LiveData MVI example

LoginActivity.kt

package com.nasladdin.partner.activities.login

import android.os.Bundle
import android.view.KeyEvent
import androidx.appcompat.app.AppCompatActivity
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import com.nasladdin.partner.R
import com.nasladdin.partner.helpers.SnackbarFacade

/**
 * Переадресовываем сюда при на всех Activity и фрагментах, защищённых аутентификацией.
 */
class LoginActivity : AppCompatActivity() {

    private lateinit var viewModel: LoginViewModel
    private lateinit var snackbarFacade: SnackbarFacade
    private lateinit var store: LoginStore
    private lateinit var view: LoginView


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.login_activity)
        initViewModel()
        view = LoginView(this)
        snackbarFacade = SnackbarFacade(this, findViewById(R.id.login_activity_intro_text))
        store = LoginStore(viewModel, lifecycle)
        setListeners()
    }

    private fun initViewModel() {
        viewModel = ViewModelProvider(this).get(LoginViewModel::class.java)
        viewModel.state.observe(this, Observer { render(it) })
        viewModel.viewEffect.observe(this, Observer { handleEffect(it) })
    }

    private fun render(viewState: LoginViewState) = when (viewState) {
        is LoginViewState.AwaitingCredentials -> {
            view.setLoginButtonEnabled(true)
            view.setLoaderEnabled(false)
        }
        is LoginViewState.IsLoading -> {
            view.setLoginButtonEnabled(false)
            view.setLoaderEnabled(true)
        }
        is LoginViewState.LoggedInSuccessfully -> {
            finish()
        }
    }

    private fun handleEffect(viewEffect: LoginViewEffect) = snackbarFacade.warning(viewEffect.message)

    private fun setListeners() {

        view.button.setOnClickListener {
            store.onLoginButtonClick(view.loginText, view.passwordText)
        }


        // todo в хелпер
        view.passwordEditField.setOnKeyListener { v, keyCode, event ->
            if (event.action == KeyEvent.ACTION_DOWN && keyCode == KeyEvent.KEYCODE_ENTER) {
                store.onLoginButtonClick(view.loginText, view.passwordText)
                true
            }
            false
         }
    }
}

LoginStore.kt

package com.nasladdin.partner.activities.login

import androidx.lifecycle.Lifecycle
import com.nasladdin.partner.application.GlobalApplication
import com.nasladdin.partner.boilerplate.StoreBase
import com.nasladdin.partner.helpers.sharedpreferences.LoginManager
import com.nasladdin.partner.repos.remote.fuel.FuelAuthRepository
import com.nasladdin.partner.repos.remote.fuel.HttpError
import kotlinx.coroutines.*

class LoginStore(private val vm: LoginViewModel, lifecycle: Lifecycle): StoreBase(lifecycle) {

    private val authRepository: FuelAuthRepository = GlobalApplication.dependencyContainer.fuelAuthRepository
    private val loginManager: LoginManager = GlobalApplication.dependencyContainer.loginManager

    fun onLoginButtonClick(login: String, password: String) = launch {

        if (login.isBlank() || password.isBlank()) {
            vm.viewEffect.value = LoginViewEffect("Заполните, пожалуйста, логин и пароль")
            return@launch
        }

        vm.state.value = LoginViewState.IsLoading
        withContext(Dispatchers.IO) {
            authRepository.login(login, password)
        }
                .mapLeft {
                    vm.viewEffect.value = LoginViewEffect(it.errorHandler())
                    vm.state.value = LoginViewState.AwaitingCredentials
                }
                .map {
                    loginManager.saveCredentialsToPreferences(it.accessToken, it.refreshToken)
                    vm.state.value = LoginViewState.LoggedInSuccessfully
                }
    }

    private fun HttpError.errorHandler() = when (this) {
        is HttpError.WrongCredentialsException -> "Логин или пароль неверные"
        is HttpError.NetworkUnreachableException -> "Нет связи с сервером Насладдина. Возможно, отсутствует соединение с интернетом"
        else -> "Неизвестная ошибка, пожалуйста, попробуйте позже $this"
    }
}

LoginView.kt

package com.nasladdin.partner.activities.login

import android.view.View
import android.widget.Button
import android.widget.EditText
import com.nasladdin.partner.R

class LoginView(private val activity: LoginActivity) {

    val button: Button = activity.findViewById(R.id.login_login_button)
    val passwordEditField: EditText = activity.findViewById(R.id.login_password_text)

    fun setLoginButtonEnabled(enabled: Boolean) {
        val button = activity.findViewById<Button>(R.id.login_login_button)
        button.isEnabled = enabled
        val colorCode = if (enabled) R.color.bootstrap_success else R.color.button_default
        button.setBackgroundColor(activity.resources.getColor(colorCode))
    }

    fun setLoaderEnabled(enabled: Boolean) {
        val loader = activity.findViewById<View>(R.id.progress_bar)
        loader.visibility = if (enabled) View.VISIBLE else View.GONE
    }

    val loginText: String
        get() {
            val loginText = activity.findViewById<EditText>(R.id.login_login_text)
            return loginText.text.toString()
        }

    val passwordText: String
        get() {
            val passwordText = activity.findViewById<EditText>(R.id.login_password_text)
            return passwordText.text.toString()
        }
}

LoginViewModel.kt

package com.nasladdin.partner.activities.login

import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
import com.nasladdin.partner.application.GlobalApplication
import com.nasladdin.partner.boilerplate.BaseViewModel
import com.nasladdin.partner.helpers.sharedpreferences.LoginManager
import com.nasladdin.partner.repos.remote.fuel.FuelAuthRepository
import com.nasladdin.partner.repos.remote.fuel.HttpError
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext

class LoginViewModel : ViewModel() {
    val state = MutableLiveData<LoginViewState>()
    val viewEffect = MutableLiveData<LoginViewEffect>()
}

sealed class LoginViewState {
    object AwaitingCredentials: LoginViewState()
    object IsLoading: LoginViewState()
    object LoggedInSuccessfully: LoginViewState()
}

data class LoginViewEffect(val message: String)

StoreBase.kt

package com.nasladdin.partner.boilerplate

import androidx.lifecycle.Lifecycle
import androidx.lifecycle.LifecycleObserver
import androidx.lifecycle.OnLifecycleEvent
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.Job
import kotlin.coroutines.CoroutineContext

abstract class StoreBase(private val lifecycle: Lifecycle): CoroutineScope, LifecycleObserver {

    init {
        @Suppress("LeakingThis")
        lifecycle.addObserver(this)
    }

    public val compositeJob = Job()
    override val coroutineContext: CoroutineContext
        get() = Dispatchers.Main + compositeJob

    @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)
    private fun onDestroy() {
        compositeJob.cancel()
        lifecycle.removeObserver(this)
    }
}