&self) -> Option<&W> {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &self.monitor_set
        else {
            return None;
        };

        monitors[*active_monitor_idx].focus()
    }

    /// Returns the window under the cursor and the position of its toplevel surface within the
    /// output.
    ///
    /// `Some((w, Some(p)))` means that the cursor is within the window's input region and can be
    /// used for delivering events to the window. `Some((w, None))` means that the cursor is within
    /// the window's activation region, but not within the window's input region. For example, the
    /// cursor may be on the window's server-side border.
    pub fn window_under(
        &self,
        output: &Output,
        pos_within_output: Point<f64, Logical>,
    ) -> Option<(&W, Option<Point<f64, Logical>>)> {
        let MonitorSet::Normal { monitors, .. } = &self.monitor_set else {
            return None;
        };

        let mon = monitors.iter().find(|mon| &mon.output == output)?;
        mon.window_under(pos_within_output)
    }

    pub fn resize_edges_under(
        &self,
        output: &Output,
        pos_within_output: Point<f64, Logical>,
    ) -> Option<ResizeEdge> {
        let MonitorSet::Normal { monitors, .. } = &self.monitor_set else {
            return None;
        };

        let mon = monitors.iter().find(|mon| &mon.output == output)?;
        mon.resize_edges_under(pos_within_output)
    }

    #[cfg(test)]
    fn verify_invariants(&self) {
        use std::collections::HashSet;

        use crate::layout::monitor::WorkspaceSwitch;

        let mut seen_workspace_id = HashSet::new();
        let mut seen_workspace_name = Vec::<String>::new();

        let (monitors, &primary_idx, &active_monitor_idx) = match &self.monitor_set {
            MonitorSet::Normal {
                monitors,
                primary_idx,
                active_monitor_idx,
            } => (monitors, primary_idx, active_monitor_idx),
            MonitorSet::NoOutputs { workspaces } => {
                for workspace in workspaces {
                    assert!(
                        workspace.has_windows() || workspace.name.is_some(),
                        "with no outputs there cannot be empty unnamed workspaces"
                    );

                    assert_eq!(
                        workspace.base_options, self.options,
                        "workspace base options must be synchronized with layout"
                    );

                    let options = Options::clone(&workspace.base_options)
                        .adjusted_for_scale(workspace.scale().fractional_scale());
                    assert_eq!(
                        &*workspace.options, &options,
                        "workspace options must be base options adjusted for workspace scale"
                    );

                    assert!(
                        seen_workspace_id.insert(workspace.id()),
                        "workspace id must be unique"
                    );

                    if let Some(name) = &workspace.name {
                        assert!(
                            !seen_workspace_name
                                .iter()
                                .any(|n| n.eq_ignore_ascii_case(name)),
                            "workspace name must be unique"
                        );
                        seen_workspace_name.push(name.clone());
                    }

                    workspace.verify_invariants();
                }

                return;
            }
        };

        assert!(primary_idx < monitors.len());
        assert!(active_monitor_idx < monitors.len());

        for (idx, monitor) in monitors.iter().enumerate() {
            assert!(
                !monitor.workspaces.is_empty(),
                "monitor must have at least one workspace"
            );
            assert!(monitor.active_workspace_idx < monitor.workspaces.len());

            assert_eq!(
                monitor.options, self.options,
                "monitor options must be synchronized with layout"
            );

            if let Some(WorkspaceSwitch::Animation(anim)) = &monitor.workspace_switch {
                let before_idx = anim.from() as usize;
                let after_idx = anim.to() as usize;

                assert!(before_idx < monitor.workspaces.len());
                assert!(after_idx < monitor.workspaces.len());
            }

            let monitor_id = OutputId::new(&monitor.output);

            if idx == primary_idx {
                for ws in &monitor.workspaces {
                    if ws.original_output == monitor_id {
                        // This is the primary monitor's own workspace.
                        continue;
                    }

                    let own_monitor_exists = monitors
                        .iter()
                        .any(|m| OutputId::new(&m.output) == ws.original_output);
                    assert!(
                        !own_monitor_exists,
                        "primary monitor cannot have workspaces for which their own monitor exists"
                    );
                }
            } else {
                assert!(
                    monitor
                        .workspaces
                        .iter()
                        .any(|workspace| workspace.original_output == monitor_id),
                    "secondary monitor must not have any non-own workspaces"
                );
            }

            assert!(
                monitor.workspaces.last().unwrap().columns.is_empty(),
                "monitor must have an empty workspace in the end"
            );

            assert!(
                monitor.workspaces.last().unwrap().name.is_none(),
                "monitor must have an unnamed workspace in the end"
            );

            // If there's no workspace switch in progress, there can't be any non-last non-active
            // empty workspaces.
            if monitor.workspace_switch.is_none() {
                for (idx, ws) in monitor.workspaces.iter().enumerate().rev().skip(1) {
                    if idx != monitor.active_workspace_idx {
                        assert!(
                            !ws.columns.is_empty() || ws.name.is_some(),
                            "non-active workspace can't be empty and unnamed except the last one"
                        );
                    }
                }
            }

            // FIXME: verify that primary doesn't have any workspaces for which their own monitor
            // exists.

            for workspace in &monitor.workspaces {
                assert_eq!(
                    workspace.base_options, self.options,
                    "workspace options must be synchronized with layout"
                );

                let options = Options::clone(&workspace.base_options)
                    .adjusted_for_scale(workspace.scale().fractional_scale());
                assert_eq!(
                    &*workspace.options, &options,
                    "workspace options must be base options adjusted for workspace scale"
                );

                assert!(
                    seen_workspace_id.insert(workspace.id()),
                    "workspace id must be unique"
                );

                if let Some(name) = &workspace.name {
                    assert!(
                        !seen_workspace_name
                            .iter()
                            .any(|n| n.eq_ignore_ascii_case(name)),
                        "workspace name must be unique"
                    );
                    seen_workspace_name.push(name.clone());
                }

                workspace.verify_invariants();
            }
        }
    }

    pub fn advance_animations(&mut self, current_time: Duration) {
        let _span = tracy_client::span!("Layout::advance_animations");

        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    mon.advance_animations(current_time);
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    ws.advance_animations(current_time);
                }
            }
        }
    }

    pub fn update_render_elements(&mut self, output: &Output) {
        let _span = tracy_client::span!("Layout::update_render_elements");

        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        else {
            error!("update_render_elements called with no monitors");
            return;
        };

        for (idx, mon) in monitors.iter_mut().enumerate() {
            if mon.output == *output {
                mon.update_render_elements(idx == *active_monitor_idx);
                return;
            }
        }
    }

    pub fn update_render_elements_all(&mut self) {
        let _span = tracy_client::span!("Layout::update_render_elements_all");

        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        else {
            error!("update_render_elements_all called with no monitors");
            return;
        };

        for (idx, mon) in monitors.iter_mut().enumerate() {
            mon.update_render_elements(idx == *active_monitor_idx);
        }
    }

    pub fn update_shaders(&mut self) {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        ws.update_shaders();
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    ws.update_shaders();
                }
            }
        }
    }

    pub fn ensure_named_workspace(&mut self, ws_config: &WorkspaceConfig) {
        if self.find_workspace_by_name(&ws_config.name.0).is_some() {
            return;
        }

        let options = self.options.clone();

        match &mut self.monitor_set {
            MonitorSet::Normal {
                monitors,
                primary_idx,
                active_monitor_idx,
            } => {
                let mon_idx = ws_config
                    .open_on_output
                    .as_deref()
                    .map(|name| {
                        monitors
                            .iter_mut()
                            .position(|monitor| monitor.output.name().eq_ignore_ascii_case(name))
                            .unwrap_or(*primary_idx)
                    })
                    .unwrap_or(*active_monitor_idx);
                let mon = &mut monitors[mon_idx];

                let ws = Workspace::new_with_config(
                    mon.output.clone(),
                    Some(ws_config.clone()),
                    options,
                );
                mon.workspaces.insert(0, ws);
                mon.active_workspace_idx += 1;
                mon.workspace_switch = None;
                mon.clean_up_workspaces();
            }
            MonitorSet::NoOutputs { workspaces } => {
                let ws = Workspace::new_with_config_no_outputs(Some(ws_config.clone()), options);
                workspaces.insert(0, ws);
            }
        }
    }

    pub fn update_config(&mut self, config: &Config) {
        let options = Rc::new(Options::from_config(config));

