let mut power_handle = 0;

Service::new()
    .can_stop()
    .can_accept(SERVICE_ACCEPT_POWEREVENT)
    .run(|service, command| {
        if command == Command::Start {
            power_handle = unsafe {
                RegisterPowerSettingNotification(
                    service.handle(),
                    &GUID_GLOBAL_USER_PRESENCE,
                    DEVICE_NOTIFY_SERVICE_HANDLE,
                )
            };
        }

        if let Command::Extended(command) = command {
            if command.control == SERVICE_CONTROL_POWEREVENT {
                debug_assert!(command.ty == PBT_POWERSETTINGCHANGE);
                let data = unsafe { &*(command.data as *const POWERBROADCAST_SETTING) };
                debug_assert!(&data.PowerSetting == &GUID_GLOBAL_USER_PRESENCE);
                debug_assert!(data.DataLength == 4);

                let data = unsafe {
                    std::slice::from_raw_parts(data.Data.as_ptr(), data.DataLength as usize)
                };

                let data = u32::from_le_bytes(data.try_into().unwrap());
                writeln!(log, "Present: {data}").unwrap();
            }
        }
    })
    .unwrap();