Fix IllegalStateException when clicking login after logout

The previous login result was stored as live data and
prevented AuthenticationFragment from being shown
properly. However, an attempt to destroy RecipesFragment
was made. This attempt caused IllegalStateException
when accessing view in onDestroyView.

app/src/main/java/gq/kirmanak/mealient/extensions/FragmentExtensions.kt

@@ -8,6 +8,7 @@ import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.channels.awaitClose
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.callbackFlow
+import kotlinx.coroutines.flow.collect
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.launch
 
@@ -27,4 +28,9 @@ fun OnBackPressedDispatcher.backPressedFlow(): Flow<Unit> = callbackFlow {
         callback.isEnabled = false
         callback.remove()
     }
-}
+}
+
+inline fun <T> Fragment.collectWithViewLifecycle(
+    flow: Flow<T>,
+    crossinline collector: suspend (T) -> Unit,
+) = viewLifecycleOwner.lifecycleScope.launch { flow.collect(collector) }

app/src/main/java/gq/kirmanak/mealient/extensions/ViewExtensions.kt

@@ -10,8 +10,6 @@ import androidx.annotation.RequiresApi
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.widget.doAfterTextChanged
 import androidx.lifecycle.LifecycleCoroutineScope
-import androidx.lifecycle.LiveData
-import androidx.lifecycle.asLiveData
 import androidx.swiperefreshlayout.widget.SwipeRefreshLayout
 import com.google.android.material.textfield.TextInputLayout
 import kotlinx.coroutines.ExperimentalCoroutinesApi
@@ -26,20 +24,17 @@ import kotlinx.coroutines.flow.first
 import timber.log.Timber
 
 @OptIn(ExperimentalCoroutinesApi::class)
-fun SwipeRefreshLayout.refreshesLiveData(): LiveData<Unit> {
-    val callbackFlow: Flow<Unit> = callbackFlow {
-        val listener = SwipeRefreshLayout.OnRefreshListener {
-            Timber.v("Refresh requested")
-            trySend(Unit).logErrors("refreshesFlow")
-        }
-        Timber.v("Adding refresh request listener")
-        setOnRefreshListener(listener)
-        awaitClose {
-            Timber.v("Removing refresh request listener")
-            setOnRefreshListener(null)
-        }
+fun SwipeRefreshLayout.refreshRequestFlow(): Flow<Unit> = callbackFlow {
+    Timber.v("refreshRequestFlow() called")
+    val listener = SwipeRefreshLayout.OnRefreshListener {
+        Timber.v("refreshRequestFlow: listener called")
+        trySend(Unit).logErrors("refreshesFlow")
+    }
+    setOnRefreshListener(listener)
+    awaitClose {
+        Timber.v("Removing refresh request listener")
+        setOnRefreshListener(null)
     }
-    return callbackFlow.asLiveData()
 }
 
 fun Activity.setSystemUiVisibility(isVisible: Boolean) {

app/src/main/java/gq/kirmanak/mealient/ui/auth/AuthenticationFragment.kt

@@ -14,6 +14,7 @@ import gq.kirmanak.mealient.data.network.NetworkError
 import gq.kirmanak.mealient.databinding.FragmentAuthenticationBinding
 import gq.kirmanak.mealient.extensions.checkIfInputIsEmpty
 import gq.kirmanak.mealient.extensions.executeOnceOnBackPressed
+import kotlinx.coroutines.launch
 import timber.log.Timber
 
 @AndroidEntryPoint
@@ -33,7 +34,6 @@ class AuthenticationFragment : Fragment(R.layout.fragment_authentication) {
         binding.button.setOnClickListener { onLoginClicked() }
         (requireActivity() as? AppCompatActivity)?.supportActionBar?.title =
             getString(R.string.app_name)
-        viewModel.authenticationResult.observe(viewLifecycleOwner, ::onAuthenticationResult)
     }
 
     private fun onLoginClicked(): Unit = with(binding) {
@@ -48,7 +48,9 @@ class AuthenticationFragment : Fragment(R.layout.fragment_authentication) {
         } ?: return
 