        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    mon.update_config(options.clone());
                }
            }
            MonitorSet::NoOutputs { workspaces } => {
                for ws in workspaces {
                    ws.update_config(options.clone());
                }
            }
        }

        self.options = options;
    }

    pub fn toggle_width(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.toggle_width();
    }

    pub fn toggle_full_width(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.toggle_full_width();
    }

    pub fn set_column_width(&mut self, change: SizeChange) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.set_column_width(change);
    }

    pub fn set_window_height(&mut self, change: SizeChange) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.set_window_height(change);
    }

    pub fn reset_window_height(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.reset_window_height();
    }

    pub fn focus_output(&mut self, output: &Output) {
        if let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        {
            for (idx, mon) in monitors.iter().enumerate() {
                if &mon.output == output {
                    *active_monitor_idx = idx;
                    return;
                }
            }
        }
    }

    pub fn move_to_output(&mut self, output: &Output) {
        if let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        {
            let new_idx = monitors
                .iter()
                .position(|mon| &mon.output == output)
                .unwrap();

            let current = &mut monitors[*active_monitor_idx];
            let ws = current.active_workspace();
            if !ws.has_windows() {
                return;
            }
            let column = &ws.columns[ws.active_column_idx];
            let width = column.width;
            let is_full_width = column.is_full_width;
            let window = ws
                .remove_tile_by_idx(ws.active_column_idx, column.active_tile_idx, None)
                .into_window();

            let workspace_idx = monitors[new_idx].active_workspace_idx;
            self.add_window_by_idx(new_idx, workspace_idx, window, true, width, is_full_width);
        }
    }

    pub fn move_column_to_output(&mut self, output: &Output) {
        if let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        {
            let new_idx = monitors
                .iter()
                .position(|mon| &mon.output == output)
                .unwrap();

            let current = &mut monitors[*active_monitor_idx];
            let ws = current.active_workspace();
            if !ws.has_windows() {
                return;
            }
            let column = ws.remove_column_by_idx(ws.active_column_idx);

            let workspace_idx = monitors[new_idx].active_workspace_idx;
            self.add_column_by_idx(new_idx, workspace_idx, column, true);
        }
    }

    pub fn move_window_to_output(&mut self, window: &W::Id, output: &Output) {
        let mut width = None;
        let mut is_full_width = false;

        if let MonitorSet::Normal { monitors, .. } = &mut self.monitor_set {
            for mon in &*monitors {
                for ws in &mon.workspaces {
                    for col in &ws.columns {
                        if col.contains(window) {
                            width = Some(col.width);
                            is_full_width = col.is_full_width;
                            break;
                        }
                    }
                }
            }
        }

        let Some(width) = width else { return };

        let window = self.remove_window(window).unwrap();

        if let MonitorSet::Normal { monitors, .. } = &mut self.monitor_set {
            let new_idx = monitors
                .iter()
                .position(|mon| &mon.output == output)
                .unwrap();

            let workspace_idx = monitors[new_idx].active_workspace_idx;
            // FIXME: activate only if it was already active and focused.
            self.add_window_by_idx(new_idx, workspace_idx, window, true, width, is_full_width);
        }
    }

    pub fn move_workspace_to_output(&mut self, output: &Output) {
        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = &mut self.monitor_set
        else {
            return;
        };

        let current = &mut monitors[*active_monitor_idx];
        if current.active_workspace_idx == current.workspaces.len() - 1 {
            // Insert a new empty workspace.
            let ws = Workspace::new(current.output.clone(), current.options.clone());
            current.workspaces.push(ws);
        }
        let mut ws = current.workspaces.remove(current.active_workspace_idx);
        current.active_workspace_idx = current.active_workspace_idx.saturating_sub(1);
        current.workspace_switch = None;
        current.clean_up_workspaces();

        ws.set_output(Some(output.clone()));
        ws.original_output = OutputId::new(output);

        let target_idx = monitors
            .iter()
            .position(|mon| &mon.output == output)
            .unwrap();
        let target = &mut monitors[target_idx];

        target.previous_workspace_id = Some(target.workspaces[target.active_workspace_idx].id());

        // Insert the workspace after the currently active one. Unless the currently active one is
        // the last empty workspace, then insert before.
        let target_ws_idx = min(target.active_workspace_idx + 1, target.workspaces.len() - 1);
        target.workspaces.insert(target_ws_idx, ws);
        target.active_workspace_idx = target_ws_idx;
        target.workspace_switch = None;
        target.clean_up_workspaces();

        *active_monitor_idx = target_idx;
    }

    pub fn set_fullscreen(&mut self, window: &W::Id, is_fullscreen: bool) {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        if ws.has_window(window) {
                            ws.set_fullscreen(window, is_fullscreen);
                            return;
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    if ws.has_window(window) {
                        ws.set_fullscreen(window, is_fullscreen);
                        return;
                    }
                }
            }
        }
    }

    pub fn toggle_fullscreen(&mut self, window: &W::Id) {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        if ws.has_window(window) {
                            ws.toggle_fullscreen(window);
                            return;
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    if ws.has_window(window) {
                        ws.toggle_fullscreen(window);
                        return;
                    }
                }
            }
        }
    }

    pub fn workspace_switch_gesture_begin(&mut self, output: &Output, is_touchpad: bool) {
        let monitors = match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => monitors,
            MonitorSet::NoOutputs { .. } => unreachable!(),
        };

        for monitor in monitors {
            // Cancel the gesture on other outputs.
            if &monitor.output != output {
                monitor.workspace_switch_gesture_end(true, None);
                continue;
            }

            monitor.workspace_switch_gesture_begin(is_touchpad);
        }
    }

    pub fn workspace_switch_gesture_update(
        &mut self,
        delta_y: f64,
        timestamp: Duration,
        is_touchpad: bool,
    ) -> Option<Option<Output>> {
        let monitors = match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => monitors,
            MonitorSet::NoOutputs { .. } => return None,
        };

        for monitor in monitors {
            if let Some(refresh) =
                monitor.workspace_switch_gesture_update(delta_y, timestamp, is_touchpad)
            {
                if refresh {
                    return Some(Some(monitor.output.clone()));
                } else {
                    return Some(None);
                }
            }
        }

        None
    }

    pub fn workspace_switch_gesture_end(
        &mut self,
        cancelled: bool,
        is_touchpad: Option<bool>,
    ) -> Option<Output> {
        let monitors = match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => monitors,
            MonitorSet::NoOutputs { .. } => return None,
        };

        for monitor in monitors {
            if monitor.workspace_switch_gesture_end(cancelled, is_touchpad) {
                return Some(monitor.output.clone());
            }
        }

        None
    }

    pub fn view_offset_gesture_begin(&mut self, output: &Output, is_touchpad: bool) {
        let monitors = match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => monitors,
            MonitorSet::NoOutputs { .. } => unreachable!(),
        };

        for monitor in monitors {
            for (idx, ws) in monitor.workspaces.iter_mut().enumerate() {
                // Cancel the gesture on other workspaces.
                if &monitor.output != output || idx != monitor.active_workspace_idx {
                    ws.view_offset_gesture_end(true, None);
                    continue;
                }

                ws.view_offset_gesture_begin(is_touchpad);
            }
        }
    }

    pub fn view_offset_gesture_update(
        &mut self,
        delta_x: f64,
        timestamp: Duration,
        is_touchpad: bool,
    ) -> Option<Option<Output>> {
        let monitors = match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => monitors,
            MonitorSet::NoOutputs { .. } => return None,
        };

        for monitor in monitors {
            for ws in &mut monitor.workspaces {
                if let Some(refresh) =
                    ws.view_offset_gesture_update(delta_x, timestamp, is_touchpad)
                {
                    if refresh {
                        return Some(Some(monitor.output.clone()));
                    } else {
                        return Some(None);
                    }
                }
            }
        }

        None
    }

    pub fn view_offset_gesture_end(
        &mut self,
        cancelled: bool,
        is_touchpad: Option<bool>,
    ) -> Option<Output> {
        let monitors = match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => monitors,
            MonitorSet::NoOutputs { .. } => return None,
        };

        for monitor in monitors {
            for ws in &mut monitor.workspaces {
                if ws.view_offset_gesture_end(cancelled, is_touchpad) {
                    return Some(monitor.output.clone());
                }
            }
        }

