@Composable
fun LoginScene() {
  val state by producePresenter { Presenter() }
  Scaffold {
    Column(
      modifier = Modifier.fillMaxSize(),
      horizontalAlignment = Alignment.CenterHorizontally,
      verticalArrangement = Arrangement.Center,
    ) {
      Text(text = "Login", modifier = Modifier.padding(bottom = 16.dp))
      TextField(
        value = state.email,
        placeholder = { Text("Email") },
        modifier = Modifier.padding(bottom = 16.dp),
        onValueChange = { state.action(LoginAction.UpdateEmail, it) },
      )
      TextField(
        value = state.password,
        placeholder = { Text("Password") },
        modifier = Modifier.padding(bottom = 16.dp),
        onValueChange = { state.action(LoginAction.UpdatePassword, it) },
      )
    }
  }
}

@Composable
private fun Presenter(): LoginState {
  var email by remember { mutableStateOf("") }
  var password by remember { mutableStateOf("") }

  return LoginState(
    email = email,
    password = password,
  ) { action, value ->
    println("$action: $value")
    when (action) {
      LoginAction.UpdateEmail -> email = value
      LoginAction.UpdatePassword -> password = value
    }
  }
}

private sealed interface LoginAction {
  object UpdateEmail : LoginAction
  object UpdatePassword : LoginAction
}

private data class LoginState(
  val email: String,
  val password: String,
  val action: (LoginAction, String) -> Unit,
)