endorphin-tessera-gui/src/shell/app.rs

use std::{
    num::NonZeroU32,
    sync::{Arc, RwLock},
    time::Duration,
};

use softbuffer::{Context, Surface};
use winit::{
    application::ApplicationHandler,
    dpi::{LogicalPosition, LogicalSize, PhysicalPosition},
    event::{ElementState, Ime, MouseButton, MouseScrollDelta, WindowEvent},
    event_loop::{ActiveEventLoop, EventLoopProxy},
    keyboard::{Key, ModifiersState, NamedKey},
    window::{Window, WindowAttributes, WindowId},
};

use crate::{
    activity::Activity,
    developer_tools::Workspace as DeveloperToolsState,
    document::NamespaceState,
    geometry::Point,
    scene::{self, SceneLayout},
    software_renderer::SoftwareRenderer,
};

#[derive(Clone, Debug)]
pub enum AppEvent {
    RuntimeFailed { message: String },
    DocumentUpdated,
    ShutdownComplete { error: Option<String> },
    ConsoleFailed { message: String, source: String },
}

pub struct TesseraApp {
    resource: u64,
    control: crate::api::RuntimeControl,
    exit_requested: bool,
    native_session: u64,
    startup_page_requested: bool,
    native_error: Option<String>,
    children: std::collections::BTreeMap<u64, TesseraApp>,
    proxy: EventLoopProxy<AppEvent>,
    window: Option<Arc<Window>>,
    context: Option<Context<Arc<Window>>>,
    surface: Option<Surface<Arc<Window>, Arc<Window>>>,
    namespace: Arc<RwLock<NamespaceState>>,
    developer_tools: DeveloperToolsState,
    layout: SceneLayout,
    pointer: Point,
    sidebar: crate::sidebar::State,
    sidebar_keyboard: bool,
    panning: bool,
    pan_viewport: Option<u64>,
    orbiting: bool,
    space_down: bool,
    modifiers: ModifiersState,
    activity: Activity,
    event_client: crate::events::Client,
    guest_pressed: Option<crate::events::Input>,
    guest_focus: Option<crate::events::Input>,
    guest_key: Option<(NamedKey, crate::events::Input)>,
    guest_keyboard: bool,
}

impl TesseraApp {
    pub fn new(
        namespace: Arc<RwLock<NamespaceState>>,
        activity: Activity,
        proxy: EventLoopProxy<AppEvent>,
        control: crate::api::RuntimeControl,
    ) -> anyhow::Result<Self> {
        let event_client = crate::events::Client::new(proxy.clone(), namespace.clone())?;
        Ok(Self::with_event_client(
            namespace,
            activity,
            proxy,
            control,
            event_client,
        ))
    }

    fn with_event_client(
        namespace: Arc<RwLock<NamespaceState>>,
        activity: Activity,
        proxy: EventLoopProxy<AppEvent>,
        control: crate::api::RuntimeControl,
        event_client: crate::events::Client,
    ) -> Self {
        Self {
            resource: crate::window::MAIN_WINDOW,
            control,
            exit_requested: false,
            native_session: 0,
            startup_page_requested: false,
            native_error: None,
            children: std::collections::BTreeMap::new(),
            proxy: proxy.clone(),
            window: None,
            context: None,
            surface: None,
            namespace,
            developer_tools: DeveloperToolsState::new(proxy),
            layout: SceneLayout::default(),
            pointer: Point::default(),
            sidebar: crate::sidebar::State::default(),
            sidebar_keyboard: false,
            panning: false,
            pan_viewport: None,
            orbiting: false,
            space_down: false,
            modifiers: ModifiersState::default(),
            activity,
            event_client,
            guest_pressed: None,
            guest_focus: None,
            guest_key: None,
            guest_keyboard: true,
        }
    }

    fn reconcile_windows(&mut self, event_loop: &ActiveEventLoop) {
        if self.resource != crate::window::MAIN_WINDOW {
            return;
        }
        let Ok(namespace) = self.namespace.read() else {
            return;
        };
        let session = namespace.runtime_session;
        let revision = namespace.revision;
        let submission = namespace.submission;
        let documents = namespace.document.windows.clone();
        drop(namespace);
        if session != self.native_session {
            // Console reset preserves the old projection with input disabled.
            // A real replacement changes frame sessions and drops old OS views.
            let replaces = documents
                .values()
                .any(|document| document.frame.session == session && session != 0);
            if replaces || (session != 0 && documents.is_empty()) {
                self.children.clear();
            }
            self.native_session = session;
        }
        self.children.retain(|id, child| {
            documents.get(id).is_some_and(|document| {
                document.frame.session == 0 || child.native_session == document.frame.session
            })
        });
        for (id, document) in documents {
            if let Some(child) = self.children.get_mut(&id) {
                if let Ok(mut namespace) = child.namespace.write() {
                    namespace.document = document;
                    namespace.runtime_session = session;
                    namespace.revision = revision;
                    namespace.submission = submission;
                }
                child.document_updated(event_loop);
            } else {
                let namespace = Arc::new(RwLock::new(NamespaceState {
                    document,
                    runtime_session: session,
                    revision,
                    submission,
                    ..NamespaceState::default()
                }));
                let mut child = Self::with_event_client(
                    namespace,
                    self.activity.clone(),
                    self.proxy.clone(),
                    self.control.clone(),
                    self.event_client.clone(),
                );
                child.resource = id;
                child.native_session = session;
                child.resumed(event_loop);
                if let Some(error) = &child.native_error {
                    self.developer_tools.input_error = error.clone();
                    self.developer_tools.open = true;
                }
                child.document_updated(event_loop);
                self.children.insert(id, child);
            }
        }
    }

