Kotlin

Fetch conversation events

Inside ChatViewModel class, locate the getConversationEvents() method and paste its implementation:

private fun getConversationEvents(conversation: NexmoConversation) {
    conversation.getEvents(100, NexmoPageOrder.NexmoMPageOrderAsc, null,
        object : NexmoRequestListener<NexmoEventsPage> {
            override fun onSuccess(nexmoEventsPage: NexmoEventsPage?) {
                nexmoEventsPage?.pageResponse?.data?.let {
                    _conversationEvents.postValue(it.toList())
                }
            }

            override fun onError(apiError: NexmoApiError) {
                _errorMessage.postValue("Error: Unable to load conversation events ${apiError.message}")
            }
        })
}

Once the events are retrieved (or an error is returned), we're updating the view (ChatFragment) to reflect the new data.

Now you will pass events to the view. Inside ChatFragment locate the conversationEvents property and add this code to handle our conversation history:

private var conversationEvents = Observer<List<NexmoEvent>?> { events ->
    val messages = events?.mapNotNull {
        when (it) {
            is NexmoMemberEvent -> getConversationLine(it)
            is NexmoTextEvent -> getConversationLine(it)
            else -> null
        }
    }

    conversationEventsTextView.text = if (messages.isNullOrEmpty()) {
        "Conversation has No messages"
    } else {
        messages.joinToString(separator = "\n")
    }

    progressBar.isVisible = false
    chatContainer.isVisible = true
}

To handle member related events (member invited, joined or left) you need to fill the body of the fun getConversationLine(memberEvent: NexmoMemberEvent) method:

private fun getConversationLine(memberEvent: NexmoMemberEvent): String {
    val user = memberEvent.member.user.name

    return when (memberEvent.state) {
        NexmoMemberState.JOINED -> "$user joined"
        NexmoMemberState.INVITED -> "$user invited"
        NexmoMemberState.LEFT -> "$user left"
        else -> "Error: Unknown member event state"
    }
}

Above method converts NexmoMemberEvent to a String that will be displayed as a single line in the chat conversation. Similar conversion need to be done for NexmoTextEvent. Let's fill the body of the getConversationLine(textEvent: NexmoTextEvent) method:

private fun getConversationLine(textEvent: NexmoTextEvent): String {
    val user = textEvent.fromMember.user.name
    return "$user said: ${textEvent.text}"
}