/*
 * the system tray, right of the workspaces. tray apps (StatusNotifierItem) register
 * with a watcher on the session bus; nothing on this desktop runs one, so the shell
 * owns org.kde.StatusNotifierWatcher and serves it, and is its own host. each app's
 * icon comes from its IconName (looked up in the icon themes) or its IconPixmap
 * (written out as a png, see png.rs). a left click activates the app (or opens its
 * menu if that's all it has), a right click opens its menu (com.canonical.dbusmenu)
 * drawn here in the island's look, a middle click is the app's secondary action, a
 * scroll its scroll. everything on the bus happens on threads, never while drawing
 */
use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::sync::{Mutex, PoisonError, mpsc};
use std::time::{Duration, SystemTime, UNIX_EPOCH};
use std::{env, fs, thread};

use amane::{
    Animation, Argument, Blend, Bus, Button, Center, Color, Column, Full, Horizontal, Image, InputArea, Layer,
    LayerWindow, Margin, Monitor, Padding, Parent, Pointer, Rectangle, Row, Scroll, Service, SpaceBetween,
    Start, Text, Value, Vertical, Weight, Widget, Zone,
};

use crate::config::appearance::{motion, overlays, text};
use crate::config::island::pill as island_pill;
use crate::config::tray::{menu, pill};
use crate::glyph::{Glyph, icon};
use crate::island::{CLEAR, faded, veiled};
use crate::{edge, parse, png, surface, theme};

const WATCHER: &str = "org.kde.StatusNotifierWatcher";
const WATCHER_PATH: &str = "/StatusNotifierWatcher";
const ITEM: &str = "org.kde.StatusNotifierItem";
const MENU: &str = "com.canonical.dbusmenu";
const PROPERTIES: &str = "org.freedesktop.DBus.Properties";

// the tray's pill (a slot per icon, like the workspaces' slots) and its menu are settings (config.rs: tray.*)

const INTROSPECTION: &str = r#"<!DOCTYPE node PUBLIC "-//freedesktop//DTD D-BUS Object Introspection 1.0//EN" "http://www.freedesktop.org/standards/dbus/1.0/introspect.dtd">
<node>
  <interface name="org.kde.StatusNotifierWatcher">
    <method name="RegisterStatusNotifierItem"><arg name="service" type="s" direction="in"/></method>
    <method name="RegisterStatusNotifierHost"><arg name="service" type="s" direction="in"/></method>
    <property name="RegisteredStatusNotifierItems" type="as" access="read"/>
    <property name="IsStatusNotifierHostRegistered" type="b" access="read"/>
    <property name="ProtocolVersion" type="i" access="read"/>
    <signal name="StatusNotifierItemRegistered"><arg type="s"/></signal>
    <signal name="StatusNotifierItemUnregistered"><arg type="s"/></signal>
    <signal name="StatusNotifierHostRegistered"/>
  </interface>
</node>"#;

// one app in the tray
#[derive(Clone, PartialEq)]
pub struct Item {
    // what RegisteredStatusNotifierItems lists: its bus name and object path, together
    pub key: String,
    bus: String,
    path: String,

    // its unique name (":1.42"), which its signals come from
    owner: String,

    pub title: String,
    pub icon: Option<PathBuf>,

    // NeedsAttention: a ring around it; Passive: not shown
    pub attention: bool,
    passive: bool,

    // its dbusmenu's object path, and whether a click should open that rather than activate
    menu: String,
    only_menu: bool,
}

#[derive(Default)]
pub struct Tray {
    pub items: Vec<Item>,
}

impl Service for Tray {
    fn new() -> Self {
        Self::default()
    }

    fn listen() {
        let bus = Bus::session();

        // the calls are watched before the name is taken, so none is missed
        let calls = bus.methods(WATCHER_PATH, WATCHER);
        let properties = bus.methods(WATCHER_PATH, PROPERTIES);
        let introspection = bus.methods(WATCHER_PATH, "org.freedesktop.DBus.Introspectable");

