MainActivity.kt

package com.bgrebennikovv.github.wsexample

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import com.bgrebennikovv.github.wsexample.adapters.MessagesAdapter
import com.bgrebennikovv.github.wsexample.data.messages.MessageType
import com.bgrebennikovv.github.wsexample.databinding.ActivityMainBinding
import com.bgrebennikovv.github.wsexample.repositories.ChatRepository
import kotlinx.coroutines.*
import org.koin.android.ext.android.inject
import org.koin.core.component.KoinComponent

class MainActivity : AppCompatActivity(), KoinComponent {

    private val binding by lazy {
        ActivityMainBinding.inflate(layoutInflater)
    }

    private var scope = CoroutineScope(Dispatchers.IO)

    private val messagesAdapter = MessagesAdapter()

    private val chatRepository: ChatRepository by inject()

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(binding.root)

        binding.messagesRV.layoutManager =
            LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false).also {
                it.stackFromEnd = true
            }
        binding.messagesRV.adapter = messagesAdapter

        binding.sendBtn.setOnClickListener {
            messagesAdapter.addMessage(
                binding.messageBody.text.toString(),
                MessageType.OUTGOING
            )

            scrollDown()

            runBlocking {
                chatRepository.sendMessage(binding.messageBody.text.toString())
            }
            binding.messageBody.text = null
        }

        scope.launch {
            chatRepository.receiveMessage {
                runOnUiThread {
                    messagesAdapter.addMessage(it, MessageType.INCOMING)
                    scrollDown()
                }
            }
        }

    }

    private fun scrollDown() {
        binding.messagesRV.scrollToPosition(messagesAdapter.getItemsCount() - 1)
    }

    override fun onDestroy() {
        scope.cancel()
        super.onDestroy()
    }

}