        None
    }

    pub fn interactive_resize_begin(&mut self, window: W::Id, edges: ResizeEdge) -> bool {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        if ws.has_window(&window) {
                            return ws.interactive_resize_begin(window, edges);
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    if ws.has_window(&window) {
                        return ws.interactive_resize_begin(window, edges);
                    }
                }
            }
        }

        false
    }

    pub fn interactive_resize_update(
        &mut self,
        window: &W::Id,
        delta: Point<f64, Logical>,
    ) -> bool {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        if ws.has_window(window) {
                            return ws.interactive_resize_update(window, delta);
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    if ws.has_window(window) {
                        return ws.interactive_resize_update(window, delta);
                    }
                }
            }
        }

        false
    }

    pub fn interactive_resize_end(&mut self, window: &W::Id) {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        if ws.has_window(window) {
                            ws.interactive_resize_end(Some(window));
                            return;
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    if ws.has_window(window) {
                        ws.interactive_resize_end(Some(window));
                        return;
                    }
                }
            }
        }
    }

    pub fn move_workspace_down(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_workspace_down();
    }

    pub fn move_workspace_up(&mut self) {
        let Some(monitor) = self.active_monitor() else {
            return;
        };
        monitor.move_workspace_up();
    }

    pub fn start_open_animation_for_window(&mut self, window: &W::Id) {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        for col in &mut ws.columns {
                            for tile in &mut col.tiles {
                                if tile.window().id() == window {
                                    tile.start_open_animation();
                                    return;
                                }
                            }
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    for col in &mut ws.columns {
                        for tile in &mut col.tiles {
                            if tile.window().id() == window {
                                tile.start_open_animation();
                                return;
                            }
                        }
                    }
                }
            }
        }
    }

    pub fn store_unmap_snapshot(&mut self, renderer: &mut GlesRenderer, window: &W::Id) {
        let _span = tracy_client::span!("Layout::store_unmap_snapshot");

        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        if ws.has_window(window) {
                            ws.store_unmap_snapshot_if_empty(renderer, window);
                            return;
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    if ws.has_window(window) {
                        ws.store_unmap_snapshot_if_empty(renderer, window);
                        return;
                    }
                }
            }
        }
    }

    pub fn clear_unmap_snapshot(&mut self, window: &W::Id) {
        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        if ws.has_window(window) {
                            ws.clear_unmap_snapshot(window);
                            return;
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    if ws.has_window(window) {
                        ws.clear_unmap_snapshot(window);
                        return;
                    }
                }
            }
        }
    }

    pub fn start_close_animation_for_window(
        &mut self,
        renderer: &mut GlesRenderer,
        window: &W::Id,
    ) {
        let _span = tracy_client::span!("Layout::start_close_animation_for_window");

        match &mut self.monitor_set {
            MonitorSet::Normal { monitors, .. } => {
                for mon in monitors {
                    for ws in &mut mon.workspaces {
                        if ws.has_window(window) {
                            ws.start_close_animation_for_window(renderer, window);
                            return;
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    if ws.has_window(window) {
                        ws.start_close_animation_for_window(renderer, window);
                        return;
                    }
                }
            }
        }
    }

    pub fn refresh(&mut self) {
        let _span = tracy_client::span!("Layout::refresh");

        match &mut self.monitor_set {
            MonitorSet::Normal {
                monitors,
                active_monitor_idx,
                ..
            } => {
                for (idx, mon) in monitors.iter_mut().enumerate() {
                    let is_active = idx == *active_monitor_idx;
                    for (ws_idx, ws) in mon.workspaces.iter_mut().enumerate() {
                        ws.refresh(is_active);

                        // Cancel the view offset gesture after workspace switches, moves, etc.
                        if ws_idx != mon.active_workspace_idx {
                            ws.view_offset_gesture_end(false, None);
                        }
                    }
                }
            }
            MonitorSet::NoOutputs { workspaces, .. } => {
                for ws in workspaces {
                    ws.refresh(false);
                    ws.view_offset_gesture_end(false, None);
                }
            }
        }
    }

    pub fn ipc_workspaces(&self) -> Vec<niri_ipc::Workspace> {
        match &self.monitor_set {
            MonitorSet::Normal {
                monitors,
                primary_idx: _,
                active_monitor_idx: _,
            } => {
                let mut workspaces = Vec::new();

                for monitor in monitors {
                    for (idx, workspace) in monitor.workspaces.iter().enumerate() {
                        workspaces.push(niri_ipc::Workspace {
                            idx: u8::try_from(idx + 1).unwrap_or(u8::MAX),
                            name: workspace.name.clone(),
                            output: Some(monitor.output.name()),
                            is_active: monitor.active_workspace_idx == idx,
                        })
                    }
                }

                workspaces
            }
            MonitorSet::NoOutputs { workspaces } => workspaces
                .iter()
                .enumerate()
                .map(|(idx, ws)| niri_ipc::Workspace {
                    idx: u8::try_from(idx + 1).unwrap_or(u8::MAX),
                    name: ws.name.clone(),
                    output: None,
                    is_active: false,
                })
                .collect(),
        }
    }
}

impl<W: LayoutElement> Default for MonitorSet<W> {
    fn default() -> Self {
        Self::NoOutputs { workspaces: vec![] }
    }
}

#[cfg(test)]
mod tests {
    use std::cell::Cell;

    use niri_config::{FloatOrInt, WorkspaceName};
    use proptest::prelude::*;
    use proptest_derive::Arbitrary;
    use smithay::output::{Mode, PhysicalProperties, Subpixel};
    use smithay::utils::Rectangle;

    use super::*;
    use crate::utils::round_logical_in_physical;

    impl<W: LayoutElement> Default for Layout<W> {
        fn default() -> Self {
            Self::with_options(Default::default())
        }
    }

    #[derive(Debug)]
    struct TestWindowInner {
        id: usize,
        bbox: Cell<Rectangle<i32, Logical>>,
        initial_bbox: Rectangle<i32, Logical>,
        requested_size: Cell<Option<Size<i32, Logical>>>,
        min_size: Size<i32, Logical>,
        max_size: Size<i32, Logical>,
        pending_fullscreen: Cell<bool>,
    }

    #[derive(Debug, Clone)]
    struct TestWindow(Rc<TestWindowInner>);

    impl TestWindow {
        fn new(
            id: usize,
            bbox: Rectangle<i32, Logical>,
            min_size: Size<i32, Logical>,
            max_size: Size<i32, Logical>,
        ) -> Self {
            Self(Rc::new(TestWindowInner {
                id,
                bbox: Cell::new(bbox),
                initial_bbox: bbox,
                requested_size: Cell::new(None),
                min_size,
                max_size,
                pending_fullscreen: Cell::new(false),
            }))
        }

        fn communicate(&self) -> bool {
            if let Some(size) = self.0.requested_size.take() {
                assert!(size.w >= 0);
                assert!(size.h >= 0);

                let mut new_bbox = self.0.initial_bbox;
                if size.w != 0 {
                    new_bbox.size.w = size.w;
                }
                if size.h != 0 {
                    new_bbox.size.h = size.h;
                }

                if self.0.bbox.get() != new_bbox {
                    self.0.bbox.set(new_bbox);
                    return true;
                }
            }

            false
        }
    }

    impl LayoutElement for TestWindow {
        type Id = usize;

        fn id(&self) -> &Self::Id {
            &self.0.id
        }

        fn size(&self) -> Size<i32, Logical> {
            self.0.bbox.get().size
        }

        fn buf_loc(&self) -> Point<i32, Logical> {
            (0, 0).into()
        }

        fn is_in_input_region(&self, _point: Point<f64, Logical>) -> bool {
            false
        }

        fn render<R: NiriRenderer>(
            &self,
            _renderer: &mut R,
            _location: Point<f64, Logical>,
            _scale: Scale<f64>,
            _alpha: f32,
            _target: RenderTarget,
        ) -> SplitElements<LayoutElementRenderElement<R>> {
            SplitElements::default()
        }

        fn request_size(&mut self, size: Size<i32, Logical>, _animate: bool) {
            self.0.requested_size.set(Some(size));
            self.0.pending_fullscreen.set(false);
        }

        fn request_fullscreen(&self, _size: Size<i32, Logical>) {
            self.0.pending_fullscreen.set(true);
        }

        fn min_size(&self) -> Size<i32, Logical> {
            self.0.min_size
        }

        fn max_size(&self) -> Size<i32, Logical> {
            self.0.max_size
        }

        fn is_wl_surface(&self, _wl_surface: &WlSurface) -> bool {
            false
        }

        fn set_preferred_scale_transform(&self, _scale: output::Scale, _transform: Transform) {}

        fn has_ssd(&self) -> bool {
            false
        }

        fn output_enter(&self, _output: &Output) {}

        fn output_leave(&self, _output: &Output) {}

        fn set_offscreen_element_id(&self, _id: Option<Id>) {}

        fn set_activated(&mut self, _active: bool) {}

        fn set_bounds(&self, _bounds: Size<i32, Logical>) {}

        fn send_pending_configure(&mut self) {}

        fn set_active_in_column(&mut self, _active: bool) {}

        fn is_fullscreen(&self) -> bool {
            false
        }

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

        fn refresh(&self) {}

        fn rules(&self) -> &ResolvedWindowRules {
            static EMPTY: ResolvedWindowRules = ResolvedWindowRules::empty();
            &EMPTY
        }