        // another watcher runs (another bar): leave it be, and show nothing
        if !bus.own(WATCHER) {
            return;
        }

        bus.emit(WATCHER_PATH, WATCHER, "StatusNotifierHostRegistered", &[]);

        thread::spawn(move || {
            for call in properties {
                let value = |name: &str| match name {
                    "RegisteredStatusNotifierItems" => Some(Argument::TextList(Tray::read().items.iter().map(|item| item.key.clone()).collect())),
                    "IsStatusNotifierHostRegistered" => Some(Argument::Bool(true)),
                    "ProtocolVersion" => Some(Argument::Int(0)),
                    _ => None,
                };

                match call.name() {
                    "Get" => {
                        let name = call.arguments().get(1).map(|name| name.text().to_string()).unwrap_or_default();

                        match value(&name) {
                            Some(value) => call.reply(&[Argument::Variant(Box::new(value))]),
                            None => call.reply(&[]),
                        }
                    }
                    "GetAll" => {
                        let all = ["RegisteredStatusNotifierItems", "IsStatusNotifierHostRegistered", "ProtocolVersion"]
                            .into_iter()
                            .filter_map(|name| Some((name.to_string(), value(name)?)))
                            .collect();

                        call.reply(&[Argument::Map(all)]);
                    }
                    _ => call.reply(&[]),
                }
            }
        });

        thread::spawn(move || {
            for call in introspection {
                call.reply(&[Argument::from(INTROSPECTION)]);
            }
        });

        // an app that quits leaves the bus: its icon goes
        thread::spawn(|| {
            for signal in Bus::session().signals("org.freedesktop.DBus", "NameOwnerChanged") {
                let arguments = signal.arguments();
                let (name, gone) = (arguments.first().map_or("", Value::text), arguments.get(2).is_some_and(|owner| owner.text().is_empty()));

                if gone && !name.is_empty() {
                    forget(name);
                }
            }
        });

        // an app that changed its icon, title or status says so
        for change in ["NewIcon", "NewAttentionIcon", "NewStatus", "NewTitle", "NewToolTip", "NewMenu"] {
            thread::spawn(move || {
                for signal in Bus::session().signals(ITEM, change) {
                    let stale: Vec<Item> = Tray::read().items.iter().filter(|item| item.owner == signal.sender() && item.path == signal.path()).cloned().collect();

                    for item in stale {
                        refresh(&item.bus, &item.path, &item.owner);
                    }
                }
            });
        }

        for call in calls {
            let name = call.name().to_string();
            let service = call.arguments().first().map(|service| service.text().to_string()).unwrap_or_default();

            // answered at once: the app waits for it
            call.reply(&[]);

            if name == "RegisterStatusNotifierItem" && !service.is_empty() {
                thread::spawn(move || register(&service));
            }
        }
    }
}

/*
 * an app's registration: a bus name (its item at /StatusNotifierItem), or, from
 * libappindicator, only the object path. amane doesn't say who called, so for a path
 * the newest connections are asked which one has that item
 */
fn register(service: &str) {
    let bus = Bus::session();

    let (name, path) = if service.starts_with('/') {
        let Some(owner) = find_owner(&bus, service) else {
            return;
        };

        (owner, service.to_string())
    } else {
        match service.split_once('/') {
            Some((name, path)) => (name.to_string(), format!("/{path}")),
            None => (service.to_string(), String::from("/StatusNotifierItem")),
        }
    };

    let owner = if name.starts_with(':') {
        name.clone()
    } else {
        bus.call("org.freedesktop.DBus", "/org/freedesktop/DBus", "org.freedesktop.DBus", "GetNameOwner", &[Argument::from(name.as_str())]).text().to_string()
    };

    if owner.is_empty() {
        return;
    }

    refresh(&name, &path, &owner);

    let key = format!("{name}{path}");

    bus.emit(WATCHER_PATH, WATCHER, "StatusNotifierItemRegistered", &[Argument::from(key)]);
}

