ConnectionStateMonitor.kt

/**
 * Use [enable]/[disable] to register/unregister [ConnectivityManager]
 * @property context
 * @property onNetworkAvailableCallbacks callback to notify [context] about network status changes
 */
@RequiresApi(Build.VERSION_CODES.LOLLIPOP)
class ConnectionStateMonitor(
    private val context: Context,
    private val onNetworkAvailableCallbacks: OnNetworkAvailableCallbacks
) : ConnectivityManager.NetworkCallback() {

    private val connectivityManager: ConnectivityManager by lazy {
        context.getSystemService(Context.CONNECTIVITY_SERVICE) as ConnectivityManager
    }

    private val networkRequest = NetworkRequest.Builder()
        .addTransportType(NetworkCapabilities.TRANSPORT_CELLULAR)
        .addTransportType(NetworkCapabilities.TRANSPORT_WIFI).build()!!

    /**
     * @return`true` when device is connected to network else `false`
     */
    fun hasNetworkConnection() = (connectivityManager.activeNetworkInfo != null)

    fun enable() {
        connectivityManager.registerNetworkCallback(networkRequest, this)
    }

    fun disable() {
        connectivityManager.unregisterNetworkCallback(this)
    }

    override fun onAvailable(network: Network) {
        super.onAvailable(network)
        onNetworkAvailableCallbacks.onPositive()
    }

    override fun onLost(network: Network) {
        super.onLost(network)
        onNetworkAvailableCallbacks.onNegative()
    }
    
    /**
     * Callbacks to handle the network status changes
     */
    interface OnNetworkAvailableCallbacks {
        /**
         * Callback for when network is available
         */
        fun onPositive()

        /**
         * Callback for when network is lost/disconnected
         */
        fun onNegative()
    }
}