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

        fn take_animation_snapshot(&mut self) -> Option<LayoutElementRenderSnapshot> {
            None
        }

        fn set_interactive_resize(&mut self, _data: Option<InteractiveResizeData>) {}

        fn cancel_interactive_resize(&mut self) {}

        fn update_interactive_resize(&mut self, _serial: Serial) {}

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

    fn arbitrary_bbox() -> impl Strategy<Value = Rectangle<i32, Logical>> {
        any::<(i16, i16, u16, u16)>().prop_map(|(x, y, w, h)| {
            let loc: Point<i32, _> = Point::from((x.into(), y.into()));
            let size: Size<i32, _> = Size::from((w.into(), h.into()));
            Rectangle::from_loc_and_size(loc, size)
        })
    }

    fn arbitrary_size_change() -> impl Strategy<Value = SizeChange> {
        prop_oneof![
            (0..).prop_map(SizeChange::SetFixed),
            (0f64..).prop_map(SizeChange::SetProportion),
            any::<i32>().prop_map(SizeChange::AdjustFixed),
            any::<f64>().prop_map(SizeChange::AdjustProportion),
        ]
    }

    fn arbitrary_min_max() -> impl Strategy<Value = (i32, i32)> {
        prop_oneof![
            Just((0, 0)),
            (1..65536).prop_map(|n| (n, n)),
            (1..65536).prop_map(|min| (min, 0)),
            (1..).prop_map(|max| (0, max)),
            (1..65536, 1..).prop_map(|(min, max): (i32, i32)| (min, max.max(min))),
        ]
    }

    fn arbitrary_min_max_size() -> impl Strategy<Value = (Size<i32, Logical>, Size<i32, Logical>)> {
        (arbitrary_min_max(), arbitrary_min_max()).prop_map(|((min_w, max_w), (min_h, max_h))| {
            let min_size = Size::from((min_w, min_h));
            let max_size = Size::from((max_w, max_h));
            (min_size, max_size)
        })
    }

    fn arbitrary_view_offset_gesture_delta() -> impl Strategy<Value = f64> {
        prop_oneof![(-10f64..10f64), (-50000f64..50000f64),]
    }

    fn arbitrary_resize_edge() -> impl Strategy<Value = ResizeEdge> {
        prop_oneof![
            Just(ResizeEdge::RIGHT),
            Just(ResizeEdge::BOTTOM),
            Just(ResizeEdge::LEFT),
            Just(ResizeEdge::TOP),
            Just(ResizeEdge::BOTTOM_RIGHT),
            Just(ResizeEdge::BOTTOM_LEFT),
            Just(ResizeEdge::TOP_RIGHT),
            Just(ResizeEdge::TOP_LEFT),
            Just(ResizeEdge::empty()),
        ]
    }

    fn arbitrary_scale() -> impl Strategy<Value = f64> {
        prop_oneof![Just(1.), Just(1.5), Just(2.),]
    }

    #[derive(Debug, Clone, Copy, Arbitrary)]
    enum Op {
        AddOutput(#[proptest(strategy = "1..=5usize")] usize),
        AddScaledOutput {
            #[proptest(strategy = "1..=5usize")]
            id: usize,
            #[proptest(strategy = "arbitrary_scale()")]
            scale: f64,
        },
        RemoveOutput(#[proptest(strategy = "1..=5usize")] usize),
        FocusOutput(#[proptest(strategy = "1..=5usize")] usize),
        AddNamedWorkspace {
            #[proptest(strategy = "1..=5usize")]
            ws_name: usize,
            #[proptest(strategy = "prop::option::of(1..=5usize)")]
            output_name: Option<usize>,
        },
        UnnameWorkspace {
            #[proptest(strategy = "1..=5usize")]
            ws_name: usize,
        },
        AddWindow {
            #[proptest(strategy = "1..=5usize")]
            id: usize,
            #[proptest(strategy = "arbitrary_bbox()")]
            bbox: Rectangle<i32, Logical>,
            #[proptest(strategy = "arbitrary_min_max_size()")]
            min_max_size: (Size<i32, Logical>, Size<i32, Logical>),
        },
        AddWindowRightOf {
            #[proptest(strategy = "1..=5usize")]
            id: usize,
            #[proptest(strategy = "1..=5usize")]
            right_of_id: usize,
            #[proptest(strategy = "arbitrary_bbox()")]
            bbox: Rectangle<i32, Logical>,
            #[proptest(strategy = "arbitrary_min_max_size()")]
            min_max_size: (Size<i32, Logical>, Size<i32, Logical>),
        },
        AddWindowToNamedWorkspace {
            #[proptest(strategy = "1..=5usize")]
            id: usize,
            #[proptest(strategy = "1..=5usize")]
            ws_name: usize,
            #[proptest(strategy = "arbitrary_bbox()")]
            bbox: Rectangle<i32, Logical>,
            #[proptest(strategy = "arbitrary_min_max_size()")]
            min_max_size: (Size<i32, Logical>, Size<i32, Logical>),
        },
        CloseWindow(#[proptest(strategy = "1..=5usize")] usize),
        FullscreenWindow(#[proptest(strategy = "1..=5usize")] usize),
        SetFullscreenWindow {
            #[proptest(strategy = "1..=5usize")]
            window: usize,
            is_fullscreen: bool,
        },
        FocusColumnLeft,
        FocusColumnRight,
        FocusColumnFirst,
        FocusColumnLast,
        FocusColumnRightOrFirst,
        FocusColumnLeftOrLast,
        FocusColumnOrMonitorLeft(#[proptest(strategy = "1..=2u8")] u8),
        FocusColumnOrMonitorRight(#[proptest(strategy = "1..=2u8")] u8),
        FocusWindowDown,
        FocusWindowUp,
        FocusWindowDownOrColumnLeft,
        FocusWindowDownOrColumnRight,
        FocusWindowUpOrColumnLeft,
        FocusWindowUpOrColumnRight,
        FocusWindowOrWorkspaceDown,
        FocusWindowOrWorkspaceUp,
        MoveColumnLeft,
        MoveColumnRight,
        MoveColumnToFirst,
        MoveColumnToLast,
        MoveWindowDown,
        MoveWindowUp,
        MoveWindowDownOrToWorkspaceDown,
        MoveWindowUpOrToWorkspaceUp,
        ConsumeOrExpelWindowLeft,
        ConsumeOrExpelWindowRight,
        ConsumeWindowIntoColumn,
        ExpelWindowFromColumn,
        CenterColumn,
        FocusWorkspaceDown,
        FocusWorkspaceUp,
        FocusWorkspace(#[proptest(strategy = "0..=4usize")] usize),
        FocusWorkspaceAutoBackAndForth(#[proptest(strategy = "0..=4usize")] usize),
        FocusWorkspacePrevious,
        MoveWindowToWorkspaceDown,
        MoveWindowToWorkspaceUp,
        MoveWindowToWorkspace(#[proptest(strategy = "0..=4usize")] usize),
        MoveColumnToWorkspaceDown,
        MoveColumnToWorkspaceUp,
        MoveColumnToWorkspace(#[proptest(strategy = "0..=4usize")] usize),
        MoveWorkspaceDown,
        MoveWorkspaceUp,
        MoveWindowToOutput(#[proptest(strategy = "1..=5u8")] u8),
        MoveColumnToOutput(#[proptest(strategy = "1..=5u8")] u8),
        SwitchPresetColumnWidth,
        MaximizeColumn,
        SetColumnWidth(#[proptest(strategy = "arbitrary_size_change()")] SizeChange),
        SetWindowHeight(#[proptest(strategy = "arbitrary_size_change()")] SizeChange),
        ResetWindowHeight,
        Communicate(#[proptest(strategy = "1..=5usize")] usize),
        MoveWorkspaceToOutput(#[proptest(strategy = "1..=5u8")] u8),
        ViewOffsetGestureBegin {
            #[proptest(strategy = "1..=5usize")]
            output_idx: usize,
            is_touchpad: bool,
        },
        ViewOffsetGestureUpdate {
            #[proptest(strategy = "arbitrary_view_offset_gesture_delta()")]
            delta: f64,
            timestamp: Duration,
            is_touchpad: bool,
        },
        ViewOffsetGestureEnd {
            is_touchpad: Option<bool>,
        },
        WorkspaceSwitchGestureBegin {
            #[proptest(strategy = "1..=5usize")]
            output_idx: usize,
            is_touchpad: bool,
        },
        WorkspaceSwitchGestureUpdate {
            #[proptest(strategy = "-400f64..400f64")]
            delta: f64,
            timestamp: Duration,
            is_touchpad: bool,
        },
        WorkspaceSwitchGestureEnd {
            cancelled: bool,
            is_touchpad: Option<bool>,
        },
        InteractiveResizeBegin {
            #[proptest(strategy = "1..=5usize")]
            window: usize,
            #[proptest(strategy = "arbitrary_resize_edge()")]
            edges: ResizeEdge,
        },
        InteractiveResizeUpdate {
            #[proptest(strategy = "1..=5usize")]
            window: usize,
            #[proptest(strategy = "-20000f64..20000f64")]
            dx: f64,
            #[proptest(strategy = "-20000f64..20000f64")]
            dy: f64,
        },
        InteractiveResizeEnd {
            #[proptest(strategy = "1..=5usize")]
            window: usize,
        },
    }