/*
 * the connection that serves an item at this path. asked all at once, first answer
 * wins: some connections never answer a call they don't know (the shell's own among
 * them), and each of those would hold a one-by-one search for the bus's whole timeout
 */
fn find_owner(bus: &Bus, path: &str) -> Option<String> {
    let names = bus.call("org.freedesktop.DBus", "/org/freedesktop/DBus", "org.freedesktop.DBus", "ListNames", &[]);
    let (found, answers) = mpsc::channel();

    for name in names.list().iter().map(Value::text).filter(|name| name.starts_with(':')) {
        let (name, path, found) = (name.to_string(), path.to_string(), found.clone());

        thread::spawn(move || {
            let answer = Bus::session().call(&name, &path, PROPERTIES, "Get", &[Argument::from(ITEM), Argument::from("Id")]);

            if !matches!(answer, Value::Nothing) {
                let _ = found.send(name);
            }
        });
    }

    drop(found);

    answers.recv_timeout(Duration::from_secs(5)).ok()
}

// reads an item again and puts it in the tray, or takes it out if it doesn't answer
fn refresh(name: &str, path: &str, owner: &str) {
    let key = format!("{name}{path}");
    let all = Bus::session().call(name, path, PROPERTIES, "GetAll", &[Argument::from(ITEM)]);

    if !matches!(all, Value::Map(_)) {
        Tray::write().items.retain(|item| item.key != key);

        return;
    }

    let text = |property: &str| all.get(property).text().to_string();
    let status = text("Status");
    let attention = status == "NeedsAttention";

    // the attention icon while it wants attention, else the icon; a name before pixels
    let (name_property, pixmap_property) = if attention && !text("AttentionIconName").is_empty() { ("AttentionIconName", "AttentionIconPixmap") } else { ("IconName", "IconPixmap") };

    let icon = icon_file(&text(name_property), &text("IconThemePath")).or_else(|| pixmap_file(all.get(pixmap_property)));

    // the tooltip's title is often the clearest name
    let tooltip = all.get("ToolTip").list().get(2).map(|title| title.text().to_string()).unwrap_or_default();
    let title = [text("Title"), tooltip, text("Id")].into_iter().find(|title| !title.is_empty()).unwrap_or_default();

    let item = Item {
        key: key.clone(),
        bus: name.to_string(),
        path: path.to_string(),
        owner: owner.to_string(),
        title,
        icon,
        attention,
        passive: status == "Passive",
        menu: text("Menu"),
        only_menu: all.get("ItemIsMenu").bool(),
    };

    let mut tray = Tray::write();

    match tray.items.iter_mut().find(|known| known.key == key) {
        Some(known) if *known == item => {}
        Some(known) => *known = item,
        None => tray.items.push(item),
    }
}

fn forget(name: &str) {
    let gone: Vec<String> = Tray::read().items.iter().filter(|item| item.owner == name || item.bus == name).map(|item| item.key.clone()).collect();

    if gone.is_empty() {
        return;
    }

    Tray::write().items.retain(|item| !gone.contains(&item.key));

    let bus = Bus::session();

    for key in gone {
        bus.emit(WATCHER_PATH, WATCHER, "StatusNotifierItemUnregistered", &[Argument::from(key)]);
    }
}

// icons

/*
 * an icon name as a file: the app's own theme folder first, then the icon themes
 * (gtk's choice, hicolor, Adwaita), then /usr/share/pixmaps. themes are walked once
 * per name, the answer kept
 */
pub fn icon_file(name: &str, theme_path: &str) -> Option<PathBuf> {
    static FOUND: Mutex<Option<HashMap<String, Option<PathBuf>>>> = Mutex::new(None);

    if name.is_empty() {
        return None;
    }

    if name.starts_with('/') {
        return Path::new(name).exists().then(|| PathBuf::from(name));
    }

    let key = format!("{theme_path}\u{1f}{name}");

    if let Some(found) = FOUND.lock().unwrap_or_else(PoisonError::into_inner).get_or_insert_with(HashMap::new).get(&key) {
        return found.clone();
    }

    let home = env::var("HOME").unwrap_or_default();
    let bases = [format!("{home}/.local/share/icons"), format!("{home}/.icons"), String::from("/usr/share/icons")];

    let mut themes: Vec<String> = Vec::new();

    let gtk = fs::read_to_string(format!("{home}/.config/gtk-3.0/settings.ini")).unwrap_or_default();

    if let Some(chosen) = gtk.lines().find_map(|line| line.trim().strip_prefix("gtk-icon-theme-name")).map(|rest| rest.trim_start_matches([' ', '=']).trim().to_string()) {
        themes.push(chosen);
    }