    fn apply_window_commands(&mut self) {
        let Ok(mut namespace) = self.namespace.write() else {
            return;
        };
        let session = namespace.runtime_session;
        let commands = std::mem::take(&mut namespace.window_commands);
        drop(namespace);
        for envelope in commands {
            if envelope.session == 0 || envelope.session != session {
                continue;
            }
            let id = envelope.command.window;
            if matches!(envelope.command.action, crate::window::Action::Close) {
                if id == crate::window::MAIN_WINDOW {
                    self.request_exit();
                } else {
                    self.children.remove(&id);
                }
                continue;
            }
            let target = if id == self.resource {
                self.window.as_ref()
            } else {
                self.children
                    .get(&id)
                    .and_then(|child| child.window.as_ref())
            };
            let Some(window) = target else {
                continue;
            };
            match envelope.command.action {
                crate::window::Action::Resize { width, height } => {
                    let _ = window.request_inner_size(LogicalSize::new(width, height));
                }
                crate::window::Action::SetTitle(title) => window.set_title(&title),
                crate::window::Action::MoveTo { x, y } => {
                    if window.outer_position().is_ok() {
                        window.set_outer_position(PhysicalPosition::new(x, y));
                    } else {
                        let _ = self.proxy.send_event(AppEvent::RuntimeFailed {
                            message: format!(
                                "Window {id}: desktop placement is unsupported on this platform"
                            ),
                        });
                    }
                }
                crate::window::Action::Focus => window.focus_window(),
                crate::window::Action::Close => {}
            }
        }
        self.publish_viewport();
    }

    fn publish_viewport(&self) {
        let Some(window) = &self.window else {
            return;
        };
        let size = window.inner_size().to_logical::<f32>(window.scale_factor());
        if size.width <= 0.0
            || size.height <= 0.0
            || !size.width.is_finite()
            || !size.height.is_finite()
        {
            return;
        }
        if let Ok(mut namespace) = self.namespace.write() {
            let size = crate::layout::Size {
                width: (size.width - self.sidebar.left())
                    .max(0.0)
                    .min(crate::ui_bridge::MAX_DIMENSION as f32),
                height: size.height.min(crate::ui_bridge::MAX_DIMENSION as f32),
            };
            namespace.viewport = Some(size);
            namespace.window_viewports.insert(self.resource, size);
            if self.resource == crate::window::MAIN_WINDOW {
                let session = namespace.runtime_session;
                namespace.window_viewports.retain(|id, _| {
                    *id == crate::window::MAIN_WINDOW
                        || self
                            .children
                            .get(id)
                            .is_some_and(|child| session != 0 && child.native_session == session)
                });
                for (id, child) in &self.children {
                    if child.native_session == session
                        && session != 0
                        && let Ok(local) = child.namespace.read()
                        && local.document.frame.session == session
                        && let Some(size) = local.viewport
                    {
                        namespace.window_viewports.insert(*id, size);
                    }
                }
            }
        }
    }

    fn request_redraw(&self) {
        if let Some(window) = &self.window {
            window.request_redraw();
        }
    }

    fn open_developer_tool(&mut self, name: &str) {
        let input = self.namespace.read().ok().map(|namespace| {
            let frame = &namespace.document.frame;
            crate::events::Input {
                window: self.resource,
                session: frame.session,
                layout_version: frame.layout_version,
                mount: 0,
                kind: format!("developer-open:{name}"),
                point: None,
                delta: None,
                press_point: None,
                tab_drop: None,
                screen_position: None,
            }
        });
        if let Some(input) = input {
            if input.session == 0 {
                self.developer_tools.initialize_tools(name);
            } else {
                self.send_guest(input);
            }
        }
        self.guest_keyboard = false;
        self.request_redraw();
    }

    fn document_updated(&mut self, event_loop: &ActiveEventLoop) {
        self.reconcile_windows(event_loop);
        self.apply_window_commands();
        if let Ok(namespace) = self.namespace.read() {
            self.developer_tools.document_updated(&namespace.document);
            let frame = &namespace.document.frame;
            self.guest_keyboard = !frame
                .tabs
                .iter()
                .any(|tab| tab.active && tab.developer_tool.is_some());
            self.guest_focus =
                frame
                    .focus
                    .filter(|_| frame.fault.is_none())
                    .map(|mount| crate::events::Input {
                        window: self.resource,
                        session: frame.session,
                        layout_version: frame.layout_version,
                        mount,
                        kind: "focus".into(),
                        point: None,
                        delta: None,
                        press_point: None,
                        tab_drop: None,
                        screen_position: None,
                    });
        }
        self.request_redraw();
    }