    impl Op {
        fn apply(self, layout: &mut Layout<TestWindow>) {
            match self {
                Op::AddOutput(id) => {
                    let name = format!("output{id}");
                    if layout.outputs().any(|o| o.name() == name) {
                        return;
                    }

                    let output = Output::new(
                        name,
                        PhysicalProperties {
                            size: Size::from((1280, 720)),
                            subpixel: Subpixel::Unknown,
                            make: String::new(),
                            model: String::new(),
                        },
                    );
                    output.change_current_state(
                        Some(Mode {
                            size: Size::from((1280, 720)),
                            refresh: 60000,
                        }),
                        None,
                        None,
                        None,
                    );
                    layout.add_output(output.clone());
                }
                Op::AddScaledOutput { id, scale } => {
                    let name = format!("output{id}");
                    if layout.outputs().any(|o| o.name() == name) {
                        return;
                    }

                    let output = Output::new(
                        name,
                        PhysicalProperties {
                            size: Size::from((1280, 720)),
                            subpixel: Subpixel::Unknown,
                            make: String::new(),
                            model: String::new(),
                        },
                    );
                    output.change_current_state(
                        Some(Mode {
                            size: Size::from((1280, 720)),
                            refresh: 60000,
                        }),
                        None,
                        Some(smithay::output::Scale::Fractional(scale)),
                        None,
                    );
                    layout.add_output(output.clone());
                }
                Op::RemoveOutput(id) => {
                    let name = format!("output{id}");
                    let Some(output) = layout.outputs().find(|o| o.name() == name).cloned() else {
                        return;
                    };

                    layout.remove_output(&output);
                }
                Op::FocusOutput(id) => {
                    let name = format!("output{id}");
                    let Some(output) = layout.outputs().find(|o| o.name() == name).cloned() else {
                        return;
                    };

                    layout.focus_output(&output);
                }
                Op::AddNamedWorkspace {
                    ws_name,
                    output_name,
                } => {
                    layout.ensure_named_workspace(&WorkspaceConfig {
                        name: WorkspaceName(format!("ws{ws_name}")),
                        open_on_output: output_name.map(|name| format!("output{name}")),
                    });
                }
                Op::UnnameWorkspace { ws_name } => {
                    layout.unname_workspace(&format!("ws{ws_name}"));
                }
                Op::AddWindow {
                    id,
                    bbox,
                    min_max_size,
                } => {
                    match &mut layout.monitor_set {
                        MonitorSet::Normal { monitors, .. } => {
                            for mon in monitors {
                                for ws in &mut mon.workspaces {
                                    for win in ws.windows() {
                                        if win.0.id == id {
                                            return;
                                        }
                                    }
                                }
                            }
                        }
                        MonitorSet::NoOutputs { workspaces, .. } => {
                            for ws in workspaces {
                                for win in ws.windows() {
                                    if win.0.id == id {
                                        return;
                                    }
                                }
                            }
                        }
                    }

                    let win = TestWindow::new(id, bbox, min_max_size.0, min_max_size.1);
                    layout.add_window(win, None, false);
                }
                Op::AddWindowRightOf {
                    id,
                    right_of_id,
                    bbox,
                    min_max_size,
                } => {
                    let mut found_right_of = false;

                    match &mut layout.monitor_set {
                        MonitorSet::Normal { monitors, .. } => {
                            for mon in monitors {
                                for ws in &mut mon.workspaces {
                                    for win in ws.windows() {
                                        if win.0.id == id {
                                            return;
                                        }

                                        if win.0.id == right_of_id {
                                            found_right_of = true;
                                        }
                                    }
                                }
                            }
                        }
                        MonitorSet::NoOutputs { workspaces, .. } => {
                            for ws in workspaces {
                                for win in ws.windows() {
                                    if win.0.id == id {
                                        return;
                                    }

                                    if win.0.id == right_of_id {
                                        found_right_of = true;
                                    }
                                }
                            }
                        }
                    }

                    if !found_right_of {
                        return;
                    }

                    let win = TestWindow::new(id, bbox, min_max_size.0, min_max_size.1);
                    layout.add_window_right_of(&right_of_id, win, None, false);
                }
                Op::AddWindowToNamedWorkspace {
                    id,
                    ws_name,
                    bbox,
                    min_max_size,
                } => {
                    let ws_name = format!("ws{ws_name}");
                    let mut found_workspace = false;

                    match &mut layout.monitor_set {
                        MonitorSet::Normal { monitors, .. } => {
                            for mon in monitors {
                                for ws in &mut mon.workspaces {
                                    for win in ws.windows() {
                                        if win.0.id == id {
                                            return;
                                        }
                                    }

                                    if ws
                                        .name
                                        .as_ref()
                                        .map_or(false, |name| name.eq_ignore_ascii_case(&ws_name))
                                    {
                                        found_workspace = true;
                                    }
                                }
                            }
                        }
                        MonitorSet::NoOutputs { workspaces, .. } => {
                            for ws in workspaces {
                                for win in ws.windows() {
                                    if win.0.id == id {
                                        return;
                                    }
                                }

                                if ws
                                    .name
                                    .as_ref()
                                    .map_or(false, |name| name.eq_ignore_ascii_case(&ws_name))
                                {
                                    found_workspace = true;
                                }
                            }
                        }
                    }

                    if !found_workspace {
                        return;
                    }

                    let win = TestWindow::new(id, bbox, min_max_size.0, min_max_size.1);
                    layout.add_window_to_named_workspace(&ws_name, win, None, false);
                }
                Op::CloseWindow(id) => {
                    layout.remove_window(&id);
                }
                Op::FullscreenWindow(id) => {
                    layout.toggle_fullscreen(&id);
                }
                Op::SetFullscreenWindow {
                    window,
                    is_fullscreen,
                } => {
                    layout.set_fullscreen(&window, is_fullscreen);
                }
                Op::FocusColumnLeft => layout.focus_left(),
                Op::FocusColumnRight => layout.focus_right(),
                Op::FocusColumnFirst => layout.focus_column_first(),
                Op::FocusColumnLast => layout.focus_column_last(),
                Op::FocusColumnRightOrFirst => layout.focus_column_right_or_first(),
                Op::FocusColumnLeftOrLast => layout.focus_column_left_or_last(),
                Op::FocusColumnOrMonitorLeft(id) => {
                    let name = format!("output{id}");
                    let Some(output) = layout.outputs().find(|o| o.name() == name).cloned() else {
                        return;
                    };

                    layout.focus_column_left_or_output(&output);
                }
                Op::FocusColumnOrMonitorRight(id) => {
                    let name = format!("output{id}");
                    let Some(output) = layout.outputs().find(|o| o.name() == name).cloned() else {
                        return;
                    };

                    layout.focus_column_right_or_output(&output);
                }
                Op::FocusWindowDown => layout.focus_down(),
                Op::FocusWindowUp => layout.focus_up(),
                Op::FocusWindowDownOrColumnLeft => layout.focus_down_or_left(),
                Op::FocusWindowDownOrColumnRight => layout.focus_down_or_right(),
                Op::FocusWindowUpOrColumnLeft => layout.focus_up_or_left(),
                Op::FocusWindowUpOrColumnRight => layout.focus_up_or_right(),
                Op::FocusWindowOrWorkspaceDown => layout.focus_window_or_workspace_down(),
                Op::FocusWindowOrWorkspaceUp => layout.focus_window_or_workspace_up(),
                Op::MoveColumnLeft => layout.move_left(),
                Op::MoveColumnRight => layout.move_right(),
                Op::MoveColumnToFirst => layout.move_column_to_first(),
                Op::MoveColumnToLast => layout.move_column_to_last(),
                Op::MoveWindowDown => layout.move_down(),
                Op::MoveWindowUp => layout.move_up(),
                Op::MoveWindowDownOrToWorkspaceDown => layout.move_down_or_to_workspace_down(),
                Op::MoveWindowUpOrToWorkspaceUp => layout.move_up_or_to_workspace_up(),
                Op::ConsumeOrExpelWindowLeft => layout.consume_or_expel_window_left(),
                Op::ConsumeOrExpelWindowRight => layout.consume_or_expel_window_right(),
                Op::ConsumeWindowIntoColumn => layout.consume_into_column(),
                Op::ExpelWindowFromColumn => layout.expel_from_column(),
                Op::CenterColumn => layout.center_column(),
                Op::FocusWorkspaceDown => layout.switch_workspace_down(),
                Op::FocusWorkspaceUp => layout.switch_workspace_up(),
                Op::FocusWorkspace(idx) => layout.switch_workspace(idx),
                Op::FocusWorkspaceAutoBackAndForth(idx) => {
                    layout.switch_workspace_auto_back_and_forth(idx)
                }
                Op::FocusWorkspacePrevious => layout.switch_workspace_previous(),
                Op::MoveWindowToWorkspaceDown => layout.move_to_workspace_down(),
                Op::MoveWindowToWorkspaceUp => layout.move_to_workspace_up(),
                Op::MoveWindowToWorkspace(idx) => layout.move_to_workspace(idx),
                Op::MoveColumnToWorkspaceDown => layout.move_column_to_workspace_down(),
                Op::MoveColumnToWorkspaceUp => layout.move_column_to_workspace_up(),
                Op::MoveColumnToWorkspace(idx) => layout.move_column_to_workspace(idx),
                Op::MoveWindowToOutput(id) => {
                    let name = format!("output{id}");
                    let Some(output) = layout.outputs().find(|o| o.name() == name).cloned() else {
                        return;
                    };

