style(app): 格式化并拆分长函数

lib/pages/discover/widgets/home_drama_grid.dart

@@ -25,24 +25,40 @@ class _HomeDramaGrid extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final loading = _loadingState();
+    if (loading != null) return loading;
+    final search = _searchState();
+    if (search != null) return search;
+    if (dramas.isEmpty) return _emptyState();
+    return SliverMainAxisGroup(
+      slivers: [
+        SliverToBoxAdapter(child: _masonry(dramas)),
+        const SliverToBoxAdapter(child: SizedBox(height: 24)),
+      ],
+    );
+  }
+
+  Widget? _loadingState() {
     if (categories.loading && categories.feed.sections.isEmpty) {
       return const SliverFillRemaining(
         hasScrollBody: false,
         child: Center(child: CircularProgressIndicator(strokeWidth: 2)),
       );
     }
-    if (categories.error != null) {
-      return _fill(
-        EmptyState(
-          key: const Key('home-categories-error'),
-          icon: Icons.cloud_off_rounded,
-          title: l10n.categoriesError,
-          subtitle: l10n.emptyHint,
-          actionLabel: l10n.retry,
-          onAction: categories.load,
-        ),
-      );
-    }
+    if (categories.error == null) return null;
+    return _fill(
+      EmptyState(
+        key: const Key('home-categories-error'),
+        icon: Icons.cloud_off_rounded,
+        title: l10n.categoriesError,
+        subtitle: l10n.emptyHint,
+        actionLabel: l10n.retry,
+        onAction: categories.load,
+      ),
+    );
+  }
+
+  Widget? _searchState() {
     if (searching && searchLoading) {
       return const SliverFillRemaining(
         hasScrollBody: false,
@@ -54,39 +70,33 @@ class _HomeDramaGrid extends StatelessWidget {
         ),
       );
     }
-    if (searching && searchError != null) {
-      return _fill(
-        EmptyState(
-          key: const Key('discover-search-error'),
-          icon: Icons.cloud_off_rounded,
-          title: errorText(l10n, searchError, l10n.searchFailed),
-          actionLabel: l10n.retry,
-          actionKey: const Key('discover-search-retry'),
-          onAction: onRetrySearch,
-        ),
-      );
-    }
-    if (dramas.isEmpty) {
-      return _fill(
-        EmptyState(
-          key: const Key('home-all-dramas-empty'),
-          icon: searching
-              ? Icons.search_off_rounded
-              : Icons.movie_filter_outlined,
-          title: searching
-              ? l10n.noSearchResults
-              : categories.selectedSectionMissing
-              ? l10n.noCategoryDramas
-              : l10n.noSearchResults,
-          subtitle: l10n.emptyHint,
-        ),
-      );
-    }
-    return SliverMainAxisGroup(
-      slivers: [
-        SliverToBoxAdapter(child: _masonry(dramas)),
-        const SliverToBoxAdapter(child: SizedBox(height: 24)),
-      ],
+    if (!searching || searchError == null) return null;
+    return _fill(
+      EmptyState(
+        key: const Key('discover-search-error'),
+        icon: Icons.cloud_off_rounded,
+        title: errorText(l10n, searchError, l10n.searchFailed),
+        actionLabel: l10n.retry,
+        actionKey: const Key('discover-search-retry'),
+        onAction: onRetrySearch,
+      ),
+    );
+  }
+
+  Widget _emptyState() {
+    return _fill(
+      EmptyState(
+        key: const Key('home-all-dramas-empty'),
+        icon: searching
+            ? Icons.search_off_rounded
+            : Icons.movie_filter_outlined,
+        title: searching
+            ? l10n.noSearchResults
+            : categories.selectedSectionMissing
+            ? l10n.noCategoryDramas
+            : l10n.noSearchResults,
+        subtitle: l10n.emptyHint,
+      ),
     );
   }