Simplify edge case handling

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

@@ -1,5 +1,7 @@
 package gq.kirmanak.mealient.extensions
 
+import android.widget.Toast
+import androidx.annotation.StringRes
 import androidx.fragment.app.Fragment
 import androidx.lifecycle.LifecycleOwner
 import androidx.lifecycle.lifecycleScope
@@ -19,4 +21,12 @@ fun Fragment.launchWhenViewResumed(
 
 fun <T> Flow<T>.launchIn(lifecycleOwner: LifecycleOwner) {
     launchIn(lifecycleOwner.lifecycleScope)
-}
+}
+
+fun Fragment.showLongToast(@StringRes text: Int) = showLongToast(getString(text))
+
+fun Fragment.showLongToast(text: String) = showToast(text, Toast.LENGTH_LONG)
+
+private fun Fragment.showToast(text: String, length: Int): Boolean {
+    return context?.let { Toast.makeText(it, text, length).show() } != null
+}

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

@@ -2,12 +2,14 @@ package gq.kirmanak.mealient.ui.recipes
 
 import android.os.Bundle
 import android.view.View
-import android.widget.Toast
+import androidx.annotation.StringRes
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.activityViewModels
 import androidx.fragment.app.viewModels
 import androidx.navigation.fragment.findNavController
 import androidx.paging.LoadState
+import androidx.paging.PagingDataAdapter
+import androidx.recyclerview.widget.RecyclerView
 import by.kirich1409.viewbindingdelegate.viewBinding
 import dagger.hilt.android.AndroidEntryPoint
 import gq.kirmanak.mealient.R
@@ -17,6 +19,7 @@ import gq.kirmanak.mealient.datasource.NetworkError
 import gq.kirmanak.mealient.extensions.collectWhenViewResumed
 import gq.kirmanak.mealient.extensions.launchIn
 import gq.kirmanak.mealient.extensions.refreshRequestFlow
+import gq.kirmanak.mealient.extensions.showLongToast
 import gq.kirmanak.mealient.logging.Logger
 import gq.kirmanak.mealient.ui.activity.MainActivityViewModel
 import gq.kirmanak.mealient.ui.recipes.images.RecipeImageLoader
@@ -83,7 +86,7 @@ class RecipesFragment : Fragment(R.layout.fragment_recipes) {
             binding.refresher.isRefreshing = false
         }
 
-        observeLoadStateChanges(recipesAdapter)
+        recipesAdapter.observeLoadStateChanges()
 
         collectWhenViewResumed(binding.refresher.refreshRequestFlow(logger)) {
             logger.v { "setupRecipeAdapter: received refresh request" }
@@ -100,50 +103,25 @@ class RecipesFragment : Fragment(R.layout.fragment_recipes) {
         }
     }
 
-    private fun observeLoadStateChanges(recipesAdapter: RecipesPagingAdapter) {
+    private fun <T : Any, VH : RecyclerView.ViewHolder> PagingDataAdapter<T, VH>.observeLoadStateChanges() {
-        recipesAdapter.loadStateFlow
+        appendPaginationEnd().onEach { onPaginationEnd() }.launchIn(viewLifecycleOwner)
-            .map { it.append }
+        refreshErrors().onEach { onLoadFailure(it) }.launchIn(viewLifecycleOwner)
-            .distinctUntilChanged()
-            .filter { it.endOfPaginationReached }
-            .onEach { onPaginationEnd() }
-            .launchIn(viewLifecycleOwner)
-
-        recipesAdapter.loadStateFlow
-            .map { it.refresh }
-            .distinctUntilChanged()
-            .filterIsInstance<LoadState.Error>()
-            .onEach { onLoadFailure(it.error) }
-            .launchIn(viewLifecycleOwner)
     }
 
     private fun onPaginationEnd() {
         logger.v { "onPaginationEnd() called" }
-        Toast.makeText(
+        showLongToast(R.string.fragment_recipes_last_page_loaded_toast)
-            requireContext(),
-            getString(R.string.fragment_recipes_last_page_loaded_toast),
-            Toast.LENGTH_SHORT
-        ).show()
     }
 
     private fun onLoadFailure(error: Throwable) {
-        logger.v(error) { "onLoadFailure() called" }
+        logger.w(error) { "onLoadFailure() called" }
-
+        val reason = error.toLoadErrorReasonText()?.let { getString(it) }
-        val reason = when (error) {
+        val toastText = if (reason == null) {
-            is NetworkError.Unauthorized -> R.string.fragment_recipes_load_failure_toast_unauthorized
+            getString(R.string.fragment_recipes_load_failure_toast_no_reason)
-            is NetworkError.NoServerConnection -> R.string.fragment_recipes_load_failure_toast_no_connection
-            is NetworkError.NotMealie, is NetworkError.MalformedUrl -> R.string.fragment_recipes_load_failure_toast_unexpected_response
-            else -> null
-        }?.let { getString(it) }
-
-        val generalText = getString(R.string.fragment_recipes_load_failure_toast_general)
-
-        val text = if (reason == null) {
-            generalText
         } else {
-            getString(R.string.fragment_recipes_load_failure_toast, generalText, reason)
+            getString(R.string.fragment_recipes_load_failure_toast, reason)
         }
-
+        showLongToast(toastText)
-        Toast.makeText(requireContext(), text, Toast.LENGTH_SHORT).show()
     }
 