    fn handle_keyboard(&mut self, event: &winit::event::KeyEvent) {
        let command = self.modifiers.super_key() || self.modifiers.control_key();
        if command
            && event.state == ElementState::Pressed
            && !event.repeat
            && matches!(&event.logical_key, Key::Character(key) if key.eq_ignore_ascii_case("b"))
        {
            self.sidebar_action(crate::sidebar::Action::Toggle);
            return;
        }
        if event.logical_key == Key::Named(NamedKey::Escape) {
            self.panning = false;
            self.space_down = false;
            self.guest_pressed = None;
        }
        if event.logical_key == Key::Named(NamedKey::Space)
            && self.guest_focus.is_none()
            && self
                .namespace
                .read()
                .is_ok_and(|n| n.document.frame.surface.mode == crate::page::Mode::Canvas)
        {
            self.space_down = event.state == ElementState::Pressed;
            if !self.space_down {
                self.panning = false;
            }
            return;
        }
        if self.sidebar_keyboard {
            if event.logical_key == Key::Named(NamedKey::Tab)
                && event.state == ElementState::Pressed
            {
                self.sidebar
                    .interaction
                    .focus_next(&self.sidebar.targets, self.modifiers.shift_key());
                self.request_redraw();
                return;
            }
            if matches!(
                event.logical_key,
                Key::Named(NamedKey::Enter | NamedKey::Space)
            ) {
                if event.state == ElementState::Pressed {
                    self.sidebar.interaction.key_press(&self.sidebar.targets);
                } else if let Some(action) =
                    self.sidebar.interaction.key_release(&self.sidebar.targets)
                {
                    self.sidebar_action(action);
                }
                self.request_redraw();
                return;
            }
        }
        if event.state == ElementState::Pressed
            && !event.repeat
            && (self.modifiers.super_key() || self.modifiers.control_key())
            && matches!(&event.logical_key, Key::Character(key) if key.eq_ignore_ascii_case("t"))
        {
            self.open_developer_tool("New tab");
            return;
        }

        if event.state == ElementState::Pressed && !event.repeat {
            let close = (self.modifiers.super_key() || self.modifiers.control_key())
                && matches!(&event.logical_key, Key::Character(key) if key.eq_ignore_ascii_case("w"));
            let cycle = self.modifiers.control_key()
                && matches!(event.logical_key, Key::Named(NamedKey::Tab));
            if (close || cycle) && self.send_tab_shortcut(close) {
                return;
            }
        }
        if self.guest_keyboard && self.handle_guest_key(event) {
            self.request_redraw();
            return;
        }
        if self.developer_tools.keyboard_control(
            event,
            self.modifiers.shift_key(),
            &self.layout.developer_tools,
            &self.activity,
        ) {
            self.request_redraw();
            return;
        }
        if event.state != ElementState::Pressed {
            return;
        }
        let is_f12 = matches!(event.logical_key, Key::Named(NamedKey::F12));
        let is_i =
            matches!(&event.logical_key, Key::Character(value) if value.eq_ignore_ascii_case("i"));
        let mac_shortcut = self.modifiers.super_key()
            && (self.modifiers.alt_key() || self.modifiers.shift_key())
            && is_i;
        let other_shortcut = self.modifiers.control_key() && self.modifiers.shift_key() && is_i;
        if is_f12 || mac_shortcut || other_shortcut {
            if !event.repeat {
                self.open_developer_tool("Console");
            }
            return;
        }
        if !self.developer_tools.open || self.developer_tools.focus.is_none() {
            return;
        }
        let command = self.modifiers.super_key() || self.modifiers.control_key();
        if command && let Key::Character(value) = &event.logical_key {
            match value.to_lowercase().as_str() {
                "a" => self.developer_tools.selection = true,
                "v" => match crate::clipboard::read() {
                    Ok(value) => self.developer_tools.insert(&value),
                    Err(error) => self.developer_tools.input_error = format!("Clipboard: {error}"),
                },
                "c" | "x" => {
                    let selected = self.developer_tools.selected_text();
                    if !selected.is_empty() {
                        match crate::clipboard::write(&selected) {
                            Ok(()) if value.eq_ignore_ascii_case("x") => {
                                self.developer_tools.insert("")
                            }
                            Ok(()) => {}
                            Err(error) => {
                                self.developer_tools.input_error = format!("Clipboard: {error}")
                            }
                        }
                    }
                }
                _ => {}
            }
        } else if let Key::Named(key) = &event.logical_key {
            if !self.developer_tools.preedit.is_empty() {
                return;
            }
            self.developer_tools
                .key(key, self.modifiers.shift_key(), command);
        } else if !command
            && self.developer_tools.preedit.is_empty()
            && let Some(text) = &event.text
        {
            let text: String = text.chars().filter(|c| !c.is_control()).collect();
            self.developer_tools.insert(&text);
        }
        self.request_redraw();
    }

    fn guest_covered(&self, point: Point) -> bool {
        if self.sidebar.covers(point) {
            return true;
        }
        let panel = self.layout.developer_tools.panel;
        self.developer_tools.open
            && crate::geometry::Rect::new(
                panel.x - 6.0,
                panel.y - 6.0,
                panel.width + 12.0,
                panel.height + 12.0,
            )
            .contains(point)
    }