    themes.extend(["hicolor", "AdwaitaLegacy", "Adwaita"].map(String::from));

    let mut roots: Vec<PathBuf> = Vec::new();

    if !theme_path.is_empty() {
        roots.push(PathBuf::from(theme_path));
    }

    for theme in &themes {
        for base in &bases {
            roots.push(Path::new(base).join(theme));
        }
    }

    let mut found = roots.iter().find_map(|root| best_in(root, name));

    if found.is_none() {
        found = ["png", "svg", "xpm"].iter().map(|extension| PathBuf::from(format!("/usr/share/pixmaps/{name}.{extension}"))).find(|path| path.exists() && !path.ends_with(".xpm"));
    }

    FOUND.lock().unwrap_or_else(PoisonError::into_inner).get_or_insert_with(HashMap::new).insert(key, found.clone());

    found
}

// the best-fitting file for this name anywhere under a theme folder (see parse::icon_score)
fn best_in(root: &Path, name: &str) -> Option<PathBuf> {
    let mut best: Option<(u32, PathBuf)> = None;
    let mut folders = vec![(root.to_path_buf(), 0)];

    while let Some((folder, depth)) = folders.pop() {
        let Ok(entries) = fs::read_dir(&folder) else {
            continue;
        };

        for entry in entries.flatten() {
            let path = entry.path();

            if path.is_dir() {
                if depth < 3 {
                    folders.push((path, depth + 1));
                }

                continue;
            }

            let stem = path.file_stem().and_then(|stem| stem.to_str());
            let extension = path.extension().and_then(|extension| extension.to_str());

            if stem == Some(name) && matches!(extension, Some("png" | "svg")) {
                let score = parse::icon_score(&path.to_string_lossy());

                if best.as_ref().is_none_or(|(known, _)| score < *known) {
                    best = Some((score, path));
                }
            }
        }
    }

    best.map(|(_, path)| path)
}

/*
 * IconPixmap as a png: the size nearest 32 px of those it sends, in the runtime folder,
 * named after its pixels so a new icon is a new path (amane keeps images by path)
 */
fn pixmap_file(pixmaps: &Value) -> Option<PathBuf> {
    let chosen = pixmaps.list().iter().filter(|pixmap| pixmap.list().len() == 3).min_by_key(|pixmap| (pixmap.list()[0].number() as i64 - 32).abs())?;

    let (width, height) = (chosen.list()[0].number() as u32, chosen.list()[1].number() as u32);
    let argb: Vec<u8> = chosen.list()[2].list().iter().map(|byte| byte.number() as u8).collect();

    if width == 0 || height == 0 || argb.len() != (width * height * 4) as usize {
        return None;
    }

    // fnv-1a over the pixels
    let hash = argb.iter().fold(0xcbf2_9ce4_8422_2325_u64, |hash, byte| (hash ^ u64::from(*byte)).wrapping_mul(0x0100_0000_01b3));

    let folder = Path::new(&env::var("XDG_RUNTIME_DIR").unwrap_or_else(|_| String::from("/tmp"))).join("amane-tray");
    let path = folder.join(format!("{hash:016x}.png"));

    if !path.exists() {
        fs::create_dir_all(&folder).ok()?;
        fs::write(&path, png::encode(width, height, &png::argb_to_rgba(&argb))).ok()?;
    }

    Some(path)
}

// what a click, a middle click or a scroll asks of an app; all on threads

fn activate(item: &Item, method: &'static str) {
    let item = item.clone();

    thread::spawn(move || {
        Bus::session().call(&item.bus, &item.path, ITEM, method, &[Argument::Int(0), Argument::Int(0)]);
    });
}

fn scroll(item: &Item, delta: i32) {
    let item = item.clone();

    thread::spawn(move || {
        Bus::session().call(&item.bus, &item.path, ITEM, "Scroll", &[Argument::Int(delta), Argument::from("vertical")]);
    });
}

// the menu

// one entry of an app's menu
#[derive(Clone, PartialEq)]
struct Entry {
    id: i32,
    label: String,
    enabled: bool,
    separator: bool,

