LoginActivity.kt

class LoginActivity : AppCompatActivity() {
    private val vm: LoginViewModel by viewModels()

    private lateinit var binding: ActivityLoginBinding

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

        binding = ActivityLoginBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.loginWithGoogleButton.setOnClickListener {
            lifecycleScope.launchWhenCreated {
                suspend fun tryLogin(onfail: ()->Unit ) {
                    val myUser = vm.loginAndReturnMyUser()  // Call backend with google creds
                    if (myUser!=null) {
                        startMainActivity()
                    } else {
                        onfail()
                    }
                }
                try {
                    val result = Amplify.Auth.signInWithSocialWebUI(
                        AuthProvider.google(),
                        this@LoginActivity
                    )
                    if (result.isSignInComplete) {
                        Timber.i("LoginActivity: signed in: $result")
                        tryLogin {
                            Timber.e("getMe failed")
                        }
                    } else {
                        Timber.e("LoginActivity: sign in failed")
                    }
                } catch (ex: AuthException) {
                    tryLogin {
                        Timber.e("LoginActivity: exception", ex)
                    }
                }
            }
        }
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        Timber.d("requestCode=${requestCode} resultCode=${resultCode} data=$data")
        if (requestCode == AWSCognitoAuthPlugin.WEB_UI_SIGN_IN_ACTIVITY_CODE) {
            if (data != null) {
                if (resultCode == Activity.RESULT_CANCELED) {
                    Amplify.Auth.handleWebUISignInResponse(data)
                }
            } else {
                hideProgress()
            }
        }
    }

    private fun startMainActivity() {
        startActivity(MainActivity.getStartingIntent(this))
    }

    companion object {
        fun getStartingIntent(context: Context) = Intent(context, LoginActivity::class.java)
            .apply { flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK }
    }
}