Fix empty categories

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

@@ -15,17 +15,6 @@ abstract class FavouriteCategoriesDao {
 	@Query("SELECT * FROM favourite_categories WHERE deleted_at = 0 ORDER BY sort_key")
 	abstract fun observeAll(): Flow<List<FavouriteCategoryEntity>>
 
-	@MapInfo(valueColumn = "cover")
-	@Query(
-		"""
-			SELECT favourite_categories.*, manga.cover_url AS cover 
-			FROM favourite_categories JOIN manga ON manga.manga_id IN 
-				(SELECT manga_id FROM favourites WHERE favourites.category_id == favourite_categories.category_id)
-			ORDER BY favourite_categories.sort_key
-		"""
-	) // FIXME empty categories are ignored
-	abstract fun observeAllWithDetails(): Flow<Map<FavouriteCategoryEntity, List<String>>>
-
 	@Query("SELECT * FROM favourite_categories WHERE category_id = :id AND deleted_at = 0")
 	abstract fun observe(id: Long): Flow<FavouriteCategoryEntity?>
 

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

@@ -21,7 +21,7 @@ abstract class FavouritesDao {
 			"SELECT * FROM favourites LEFT JOIN manga ON favourites.manga_id = manga.manga_id " +
 				"WHERE favourites.deleted_at = 0 GROUP BY favourites.manga_id ORDER BY $orderBy",
 		)
-		return observeAllRaw(query)
+		return observeAllImpl(query)
 	}
 
 	@Transaction
@@ -45,7 +45,7 @@ abstract class FavouritesDao {
 				"WHERE category_id = ? AND deleted_at = 0 GROUP BY favourites.manga_id ORDER BY $orderBy",
 			arrayOf<Any>(categoryId),
 		)
-		return observeAllRaw(query)
+		return observeAllImpl(query)
 	}
 
 	@Transaction
@@ -61,6 +61,16 @@ abstract class FavouritesDao {
 	)
 	abstract suspend fun findAllManga(categoryId: Int): List<MangaEntity>
 
+	suspend fun findCovers(categoryId: Long, order: SortOrder, limit: Int): List<String> {
+		val orderBy = getOrderBy(order)
+		@Language("RoomSql") val query = SimpleSQLiteQuery(
+			"SELECT m.cover_url FROM favourites AS f LEFT JOIN manga AS m ON f.manga_id = m.manga_id " +
+				"WHERE f.category_id = ? AND deleted_at = 0 ORDER BY $orderBy LIMIT ?",
+			arrayOf<Any>(categoryId, limit),
+		)
+		return findCoversImpl(query)
+	}
+
 	@Query("SELECT * FROM manga WHERE manga_id IN (SELECT manga_id FROM favourites WHERE deleted_at = 0)")
 	abstract suspend fun findAllManga(): List<MangaEntity>
 
@@ -103,7 +113,10 @@ abstract class FavouritesDao {
 
 	@Transaction
 	@RawQuery(observedEntities = [FavouriteEntity::class])
-	protected abstract fun observeAllRaw(query: SupportSQLiteQuery): Flow<List<FavouriteManga>>
+	protected abstract fun observeAllImpl(query: SupportSQLiteQuery): Flow<List<FavouriteManga>>
+
+	@RawQuery
+	protected abstract suspend fun findCoversImpl(query: SupportSQLiteQuery): List<String>
 
 	private fun getOrderBy(sortOrder: SortOrder) = when (sortOrder) {
 		SortOrder.RATING -> "rating DESC"
@@ -112,4 +125,4 @@ abstract class FavouritesDao {
 		SortOrder.ALPHABETICAL -> "title ASC"
 		else -> throw IllegalArgumentException("Sort order $sortOrder is not supported")
 	}
-}
+}

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

@@ -1,5 +1,6 @@
 package org.koitharu.kotatsu.favourites.domain
 
+import android.util.ArrayMap
 import androidx.room.withTransaction
 import kotlinx.coroutines.flow.*
 import org.koitharu.kotatsu.base.domain.ReversibleHandle
@@ -50,10 +51,21 @@ class FavouritesRepository(
 		}.distinctUntilChanged()
 	}
 
-	fun observeCategoriesWithDetails(): Flow<Map<FavouriteCategory, List<String>>> {
-		return db.favouriteCategoriesDao.observeAllWithDetails()
+	fun observeCategoriesWithCovers(coversLimit: Int): Flow<Map<FavouriteCategory, List<String>>> {
+		return db.favouriteCategoriesDao.observeAll()
 			.map {
-				it.mapKeys { (k, _) -> k.toFavouriteCategory() }
+				db.withTransaction {
+					val res = ArrayMap<FavouriteCategory, List<String>>()
+					for (entity in it) {
+						val cat = entity.toFavouriteCategory()
+						res[cat] = db.favouritesDao.findCovers(
+							categoryId = cat.id,
+							order = cat.order,
+							limit = coversLimit,
+						)
+					}
+					res
+				}
 			}
 	}
 

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

@@ -39,13 +39,13 @@ class FavouritesCategoriesViewModel(
 		}.asLiveDataDistinct(viewModelScope.coroutineContext + Dispatchers.Default, emptyList())
 
 	val detalizedCategories = combine(
-		repository.observeCategoriesWithDetails(),
+		repository.observeCategoriesWithCovers(coversLimit = 3),
 		isReorder,
 	) { list, reordering ->
 		list.map { (category, covers) ->
 			CategoryListModel(
 				mangaCount = covers.size,
-				covers = covers.take(3),
+				covers = covers,
 				category = category,
 				isReorderMode = reordering,
 			)