homelab/dotfiles/quickshell/HyprChrome/Widgets/HyprChromeShell.qml

pragma ComponentBehavior: Bound

import Quickshell
import Quickshell.Hyprland
import Quickshell.Wayland
import qs.HyprChrome.Widgets.Bar
import qs.HyprChrome.Widgets
import qs.HyprChrome.Widgets.Polkit

// The hyprchrome shell: owns everything the rail's surfaces have to agree on,
// and instantiates them.
//
// State lives here rather than in any one surface because more than one of them
// reads it, and a second reader is what turns a local property into shared
// state. Four things qualify so far:
//
//   * which monitor the shell lives on — every surface has to pick the same one
//   * the density — the whole rail expands and collapses as one, so the toggle
//     and the shortcut that drives it belong to the shell, not to the bar
//   * whether an authorization prompt is up — it raises the same scrim the rail
//     uses and freezes the density while it is open, so two surfaces read it.
//     That is why the agent lives here rather than as a sibling of the
//     launchers in shell.qml
//   * the layer PAIR — the backdrop must sit exactly one layer below the bar in
//     both densities. Two surfaces on the same layer stack by creation order,
//     which is not something to rely on; one layer apart is a guarantee. Split
//     across two files those two assignments drifted apart and the scrim ended
//     up over the bar, so they are derived together here and passed down.
//
// A future widget joins by taking `targetScreen` and `expanded` the same way.
Scope {
    id: shell

    // Monitor the rail lives on. Falls back to the FIRST connected screen when
    // the name matches nothing, so the bar still appears on a single-monitor
    // session or after a cable swap (DebugWindow falls back to the last one
    // instead — it wants the secondary).
    property string screenName: "DP-2"

    // Quickshell.screens is a QML list, not a JS array — no .find() on it.
    readonly property var targetScreen: {
        const screens = Quickshell.screens;
        if (screens.length === 0)
            return null;
        for (let i = 0; i < screens.length; i++) {
            if (screens[i].name === shell.screenName)
                return screens[i];
        }
        return screens[0];
    }

    // Every output the rail does NOT live on. They get a scrim of their own
    // while a prompt is up, because a modal that dims one monitor and leaves
    // the others lit does not read as modal at all — and the rail's backdrop
    // covers exactly one output.
    readonly property var otherScreens: {
        const out = [];
        const screens = Quickshell.screens;
        for (let i = 0; i < screens.length; i++) {
            if (screens[i] !== shell.targetScreen)
                out.push(screens[i]);
        }
        return out;
    }

    // Where a prompt appears: wherever the user is actually looking, which is
    // not necessarily where the rail lives. Hyprland reports the focused
    // monitor by name, and Quickshell.screens is keyed the same way, so the
    // two are matched by name exactly as targetScreen is above.
    //
    // Falls back to the rail's own screen rather than to nothing: a prompt that
    // fails to place itself would leave its caller blocked on a dialog nobody
    // can see.
    readonly property var focusedScreen: {
        const focused = Hyprland.focusedMonitor;
        if (!focused)
            return shell.targetScreen;

        const screens = Quickshell.screens;
        for (let i = 0; i < screens.length; i++) {
            if (screens[i].name === focused.name)
                return screens[i];
        }
        return shell.targetScreen;
    }

    // Density is a property of the SHELL: every panel follows it, so the whole
    // rail expands and collapses as one. Panels keep their own animation; only
    // the decision is centralised here.
    //
    // A prompt does NOT change it: an authorization request leaves the rail at
    // whatever density it was, and only freezes it there.
    property bool expanded: false

    function toggle() {
        // Frozen while a prompt is up, and dropped rather than queued: SUPER A
        // during a prompt does nothing at all, instead of arming a change that
        // springs the rail open or shut the moment the dialog goes.
        if (polkit.prompting)
            return;

        shell.expanded = !shell.expanded;
    }

    // Whether the scrim is up, from EITHER cause. This is the fact the surfaces
    // actually share — the rail's density is only one of the two things that
    // can raise it — so the backdrop and the layer pair below key off this
    // rather than off `expanded`.
    //
    // One backdrop instance serves both. A prompt arriving over an already
    // expanded rail therefore changes nothing about the scrim: it is already up,
    // already full height, and the dialog simply appears above it. A prompt over
    // a COLLAPSED rail expands that same scrim from its bar-height band to the
    // whole output, using the animation it already has, and the rail stays
    // collapsed throughout.
    readonly property bool scrimUp: shell.expanded || polkit.prompting

