import Gtk from "gi://Gtk?version=3.0"
import AstalBattery from "gi://AstalBattery"
import { type Binding, Variable, bind } from "astal"

const battery = AstalBattery.get_default()

const CHARGING = 1
const DISCHARGING = 2
const FULLY_CHARGED = 4

function fmtTime(seconds: number) {
    if (!seconds || seconds <= 0) return null
    const h = Math.floor(seconds / 3600)
    const m = Math.round((seconds % 3600) / 60)
    return h > 0 ? `${h}h ${m}m` : `${m}m`
}

const status = Variable.derive(
    [bind(battery, "state"), bind(battery, "time-to-empty"), bind(battery, "time-to-full")],
    (state, toEmpty, toFull) => {
        if (state === FULLY_CHARGED) return "fully charged"
        if (state === CHARGING) {
            const t = fmtTime(toFull)
            return t ? `charging · ${t} to full` : "charging"
        }
        if (state === DISCHARGING) {
            const t = fmtTime(toEmpty)
            return t ? `${t} left` : "on battery"
        }
        return ""
    },
)

export const batteryIcon: Binding<string> | null = battery.isBattery
    ? bind(battery, "icon-name")
    : null

export const batteryPercent: Binding<string> | null = battery.isBattery
    ? bind(battery, "percentage").as((p) => `${Math.round(p * 100)}%`)
    : null

export function BatterySection() {
    if (!battery.isBattery) return <box />

    return (
        <box className="battery-section">
            <icon icon={bind(battery, "icon-name")} />
            <label
                className="battery-percent"
                label={bind(battery, "percentage").as((p) => `${Math.round(p * 100)}%`)}
            />
            <label
                className="battery-status"
                label={status()}
                visible={status().as((text) => text !== "")}
                hexpand
                halign={Gtk.Align.START}
            />
        </box>
    )
}