         button.isClickable = false
-        viewModel.authenticate(email, pass)
+        viewLifecycleOwner.lifecycleScope.launch {
+            onAuthenticationResult(viewModel.authenticate(email, pass))
+        }
     }
 
     private fun onAuthenticationResult(result: Result<Unit>) {

app/src/main/java/gq/kirmanak/mealient/ui/auth/AuthenticationViewModel.kt

@@ -1,6 +1,9 @@
 package gq.kirmanak.mealient.ui.auth
 
-import androidx.lifecycle.*
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.asLiveData
+import androidx.lifecycle.viewModelScope
 import dagger.hilt.android.lifecycle.HiltViewModel
 import gq.kirmanak.mealient.data.auth.AuthRepo
 import kotlinx.coroutines.flow.MutableStateFlow
@@ -28,10 +31,6 @@ class AuthenticationViewModel @Inject constructor(
     var authRequested: Boolean by authRequestsFlow::value
     var showLoginButton: Boolean by showLoginButtonFlow::value
 
-    private val _authenticationResult = MutableLiveData<Result<Unit>>()
-    val authenticationResult: LiveData<Result<Unit>>
-        get() = _authenticationResult
-
     init {
         viewModelScope.launch {
             authRequestsFlow.collect { isRequested ->
@@ -41,18 +40,9 @@ class AuthenticationViewModel @Inject constructor(
         }
     }
 
-    fun authenticate(username: String, password: String) {
-        Timber.v("authenticate() called with: username = $username, password = $password")
-        viewModelScope.launch {
-            runCatching {
-                authRepo.authenticate(username, password)
-            }.onFailure {
-                Timber.e(it, "authenticate: can't authenticate")
-                _authenticationResult.value = Result.failure(it)
-            }.onSuccess {
-                Timber.d("authenticate: authenticated")
-                _authenticationResult.value = Result.success(Unit)
-            }
-        }
+    suspend fun authenticate(username: String, password: String): Result<Unit> = runCatching {
+        authRepo.authenticate(username, password)
+    }.onFailure {
+        Timber.e(it, "authenticate: can't authenticate")
     }
 }

app/src/main/java/gq/kirmanak/mealient/ui/recipes/RecipeViewHolder.kt

@@ -9,7 +9,7 @@ import timber.log.Timber
 class RecipeViewHolder(
     private val binding: ViewHolderRecipeBinding,
     private val recipeViewModel: RecipeViewModel,
-    private val clickListener: (RecipeSummaryEntity) -> Unit
+    private val clickListener: (RecipeSummaryEntity) -> Unit,
 ) : RecyclerView.ViewHolder(binding.root) {
     private val loadingPlaceholder by lazy {
         binding.root.resources.getString(R.string.view_holder_recipe_text_placeholder)

app/src/main/java/gq/kirmanak/mealient/ui/recipes/RecipeViewModel.kt

@@ -1,8 +1,6 @@
 package gq.kirmanak.mealient.ui.recipes
 
 import android.widget.ImageView
-import androidx.lifecycle.LiveData
-import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
 import androidx.paging.cachedIn
@@ -10,34 +8,17 @@ import dagger.hilt.android.lifecycle.HiltViewModel
 import gq.kirmanak.mealient.data.recipes.RecipeImageLoader
 import gq.kirmanak.mealient.data.recipes.RecipeRepo
 import gq.kirmanak.mealient.data.recipes.db.entity.RecipeSummaryEntity
-import kotlinx.coroutines.channels.Channel
-import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.collect
-import kotlinx.coroutines.flow.receiveAsFlow
 import kotlinx.coroutines.launch
 import timber.log.Timber
 import javax.inject.Inject
 
 @HiltViewModel
 class RecipeViewModel @Inject constructor(
-    private val recipeRepo: RecipeRepo,
+    recipeRepo: RecipeRepo,
     private val recipeImageLoader: RecipeImageLoader
 ) : ViewModel() {
-    private var _isRefreshing = MutableLiveData<Boolean>()
-    val isRefreshing: LiveData<Boolean> get() = _isRefreshing
 
