Show stub if favourite categories empty

app/src/main/java/org/koitharu/kotatsu/favourites/data/FavouriteCategoriesDao.kt

@@ -13,7 +13,7 @@ abstract class FavouriteCategoriesDao {
 	abstract fun observeAll(): Flow<List<FavouriteCategoryEntity>>
 
 	@Query("SELECT * FROM favourite_categories WHERE category_id = :id")
-	abstract fun observe(id: Long): Flow<FavouriteCategoryEntity>
+	abstract fun observe(id: Long): Flow<FavouriteCategoryEntity?>
 
 	@Insert(onConflict = OnConflictStrategy.ABORT)
 	abstract suspend fun insert(category: FavouriteCategoryEntity): Long

app/src/main/java/org/koitharu/kotatsu/favourites/domain/FavouritesRepository.kt

@@ -1,10 +1,7 @@
 package org.koitharu.kotatsu.favourites.domain
 
 import androidx.room.withTransaction
-import kotlinx.coroutines.flow.Flow
+import kotlinx.coroutines.flow.*
-import kotlinx.coroutines.flow.distinctUntilChanged
-import kotlinx.coroutines.flow.flatMapLatest
-import kotlinx.coroutines.flow.map
 import org.koitharu.kotatsu.core.db.MangaDatabase
 import org.koitharu.kotatsu.core.db.entity.*
 import org.koitharu.kotatsu.core.model.FavouriteCategory
@@ -48,6 +45,11 @@ class FavouritesRepository(private val db: MangaDatabase) {
 		}.distinctUntilChanged()
 	}
 
+	fun observeCategory(id: Long): Flow<FavouriteCategory?> {
+		return db.favouriteCategoriesDao.observe(id)
+			.map { it?.toFavouriteCategory() }
+	}
+
 	fun observeCategories(mangaId: Long): Flow<List<FavouriteCategory>> {
 		return db.favouritesDao.observe(mangaId).map { entity ->
 			entity?.categories?.map { it.toFavouriteCategory() }.orEmpty()
@@ -121,6 +123,7 @@ class FavouritesRepository(private val db: MangaDatabase) {
 
 	private fun observeOrder(categoryId: Long): Flow<SortOrder> {
 		return db.favouriteCategoriesDao.observe(categoryId)
+			.filterNotNull()
 			.map { x -> SortOrder(x.order, SortOrder.NEWEST) }
 			.distinctUntilChanged()
 	}

app/src/main/java/org/koitharu/kotatsu/favourites/ui/FavouritesContainerFragment.kt

@@ -6,6 +6,7 @@ import androidx.appcompat.view.ActionMode
 import androidx.appcompat.widget.PopupMenu
 import androidx.core.graphics.Insets
 import androidx.core.view.children
+import androidx.core.view.isVisible
 import androidx.core.view.updateLayoutParams
 import androidx.core.view.updatePadding
 import com.google.android.material.snackbar.Snackbar
@@ -18,6 +19,7 @@ import org.koitharu.kotatsu.base.ui.util.ActionModeListener
 import org.koitharu.kotatsu.core.model.FavouriteCategory
 import org.koitharu.kotatsu.core.ui.titleRes
 import org.koitharu.kotatsu.databinding.FragmentFavouritesBinding
+import org.koitharu.kotatsu.databinding.ItemEmptyStateBinding
 import org.koitharu.kotatsu.favourites.ui.categories.CategoriesActivity
 import org.koitharu.kotatsu.favourites.ui.categories.CategoriesEditDelegate
 import org.koitharu.kotatsu.favourites.ui.categories.FavouritesCategoriesViewModel
@@ -31,13 +33,15 @@ class FavouritesContainerFragment :
 	BaseFragment<FragmentFavouritesBinding>(),
 	FavouritesTabLongClickListener,
 	CategoriesEditDelegate.CategoriesEditCallback,
-	ActionModeListener {
+	ActionModeListener,
+	View.OnClickListener {
 
 	private val viewModel by viewModel<FavouritesCategoriesViewModel>()
 	private val editDelegate by lazy(LazyThreadSafetyMode.NONE) {
 		CategoriesEditDelegate(requireContext(), this)
 	}
 	private var pagerAdapter: FavouritesPagerAdapter? = null
+	private var stubBinding: ItemEmptyStateBinding? = null
 
 	override fun onCreate(savedInstanceState: Bundle?) {
 		super.onCreate(savedInstanceState)
@@ -52,9 +56,7 @@ class FavouritesContainerFragment :
 	override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
 		super.onViewCreated(view, savedInstanceState)
 		val adapter = FavouritesPagerAdapter(this, this)
-		viewModel.visibleCategories.value?.let {
+		viewModel.visibleCategories.value?.let(::onCategoriesChanged)
-			adapter.replaceData(it)
-		}
 		binding.pager.adapter = adapter
 		pagerAdapter = adapter
 		TabLayoutMediator(binding.tabs, binding.pager, adapter).attach()
@@ -66,6 +68,7 @@ class FavouritesContainerFragment :
 
 	override fun onDestroyView() {
 		pagerAdapter = null
+		stubBinding = null
 		super.onDestroyView()
 	}
 