                    layout.move_to_output(&output);
                }
                Op::MoveColumnToOutput(id) => {
                    let name = format!("output{id}");
                    let Some(output) = layout.outputs().find(|o| o.name() == name).cloned() else {
                        return;
                    };

                    layout.move_column_to_output(&output);
                }
                Op::MoveWorkspaceDown => layout.move_workspace_down(),
                Op::MoveWorkspaceUp => layout.move_workspace_up(),
                Op::SwitchPresetColumnWidth => layout.toggle_width(),
                Op::MaximizeColumn => layout.toggle_full_width(),
                Op::SetColumnWidth(change) => layout.set_column_width(change),
                Op::SetWindowHeight(change) => layout.set_window_height(change),
                Op::ResetWindowHeight => layout.reset_window_height(),
                Op::Communicate(id) => {
                    let mut update = false;
                    match &mut layout.monitor_set {
                        MonitorSet::Normal { monitors, .. } => {
                            'outer: for mon in monitors {
                                for ws in &mut mon.workspaces {
                                    for win in ws.windows() {
                                        if win.0.id == id {
                                            if win.communicate() {
                                                update = true;
                                            }
                                            break 'outer;
                                        }
                                    }
                                }
                            }
                        }
                        MonitorSet::NoOutputs { workspaces, .. } => {
                            'outer: for ws in workspaces {
                                for win in ws.windows() {
                                    if win.0.id == id {
                                        if win.communicate() {
                                            update = true;
                                        }
                                        break 'outer;
                                    }
                                }
                            }
                        }
                    }

                    if update {
                        // FIXME: serial.
                        layout.update_window(&id, None);
                    }
                }
                Op::MoveWorkspaceToOutput(id) => {
                    let name = format!("output{id}");
                    let Some(output) = layout.outputs().find(|o| o.name() == name).cloned() else {
                        return;
                    };

                    layout.move_workspace_to_output(&output);
                }
                Op::ViewOffsetGestureBegin {
                    output_idx: id,
                    is_touchpad: normalize,
                } => {
                    let name = format!("output{id}");
                    let Some(output) = layout.outputs().find(|o| o.name() == name).cloned() else {
                        return;
                    };

                    layout.view_offset_gesture_begin(&output, normalize);
                }
                Op::ViewOffsetGestureUpdate {
                    delta,
                    timestamp,
                    is_touchpad,
                } => {
                    layout.view_offset_gesture_update(delta, timestamp, is_touchpad);
                }
                Op::ViewOffsetGestureEnd { is_touchpad } => {
                    // We don't handle cancels in this gesture.
                    layout.view_offset_gesture_end(false, is_touchpad);
                }
                Op::WorkspaceSwitchGestureBegin {
                    output_idx: id,
                    is_touchpad,
                } => {
                    let name = format!("output{id}");
                    let Some(output) = layout.outputs().find(|o| o.name() == name).cloned() else {
                        return;
                    };

                    layout.workspace_switch_gesture_begin(&output, is_touchpad);
                }
                Op::WorkspaceSwitchGestureUpdate {
                    delta,
                    timestamp,
                    is_touchpad,
                } => {
                    layout.workspace_switch_gesture_update(delta, timestamp, is_touchpad);
                }
                Op::WorkspaceSwitchGestureEnd {
                    cancelled,
                    is_touchpad,
                } => {
                    layout.workspace_switch_gesture_end(cancelled, is_touchpad);
                }
                Op::InteractiveResizeBegin { window, edges } => {
                    layout.interactive_resize_begin(window, edges);
                }
                Op::InteractiveResizeUpdate { window, dx, dy } => {
                    layout.interactive_resize_update(&window, Point::from((dx, dy)));
                }
                Op::InteractiveResizeEnd { window } => {
                    layout.interactive_resize_end(&window);
                }
            }
        }
    }

    #[track_caller]
    fn check_ops(ops: &[Op]) {
        let mut layout = Layout::default();
        for op in ops {
            op.apply(&mut layout);
            layout.verify_invariants();
        }
    }

    #[track_caller]
    fn check_ops_with_options(options: Options, ops: &[Op]) {
        let mut layout = Layout::with_options(options);

        for op in ops {
            op.apply(&mut layout);
            layout.verify_invariants();
        }
    }

    #[test]
    fn operations_dont_panic() {
        let every_op = [
            Op::AddOutput(0),
            Op::AddOutput(1),
            Op::AddOutput(2),
            Op::RemoveOutput(0),
            Op::RemoveOutput(1),
            Op::RemoveOutput(2),
            Op::FocusOutput(0),
            Op::FocusOutput(1),
            Op::FocusOutput(2),
            Op::AddNamedWorkspace {
                ws_name: 1,
                output_name: Some(1),
            },
            Op::UnnameWorkspace { ws_name: 1 },
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindowRightOf {
                id: 2,
                right_of_id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindowToNamedWorkspace {
                id: 3,
                ws_name: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::CloseWindow(0),
            Op::CloseWindow(1),
            Op::CloseWindow(2),
            Op::FullscreenWindow(1),
            Op::FullscreenWindow(2),
            Op::FullscreenWindow(3),
            Op::FocusColumnLeft,
            Op::FocusColumnRight,
            Op::FocusColumnRightOrFirst,
            Op::FocusColumnLeftOrLast,
            Op::FocusColumnOrMonitorLeft(0),
            Op::FocusColumnOrMonitorRight(1),
            Op::FocusWindowUp,
            Op::FocusWindowUpOrColumnLeft,
            Op::FocusWindowUpOrColumnRight,
            Op::FocusWindowOrWorkspaceUp,
            Op::FocusWindowDown,
            Op::FocusWindowDownOrColumnLeft,
            Op::FocusWindowDownOrColumnRight,
            Op::FocusWindowOrWorkspaceDown,
            Op::MoveColumnLeft,
            Op::MoveColumnRight,
            Op::ConsumeWindowIntoColumn,
            Op::ExpelWindowFromColumn,
            Op::CenterColumn,
            Op::FocusWorkspaceDown,
            Op::FocusWorkspaceUp,
            Op::FocusWorkspace(1),
            Op::FocusWorkspace(2),
            Op::MoveWindowToWorkspaceDown,
            Op::MoveWindowToWorkspaceUp,
            Op::MoveWindowToWorkspace(1),
            Op::MoveWindowToWorkspace(2),
            Op::MoveColumnToWorkspaceDown,
            Op::MoveColumnToWorkspaceUp,
            Op::MoveColumnToWorkspace(1),
            Op::MoveColumnToWorkspace(2),
            Op::MoveWindowDown,
            Op::MoveWindowDownOrToWorkspaceDown,
            Op::MoveWindowUp,
            Op::MoveWindowUpOrToWorkspaceUp,
            Op::ConsumeOrExpelWindowLeft,
            Op::ConsumeOrExpelWindowRight,
            Op::MoveWorkspaceToOutput(1),
        ];

        for third in every_op {
            for second in every_op {
                for first in every_op {
                    // eprintln!("{first:?}, {second:?}, {third:?}");

                    let mut layout = Layout::default();
                    first.apply(&mut layout);
                    layout.verify_invariants();
                    second.apply(&mut layout);
                    layout.verify_invariants();
                    third.apply(&mut layout);
                    layout.verify_invariants();
                }
            }
        }
    }