    // a checkmark or radio, and whether it's on
    toggle: Option<bool>,
    submenu: bool,
}

#[derive(Clone)]
struct Open {
    item: Item,
    monitor: String,

    // the menu's left edge, from the monitor's left
    x: f32,

    // the submenus entered, with their labels, for the way back
    trail: Vec<(i32, String)>,
    entries: Vec<Entry>,
}

pub struct TrayUi {
    // icons and menu rows under the pointer
    hover: HashMap<String, Animation>,

    open: Option<Open>,
    appear: Animation,
    inside: bool,

    // bumped when a menu opens or the pointer comes back, so an older close timer does nothing
    moves: u32,
}

impl Service for TrayUi {
    fn new() -> Self {
        Self { hover: HashMap::new(), open: None, appear: Animation::new(0.0), inside: false, moves: 0 }
    }

    // changes only through input and the apps' answers
    fn listen() {}
}

fn hovering(spot: String) -> impl Fn(bool) + 'static {
    move |inside| {
        TrayUi::write()
            .hover
            .entry(spot.clone())
            .or_insert_with(|| Animation::new(0.0).duration(Duration::from_millis(motion::hover_ms())))
            .to(if inside { 1.0 } else { 0.0 });
    }
}

/*
 * the app's menu (or the submenu `parent`): AboutToShow lets it fill in what it fills
 * in late, GetLayout gives the entries. (u revision, (i id, a{sv} properties, av children))
 */
fn layout(item: &Item, parent: i32) -> Vec<Entry> {
    let bus = Bus::session();

    bus.call(&item.bus, &item.menu, MENU, "AboutToShow", &[Argument::Int(parent)]);

    let answer = bus.call(&item.bus, &item.menu, MENU, "GetLayout", &[Argument::Int(parent), Argument::Int(1), Argument::TextList(Vec::new())]);

    let root = answer.list().get(1);
    let children = root.and_then(|root| root.list().get(2)).map_or(&[][..], Value::list);

    children
        .iter()
        .filter_map(|child| {
            let fields = child.list();
            let properties = fields.get(1)?;

            // missing properties have their defaults: visible, enabled, a plain entry
            let visible = !matches!(properties.get("visible"), Value::Bool(false));

            if !visible {
                return None;
            }

            let toggle_type = properties.get("toggle-type").text();

            Some(Entry {
                id: fields.first()?.number() as i32,
                label: parse::strip_mnemonic(properties.get("label").text()),
                enabled: !matches!(properties.get("enabled"), Value::Bool(false)),
                separator: properties.get("type").text() == "separator",
                toggle: (!toggle_type.is_empty()).then(|| properties.get("toggle-state").number() == 1.0),
                submenu: properties.get("children-display").text() == "submenu",
            })
        })
        .collect()
}

// opens the app's menu under its icon, once it has answered
fn open_menu(item: &Item, monitor: &str, x: f32) {
    let (item, monitor) = (item.clone(), monitor.to_string());

    thread::spawn(move || {
        if item.menu.is_empty() {
            Bus::session().call(&item.bus, &item.path, ITEM, "ContextMenu", &[Argument::Int(0), Argument::Int(0)]);

            return;
        }

        let entries = layout(&item, 0);

        if entries.is_empty() {
            return;
        }

        let mut ui = TrayUi::write();

        ui.open = Some(Open { item, monitor, x, trail: Vec::new(), entries });
        ui.appear = Animation::new(0.0).duration(Duration::from_millis(menu::appear_ms()));
        ui.appear.to(1.0);
        ui.moves += 1;
        ui.hover.retain(|spot, _| !spot.starts_with("row:"));
    });
}

// into a submenu, or back out of one (`id` none)
fn enter(id: Option<(i32, String)>) {
    let Some(mut open) = TrayUi::read().open.clone() else {
        return;
    };

    thread::spawn(move || {
        match id {
            Some(step) => open.trail.push(step),
            None => {
                open.trail.pop();
            }
        }

        let parent = open.trail.last().map_or(0, |(id, _)| *id);

        open.entries = layout(&open.item, parent);

        let mut ui = TrayUi::write();

        ui.open = Some(open);
        ui.hover.retain(|spot, _| !spot.starts_with("row:"));
    });
}

