import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';

/// 选择结果（新增）
class PickerResult<T> {
  final T value;
  final int index;

  PickerResult(this.value, this.index);
}

/// 通用底部弹窗选择器
class BottomPicker {
  /// 显示底部选择器弹窗
  ///
  /// [withIndex] = true 时返回 PickerResult<T>
  /// [withIndex] = false 时返回 T（兼容旧代码）
  static Future<dynamic> show<T>(
      BuildContext context, {
        required List<T> items,
        required Widget Function(T item) itemBuilder,
        int initialIndex = 0,
        double itemExtent = 50.0,
        double height = 250,

        /// 新增参数
        bool withIndex = false,
      }) {
    if (items.isEmpty) return Future.value(null);

    final safeIndex = initialIndex.clamp(0, items.length - 1);

    T selected = items[safeIndex];
    int selectedIndex = safeIndex;

    return showModalBottomSheet<dynamic>(
      context: context,
      backgroundColor: Colors.white,
      shape: const RoundedRectangleBorder(
        borderRadius: BorderRadius.vertical(top: Radius.circular(12)),
      ),
      builder: (ctx) {
        return SizedBox(
          height: height,
          child: Column(
            children: [
              // 按钮行
              Padding(
                padding: const EdgeInsets.symmetric(
                  horizontal: 16,
                  vertical: 8,
                ),
                child: Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    TextButton(
                      onPressed: () {
                        FocusScope.of(context).unfocus();
                        Navigator.of(ctx).pop();
                      },
                      child: const Text(
                        '取消',
                        style: TextStyle(color: Colors.black54, fontSize: 16),
                      ),
                    ),
                    TextButton(
                      onPressed: () {
                        FocusScope.of(context).unfocus();

                        if (withIndex) {
                          Navigator.of(ctx).pop(
                            PickerResult(selected, selectedIndex),
                          );
                        } else {
                          Navigator.of(ctx).pop(selected);
                        }
                      },
                      child: const Text(
                        '确定',
                        style: TextStyle(color: Colors.blue, fontSize: 16),
                      ),
                    ),
                  ],
                ),
              ),
              const Divider(height: 1),

              // 滚动选择器
              Expanded(
                child: CupertinoPicker(
                  scrollController: FixedExtentScrollController(
                    initialItem: initialIndex,
                  ),
                  itemExtent: itemExtent,
                  onSelectedItemChanged: (index) {
                    selected = items[index];
                    selectedIndex = index;
                  },
                  children: items
                      .map((item) => Center(child: itemBuilder(item)))
                      .toList(),
                ),
              ),
            ],
          ),
        );
      },
    );
  }
}