    fn guest_point(&self) -> Option<Point> {
        if self.guest_covered(self.pointer) {
            return None;
        }
        let current = self.namespace.read().ok()?;
        let point = Point::new(self.pointer.x - self.sidebar.left(), self.pointer.y);
        if point.x < 0.0
            || point.y < 0.0
            || current
                .viewport
                .is_some_and(|size| point.x >= size.width || point.y >= size.height)
        {
            return None;
        }
        Some(current.document.frame.surface.to_world(point))
    }

    fn guest_hit(&self) -> Option<crate::events::Input> {
        let point = self.guest_point()?;
        let current = self.namespace.read().ok()?;
        let frame = &current.document.frame;
        if frame.session == 0 {
            return None;
        }
        let mount = frame.hit_test(point)?;
        Some(crate::events::Input {
            window: self.resource,
            session: frame.session,
            layout_version: frame.layout_version,
            mount: mount.id,
            kind: "click".into(),
            point: Some([point.x, point.y]),
            press_point: Some([point.x, point.y]),
            delta: None,
            tab_drop: None,
            screen_position: None,
        })
    }

    fn send_tab_shortcut(&mut self, close: bool) -> bool {
        let input = self.namespace.read().ok().and_then(|namespace| {
            let frame = &namespace.document.frame;
            if frame.session == 0 || frame.fault.is_some() || frame.tabs.is_empty() {
                return None;
            }
            let active = frame.tabs.iter().position(|tab| tab.active).unwrap_or(0);
            let index = if close {
                active
            } else if self.modifiers.shift_key() {
                (active + frame.tabs.len() - 1) % frame.tabs.len()
            } else {
                (active + 1) % frame.tabs.len()
            };
            Some(crate::events::Input {
                window: self.resource,
                session: frame.session,
                layout_version: frame.layout_version,
                mount: frame.tabs[index].id,
                kind: if close { "tab-close" } else { "tab-activate" }.into(),
                point: None,
                delta: None,
                press_point: None,
                tab_drop: None,
                screen_position: None,
            })
        });
        if let Some(input) = input {
            self.guest_pressed = None;
            self.guest_key = None;
            self.send_guest(input);
            true
        } else {
            false
        }
    }

    fn sidebar_action(&mut self, action: crate::sidebar::Action) {
        use crate::sidebar::Action;
        match action {
            Action::Toggle => {
                self.sidebar.open = !self.sidebar.open;
                self.sidebar.interaction.cancel();
                self.sidebar_keyboard = self.sidebar.open;
                self.guest_pressed = None;
                self.publish_viewport();
            }
            Action::NewPage => self.open_developer_tool("New tab"),
            Action::Tool(name) => self.open_developer_tool(name),
            Action::Activate(id) | Action::Close(id) => {
                let input = self
                    .namespace
                    .read()
                    .ok()
                    .map(|current| crate::events::Input {
                        window: self.resource,
                        session: current.document.frame.session,
                        layout_version: current.document.frame.layout_version,
                        mount: id,
                        kind: if matches!(action, Action::Close(_)) {
                            "tab-close"
                        } else {
                            "tab-activate"
                        }
                        .into(),
                        point: None,
                        press_point: None,
                        delta: None,
                        tab_drop: None,
                        screen_position: None,
                    });
                if let Some(input) = input {
                    self.send_guest(input);
                }
            }
        }
        self.request_redraw();
    }

    fn begin_pan(&mut self) -> bool {
        self.pan_viewport = None;
        let Some(point) = self.guest_point() else {
            return false;
        };
        let Ok(current) = self.namespace.read() else {
            return false;
        };
        let frame = &current.document.frame;
        self.pan_viewport = frame.camera_at(point).map(|mount| mount.id);
        self.pan_viewport.is_some() || frame.surface.mode != crate::page::Mode::Window
    }

    fn page_view(&mut self, kind: &str, delta: [f32; 2]) {
        if !self.panning && self.guest_covered(self.pointer) {
            return;
        }
        let point = Point::new(self.pointer.x - self.sidebar.left(), self.pointer.y);
        let input = self.namespace.read().ok().and_then(|current| {
            let frame = &current.document.frame;
            if frame.session == 0
                || frame.fault.is_some()
                || !self.panning
                    && (point.x < 0.0
                        || point.y < 0.0
                        || current
                            .viewport
                            .is_some_and(|size| point.x >= size.width || point.y >= size.height))
            {
                return None;
            }
            let world = frame.surface.to_world(point);
            let viewport = if self.panning {
                self.pan_viewport.and_then(|id| {
                    frame.mounts.iter().find(|mount| {
                        mount.id == id
                            && (mount.canvas_viewport
                                || mount.scene3d_viewport && mount.camera_controls)
                    })
                })
            } else {
                frame.camera_at(world)
            };
            if self.panning && self.pan_viewport.is_some() && viewport.is_none() {
                return None;
            }
            if let Some(viewport) = viewport {
                return Some(crate::events::Input {
                    window: self.resource,
                    session: frame.session,
                    layout_version: frame.layout_version,
                    mount: viewport.id,
                    kind: if viewport.scene3d_viewport {
                        if kind == "page-zoom" {
                            "scene-zoom"
                        } else if self.orbiting {
                            "scene-orbit"
                        } else {
                            "scene-pan"
                        }
                    } else if kind == "page-zoom" {
                        "viewport-zoom"
                    } else {
                        "viewport-pan"
                    }
                    .into(),
                    point: Some([world.x, world.y]),
                    press_point: None,
                    delta: Some([
                        delta[0]
                            / if kind == "page-pan" {
                                frame.surface.zoom
                            } else {
                                1.0
                            },
                        delta[1] / frame.surface.zoom,
                    ]),
                    tab_drop: None,
                    screen_position: None,
                });
            }
            if frame.surface.mode == crate::page::Mode::Window
                || kind == "page-zoom" && frame.surface.mode != crate::page::Mode::Canvas
            {
                return None;
            }
            Some(crate::events::Input {
                window: self.resource,
                session: frame.session,
                layout_version: frame.layout_version,
                mount: 0,
                kind: kind.into(),
                point: (kind == "page-zoom").then_some([point.x, point.y]),
                press_point: None,
                delta: Some(delta),
                tab_drop: None,
                screen_position: None,
            })
        });
        if let Some(input) = input {
            self.guest_pressed = None;
            self.send_guest(input);
        }
    }

