Wake Lock

import { browser, to_readable, to_writable, unstore } from "@sveu/shared"

import { on } from "../event_listener"
import { support } from "../support"
import type {
    NavigatorWithWakeLock,
    WakeLockSentinel,
    WakeLockType,
} from "../utils"

/**
 * Reactive Screen Wake Lock API.
 *
 * @returns
 * - `supported` - Whether the Wake Lock API is supported.
 * - `active` - Whether the Wake Lock is active.
 * - `request` - Request a Wake Lock.
 * - `release` - Release the Wake Lock.
 */
export function wake_lock() {
    let _wake_lock: WakeLockSentinel | null

    const supported = support("wakeLock")

    const active = to_writable(false)

    async function on_visibility_change() {
        if (!unstore(supported) || !_wake_lock) return

        if (document.visibilityState === "visible")
            _wake_lock = await (
                navigator as NavigatorWithWakeLock
            ).wakeLock.request("screen")

        active.set(!_wake_lock.released)
    }

    if (browser)
        on(document, "visibilitychange", on_visibility_change, {
            passive: true,
        })

    /**
     * Request a Wake Lock.
     *
     * @param type - The type of Wake Lock to request. Defaults to "screen".
     *
     */
    async function request(type: WakeLockType) {
        if (!unstore(supported)) return

        _wake_lock = await (
            navigator as NavigatorWithWakeLock
        ).wakeLock.request(type)

        active.set(!_wake_lock.released)
    }

    /** Release the Wake Lock. */
    async function release() {
        if (!unstore(supported) || !_wake_lock) return

        await _wake_lock.release()

        active.set(!_wake_lock.released)

        _wake_lock = null
    }

    return {
        supported,
        active: to_readable(active),
        request,
        release,
    }
}