    #[test]
    fn operations_from_starting_state_dont_panic() {
        if std::env::var_os("RUN_SLOW_TESTS").is_none() {
            eprintln!("ignoring slow test");
            return;
        }

        // Running every op from an empty state doesn't get us to all the interesting states. So,
        // also run it from a manually-created starting state with more things going on to exercise
        // more code paths.
        let setup_ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::MoveWindowToWorkspaceDown,
            Op::AddWindow {
                id: 2,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindow {
                id: 3,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::FocusColumnLeft,
            Op::ConsumeWindowIntoColumn,
            Op::AddWindow {
                id: 4,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddOutput(2),
            Op::AddWindow {
                id: 5,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::MoveWindowToOutput(2),
            Op::FocusOutput(1),
            Op::Communicate(1),
            Op::Communicate(2),
            Op::Communicate(3),
            Op::Communicate(4),
            Op::Communicate(5),
        ];

        let every_op = [
            Op::AddOutput(0),
            Op::AddOutput(1),
            Op::AddOutput(2),
            Op::RemoveOutput(0),
            Op::RemoveOutput(1),
            Op::RemoveOutput(2),
            Op::FocusOutput(0),
            Op::FocusOutput(1),
            Op::FocusOutput(2),
            Op::AddNamedWorkspace {
                ws_name: 1,
                output_name: Some(1),
            },
            Op::UnnameWorkspace { ws_name: 1 },
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindow {
                id: 2,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindowRightOf {
                id: 6,
                right_of_id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindowRightOf {
                id: 7,
                right_of_id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindowToNamedWorkspace {
                id: 5,
                ws_name: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::CloseWindow(0),
            Op::CloseWindow(1),
            Op::CloseWindow(2),
            Op::FullscreenWindow(1),
            Op::FullscreenWindow(2),
            Op::FullscreenWindow(3),
            Op::SetFullscreenWindow {
                window: 1,
                is_fullscreen: false,
            },
            Op::SetFullscreenWindow {
                window: 1,
                is_fullscreen: true,
            },
            Op::SetFullscreenWindow {
                window: 2,
                is_fullscreen: false,
            },
            Op::SetFullscreenWindow {
                window: 2,
                is_fullscreen: true,
            },
            Op::FocusColumnLeft,
            Op::FocusColumnRight,
            Op::FocusColumnRightOrFirst,
            Op::FocusColumnLeftOrLast,
            Op::FocusColumnOrMonitorLeft(0),
            Op::FocusColumnOrMonitorRight(1),
            Op::FocusWindowUp,
            Op::FocusWindowUpOrColumnLeft,
            Op::FocusWindowUpOrColumnRight,
            Op::FocusWindowOrWorkspaceUp,
            Op::FocusWindowDown,
            Op::FocusWindowDownOrColumnLeft,
            Op::FocusWindowDownOrColumnRight,
            Op::FocusWindowOrWorkspaceDown,
            Op::MoveColumnLeft,
            Op::MoveColumnRight,
            Op::ConsumeWindowIntoColumn,
            Op::ExpelWindowFromColumn,
            Op::CenterColumn,
            Op::FocusWorkspaceDown,
            Op::FocusWorkspaceUp,
            Op::FocusWorkspace(1),
            Op::FocusWorkspace(2),
            Op::FocusWorkspace(3),
            Op::MoveWindowToWorkspaceDown,
            Op::MoveWindowToWorkspaceUp,
            Op::MoveWindowToWorkspace(1),
            Op::MoveWindowToWorkspace(2),
            Op::MoveWindowToWorkspace(3),
            Op::MoveColumnToWorkspaceDown,
            Op::MoveColumnToWorkspaceUp,
            Op::MoveColumnToWorkspace(1),
            Op::MoveColumnToWorkspace(2),
            Op::MoveColumnToWorkspace(3),
            Op::MoveWindowDown,
            Op::MoveWindowDownOrToWorkspaceDown,
            Op::MoveWindowUp,
            Op::MoveWindowUpOrToWorkspaceUp,
            Op::ConsumeOrExpelWindowLeft,
            Op::ConsumeOrExpelWindowRight,
        ];

        for third in every_op {
            for second in every_op {
                for first in every_op {
                    // eprintln!("{first:?}, {second:?}, {third:?}");

                    let mut layout = Layout::default();
                    for op in setup_ops {
                        op.apply(&mut layout);
                    }

                    first.apply(&mut layout);
                    layout.verify_invariants();
                    second.apply(&mut layout);
                    layout.verify_invariants();
                    third.apply(&mut layout);
                    layout.verify_invariants();
                }
            }
        }
    }

    #[test]
    fn primary_active_workspace_idx_not_updated_on_output_add() {
        let ops = [
            Op::AddOutput(1),
            Op::AddOutput(2),
            Op::FocusOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::FocusOutput(2),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::RemoveOutput(2),
            Op::FocusWorkspace(3),
            Op::AddOutput(2),
        ];

        check_ops(&ops);
    }

    #[test]
    fn window_closed_on_previous_workspace() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::FocusWorkspaceDown,
            Op::CloseWindow(0),
        ];

        check_ops(&ops);
    }

    #[test]
    fn removing_output_must_keep_empty_focus_on_primary() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddOutput(2),
            Op::RemoveOutput(1),
        ];

        let mut layout = Layout::default();
        for op in ops {
            op.apply(&mut layout);
        }

        let MonitorSet::Normal { monitors, .. } = layout.monitor_set else {
            unreachable!()
        };

        // The workspace from the removed output was inserted at position 0, so the active workspace
        // must change to 1 to keep the focus on the empty workspace.
        assert_eq!(monitors[0].active_workspace_idx, 1);
    }

    #[test]
    fn move_to_workspace_by_idx_does_not_leave_empty_workspaces() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::MoveWindowToWorkspace(2),
        ];

        let mut layout = Layout::default();
        for op in ops {
            op.apply(&mut layout);
        }

        let MonitorSet::Normal { monitors, .. } = layout.monitor_set else {
            unreachable!()
        };

        assert!(monitors[0].workspaces[0].has_windows());
    }

    #[test]
    fn focus_workspace_by_idx_does_not_leave_empty_workspaces() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::FocusWorkspaceDown,
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::FocusWorkspaceUp,
            Op::CloseWindow(0),
            Op::FocusWorkspace(3),
        ];

        let mut layout = Layout::default();
        for op in ops {
            op.apply(&mut layout);
        }

        let MonitorSet::Normal { monitors, .. } = layout.monitor_set else {
            unreachable!()
        };

        assert!(monitors[0].workspaces[0].has_windows());
    }

    #[test]
    fn empty_workspaces_dont_move_back_to_original_output() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::FocusWorkspaceDown,
            Op::AddWindow {
                id: 2,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddOutput(2),
            Op::RemoveOutput(1),
            Op::FocusWorkspace(1),
            Op::CloseWindow(1),
            Op::AddOutput(1),
        ];

        check_ops(&ops);
    }

    #[test]
    fn large_negative_height_change() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::SetWindowHeight(SizeChange::AdjustProportion(-1e129)),
        ];

        let mut options = Options::default();
        options.border.off = false;
        options.border.width = FloatOrInt(1.);

        check_ops_with_options(options, &ops);
    }

    #[test]
    fn large_max_size() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
        ];

        let mut options = Options::default();
        options.border.off = false;
        options.border.width = FloatOrInt(1.);

        check_ops_with_options(options, &ops);
    }

    #[test]
    fn workspace_cleanup_during_switch() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
            Op::FocusWorkspaceDown,
            Op::CloseWindow(1),
        ];

        check_ops(&ops);
    }

    #[test]
    fn workspace_transfer_during_switch() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
            Op::AddOutput(2),
            Op::FocusOutput(2),
            Op::AddWindow {
                id: 2,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
            Op::RemoveOutput(1),
            Op::FocusWorkspaceDown,
            Op::FocusWorkspaceDown,
            Op::AddOutput(1),
        ];

        check_ops(&ops);
    }

    #[test]
    fn workspace_transfer_during_switch_from_last() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
            Op::AddOutput(2),
            Op::RemoveOutput(1),
            Op::FocusWorkspaceUp,
            Op::AddOutput(1),
        ];

        check_ops(&ops);
    }

    #[test]
    fn workspace_transfer_during_switch_gets_cleaned_up() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
            Op::RemoveOutput(1),
            Op::AddOutput(2),
            Op::MoveColumnToWorkspaceDown,
            Op::MoveColumnToWorkspaceDown,
            Op::AddOutput(1),
        ];

        check_ops(&ops);
    }

    #[test]
    fn move_workspace_to_output() {
        let ops = [
            Op::AddOutput(1),
            Op::AddOutput(2),
            Op::FocusOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::MoveWorkspaceToOutput(2),
        ];

        let mut layout = Layout::default();
        for op in ops {
            op.apply(&mut layout);
        }

        let MonitorSet::Normal {
            monitors,
            active_monitor_idx,
            ..
        } = layout.monitor_set
        else {
            unreachable!()
        };

        assert_eq!(active_monitor_idx, 1);
        assert_eq!(monitors[0].workspaces.len(), 1);
        assert!(!monitors[0].workspaces[0].has_windows());
        assert_eq!(monitors[1].active_workspace_idx, 0);
        assert_eq!(monitors[1].workspaces.len(), 2);
        assert!(monitors[1].workspaces[0].has_windows());
    }