    fn send_guest(&mut self, event: crate::events::Input) {
        if !self.event_client.send(event) {
            self.developer_tools.input_error = "Native event queue is unavailable or full".into();
            self.developer_tools.open = true;
        }
    }

    fn handle_guest_key(&mut self, event: &winit::event::KeyEvent) -> bool {
        let Key::Named(key) = &event.logical_key else {
            return false;
        };
        if *key == NamedKey::Tab {
            if event.state == ElementState::Pressed && !event.repeat {
                let next = self.namespace.read().ok().and_then(|namespace| {
                    let frame = &namespace.document.frame;
                    if frame.session == 0 || frame.fault.is_some() {
                        return None;
                    }
                    let targets: Vec<_> = frame
                        .mounts
                        .iter()
                        .filter(|mount| mount.interactive)
                        .collect();
                    if targets.is_empty() {
                        return None;
                    }
                    let current = self
                        .guest_focus
                        .as_ref()
                        .and_then(|focus| targets.iter().position(|mount| mount.id == focus.mount));
                    let index = if self.modifiers.shift_key() {
                        current
                            .map(|i| (i + targets.len() - 1) % targets.len())
                            .unwrap_or(targets.len() - 1)
                    } else {
                        current.map(|i| (i + 1) % targets.len()).unwrap_or(0)
                    };
                    Some(crate::events::Input {
                        window: self.resource,
                        session: frame.session,
                        layout_version: frame.layout_version,
                        mount: targets[index].id,
                        kind: "focus".into(),
                        point: None,
                        delta: None,
                        press_point: None,
                        tab_drop: None,
                        screen_position: None,
                    })
                });
                if let Some(next) = next {
                    self.guest_key = None;
                    self.guest_focus = Some(next.clone());
                    self.send_guest(next);
                    return true;
                }
                return false;
            }
            return self.guest_focus.is_some();
        }
        if matches!(key, NamedKey::Enter | NamedKey::Space) && self.guest_focus.is_some() {
            if event.state == ElementState::Pressed {
                if !event.repeat {
                    self.guest_key = self.guest_focus.clone().map(|focus| (*key, focus));
                }
            } else if let Some((pressed, mut input)) = self.guest_key.take()
                && pressed == *key
            {
                input.kind = "click".into();
                self.send_guest(input);
            }
            return true;
        }
        false
    }

    fn create_native(&mut self, event_loop: &ActiveEventLoop) -> anyhow::Result<()> {
        if self.window.is_some() {
            return Ok(());
        }

        let attributes = WindowAttributes::default()
            .with_title(if self.resource == crate::window::MAIN_WINDOW {
                "Tessera".into()
            } else {
                format!("Endor Window {}", self.resource)
            })
            .with_inner_size(if self.resource == crate::window::MAIN_WINDOW {
                LogicalSize::new(1_280.0, 800.0)
            } else {
                LogicalSize::new(960.0, 640.0)
            })
            .with_min_inner_size(LogicalSize::new(720.0, 480.0))
            .with_max_inner_size(LogicalSize::new(
                crate::window::MAX_WINDOW_DIMENSION,
                crate::window::MAX_WINDOW_DIMENSION,
            ));
        #[cfg(target_os = "macos")]
        let attributes = {
            use winit::platform::macos::WindowAttributesExtMacOS;
            attributes
                .with_title_hidden(true)
                .with_titlebar_transparent(true)
                .with_fullsize_content_view(true)
        };
        let window = Arc::new(event_loop.create_window(attributes)?);
        #[cfg(target_os = "macos")]
        crate::native_chrome::align_controls(&window);
        let context = Context::new(window.clone()).map_err(|error| anyhow::anyhow!("{error}"))?;
        let surface =
            Surface::new(&context, window.clone()).map_err(|error| anyhow::anyhow!("{error}"))?;

        window.set_ime_allowed(true);
        self.window = Some(window.clone());
        self.context = Some(context);
        self.surface = Some(surface);
        self.apply_window_commands();
        self.publish_viewport();
        window.request_redraw();
        self.native_error = None;
        Ok(())
    }