    // Scrim up, the rail is over everything; scrim down, it drops below ordinary
    // windows. BOTTOM rather than BACKGROUND for the lowered bar: it is the
    // lowest level that still leaves a layer underneath for the backdrop, and
    // it keeps the rail off the wallpaper's own level.
    //
    // Both key off `scrimUp`, not `expanded`, so the pair stays exactly one
    // level apart in every state — which is the whole point of deriving them
    // together. A prompt over a collapsed rail raises BOTH: the scrim has to
    // clear ordinary windows to dim them at all (BACKGROUND sits under them),
    // and the bar has to stay one above the scrim or the shell would be dimming
    // its own chrome. The rail is raised but still collapsed: its layer answers
    // to the scrim, its height to `expanded`.
    readonly property int barLayer: shell.scrimUp ? WlrLayer.Overlay : WlrLayer.Bottom
    readonly property int backdropLayer: shell.scrimUp ? WlrLayer.Top : WlrLayer.Background

    // SUPER A — see hosts/terra/home/hyprland.nix.
    GlobalShortcut {
        name: "chrome"
        description: "Expand or collapse the hyprchrome bar"
        onPressed: shell.toggle()
    }

    // Backdrop first: it is a layer below the bar, so stacking does not depend
    // on creation order, but keeping the declaration order the same as the
    // visual order costs nothing.
    ChromeBackdrop {
        screen: shell.targetScreen
        active: shell.scrimUp
        wlrLayer: shell.backdropLayer

        // Collapsed, the scrim only backs the rail, so it needs the band the
        // rail occupies. contentHeight is the SETTLED height for the current
        // state — it jumps once per toggle rather than tracking the panels
        // frame by frame, so the backdrop animates the change itself instead of
        // chasing a value that is already being animated.
        barHeight: bar.contentHeight
    }

    // The same scrim on every other output, up only while a prompt is. These
    // have no rail to back, so barHeight stays 0 and revealHeight falls to
    // nothing between prompts — the surfaces take themselves off screen rather
    // than lingering as a strip the way the rail's does.
    //
    // Deliberately NOT tied to `scrimUp`: expanding the rail dims the rail's
    // monitor only, which is the existing behaviour and the right one — the
    // rail is a thing on one screen. A prompt is the only event that concerns
    // every screen at once.
    //
    // TOP unconditionally: there is no bar on these outputs to keep one level
    // above the scrim, and BACKGROUND would put the dim under ordinary windows
    // where it would dim nothing. Inactive they are invisible, so the level
    // costs nothing between prompts.
    Variants {
        model: shell.otherScreens

        ChromeBackdrop {
            required property var modelData

            screen: modelData
            active: polkit.prompting
            wlrLayer: WlrLayer.Top
            barHeight: 0
        }
    }

    HyprChromeBar {
        id: bar

        screen: shell.targetScreen
        // Set here, not from the window's own `screen`: reading that inside
        // `visible` is circular — a hidden window has no screen to report.
        visible: shell.targetScreen !== null
        expanded: shell.expanded
        wlrLayer: shell.barLayer
    }

    // Polkit authentication agent. It registers for this logind session on
    // creation, so it replaces hyprpolkitagent rather than coexisting with it —
    // only one agent may hold a session (see hosts/terra/home/hyprland.nix).
    //
    // It lives here rather than beside the launchers in shell.qml because its
    // state is shared: `prompting` raises the scrim and freezes the density,
    // which makes it shell state by the same rule as the screen and the layer
    // pair. It owns only its dialog; the scrim above is the rail's.
    //
    // Declared LAST on purpose. While a prompt is up the bar is on Overlay too,
    // and there is no layer above Overlay to escape to, so the dialog stays on
    // top by being the later surface. In practice it is later regardless — its
    // window only exists while a request is open, so it is always created after
    // the bar's — but the declaration order says so without relying on that.
    PolkitPrompt {
        id: polkit

        screen: shell.focusedScreen
    }
}