nixos/modules/home/ags/app/widget/Bluetooth.tsx

import Gtk from "gi://Gtk?version=3.0"
import Gio from "gi://Gio"
import AstalBluetooth from "gi://AstalBluetooth"
import { bind, Variable } from "astal"
import { ArrowToggleButton, Menu } from "./ToggleButton"

const bt = AstalBluetooth.get_default()

function power(on: boolean) {
    if (bt.adapter) bt.adapter.powered = on
}

function setDiscovery(on: boolean) {
    if (!bt.adapter) return
    try {
        if (on) bt.adapter.start_discovery()
        else bt.adapter.stop_discovery()
    } catch {
        // expected when already in the requested state: bluez stops
        // discovery itself on connect, auto-starts it, etc.
    }
}

// bluez only registers devices that are paired or seen during discovery;
// the list is mirrored into a Variable refreshed on device add/remove
const devices = Variable<AstalBluetooth.Device[]>(bt.get_devices())
const refreshDevices = () => devices.set(bt.get_devices())
bt.connect("notify::devices", refreshDevices)
bt.connect("device_added", refreshDevices)
bt.connect("device_removed", refreshDevices)

const btIcon = bind(bt, "is_powered").as((p) =>
    p ? "bluetooth-active-symbolic" : "bluetooth-disabled-symbolic",
)

const connectedCount = devices().as(
    (ds) => ds.filter((d) => d.connected).length,
)

const pillLabel = Variable.derive(
    [bind(bt, "is_powered"), devices],
    (powered, ds) => {
        if (!powered) return "Disabled"
        const connected = ds.filter((d) => d.connected)
        if (connected.length === 1) return connected[0].alias
        return `${connected.length} Connected`
    },
)

// ported from AlfheimOS: icon, name, battery, busy icon while connecting,
// switch reflecting the bluez connected state
function DeviceItem(device: AstalBluetooth.Device) {
    const battery = bind(device, "battery_percentage")
    const connecting = bind(device, "connecting")
    // bluez reports br-connection-busy when attempts pile up, so debounce
    let lastAttempt = 0
    return (
        <box className="device-item">
            <icon
                icon={
                    device.icon
                        ? `${device.icon}-symbolic`
                        : "bluetooth-active-symbolic"
                }
            />
            <label
                className="device-name"
                label={device.alias ?? device.address}
                halign={Gtk.Align.START}
                hexpand
            />
            <label
                className="device-battery"
                visible={battery.as((p) => p > 0)}
                label={battery.as((p) => `${Math.round(p * 100)}%`)}
            />
            <icon
                className="device-connecting"
                icon="view-refresh-symbolic"
                visible={connecting}
            />
            <switch
                visible={connecting.as((c) => !c)}
                active={bind(device, "connected")}
                onStateSet={(_, state) => {
                    // bluez rejects connects while the controller is busy scanning
                    if (state) setDiscovery(false)
                    // skip no-ops and retries within the debounce window
                    const now = Date.now()
                    if (state === device.connected || now - lastAttempt < 1500) {
                        return true
                    }
                    lastAttempt = now
                    // vala async: begin with a callback, finish() throws
                    const done = (_source: AstalBluetooth.Device, res: Gio.AsyncResult) => {
                        try {
                            if (state) device.connect_device_finish(res)
                            else device.disconnect_device_finish(res)
                        } catch (e) {
                            console.error(e)
                        }
                    }
                    if (state) device.connect_device(done)
                    else device.disconnect_device(done)
                    return true
                }}
            />
        </box>
    )
}

export function BluetoothSection({ open }: { open: Variable<boolean> }) {
    if (!bt.adapter) return null

    const expanded = Variable(false)
    open.subscribe((v) => {
        if (!v) {
            expanded.set(false)
            setDiscovery(false)
        }
    })

    const toggle = (
        <ArrowToggleButton
            open={expanded}
            icon={btIcon}
            label={pillLabel()}
            active={bind(bt, "is_powered")}
            onMainClick={() => {
                if (bt.is_powered) {
                    power(false)
                    expanded.set(false)
                    setDiscovery(false)
                } else {
                    power(true)
                }
            }}
            onArrowClick={() => {
                const next = !expanded.get()
                expanded.set(next)
                if (next) {
                    if (!bt.is_powered) power(true)
                    setDiscovery(true)
                } else {
                    setDiscovery(false)
                }
            }}
        />
    )

    const menu = (
        <Menu open={expanded} icon="bluetooth-active-symbolic" title="Bluetooth">
            <label
                className="wifi-empty"
                label="bluetooth is off"
                visible={bind(bt, "is_powered").as((p) => !p)}
            />
            <label
                className="wifi-empty"
                label="searching for devices…"
                visible={Variable.derive(
                    [bind(bt, "is_powered"), devices],
                    (powered, ds) => powered && ds.filter((d) => d.name).length === 0,
                )()}
            />
            <box vertical visible={bind(bt, "is_powered")}>
                {devices().as((ds) =>
                    ds.filter((d) => d.name).map(DeviceItem),
                )}
            </box>
        </Menu>
    )

    return { toggle, menu }
}

// bar cluster indicator: shown while bluetooth is powered, with a count
// badge when devices are connected
export const bluetoothIndicator: JSX.Element | null = bt.adapter ? (
    <box className="bt-indicator" spacing={3} visible={bind(bt, "is_powered")}>
        <icon icon="bluetooth-active-symbolic" />
        <label
            className="bt-count"
            visible={connectedCount.as((n) => n > 0)}
            label={connectedCount.as((n) => `${n}`)}
        />
    </box>
) : null