     override fun onDestroyView() {
@@ -152,4 +130,28 @@ class RecipesFragment : Fragment(R.layout.fragment_recipes) {
         // Prevent RV leaking through mObservers list in adapter
         binding.recipes.adapter = null
     }
+}
+
+@StringRes
+private fun Throwable.toLoadErrorReasonText(): Int? = when (this) {
+    is NetworkError.Unauthorized -> R.string.fragment_recipes_load_failure_toast_unauthorized
+    is NetworkError.NoServerConnection -> R.string.fragment_recipes_load_failure_toast_no_connection
+    is NetworkError.NotMealie, is NetworkError.MalformedUrl -> R.string.fragment_recipes_load_failure_toast_unexpected_response
+    else -> null
+}
+
+private fun <T : Any, VH : RecyclerView.ViewHolder> PagingDataAdapter<T, VH>.refreshErrors(): Flow<Throwable> {
+    return loadStateFlow
+        .map { it.refresh }
+        .distinctUntilChanged()
+        .filterIsInstance<LoadState.Error>()
+        .map { it.error }
+}
+
+private fun <T : Any, VH : RecyclerView.ViewHolder> PagingDataAdapter<T, VH>.appendPaginationEnd(): Flow<Unit> {
+    return loadStateFlow
+        .map { it.append.endOfPaginationReached }
+        .distinctUntilChanged()
+        .filter { it }
+        .map { }
 }

app/src/main/res/values-ru/strings.xml

@@ -42,9 +42,9 @@
 	<string name="fragment_authentication_email_input_helper_text">Пример: changeme@email.com</string>
 	<string name="fragment_authentication_password_input_helper_text">Пример: demo</string>
 	<string name="fragment_recipes_last_page_loaded_toast">Последняя страница</string>
-	<string name="fragment_recipes_load_failure_toast">%1$s %2$s</string>
+	<string name="fragment_recipes_load_failure_toast">Ошибка загрузки: %1$s.</string>
-	<string name="fragment_recipes_load_failure_toast_general">Ошибка загрузки.</string>
+	<string name="fragment_recipes_load_failure_toast_unauthorized">неавторизован</string>
-	<string name="fragment_recipes_load_failure_toast_unauthorized">Неавторизован</string>
+	<string name="fragment_recipes_load_failure_toast_unexpected_response">неожиданный ответ</string>
-	<string name="fragment_recipes_load_failure_toast_unexpected_response">Неожиданный ответ</string>
+	<string name="fragment_recipes_load_failure_toast_no_connection">нет соединения</string>
-	<string name="fragment_recipes_load_failure_toast_no_connection">Нет соединения</string>
+	<string name="fragment_recipes_load_failure_toast_no_reason">Ошибка загрузки.</string>
 </resources>

app/src/main/res/values/strings.xml

@@ -46,9 +46,9 @@
 	<string name="fragment_authentication_email_input_helper_text">Example: changeme@email.com</string>
 	<string name="fragment_authentication_password_input_helper_text">Example: demo</string>
 	<string name="fragment_recipes_last_page_loaded_toast">Last page loaded</string>
-	<string name="fragment_recipes_load_failure_toast" comment="EXAMPLE: Load failed! Unauthorized">%1$s %2$s</string>
+	<string name="fragment_recipes_load_failure_toast" comment="EXAMPLE: Load error: unauthorized.">Load error: %1$s.</string>
-	<string name="fragment_recipes_load_failure_toast_general">Load failed.</string>
+	<string name="fragment_recipes_load_failure_toast_no_reason">Load failed.</string>
-	<string name="fragment_recipes_load_failure_toast_unauthorized">Unauthorized</string>
+	<string name="fragment_recipes_load_failure_toast_unauthorized">unauthorized</string>
-	<string name="fragment_recipes_load_failure_toast_unexpected_response">Unexpected response</string>
+	<string name="fragment_recipes_load_failure_toast_unexpected_response">unexpected response</string>
-	<string name="fragment_recipes_load_failure_toast_no_connection">No connection</string>
+	<string name="fragment_recipes_load_failure_toast_no_connection">no connection</string>
 </resources>