Handle filter loading errors

app/src/main/java/org/koitharu/kotatsu/list/ui/filter/FilterAdapter.kt

@@ -10,4 +10,5 @@ class FilterAdapter(
 	filterTagDelegate(listener),
 	filterHeaderDelegate(),
 	filterLoadingDelegate(),
+	filterErrorDelegate(),
 )

app/src/main/java/org/koitharu/kotatsu/list/ui/filter/FilterAdapterDelegates.kt

@@ -1,10 +1,12 @@
 package org.koitharu.kotatsu.list.ui.filter
 
+import android.widget.TextView
+import com.hannesdorfmann.adapterdelegates4.dsl.adapterDelegate
 import com.hannesdorfmann.adapterdelegates4.dsl.adapterDelegateViewBinding
+import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.databinding.ItemCheckableMultipleBinding
 import org.koitharu.kotatsu.databinding.ItemCheckableSingleBinding
 import org.koitharu.kotatsu.databinding.ItemFilterHeaderBinding
-import org.koitharu.kotatsu.databinding.ItemLoadingFooterBinding
 
 fun filterSortDelegate(
 	listener: OnFilterChangedListener,
@@ -47,6 +49,11 @@ fun filterHeaderDelegate() = adapterDelegateViewBinding<FilterItem.Header, Filte
 	}
 }
 
-fun filterLoadingDelegate() = adapterDelegateViewBinding<FilterItem.Loading, FilterItem, ItemLoadingFooterBinding>(
-	{ layoutInflater, parent -> ItemLoadingFooterBinding.inflate(layoutInflater, parent, false) }
-) { }
+fun filterLoadingDelegate() = adapterDelegate<FilterItem.Loading, FilterItem>(R.layout.item_loading_footer) {}
+
+fun filterErrorDelegate() = adapterDelegate<FilterItem.Error, FilterItem>(R.layout.item_sources_empty) {
+
+	bind {
+		(itemView as TextView).setText(item.textResId)
+	}
+}

app/src/main/java/org/koitharu/kotatsu/list/ui/filter/FilterDiffCallback.kt

@@ -17,14 +17,18 @@ class FilterDiffCallback : DiffUtil.ItemCallback<FilterItem>() {
 			oldItem is FilterItem.Sort && newItem is FilterItem.Sort -> {
 				oldItem.order == newItem.order
 			}
+			oldItem is FilterItem.Error && newItem is FilterItem.Error -> {
+				oldItem.textResId == newItem.textResId
+			}
 			else -> false
 		}
 	}
 
 	override fun areContentsTheSame(oldItem: FilterItem, newItem: FilterItem): Boolean {
 		return when {
-			oldItem === newItem -> true
+			oldItem == FilterItem.Loading && newItem == FilterItem.Loading -> true
 			oldItem is FilterItem.Header && newItem is FilterItem.Header -> true
+			oldItem is FilterItem.Error && newItem is FilterItem.Error -> true
 			oldItem is FilterItem.Tag && newItem is FilterItem.Tag -> {
 				oldItem.isChecked == newItem.isChecked
 			}

app/src/main/java/org/koitharu/kotatsu/list/ui/filter/FilterItem.kt

@@ -21,4 +21,8 @@ sealed interface FilterItem {
 	) : FilterItem
 
 	object Loading : FilterItem
+
+	class Error(
+		@StringRes val textResId: Int,
+	) : FilterItem
 }

