feat: Remember Last Used Library Category

[skip ci]

Closes #1026

src/components/Context/LibraryContext.tsx

@@ -4,12 +4,11 @@ import {
   UseLibraryReturnType,
 } from '@screens/library/hooks/useLibrary';
 import { useLibrarySettings } from '@hooks/persisted';
-import { LibrarySettings } from '@hooks/persisted/useSettings';
 
 // type Library = Category & { novels: LibraryNovelInfo[] };
 
 type LibraryContextType = UseLibraryReturnType & {
-  settings: LibrarySettings;
+  settings: ReturnType<typeof useLibrarySettings>;
 };
 
 const defaultValue = {} as LibraryContextType;

src/hooks/persisted/useSettings.ts

@@ -103,6 +103,8 @@ export interface BrowseSettings {
 export interface LibrarySettings {
   /** User-selected category for newly added novels. */
   defaultCategoryId?: number;
+  /** Last category viewed in the library. */
+  lastUsedCategoryId?: number;
   globalUpdateExcludeCategoryIds?: number[];
   globalUpdateIncludeCategoryIds?: number[];
   sortOrder?: LibrarySortOrder;

src/screens/library/LibraryScreen.tsx

@@ -54,6 +54,7 @@ import { ThemeColors } from '@theme/types';
 import { useLibraryContext } from '@components/Context/LibraryContext';
 import { xor } from 'lodash-es';
 import { SelectionContext } from './SelectionContext';
+import { getLibraryCategoryIndex } from './constants/constants';
 
 type State = NavigationState<{
   key: string;
@@ -86,7 +87,13 @@ const LibraryScreen = ({ navigation }: LibraryScreenProps) => {
     categories,
     refetchLibrary,
     isLoading,
-    settings: { showNumberOfNovels, downloadedOnlyMode, incognitoMode },
+    settings: {
+      showNumberOfNovels,
+      downloadedOnlyMode,
+      incognitoMode,
+      lastUsedCategoryId,
+      setLibrarySettings,
+    },
   } = useLibraryContext();
 
   const { importNovel } = useImport();
@@ -98,7 +105,19 @@ const LibraryScreen = ({ navigation }: LibraryScreenProps) => {
 
   const bottomSheetRef = useRef<BottomSheetModalMethods | null>(null);
 
-  const [index, setIndex] = useState(0);
+  const [selectedCategoryId, setSelectedCategoryId] =
+    useState(lastUsedCategoryId);
+  const index = getLibraryCategoryIndex(categories, selectedCategoryId);
+  const setIndex = useCallback(
+    (nextIndex: number) => {
+      const categoryId = categories[nextIndex]?.id;
+      if (categoryId !== undefined) {
+        setSelectedCategoryId(categoryId);
+        setLibrarySettings({ lastUsedCategoryId: categoryId });
+      }
+    },
+    [categories, setLibrarySettings],
+  );
 
   const {
     value: setCategoryModalVisible,
@@ -483,17 +502,21 @@ const LibraryScreen = ({ navigation }: LibraryScreenProps) => {
       ) : null}
 
       <SelectionContext.Provider value={selectionContextValue}>
-        <TabView
-          commonOptions={{
-            label: renderLabel,
-          }}
-          lazy
-          navigationState={navigationState}
-          renderTabBar={renderTabBar}
-          renderScene={renderScene}
-          onIndexChange={setIndex}
-          initialLayout={{ width: layout.width }}
-        />
+        {categories.length ? (
+          <TabView
+            commonOptions={{
+              label: renderLabel,
+            }}
+            lazy
+            navigationState={navigationState}
+            renderTabBar={renderTabBar}
+            renderScene={renderScene}
+            onIndexChange={setIndex}
+            initialLayout={{ width: layout.width }}
+          />
+        ) : (
+          <SourceScreenSkeletonLoading theme={theme} />
+        )}
       </SelectionContext.Provider>
 
       {useLibraryFAB &&

src/screens/library/constants/__tests__/constants.test.ts

@@ -0,0 +1,19 @@
+import { getLibraryCategoryIndex } from '../constants';
+
+const categories = [{ id: 1 }, { id: 7 }, { id: 12 }];
+
+describe('getLibraryCategoryIndex', () => {
+  it('returns the index of the saved category', () => {
+    expect(getLibraryCategoryIndex(categories, 7)).toBe(1);
+  });
+
+  it('falls back to the first category when the saved category is unavailable', () => {
+    expect(getLibraryCategoryIndex(categories, 99)).toBe(0);
+  });
+
+  it('finds the saved category after categories are reordered', () => {
+    expect(getLibraryCategoryIndex([{ id: 7 }, { id: 1 }, { id: 12 }], 7)).toBe(
+      0,
+    );
+  });
+});

src/screens/library/constants/constants.ts

@@ -1,5 +1,13 @@
 import { getString } from '@i18n/translations';
 
+export const getLibraryCategoryIndex = (
+  categories: { id: number }[],
+  categoryId?: number,
+): number => {
+  const index = categories.findIndex(category => category.id === categoryId);
+  return index === -1 ? 0 : index;
+};
+
 export enum LibraryFilter {
   Downloaded = '(chaptersDownloaded > 0 OR isLocal = 1)',
   Unread = 'lastReadAt IS NULL',