Widget _buildTypedSelectionItem()

in example/lib/pages/settings/settings_page.dart [200:293]
88 lines of code
12 McCabe index (conditional complexity)

  Widget _buildTypedSelectionItem<T>(SelectionItem<T> item) {
    return FutureBuilder<List<T>>(
      future: item.optionsLoader(),
      builder: (context, optionsSnapshot) {
        if (optionsSnapshot.connectionState == ConnectionState.waiting) {
          return ListTile(
            title: Text(item.title),
            trailing: const CircularProgressIndicator(),
          );
        } else if (optionsSnapshot.hasError) {
          return ListTile(
            title: Text(item.title),
            subtitle: Text("Error: ${optionsSnapshot.error}"),
          );
        } else if (optionsSnapshot.hasData) {
          final options = optionsSnapshot.data!;
          return FutureBuilder<T?>(
            future: item.selectedOptionLoader != null
                ? item.selectedOptionLoader!(options)
                : Future.value(options.isNotEmpty ? options.first : null),
            builder: (context, selectedSnapshot) {
              // 显示加载中状态
              if (selectedSnapshot.connectionState == ConnectionState.waiting) {
                return ListTile(
                  title: Text(item.title),
                  trailing: const CircularProgressIndicator(strokeWidth: 2),
                );
              }

              // 获取当前选中项
              final selectedOption = selectedSnapshot.data;
              return ListTile(
                title: Text(item.title),
                subtitle: selectedOption != null
                    ? Text(item.displayFormatter(selectedOption))
                    : const Text("未选择"),
                trailing: const Icon(Icons.arrow_forward_ios, size: 16),
                onTap: () async {
                  final selected = await showDialog<T>(
                    context: context,
                    builder: (context) => SimpleDialog(
                      title: Text(item.title),
                      children: [
                        ...options.map<Widget>(
                          (T option) {
                            final isSelected = selectedOption != null &&
                                item.displayFormatter(selectedOption) ==
                                    item.displayFormatter(option);

                            return ListTile(
                              title: Text(item.displayFormatter(option)),
                              // 在当前选中项旁边显示勾选图标
                              trailing: isSelected
                                  ? const Icon(Icons.check, color: Colors.blue)
                                  : null,
                              onTap: () {
                                Navigator.pop(context, option);
                              },
                            );
                          },
                        ),
                        // 添加顶部的清除选项
                        if (selectedOption != null)
                          ListTile(
                            leading: const Icon(
                              Icons.delete_outline,
                              color: Colors.red,
                            ),
                            title: const Text(
                              "清除选择",
                              style: TextStyle(color: Colors.red),
                            ),
                            onTap: () {
                              Navigator.pop(context);
                              _showClearConfirmDialog<T>(context, item);
                            },
                          ),
                      ],
                    ),
                  );
                  if (selected != null) {
                    setState(() {
                      item.onSelected(selected);
                    });
                  }
                },
              );
            },
          );
        }
        return const SizedBox.shrink();
      },
    );
  }