feat(flutter): 增加榜单新剧分页与预约刷新

lib/core/widgets/paged_local_list.dart

@@ -0,0 +1,116 @@
+// Author: fruit.com.cn
+
+import 'package:flutter/material.dart';
+
+import '../theme/app_colors.dart';
+
+const int _defaultPageSize = 20;
+const Duration _defaultLoadDelay = Duration(milliseconds: 300);
+
+/// 客户端本地列表分页状态。
+class PagedLocalListController<T> extends ChangeNotifier {
+  PagedLocalListController({
+    List<T> items = const [],
+    this.pageSize = _defaultPageSize,
+    this.minimumLoadDelay = _defaultLoadDelay,
+  }) : _items = List<T>.unmodifiable(items);
+
+  final int pageSize;
+  final Duration minimumLoadDelay;
+
+  List<T> _items;
+  int _pageCount = 1;
+  int _generation = 0;
+  bool _loading = false;
+  bool _disposed = false;
+
+  List<T> get items => _items;
+  bool get loading => _loading;
+  bool get hasMore => visibleItems.length < _items.length;
+
+  List<T> get visibleItems =>
+      _items.take(_pageCount * pageSize).toList(growable: false);
+
+  /// 用最新目录替换本地数据，并回到第一页。
+  void replaceAll(List<T> items) {
+    _generation++;
+    _items = List<T>.unmodifiable(items);
+    _pageCount = 1;
+    _loading = false;
+    _notify();
+  }
+
+  /// 追加下一页；已加载完或正在加载时不重复触发。
+  Future<void> loadMore() async {
+    if (_loading || !hasMore) return;
+    final generation = _generation;
+    _loading = true;
+    _notify();
+    await Future<void>.delayed(minimumLoadDelay);
+    if (_disposed || generation != _generation) return;
+    _pageCount++;
+    _loading = false;
+    _notify();
+  }
+
+  void _notify() {
+    if (!_disposed) notifyListeners();
+  }
+
+  @override
+  void dispose() {
+    _disposed = true;
+    super.dispose();
+  }
+}
+
+/// 分页列表底部加载态与到底提示。
+class PagedLoadFooter extends StatelessWidget {
+  const PagedLoadFooter({
+    super.key,
+    required this.loading,
+    required this.hasMore,
+    required this.hasItems,
+    required this.loadMoreKey,
+    required this.noMoreKey,
+    required this.noMoreLabel,
+  });
+
+  final bool loading;
+  final bool hasMore;
+  final bool hasItems;
+  final Key loadMoreKey;
+  final Key noMoreKey;
+  final String noMoreLabel;
+
+  @override
+  Widget build(BuildContext context) {
+    if (loading) {
+      return SizedBox(
+        key: loadMoreKey,
+        height: 56,
+        child: const Center(
+          child: SizedBox.square(
+            dimension: 20,
+            child: CircularProgressIndicator(
+              strokeWidth: 2,
+              color: AppColors.blue,
+            ),
+          ),
+        ),
+      );
+    }
+    if (hasItems && !hasMore) {
+      return Padding(
+        key: noMoreKey,
+        padding: const EdgeInsets.symmetric(vertical: 14),
+        child: Text(
+          noMoreLabel,
+          textAlign: TextAlign.center,
+          style: const TextStyle(color: AppColors.muted, fontSize: 12),
+        ),
+      );
+    }
+    return const SizedBox(height: 16);
+  }
+}