Add authors to filter

app/src/main/kotlin/org/koitharu/kotatsu/core/db/dao/MangaDao.kt

@@ -34,6 +34,9 @@ abstract class MangaDao {
 	@Query("SELECT author FROM manga WHERE author LIKE :query GROUP BY author ORDER BY COUNT(author) DESC LIMIT :limit")
 	abstract suspend fun findAuthors(query: String, limit: Int): List<String>
 
+    @Query("SELECT author FROM manga WHERE manga.source = :source AND author IS NOT NULL AND author != '' GROUP BY author ORDER BY COUNT(author) DESC LIMIT :limit")
+    abstract suspend fun findAuthorsBySource(source: String, limit: Int): List<String>
+
 	@Transaction
 	@Query("SELECT * FROM manga WHERE (title LIKE :query OR alt_title LIKE :query) AND manga_id IN (SELECT manga_id FROM favourites UNION SELECT manga_id FROM history) LIMIT :limit")
 	abstract suspend fun searchByTitle(query: String, limit: Int): List<MangaWithTags>

app/src/main/kotlin/org/koitharu/kotatsu/filter/ui/FilterCoordinator.kt

@@ -124,6 +124,20 @@ class FilterCoordinator @Inject constructor(
         MutableStateFlow(FilterProperty.EMPTY)
     }
 
+    val authors: StateFlow<FilterProperty<String>> = if (capabilities.isAuthorSearchSupported) {
+        combine(
+            flow { emit(searchRepository.getAuthors(repository.source, TAGS_LIMIT)) },
+            currentListFilter.distinctUntilChangedBy { it.author },
+        ) { available, selected ->
+            FilterProperty(
+                availableItems = available,
+                selectedItems = setOfNotNull(selected.author),
+            )
+        }.stateIn(coroutineScope, SharingStarted.Lazily, FilterProperty.LOADING)
+    } else {
+        MutableStateFlow(FilterProperty.EMPTY)
+    }
+
     val states: StateFlow<FilterProperty<MangaState>> = combine(
         filterOptions.asFlow(),
         currentListFilter.distinctUntilChangedBy { it.states },

app/src/main/kotlin/org/koitharu/kotatsu/filter/ui/sheet/FilterSheetFragment.kt

@@ -78,6 +78,7 @@ class FilterSheetFragment : BaseAdaptiveSheet<SheetFilterBinding>(),
         filter.originalLocale.observe(viewLifecycleOwner, this::onOriginalLocaleChanged)
         filter.tags.observe(viewLifecycleOwner, this::onTagsChanged)
         filter.tagsExcluded.observe(viewLifecycleOwner, this::onTagsExcludedChanged)
+        filter.authors.observe(viewLifecycleOwner, this::onAuthorsChanged)
         filter.states.observe(viewLifecycleOwner, this::onStateChanged)
         filter.contentTypes.observe(viewLifecycleOwner, this::onContentTypesChanged)
         filter.contentRating.observe(viewLifecycleOwner, this::onContentRatingChanged)
@@ -103,6 +104,7 @@ class FilterSheetFragment : BaseAdaptiveSheet<SheetFilterBinding>(),
         binding.chipsDemographics.onChipClickListener = this
         binding.chipsGenres.onChipClickListener = this
         binding.chipsGenresExclude.onChipClickListener = this
+        binding.chipsAuthor.onChipClickListener = this
         binding.chipsSavedFilters.onChipLongClickListener = this
         binding.chipsSavedFilters.onChipCloseClickListener = this
         binding.sliderYear.addOnChangeListener(this::onSliderValueChange)
@@ -199,6 +201,11 @@ class FilterSheetFragment : BaseAdaptiveSheet<SheetFilterBinding>(),
             is ContentRating -> filter.toggleContentRating(data, !chip.isChecked)
             is Demographic -> filter.toggleDemographic(data, !chip.isChecked)
             is PersistableFilter -> filter.setAdjusted(data.filter)
+            is String -> if (chip.isChecked) {
+                filter.setAuthor(null)
+            } else {
+                filter.setAuthor(data)
+            }
             null -> router.showTagsCatalogSheet(excludeMode = chip.parentView?.id == R.id.chips_genresExclude)
         }
     }
@@ -312,6 +319,22 @@ class FilterSheetFragment : BaseAdaptiveSheet<SheetFilterBinding>(),
         b.chipsGenresExclude.setChips(chips)
     }
 
+    private fun onAuthorsChanged(value: FilterProperty<String>) {
+        val b = viewBinding ?: return
+        b.layoutAuthor.isGone = value.isEmpty()
+        if (value.isEmpty()) {
+            return
+        }
+        val chips = value.availableItems.map { author ->
+            ChipsView.ChipModel(
+                title = author,
+                isChecked = author in value.selectedItems,
+                data = author,
+            )
+        }
+        b.chipsAuthor.setChips(chips)
+    }
+
     private fun onStateChanged(value: FilterProperty<MangaState>) {
         val b = viewBinding ?: return
         b.layoutState.isGone = value.isEmpty()

app/src/main/kotlin/org/koitharu/kotatsu/search/domain/MangaSearchRepository.kt

@@ -169,4 +169,8 @@ class MangaSearchRepository @Inject constructor(
 			null,
 		)?.use { cursor -> cursor.count } ?: 0
 	}
+
+    suspend fun getAuthors(source: MangaSource, limit: Int): List<String> {
+        return db.getMangaDao().findAuthorsBySource(source.name, limit)
+    }
 }

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

@@ -162,6 +162,24 @@
 
             </org.koitharu.kotatsu.filter.ui.FilterFieldLayout>
 
+            <org.koitharu.kotatsu.filter.ui.FilterFieldLayout
+                android:id="@+id/layout_author"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="@dimen/margin_small"
+                app:showMoreButton="false"
+                app:title="@string/author">
+
+                <org.koitharu.kotatsu.core.ui.widgets.ChipsView
+                    android:id="@+id/chips_author"
+                    android:layout_width="match_parent"
+                    android:layout_height="wrap_content"
+                    android:layout_marginHorizontal="@dimen/margin_small"
+                    android:layout_marginTop="@dimen/margin_small"
+                    app:chipStyle="@style/Widget.Kotatsu.Chip.Filter" />
+
+            </org.koitharu.kotatsu.filter.ui.FilterFieldLayout>
+
             <org.koitharu.kotatsu.filter.ui.FilterFieldLayout
                 android:id="@+id/layout_types"
                 android:layout_width="match_parent"