    fn request_exit(&mut self) {
        if self.exit_requested {
            return;
        }
        self.guest_pressed = None;
        self.guest_key = None;
        if self.control.request_shutdown() {
            self.exit_requested = true;
        } else {
            self.native_error = Some("VM worker unavailable during shutdown".into());
            let _ = self.proxy.send_event(AppEvent::ShutdownComplete {
                error: self.native_error.clone(),
            });
        }
    }

    pub fn exit_result(&self) -> anyhow::Result<()> {
        if let Some(error) = &self.native_error {
            anyhow::bail!("{error}");
        }
        Ok(())
    }

    fn redraw(&mut self) {
        #[cfg(target_os = "macos")]
        if let Some(window) = self.window.as_ref() {
            crate::native_chrome::align_controls(window);
        }
        match self.try_redraw() {
            Ok(()) => {
                if self.window.is_some() && self.surface.is_some() {
                    self.native_error = None;
                }
            }
            Err(error) => {
                let message = format!("Window {} redraw failed: {error:#}", self.resource);
                if self.native_error.as_ref() != Some(&message) {
                    self.native_error = Some(message.clone());
                    let _ = self.proxy.send_event(AppEvent::RuntimeFailed { message });
                }
            }
        }
    }

    fn try_redraw(&mut self) -> anyhow::Result<()> {
        let guest_cursor = self.guest_hit().is_some()
            || self
                .sidebar
                .interaction
                .hit(&self.sidebar.targets)
                .is_some();
        let (Some(window), Some(surface)) = (self.window.as_ref(), self.surface.as_mut()) else {
            return Ok(());
        };
        let size = window.inner_size();
        let (Some(width), Some(height)) =
            (NonZeroU32::new(size.width), NonZeroU32::new(size.height))
        else {
            return Ok(());
        };

        let Ok(namespace) = self.namespace.read() else {
            return Ok(());
        };
        let scene = scene::build_scene(
            size.width,
            size.height,
            window.scale_factor() as f32,
            &namespace.document,
            &mut self.developer_tools,
            &self.activity,
            &mut self.sidebar,
        );
        drop(namespace);
        self.layout = scene.layout;
        window.set_cursor(if guest_cursor {
            winit::window::CursorIcon::Pointer
        } else {
            self.developer_tools
                .cursor_kind(&self.layout.developer_tools)
        });
        if self.developer_tools.repaint {
            self.developer_tools.repaint = false;
            window.request_redraw();
        }
        let ime = self
            .developer_tools
            .ime_position(&self.layout.developer_tools);
        window.set_ime_cursor_area(
            LogicalPosition::new(ime.x as f64, ime.y as f64),
            LogicalSize::new(1.0, 19.0),
        );

        surface
            .resize(width, height)
            .map_err(|error| anyhow::anyhow!("{error}"))?;
        let mut buffer = surface
            .buffer_mut()
            .map_err(|error| anyhow::anyhow!("{error}"))?;
        SoftwareRenderer::render(&scene.display_list, &mut buffer, size.width, size.height)
            .map_err(anyhow::Error::msg)?;
        buffer
            .present()
            .map_err(|error| anyhow::anyhow!("{error}"))?;
        Ok(())
    }
}

impl ApplicationHandler<AppEvent> for TesseraApp {
    fn exiting(&mut self, _: &ActiveEventLoop) {
        // OS termination can bypass CloseRequested. The loop is already ending;
        // use a bounded fallback rather than silently dropping every callback.
        if !self.control.request_shutdown() {
            self.native_error = Some("VM worker unavailable during shutdown".into());
            return;
        }
        match self.control.wait_shutdown(Duration::from_secs(5)) {
            Some(outcome) => {
                if let Some(error) = outcome.error {
                    self.native_error = Some(error);
                }
            }
            None => self.native_error = Some("VM shutdown did not finish within 5 seconds".into()),
        }
    }

    fn about_to_wait(&mut self, _event_loop: &ActiveEventLoop) {}

    fn resumed(&mut self, event_loop: &ActiveEventLoop) {
        if self.resource == crate::window::MAIN_WINDOW
            && !self.startup_page_requested
            && self
                .namespace
                .read()
                .is_ok_and(|n| n.runtime_session == 0 && n.document.frame.tabs.is_empty())
        {
            self.startup_page_requested = true;
            self.developer_tools.initialize_tools("New tab");
        }

        if let Err(error) = self.create_native(event_loop) {
            self.native_error = Some(format!(
                "Window {} initialization failed: {error:#}",
                self.resource
            ));
            if self.resource == crate::window::MAIN_WINDOW {
                event_loop.exit();
            }
        }
    }

    fn user_event(&mut self, event_loop: &ActiveEventLoop, event: AppEvent) {
        if self.control.is_exiting() && !matches!(&event, AppEvent::ShutdownComplete { .. }) {
            return;
        }
        match event {
            AppEvent::ShutdownComplete { error } => {
                if let Some(error) = error {
                    self.native_error = Some(error);
                }
                event_loop.exit();
            }
            AppEvent::RuntimeFailed { message } => {
                self.developer_tools.input_error = message;
                self.developer_tools.open = true;
                self.guest_pressed = None;
                self.guest_key = None;
                self.request_redraw();
            }
            AppEvent::DocumentUpdated => self.document_updated(event_loop),
            AppEvent::ConsoleFailed { message, source } => {
                self.developer_tools.input_error = format!("Request failed: {message}");
                if self.developer_tools.input.is_empty() {
                    self.developer_tools.input = source;
                    self.developer_tools.cursor = self.developer_tools.input.len();
                    self.developer_tools.reveal_cursor();
                }
                self.request_redraw();
            }
        }
    }