    #[test]
    fn fullscreen() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
            Op::FullscreenWindow(1),
        ];

        check_ops(&ops);
    }

    #[test]
    fn unfullscreen_window_in_column() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
            Op::AddWindow {
                id: 2,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
            Op::ConsumeOrExpelWindowLeft,
            Op::SetFullscreenWindow {
                window: 2,
                is_fullscreen: false,
            },
        ];

        check_ops(&ops);
    }

    #[test]
    fn open_right_of_on_different_workspace() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
            Op::FocusWorkspaceDown,
            Op::AddWindow {
                id: 2,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
            Op::AddWindowRightOf {
                id: 3,
                right_of_id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: (Size::from((0, 0)), Size::from((i32::MAX, i32::MAX))),
            },
        ];

        let mut layout = Layout::default();
        for op in ops {
            op.apply(&mut layout);
        }

        let MonitorSet::Normal { monitors, .. } = layout.monitor_set else {
            unreachable!()
        };

        let mon = monitors.into_iter().next().unwrap();
        assert_eq!(
            mon.active_workspace_idx, 1,
            "the second workspace must remain active"
        );
        assert_eq!(
            mon.workspaces[0].active_column_idx, 1,
            "the new window must become active"
        );
    }

    #[test]
    fn unfullscreen_view_offset_not_reset_on_removal() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::FullscreenWindow(0),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::ConsumeOrExpelWindowRight,
        ];

        check_ops(&ops);
    }

    #[test]
    fn unfullscreen_view_offset_not_reset_on_consume() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::FullscreenWindow(0),
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::ConsumeWindowIntoColumn,
        ];

        check_ops(&ops);
    }

    #[test]
    fn unfullscreen_view_offset_not_reset_on_quick_double_toggle() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::FullscreenWindow(0),
            Op::FullscreenWindow(0),
        ];

        check_ops(&ops);
    }

    #[test]
    fn unfullscreen_view_offset_set_on_fullscreening_inactive_tile_in_column() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (100, 200)),
                min_max_size: Default::default(),
            },
            Op::ConsumeOrExpelWindowLeft,
            Op::FullscreenWindow(0),
        ];

        check_ops(&ops);
    }

    #[test]
    fn unfullscreen_view_offset_not_reset_on_gesture() {
        let ops = [
            Op::AddOutput(1),
            Op::AddWindow {
                id: 0,
                bbox: Rectangle::from_loc_and_size((0, 0), (200, 200)),
                min_max_size: Default::default(),
            },
            Op::AddWindow {
                id: 1,
                bbox: Rectangle::from_loc_and_size((0, 0), (1280, 200)),
                min_max_size: Default::default(),
            },
            Op::FullscreenWindow(1),
            Op::ViewOffsetGestureBegin {
                output_idx: 1,
                is_touchpad: true,
            },
            Op::ViewOffsetGestureEnd {
                is_touchpad: Some(true),
            },
        ];

        check_ops(&ops);
    }

    #[test]
    fn removing_all_outputs_preserves_empty_named_workspaces() {
        let ops = [
            Op::AddOutput(1),
            Op::AddNamedWorkspace {
                ws_name: 1,
                output_name: None,
            },
            Op::AddNamedWorkspace {
                ws_name: 2,
                output_name: None,
            },
            Op::RemoveOutput(1),
        ];

        let mut layout = Layout::default();
        for op in ops {
            op.apply(&mut layout);
        }

        let MonitorSet::NoOutputs { workspaces } = layout.monitor_set else {
            unreachable!()
        };

        assert_eq!(workspaces.len(), 2);
    }

    #[test]
    fn config_change_updates_cached_sizes() {
        let mut config = Config::default();
        config.layout.border.off = false;
        config.layout.border.width = FloatOrInt(2.);

        let mut layout = Layout::new(&config);

        Op::AddWindow {
            id: 1,
            bbox: Rectangle::from_loc_and_size((0, 0), (1280, 200)),
            min_max_size: Default::default(),
        }
        .apply(&mut layout);

        config.layout.border.width = FloatOrInt(4.);
        layout.update_config(&config);

        layout.verify_invariants();
    }

    #[test]
    fn working_area_starts_at_physical_pixel() {
        let struts = Struts {
            left: FloatOrInt(0.5),
            right: FloatOrInt(1.),
            top: FloatOrInt(0.75),
            bottom: FloatOrInt(1.),
        };

        let output = Output::new(
            String::from("output"),
            PhysicalProperties {
                size: Size::from((1280, 720)),
                subpixel: Subpixel::Unknown,
                make: String::new(),
                model: String::new(),
            },
        );
        output.change_current_state(
            Some(Mode {
                size: Size::from((1280, 720)),
                refresh: 60000,
            }),
            None,
            None,
            None,
        );

        let area = compute_working_area(&output, struts);

        assert_eq!(round_logical_in_physical(1., area.loc.x), area.loc.x);
        assert_eq!(round_logical_in_physical(1., area.loc.y), area.loc.y);
    }

    #[test]
    fn large_fractional_strut() {
        let struts = Struts {
            left: FloatOrInt(0.),
            right: FloatOrInt(0.),
            top: FloatOrInt(50000.5),
            bottom: FloatOrInt(0.),
        };

        let output = Output::new(
            String::from("output"),
            PhysicalProperties {
                size: Size::from((1280, 720)),
                subpixel: Subpixel::Unknown,
                make: String::new(),
                model: String::new(),
            },
        );
        output.change_current_state(
            Some(Mode {
                size: Size::from((1280, 720)),
                refresh: 60000,
            }),
            None,
            None,
            None,
        );

        compute_working_area(&output, struts);
    }

    fn arbitrary_spacing() -> impl Strategy<Value = f64> {
        // Give equal weight to:
        // - 0: the element is disabled
        // - 4: some reasonable value
        // - random value, likely unreasonably big
        prop_oneof![Just(0.), Just(4.), ((1.)..=65535.)]
    }

    fn arbitrary_struts() -> impl Strategy<Value = Struts> {
        (
            arbitrary_spacing(),
            arbitrary_spacing(),
            arbitrary_spacing(),
            arbitrary_spacing(),
        )
            .prop_map(|(left, right, top, bottom)| Struts {
                left: FloatOrInt(left),
                right: FloatOrInt(right),
                top: FloatOrInt(top),
                bottom: FloatOrInt(bottom),
            })
    }

    fn arbitrary_center_focused_column() -> impl Strategy<Value = CenterFocusedColumn> {
        prop_oneof![
            Just(CenterFocusedColumn::Never),
            Just(CenterFocusedColumn::OnOverflow),
            Just(CenterFocusedColumn::Always),
        ]
    }

    prop_compose! {
        fn arbitrary_focus_ring()(
            off in any::<bool>(),
            width in arbitrary_spacing(),
        ) -> niri_config::FocusRing {
            niri_config::FocusRing {
                off,
                width: FloatOrInt(width),
                ..Default::default()
            }
        }
    }

    prop_compose! {
        fn arbitrary_border()(
            off in any::<bool>(),
            width in arbitrary_spacing(),
        ) -> niri_config::Border {
            niri_config::Border {
                off,
                width: FloatOrInt(width),
                ..Default::default()
            }
        }
    }

    prop_compose! {
        fn arbitrary_options()(
            gaps in arbitrary_spacing(),
            struts in arbitrary_struts(),
            focus_ring in arbitrary_focus_ring(),
            border in arbitrary_border(),
            center_focused_column in arbitrary_center_focused_column(),
        ) -> Options {
            Options {
                gaps,
                struts,
                center_focused_column,
                focus_ring,
                border,
                ..Default::default()
            }
        }
    }

    proptest! {
        #![proptest_config(ProptestConfig {
            cases: if std::env::var_os("RUN_SLOW_TESTS").is_none() {
                eprintln!("ignoring slow test");
                0
            } else {
                ProptestConfig::default().cases
            },
            ..ProptestConfig::default()
        })]

        #[test]
        fn random_operations_dont_panic(ops: Vec<Op>, options in arbitrary_options()) {
            // eprintln!("{ops:?}");
            check_ops_with_options(options, &ops);
        }
    }
}