Activity with viewModel pattern applied

SubActivity.kt

import android.app.ProgressDialog
import android.arch.lifecycle.Observer
import android.arch.lifecycle.ViewModelProviders
import android.databinding.DataBindingUtil
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.text.TextUtils
import android.view.View
import android.widget.Toast
import com.google.firebase.auth.FirebaseAuth
import com.nezspencer.testapp.databinding.ActivitySubBinding

class SubActivity : AppCompatActivity(), FirebaseAuth.AuthStateListener, View.OnClickListener{

    private lateinit var progress : ProgressDialog
    private lateinit var binding : ActivitySubBinding
    lateinit var viewModel: SubViewModel
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding = DataBindingUtil.setContentView(this, R.layout.activity_sub)
        viewModel = ViewModelProviders.of(this)[SubViewModel::class.java]
        viewModel.authLivedata.observe(this, Observer<AuthState> {p0 ->
            p0?.let {
                if (it.state == Progress.LOADING)
                    showProgress()
                else {
                    hideProgress()
                    onAuthStateChanged(it.auth!!)
                }
            }
        })
        progress = ProgressDialog(this)
        progress.setCanceledOnTouchOutside(false)
        progress.setCancelable(false)

        binding.btnSignin.setOnClickListener(this)
        binding.btnSignup.setOnClickListener(this)

    }

    override fun onAuthStateChanged(p0: FirebaseAuth) {
        val message : String = if (p0.currentUser != null) "Auth successful" else "Auth failed"
        Toast.makeText(this, message, Toast.LENGTH_SHORT).show()
    }

    override fun onClick(p0: View?) {
        val email : String
        val password : String
        when(p0!!.id){
            R.id.btn_signup -> {
                email = binding.etEmail.text.toString()
                password = binding.etPwd.text.toString()
                viewModel.createAccount(email, password)
            }
            R.id.btn_signin ->{
                email = binding.etEmail.text.toString()
                password = binding.etPwd.text.toString()
                viewModel.signInUser(email, password)
            }
        }
    }

    private fun showProgress() {
        if (!progress.isShowing)
            progress.show()
    }

    private fun hideProgress(){
        if (progress.isShowing)
            progress.dismiss()
    }
}