    fn window_event(
        &mut self,
        _event_loop: &ActiveEventLoop,
        window_id: WindowId,
        event: WindowEvent,
    ) {
        if self.control.is_exiting() {
            return;
        }
        let Some(window) = self.window.as_ref().cloned() else {
            return;
        };
        if window.id() != window_id {
            if let Some(child) = self.children.values_mut().find(|child| {
                child
                    .window
                    .as_ref()
                    .is_some_and(|window| window.id() == window_id)
            }) {
                child.window_event(_event_loop, window_id, event);
                self.publish_viewport();
            }
            return;
        }

        match event {
            WindowEvent::CloseRequested => {
                if self.resource == crate::window::MAIN_WINDOW {
                    self.request_exit();
                } else {
                    let input = self
                        .namespace
                        .read()
                        .ok()
                        .map(|namespace| crate::events::Input {
                            window: self.resource,
                            session: namespace.document.frame.session,
                            layout_version: namespace.document.frame.layout_version,
                            mount: 0,
                            kind: "window-close".into(),
                            point: None,
                            delta: None,
                            press_point: None,
                            tab_drop: None,
                            screen_position: None,
                        });
                    if let Some(input) = input {
                        self.send_guest(input);
                    }
                }
            }
            WindowEvent::Resized(_) | WindowEvent::ScaleFactorChanged { .. } => {
                self.publish_viewport();
                window.request_redraw();
            }
            WindowEvent::CursorMoved {
                position: PhysicalPosition { x, y },
                ..
            } => {
                let scale = window.scale_factor() as f32;
                let next = Point::new(x as f32 / scale, y as f32 / scale);
                let delta = Point::new(next.x - self.pointer.x, next.y - self.pointer.y);
                self.pointer = next;
                self.sidebar
                    .interaction
                    .pointer_moved(next, &self.sidebar.targets);
                if !self.panning
                    && let Some(press) = &self.guest_pressed
                    && let Some(point) = self.guest_point()
                    && let Some(start) = press.point
                {
                    let is_3d = self.namespace.read().is_ok_and(|current| {
                        current.document.frame.mounts.iter().any(|mount| {
                            mount.id == press.mount
                                && mount.scene3d_viewport
                                && mount.camera_controls
                        })
                    });
                    if is_3d && (point.x - start[0]).hypot(point.y - start[1]) > 3. {
                        self.orbiting = true;
                        self.panning = self.begin_pan();
                        self.guest_pressed = None;
                    }
                }
                if self.panning {
                    self.page_view("page-pan", [-delta.x, -delta.y]);
                    window.request_redraw();
                    return;
                }
                self.developer_tools.move_pointer(
                    next,
                    delta,
                    &self.layout.developer_tools,
                    window.inner_size().width as f32 / scale,
                );
                window.set_cursor(
                    if self.guest_hit().is_some()
                        || self
                            .sidebar
                            .interaction
                            .hit(&self.sidebar.targets)
                            .is_some()
                    {
                        winit::window::CursorIcon::Pointer
                    } else {
                        self.developer_tools
                            .cursor_kind(&self.layout.developer_tools)
                    },
                );
                window.request_redraw();
            }
            WindowEvent::CursorLeft { .. } => {
                self.guest_pressed = None;
                self.panning = false;
                self.sidebar.interaction.pointer_left();
                self.developer_tools.pointer_left();
                window.set_cursor(winit::window::CursorIcon::Default);
                window.request_redraw();
            }
            WindowEvent::MouseInput {
                state,
                button: MouseButton::Middle,
                ..
            } => {
                self.orbiting = false;
                self.panning = state == ElementState::Pressed && self.begin_pan();
                self.guest_pressed = None;
                window.request_redraw();
            }
            WindowEvent::MouseInput {
                state,
                button: MouseButton::Left,
                ..
            } => {
                if state == ElementState::Pressed {
                    if self.sidebar.covers(self.pointer) {
                        self.sidebar_keyboard = true;
                        self.sidebar.interaction.press(&self.sidebar.targets);
                        self.guest_pressed = None;
                        if self.sidebar.open
                            && self.pointer.y < crate::sidebar::HEADER
                            && self.pointer.x >= crate::sidebar::CONTROLS
                            && self
                                .sidebar
                                .interaction
                                .hit(&self.sidebar.targets)
                                .is_none()
                        {
                            #[cfg(target_os = "macos")]
                            if crate::native_chrome::titlebar_double_click(&window) {
                                return;
                            }
                            let _ = window.drag_window();
                        }
                    } else if self.space_down && self.guest_point().is_some() {
                        self.orbiting = false;
                        self.panning = self.begin_pan();
                        self.guest_pressed = None;
                    } else {
                        self.sidebar_keyboard = false;
                        self.sidebar.interaction.blur();