@@ -101,6 +104,15 @@ class FavouritesContainerFragment :
 
 	private fun onCategoriesChanged(categories: List<CategoryListModel>) {
 		pagerAdapter?.replaceData(categories)
+		if (categories.isEmpty()) {
+			binding.pager.isVisible = false
+			binding.tabs.isVisible = false
+			showStub()
+		} else {
+			binding.pager.isVisible = true
+			binding.tabs.isVisible = true
+			(stubBinding?.root ?: binding.stubEmptyState).isVisible = false
+		}
 	}
 
 	override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
@@ -130,6 +142,12 @@ class FavouritesContainerFragment :
 		return true
 	}
 
+	override fun onClick(v: View) {
+		when (v.id) {
+			R.id.button_retry -> editDelegate.createCategory()
+		}
+	}
+
 	override fun onDeleteCategory(category: FavouriteCategory) {
 		viewModel.deleteCategory(category.id)
 	}
@@ -193,6 +211,18 @@ class FavouritesContainerFragment :
 		menu.show()
 	}
 
+	private fun showStub() {
+		val stub = stubBinding ?: ItemEmptyStateBinding.bind(binding.stubEmptyState.inflate())
+		stub.root.isVisible = true
+		stub.icon.setImageResource(R.drawable.ic_heart_outline)
+		stub.textPrimary.setText(R.string.text_empty_holder_primary)
+		stub.textSecondary.setText(R.string.empty_favourite_categories)
+		stub.buttonRetry.setText(R.string.add)
+		stub.buttonRetry.isVisible = true
+		stub.buttonRetry.setOnClickListener(this)
+		stubBinding = stub
+	}
+
 	companion object {
 
 		fun newInstance() = FavouritesContainerFragment()

app/src/main/java/org/koitharu/kotatsu/favourites/ui/categories/FavouritesCategoriesViewModel.kt

@@ -31,7 +31,7 @@ class FavouritesCategoriesViewModel(
 		repository.observeCategories(),
 		observeAllCategoriesVisible(),
 	) { list, showAll ->
-		mapCategories(list, showAll, showAll)
+		mapCategories(list, showAll, showAll && list.isNotEmpty())
 	}.asLiveDataDistinct(viewModelScope.coroutineContext + Dispatchers.Default)
 
 	fun createCategory(name: String) {

app/src/main/java/org/koitharu/kotatsu/favourites/ui/list/FavouritesListViewModel.kt

@@ -1,9 +1,13 @@
 package org.koitharu.kotatsu.favourites.ui.list
 
+import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
 import androidx.lifecycle.viewModelScope
+import androidx.recyclerview.widget.RecyclerView.NO_ID
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.map
 import org.koitharu.kotatsu.R
 import org.koitharu.kotatsu.core.prefs.AppSettings
 import org.koitharu.kotatsu.favourites.domain.FavouritesRepository
@@ -24,6 +28,14 @@ class FavouritesListViewModel(
 	settings: AppSettings,
 ) : MangaListViewModel(settings), CountersProvider {
 
+	var sortOrder: LiveData<SortOrder?> = if (categoryId == NO_ID) {
+		MutableLiveData(null)
+	} else {
+		repository.observeCategory(categoryId)
+			.map { it?.order }
+			.asLiveDataDistinct(viewModelScope.coroutineContext + Dispatchers.Default)
+	}
+
 	override val content = combine(
 		if (categoryId == 0L) {
 			repository.observeAll(SortOrder.NEWEST)

app/src/main/res/layout/fragment_favourites.xml

@@ -17,4 +17,10 @@
 		android:layout_width="match_parent"
 		android:layout_height="match_parent" />
 
+	<ViewStub
+		android:id="@+id/stub_empty_state"
+		android:layout_width="match_parent"
+		android:layout_height="match_parent"
+		android:layout="@layout/item_empty_state" />
+
 </LinearLayout>

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

@@ -278,4 +278,5 @@
 	<string name="chapters_will_removed_background">Главы будут удалены в фоновом режиме. Это может занять какое-то время</string>
 	<string name="hide">Скрыть</string>
 	<string name="new_sources_text">Доступны новые источники манги</string>
+	<string name="empty_favourite_categories">Нет категорий избранного</string>
 </resources>

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

@@ -281,4 +281,5 @@
 	<string name="chapters_will_removed_background">Chapters will be removed in the background. It can take some time</string>
 	<string name="hide">Hide</string>
 	<string name="new_sources_text">New manga sources are available</string>
+	<string name="empty_favourite_categories">No favourite categories</string>
 </resources>