// a click on an entry: the app hears it, the menu closes
fn choose(item: &Item, id: i32) {
    let item = item.clone();

    close_menu();

    thread::spawn(move || {
        let now = SystemTime::now().duration_since(UNIX_EPOCH).map_or(0, |time| time.as_secs() as u32);

        Bus::session().call(&item.bus, &item.menu, MENU, "Event", &[Argument::Int(id), Argument::from("clicked"), Argument::Variant(Box::new(Argument::Int(0))), Argument::Unsigned(now)]);
    });
}

fn close_menu() {
    let mut ui = TrayUi::write();

    ui.open = None;
    ui.inside = false;
}

// the pointer left the menu: it closes unless it comes back within a moment
fn leave_soon() {
    let moves = {
        let mut ui = TrayUi::write();

        ui.inside = false;
        ui.moves += 1;
        ui.moves
    };

    thread::spawn(move || {
        thread::sleep(Duration::from_millis(menu::close_ms()));

        let gone = {
            let ui = TrayUi::read();

            ui.moves == moves && !ui.inside
        };

        if gone {
            close_menu();
        }
    });
}

/*
 * the tray's pill for the workspaces' window: (the pill, its width), nothing without
 * icons. `left` is where it starts, from the monitor's left, for its menus
 */
pub fn pill(monitor: &str, left: f32) -> Option<(Rectangle, f32)> {
    let tray = Tray::read();
    let ui = TrayUi::read();

    let shown: Vec<&Item> = tray.items.iter().filter(|item| !item.passive).collect();

    if shown.is_empty() {
        return None;
    }

    let theme = theme::now();
    let count = shown.len() as f32;
    let width = 2.0 * pill::inset() + count * pill::slot() + (count - 1.0) * pill::slot_gap();

    let mut slots: Vec<Box<dyn Widget>> = Vec::new();

    for (index, item) in shown.iter().enumerate() {
        let spot = format!("icon:{}", item.key);
        let lit = ui.hover.get(&spot).map_or(0.0, Animation::value);
        let open = ui.open.as_ref().is_some_and(|open| open.item.key == item.key && open.monitor == monitor);

        let picture = match &item.icon {
            Some(path) => Rectangle::new().width(pill::icon()).height(pill::icon()).fill(Image::contain(path.clone())),
            // no icon to find: its first letter
            None => Rectangle::new()
                .width(pill::icon())
                .height(pill::icon())
                .align_child(Center, Center)
                .child(Text::new(item.title.chars().next().map_or(String::from("?"), |letter| letter.to_uppercase().collect())).size(text::body()).weight(Weight::Bold).color(theme.text)),
        };

        let slot = Rectangle::new()
            .width(pill::slot())
            .height(pill::slot())
            .radius(Full)
            .fill(if open { faded(theme.accent, 90) } else { Color::blend(CLEAR, overlays::chip_hover(), lit) })
            .scale(1.0 + 0.08 * lit)
            .align_child(Center, Center)
            .cursor(Pointer)
            .on_hover(hovering(spot));

        let slot = if item.attention { slot.border(1.5, theme.accent) } else { slot };

        let x = left + pill::inset() + index as f32 * (pill::slot() + pill::slot_gap());
        let (clicked, scrolled, monitor) = ((*item).clone(), (*item).clone(), monitor.to_string());

        let slot = slot
            .on_click(move |button| match button {
                Button::Left if clicked.only_menu => open_menu(&clicked, &monitor, x),
                Button::Left => activate(&clicked, "Activate"),
                Button::Middle => activate(&clicked, "SecondaryActivate"),
                Button::Right => open_menu(&clicked, &monitor, x),
            })
            .on_scroll(move |step: Scroll| scroll(&scrolled, if step.y > 0.0 { 1 } else { -1 }))
            .child(picture);

        slots.push(Box::new(slot));
    }

    let content = Rectangle::new().width(width).height(island_pill::height()).padding(pill::inset()).align_child(Start, Center).child(Row::new(slots).gap(pill::slot_gap()).align(Center));

    let pill = surface::shell(width, island_pill::height(), island_pill::height() / 2.0, &theme.surfaces(), 0.0, content).on_hover(edge::over_bar);