                        self.guest_keyboard = !self.guest_covered(self.pointer);
                        if self.guest_keyboard {
                            self.developer_tools.blur();
                        }
                        self.guest_pressed = self.guest_hit();
                        self.developer_tools.press(
                            &self.layout.developer_tools,
                            self.pointer,
                            &self.activity,
                        );
                    }
                } else {
                    if self.panning {
                        self.panning = false;
                        self.guest_pressed = None;
                        window.request_redraw();
                        return;
                    }
                    if let Some(action) = self.sidebar.interaction.release(&self.sidebar.targets) {
                        self.sidebar_action(action);
                    } else if let Some(pressed) = self.guest_pressed.take()
                        && let Some(mut released) = self.guest_hit()
                        && released.session == pressed.session
                        && released.layout_version == pressed.layout_version
                    {
                        released.press_point = pressed.point;
                        self.send_guest(released);
                    }
                    self.developer_tools.release(
                        &self.layout.developer_tools,
                        self.pointer,
                        &self.activity,
                    );
                }
                window.request_redraw();
            }
            WindowEvent::PinchGesture { delta, .. } => {
                self.page_view("page-zoom", [(delta as f32).exp(), 0.0]);
                window.request_redraw();
            }
            WindowEvent::MouseWheel { delta, .. } => {
                let (mut dx, mut dy) = match delta {
                    MouseScrollDelta::LineDelta(x, y) => (x * 38.0, y * 38.0),
                    MouseScrollDelta::PixelDelta(p) => (
                        p.x as f32 / window.scale_factor() as f32,
                        p.y as f32 / window.scale_factor() as f32,
                    ),
                };
                if self.modifiers.shift_key() && dx.abs() < 0.1 {
                    dx = dy;
                    dy = 0.0;
                }
                if self.sidebar.covers(self.pointer) {
                    if self.sidebar.open && self.pointer.y >= 333.0 {
                        self.sidebar.scroll -= dy;
                    }
                    window.request_redraw();
                    return;
                }
                let point = self.guest_point();
                let canvas = self.namespace.read().is_ok_and(|n| {
                    n.document.frame.surface.mode == crate::page::Mode::Canvas
                        || point.is_some_and(|point| n.document.frame.camera_at(point).is_some())
                });
                if canvas && (self.modifiers.super_key() || self.modifiers.control_key()) {
                    self.page_view("page-zoom", [(dy * 0.005).exp().clamp(0.1, 10.0), 0.0]);
                    window.request_redraw();
                    return;
                }
                let scene3d = self.namespace.read().is_ok_and(|current| {
                    point
                        .and_then(|point| current.document.frame.camera_at(point))
                        .is_some_and(|mount| mount.scene3d_viewport)
                });
                let point = self.guest_point();
                let input = point.and_then(|point| {
                    self.namespace.read().ok().and_then(|namespace| {
                        let frame = &namespace.document.frame;
                        if frame.session == 0 || frame.fault.is_some() {
                            return None;
                        }
                        let delta = [-dx / frame.surface.zoom, -dy / frame.surface.zoom];
                        let mount = crate::scroll::wheel_target(frame, point, delta)?;
                        Some(crate::events::Input {
                            window: self.resource,
                            session: frame.session,
                            layout_version: frame.layout_version,
                            mount,
                            kind: "scroll".into(),
                            point: Some([point.x, point.y]),
                            press_point: None,
                            tab_drop: None,
                            screen_position: None,
                            delta: Some(delta),
                        })
                    })
                });
                if let Some(input) = input {
                    self.send_guest(input);
                } else if scene3d {
                    self.page_view("page-zoom", [(dy * 0.005).exp().clamp(0.1, 10.), 0.]);
                } else {
                    let horizontal = self.namespace.read().is_ok_and(|n| {
                        n.document.frame.surface.mode == crate::page::Mode::Horizontal
                    });
                    self.page_view(
                        "page-pan",
                        if horizontal && dx.abs() < 0.1 {
                            [-dy, 0.0]
                        } else {
                            [-dx, -dy]
                        },
                    );
                }
                self.developer_tools
                    .wheel(&self.layout.developer_tools, self.pointer, dx, dy);
                window.request_redraw();
            }
            WindowEvent::Ime(Ime::Preedit(value, _)) => {
                self.developer_tools.preedit = value;
                window.request_redraw();
            }
            WindowEvent::Ime(Ime::Commit(value)) => {
                self.developer_tools.preedit.clear();
                if self.developer_tools.open {
                    self.developer_tools.insert(&value);
                }
                window.request_redraw();
            }
            WindowEvent::Focused(false) => {
                self.guest_pressed = None;
                self.guest_key = None;
                self.developer_tools.blur();
                self.sidebar.interaction.blur();
                self.panning = false;
                self.space_down = false;
                self.modifiers = ModifiersState::default();
                window.request_redraw();
            }
            WindowEvent::ModifiersChanged(modifiers) => self.modifiers = modifiers.state(),
            WindowEvent::KeyboardInput { event, .. } => self.handle_keyboard(&event),
            WindowEvent::RedrawRequested => self.redraw(),
            _ => {}
        }
    }
}