Activity subscription to a ViewModel SnackData PublishSubject

BaseActivity.kt

fun bindViewModel(root:View, viewModel: BaseViewModel) {
  viewModel.snackPub.subscribe { snackData ->
    showSnackbar(rootView, snackData)
  }
}

/**
 * Maps the passed [SnackData] to the appropriate UI representation of a [Snackbar]
 */
private fun showSnackbar(root: View, data: SnackData) {
    fun configureSnackBar(newSnackbar: Snackbar, dissmissCallback:SnackFinishedListener, @StringRes actionMsgId:Int, actionCallback:SnackActionListener) {
        snackbar = newSnackbar
        snackbarDismissCallback = dissmissCallback

        if (actionMsgId > 0) {
            newSnackbar.setAction(actionMsgId, { actionCallback()})
        }
    }

    // handle each of the SnackData states
    when (data) {
        NoSnack -> snackbar?.dismiss()
        is ShortSnack -> with(Snackbar.make(root, data.msgId, Snackbar.LENGTH_SHORT)) {
            configureSnackBar(this, data.dismissListener, data.actionMsgId, data.actionListener)
        }
        is LongSnack -> with(Snackbar.make(root, data.msgId, Snackbar.LENGTH_LONG)) {
            configureSnackBar(this, data.dismissListener, data.actionMsgId, data.actionListener)
        }
        is StickySnack -> with(Snackbar.make(root, data.msgId, Snackbar.LENGTH_INDEFINITE)) {
            configureSnackBar(this, data.dismissListener, data.actionMsgId, data.actionListener)
        }
    }

    // setup a dismiss listener in case any listener needs to take action once the 
    // message is displayed
    //
    snackbar?.addCallback(object: BaseTransientBottomBar.BaseCallback<Snackbar>() {
        override fun onDismissed(transientBottomBar: Snackbar?, event: Int) {
            super.onDismissed(transientBottomBar, event)
            snackbarDismissCallback?.invoke()
            snackbar = null
            snackbarDismissCallback = null
        }
    })

    snackbar?.show()
}