    Some((pill, width))
}

// an app's menu, under its icon on the monitor it was opened on
pub fn menu_view(monitor: &Monitor) -> LayerWindow {
    theme::begin();

    let ui = TrayUi::read();

    let window = |width: f32, height: f32| {
        LayerWindow::new()
            .width(width)
            .height(height)
            .anchor_vertical(Vertical::Top)
            .anchor_horizontal(Horizontal::Left)
            .layer(Layer::Overlay)
            .space(Zone::Ignore)
            .namespace("magic-tray-menu")
    };

    // never hidden (see the island's view): a tiny, empty click-through window instead
    let Some(open) = ui.open.as_ref().filter(|open| open.monitor == monitor.name) else {
        return window(1.0, 1.0).click_through().child(Rectangle::new().width(0.0).height(0.0));
    };

    let theme = theme::now();
    let colors = theme.surfaces();
    let inner_w = menu::width() - 2.0 * menu::pad();

    let mut rows: Vec<Box<dyn Widget>> = Vec::new();
    let mut height = 2.0 * menu::pad();

    // the app's name, or the submenu's with the way back
    let lit_back = ui.hover.get("row:back").map_or(0.0, Animation::value);

    let heading: Box<dyn Widget> = match open.trail.last() {
        Some((_, label)) => Box::new(
            Rectangle::new()
                .width(inner_w)
                .height(menu::row_height())
                .radius(9.0)
                .fill(Color::blend(CLEAR, overlays::chip_hover(), lit_back))
                .padding(Padding { top: 0.0, right: 8.0, bottom: 0.0, left: 6.0 })
                .align_child(Start, Center)
                .cursor(Pointer)
                .on_hover(hovering(String::from("row:back")))
                .on_click(|_| enter(None))
                .child(Row::new(vec![Box::new(icon(Glyph::Back, 12.0, theme.dim)) as Box<dyn Widget>, Box::new(Text::new(label.as_str()).size(text::body()).weight(Weight::Bold).color(theme.text).elide())]).gap(8.0).align(Center)),
        ),
        None => Box::new(Rectangle::new().width(inner_w).height(menu::row_height()).padding(Padding { top: 0.0, right: 8.0, bottom: 0.0, left: 10.0 }).align_child(Start, Center).child(Text::new(open.item.title.as_str()).size(text::small()).weight(Weight::Bold).color(theme.dim).elide())),
    };

    rows.push(heading);
    height += menu::row_height();

    for entry in open.entries.iter().take(menu::max_rows()) {
        if entry.separator {
            rows.push(Box::new(Rectangle::new().width(inner_w).height(menu::separator_height()).align_child(Center, Center).child(Rectangle::new().width(inner_w - 16.0).height(1.0).fill(faded(theme.outline, 160)))));
            height += menu::separator_height();

            continue;
        }

        let spot = format!("row:{}", entry.id);
        let lit = if entry.enabled { ui.hover.get(&spot).map_or(0.0, Animation::value) } else { 0.0 };
        let ink = if entry.enabled { Color::blend(theme.text, theme.flame, 0.25 * lit) } else { faded(theme.dim, 140) };

        // a mark at the left for checkmarks and radios that are on, a chevron at the right for submenus
        let mark: Box<dyn Widget> = match entry.toggle {
            Some(true) => Box::new(Rectangle::new().width(14.0).height(14.0).align_child(Center, Center).child(Rectangle::new().width(7.0).height(7.0).radius(Full).fill(theme.accent))),
            _ => Box::new(Rectangle::new().width(14.0).height(14.0)),
        };

        let more: Box<dyn Widget> = Box::new(Text::new(if entry.submenu { "›" } else { "" }).size(text::heading()).color(theme.dim));