-    private val _nextRecipeInfoChannel = Channel<RecipeSummaryEntity>()
-    val nextRecipeInfo: Flow<RecipeSummaryEntity> =
-        _nextRecipeInfoChannel.receiveAsFlow()
-
-    val adapter = RecipesPagingAdapter(this) {
-        Timber.d("onClick: recipe clicked $it")
-        viewModelScope.launch { _nextRecipeInfoChannel.send(it) }
-    }
-
-    init {
-        setupAdapter()
-    }
+    val pagingData = recipeRepo.createPager().flow.cachedIn(viewModelScope)
 
     fun loadRecipeImage(view: ImageView, recipeSummary: RecipeSummaryEntity?) {
         Timber.v("loadRecipeImage() called with: view = $view, recipeSummary = $recipeSummary")
@@ -45,21 +26,4 @@ class RecipeViewModel @Inject constructor(
             recipeImageLoader.loadRecipeImage(view, recipeSummary?.slug)
         }
     }
-
-    private fun setupAdapter() {
-        with(viewModelScope) {
-            launch {
-                recipeRepo.createPager().flow.cachedIn(this).collect {
-                    Timber.d("setupAdapter: received data update")
-                    adapter.submitData(it)
-                }
-            }
-            launch {
-                adapter.onPagesUpdatedFlow.collect {
-                    Timber.d("setupAdapter: pages have been updated")
-                    _isRefreshing.value = false
-                }
-            }
-        }
-    }
 }

app/src/main/java/gq/kirmanak/mealient/ui/recipes/RecipesFragment.kt

@@ -6,17 +6,16 @@ import androidx.appcompat.app.AppCompatActivity
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
 import androidx.fragment.app.viewModels
-import androidx.lifecycle.lifecycleScope
 import androidx.navigation.fragment.findNavController
 import by.kirich1409.viewbindingdelegate.viewBinding
 import dagger.hilt.android.AndroidEntryPoint
 import gq.kirmanak.mealient.R
 import gq.kirmanak.mealient.data.recipes.db.entity.RecipeSummaryEntity
 import gq.kirmanak.mealient.databinding.FragmentRecipesBinding
-import gq.kirmanak.mealient.extensions.refreshesLiveData
+import gq.kirmanak.mealient.extensions.collectWithViewLifecycle
+import gq.kirmanak.mealient.extensions.refreshRequestFlow
 import gq.kirmanak.mealient.ui.auth.AuthenticationState
 import gq.kirmanak.mealient.ui.auth.AuthenticationViewModel
-import kotlinx.coroutines.flow.collect
 import timber.log.Timber
 
 @AndroidEntryPoint
@@ -58,20 +57,19 @@ class RecipesFragment : Fragment(R.layout.fragment_recipes) {
 
     private fun setupRecipeAdapter() {
         Timber.v("setupRecipeAdapter() called")
-        binding.recipes.adapter = viewModel.adapter
-        viewModel.isRefreshing.observe(viewLifecycleOwner) {
-            Timber.d("setupRecipeAdapter: isRefreshing = $it")
-            binding.refresher.isRefreshing = it
+        val adapter = RecipesPagingAdapter(viewModel, ::navigateToRecipeInfo)
+        binding.recipes.adapter = adapter
+        collectWithViewLifecycle(viewModel.pagingData) {
+            Timber.v("setupRecipeAdapter: received data update")
+            adapter.submitData(lifecycle, it)
         }
-        binding.refresher.refreshesLiveData().observe(viewLifecycleOwner) {
-            Timber.d("setupRecipeAdapter: received refresh request")
-            viewModel.adapter.refresh()
+        collectWithViewLifecycle(adapter.onPagesUpdatedFlow) {
+            Timber.v("setupRecipeAdapter: pages updated")
+            binding.refresher.isRefreshing = false
         }
-        viewLifecycleOwner.lifecycleScope.launchWhenResumed {
-            viewModel.nextRecipeInfo.collect {
-                Timber.d("setupRecipeAdapter: navigating to recipe $it")
-                navigateToRecipeInfo(it)
-            }
+        collectWithViewLifecycle(binding.refresher.refreshRequestFlow()) {
+            Timber.v("setupRecipeAdapter: received refresh request")
+            adapter.refresh()
         }
     }