app/src/main/java/org/koitharu/kotatsu/list/ui/filter/FilterViewModel.kt

@@ -6,6 +6,7 @@ import kotlinx.coroutines.*
 import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.base.domain.MangaDataRepository
 import org.koitharu.kotatsu.base.ui.BaseViewModel
+import org.koitharu.kotatsu.core.model.MangaTag
 import org.koitharu.kotatsu.core.model.SortOrder
 import org.koitharu.kotatsu.core.parser.RemoteMangaRepository
 import java.util.*
@@ -21,12 +22,10 @@ class FilterViewModel(
 	private var job: Job? = null
 	private var selectedSortOrder: SortOrder? = state.sortOrder
 	private val selectedTags = HashSet(state.tags)
-	private val availableTagsDeferred = viewModelScope.async(Dispatchers.Default + createErrorHandler()) {
-		repository.getTags()
-	}
-	private val localTagsDeferred = viewModelScope.async(Dispatchers.Default + createErrorHandler()) {
+	private val localTagsDeferred = viewModelScope.async(Dispatchers.Default) {
 		dataRepository.findTags(repository.source)
 	}
+	private var availableTagsDeferred = loadTagsAsync()
 
 	init {
 		showFilter()
@@ -52,21 +51,24 @@ class FilterViewModel(
 		val previousJob = job
 		job = launchJob(Dispatchers.Default) {
 			previousJob?.cancelAndJoin()
-			val tags = availableTagsDeferred.await()
+			val tags = tryLoadTags()
 			val localTags = localTagsDeferred.await()
 			val sortOrders = repository.sortOrders
-			val list = ArrayList<FilterItem>(sortOrders.size + tags.size + 2)
+			val list = ArrayList<FilterItem>(sortOrders.size + (tags?.size ?: 1) + 2)
 			list.add(FilterItem.Header(R.string.sort_order))
 			sortOrders.sortedBy { it.ordinal }.mapTo(list) {
 				FilterItem.Sort(it, isSelected = it == selectedSortOrder)
 			}
-			if (tags.isNotEmpty() || selectedTags.isNotEmpty()) {
+			if (tags == null || tags.isNotEmpty() || selectedTags.isNotEmpty()) {
 				list.add(FilterItem.Header(R.string.genres))
 				val mappedTags = TreeSet<FilterItem.Tag>(compareBy({ !it.isChecked }, { it.tag.title }))
 				localTags.mapTo(mappedTags) { FilterItem.Tag(it, isChecked = it in selectedTags) }
-				tags.mapTo(mappedTags) { FilterItem.Tag(it, isChecked = it in selectedTags) }
+				tags?.mapTo(mappedTags) { FilterItem.Tag(it, isChecked = it in selectedTags) }
 				selectedTags.mapTo(mappedTags) { FilterItem.Tag(it, isChecked = true) }
 				list.addAll(mappedTags)
+				if (tags == null) {
+					list.add(FilterItem.Error(R.string.filter_load_error))
+				}
 			}
 			ensureActive()
 			filter.postValue(list)
@@ -93,4 +95,20 @@ class FilterViewModel(
 			updateFilters()
 		}
 	}
+
+	private suspend fun tryLoadTags(): Set<MangaTag>? {
+		val shouldRetryOnError = availableTagsDeferred.isCompleted
+		val result = availableTagsDeferred.await()
+		if (result == null && shouldRetryOnError) {
+			availableTagsDeferred = loadTagsAsync()
+			return availableTagsDeferred.await()
+		}
+		return result
+	}
+
+	private fun loadTagsAsync() = viewModelScope.async(Dispatchers.Default) {
+		kotlin.runCatching {
+			repository.getTags()
+		}.getOrNull()
+	}
 }

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

@@ -253,4 +253,5 @@
 	<string name="screenshots_allow">Разрешить</string>
 	<string name="screenshots_block_nsfw">Запретить для NSFW</string>
 	<string name="screenshots_block_all">Запретить всегда</string>
+	<string name="filter_load_error">Не удалось загрузить список жанров</string>
 </resources>

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

@@ -255,4 +255,5 @@
 	<string name="screenshots_allow">Allow</string>
 	<string name="screenshots_block_nsfw">Block on NSFW</string>
 	<string name="screenshots_block_all">Block always</string>
+	<string name="filter_load_error">Unable to load genres list</string>
 </resources>