        let row = Rectangle::new()
            .width(inner_w)
            .height(menu::row_height())
            .radius(9.0)
            .fill(Color::blend(CLEAR, overlays::chip_hover(), lit))
            .padding(Padding { top: 0.0, right: 8.0, bottom: 0.0, left: 6.0 })
            .align_child(Start, Center)
            .child(
                Row::new(vec![
                    Box::new(Row::new(vec![mark, Box::new(Text::new(entry.label.as_str()).size(text::body()).color(ink).elide())]).gap(8.0).align(Center)) as Box<dyn Widget>,
                    more,
                ])
                .justify(SpaceBetween)
                .align(Center)
                .width(inner_w - 14.0),
            );

        let row = if entry.enabled {
            let (item, id, label, submenu) = (open.item.clone(), entry.id, entry.label.clone(), entry.submenu);

            row.cursor(Pointer).on_hover(hovering(spot)).on_click(move |_| if submenu { enter(Some((id, label.clone()))) } else { choose(&item, id) })
        } else {
            row
        };

        rows.push(Box::new(row));
        height += menu::row_height();
    }

    let appear = ui.appear.value();

    let content = Rectangle::new().width(menu::width()).height(height).padding(menu::pad()).child(Column::new(rows));

    // raised a little over the bar
    let card = surface::shell(menu::width(), height, 16.0, &colors, 0.125, veiled(content, menu::width(), height, 16.0, appear, &colors))
        .translate(0.0, -6.0 * (1.0 - appear))
        .on_hover(|inside| {
            if inside {
                let mut ui = TrayUi::write();

                ui.inside = true;
                ui.moves += 1;
            } else {
                leave_soon();
            }
        });

    let left = (open.x - 8.0 - island_pill::shadow()).max(0.0);
    let top = island_pill::top_gap() + island_pill::height() + 6.0 - island_pill::shadow();

    let region = InputArea { x: island_pill::shadow() as i32, y: island_pill::shadow() as i32, width: menu::width() as i32, height: height.ceil() as i32 };

    window(menu::width() + 2.0 * island_pill::shadow(), height + 2.0 * island_pill::shadow())
        .margin(Margin { top: top.max(0.0) as i32, right: 0, bottom: 0, left: left as i32 })
        .input_region(vec![region])
        .child(Rectangle::new().width(Parent).height(Parent).padding(island_pill::shadow()).align_child(Start, Start).child(card))
}

// for `amane ipc call tray ...`: list the items; open an item's menu (as a right click), choose or enter an entry, go back, close
pub fn command(words: &[String]) -> String {
    let words: Vec<&str> = words.iter().map(String::as_str).collect();

    match words.as_slice() {
        ["list"] | [] => Tray::read().items.iter().map(|item| format!("{}\t{}\t{}{}", item.key, item.title, item.icon.as_ref().map_or(String::from("-"), |path| path.display().to_string()), if item.passive { "\tpassive" } else { "" })).collect::<Vec<_>>().join("\n"),
        ["menu"] => TrayUi::read().open.as_ref().map_or(String::from("closed"), |open| open.entries.iter().map(|entry| if entry.separator { String::from("---") } else { format!("{} {}{}{}", entry.id, entry.label, if entry.toggle == Some(true) { " [on]" } else { "" }, if entry.submenu { " >" } else { "" }) }).collect::<Vec<_>>().join("\n")),
        ["open", index] | ["activate", index] => {
            let Some(item) = index.parse::<usize>().ok().and_then(|index| Tray::read().items.iter().filter(|item| !item.passive).nth(index).cloned()) else {
                return String::from("no such item");
            };

            if words[0] == "open" {
                open_menu(&item, &crate::island::focused_monitor().unwrap_or_default(), 200.0);
            } else {
                activate(&item, "Activate");
            }

            String::from("ok")
        }
        ["choose", id] | ["enter", id] => {
            let Some((item, entry)) = TrayUi::read().open.as_ref().and_then(|open| Some((open.item.clone(), open.entries.iter().find(|entry| entry.id.to_string() == *id)?.clone()))) else {
                return String::from("no such entry");
            };

            if entry.submenu { enter(Some((entry.id, entry.label))) } else { choose(&item, entry.id) }

            String::from("ok")
        }
        ["back"] => {
            enter(None);

            String::from("ok")
        }
        ["close"] => {
            close_menu();

            String::from("ok")
        }
        _ => String::from("usage: tray list|menu|open N|activate N|choose ID|enter ID|back|close"),
    }
}