Use single UI state for activity

app/src/main/java/gq/kirmanak/mealient/ui/activity/MainActivity.kt

@@ -12,16 +12,14 @@ import com.google.android.material.shape.MaterialShapeDrawable
 import dagger.hilt.android.AndroidEntryPoint
 import gq.kirmanak.mealient.R
 import gq.kirmanak.mealient.databinding.MainActivityBinding
-import gq.kirmanak.mealient.ui.auth.AuthenticationState
-import gq.kirmanak.mealient.ui.auth.AuthenticationState.AUTHORIZED
-import gq.kirmanak.mealient.ui.auth.AuthenticationState.UNAUTHORIZED
 import timber.log.Timber
 
 @AndroidEntryPoint
 class MainActivity : AppCompatActivity() {
     private lateinit var binding: MainActivityBinding
     private val viewModel by viewModels<MainActivityViewModel>()
-    private var lastAuthenticationState: AuthenticationState? = null
+    private val title: String by lazy { getString(R.string.app_name) }
+    private val uiState: MainActivityUiState get() = viewModel.uiState
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -31,7 +29,13 @@ class MainActivity : AppCompatActivity() {
         setSupportActionBar(binding.toolbar)
         supportActionBar?.setIcon(R.drawable.ic_toolbar)
         setToolbarRoundCorner()
-        listenToAuthStatuses()
+        viewModel.uiStateLive.observe(this, ::onUiStateChange)
+    }
+
+    private fun onUiStateChange(uiState: MainActivityUiState) {
+        Timber.v("onUiStateChange() called with: uiState = $uiState")
+        supportActionBar?.title = if (uiState.titleVisible) title else null
+        invalidateOptionsMenu()
     }
 
     private fun setToolbarRoundCorner() {
@@ -51,22 +55,11 @@ class MainActivity : AppCompatActivity() {
         }
     }
 
-    private fun listenToAuthStatuses() {
-        Timber.v("listenToAuthStatuses() called")
-        viewModel.authenticationStateLive.observe(this, ::onAuthStateUpdate)
-    }
-
-    private fun onAuthStateUpdate(authState: AuthenticationState) {
-        Timber.v("onAuthStateUpdate() called with: it = $authState")
-        lastAuthenticationState = authState
-        invalidateOptionsMenu()
-    }
-
     override fun onCreateOptionsMenu(menu: Menu): Boolean {
         Timber.v("onCreateOptionsMenu() called with: menu = $menu")
         menuInflater.inflate(R.menu.main_toolbar, menu)
-        menu.findItem(R.id.logout).isVisible = lastAuthenticationState == AUTHORIZED
-        menu.findItem(R.id.login).isVisible = lastAuthenticationState == UNAUTHORIZED
+        menu.findItem(R.id.logout).isVisible = uiState.canShowLogout
+        menu.findItem(R.id.login).isVisible = uiState.canShowLogin
         return true
     }
 

app/src/main/java/gq/kirmanak/mealient/ui/activity/MainActivityUiState.kt

@@ -0,0 +1,13 @@
+package gq.kirmanak.mealient.ui.activity
+
+data class MainActivityUiState(
+    val loginButtonVisible: Boolean = false,
+    val titleVisible: Boolean = true,
+    val isAuthorized: Boolean = false,
+) {
+    val canShowLogin: Boolean
+        get() = !isAuthorized && loginButtonVisible
+
+    val canShowLogout: Boolean
+        get() = isAuthorized && loginButtonVisible
+}

app/src/main/java/gq/kirmanak/mealient/ui/activity/MainActivityViewModel.kt

@@ -1,14 +1,10 @@
 package gq.kirmanak.mealient.ui.activity
 
-import androidx.lifecycle.LiveData
-import androidx.lifecycle.ViewModel
-import androidx.lifecycle.asLiveData
-import androidx.lifecycle.viewModelScope
+import androidx.lifecycle.*
 import dagger.hilt.android.lifecycle.HiltViewModel
 import gq.kirmanak.mealient.data.auth.AuthRepo
-import gq.kirmanak.mealient.ui.auth.AuthenticationState
-import kotlinx.coroutines.flow.MutableStateFlow
-import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.launchIn
+import kotlinx.coroutines.flow.onEach
 import kotlinx.coroutines.launch
 import timber.log.Timber
 import javax.inject.Inject
@@ -18,16 +14,22 @@ class MainActivityViewModel @Inject constructor(
     private val authRepo: AuthRepo,
 ) : ViewModel() {
 
-    private val showLoginButtonFlow = MutableStateFlow(false)
-    var showLoginButton: Boolean by showLoginButtonFlow::value
+    private val _uiState = MutableLiveData(MainActivityUiState())
+    val uiStateLive: LiveData<MainActivityUiState>
+        get() = _uiState.distinctUntilChanged()
+    var uiState: MainActivityUiState
+        get() = checkNotNull(_uiState.value) { "UiState must not be null" }
+        private set(value) = _uiState.postValue(value)
 
-    private val authenticationStateFlow = combine(
-        showLoginButtonFlow,
-        authRepo.isAuthorizedFlow,
-        AuthenticationState::determineState
-    )
-    val authenticationStateLive: LiveData<AuthenticationState>
-        get() = authenticationStateFlow.asLiveData()
+    init {
+        authRepo.isAuthorizedFlow
+            .onEach { isAuthorized -> updateUiState { it.copy(isAuthorized = isAuthorized) } }
+            .launchIn(viewModelScope)
+    }
+
+    fun updateUiState(updater: (MainActivityUiState) -> MainActivityUiState) {
+        uiState = updater(uiState)
+    }
 
     fun logout() {
         Timber.v("logout() called")