flutter_integrated_whb/lib/customWidget/center_multi_picker.dart

import 'package:flutter/material.dart';
import 'package:qhd_prevention/customWidget/custom_button.dart';
import 'package:qhd_prevention/customWidget/toast_util.dart';

/// 居中多选弹窗（Dialog）
/// 返回 Future<List<T>?>：用户点击确定返回所选项列表；取消或关闭返回 null。
class CenterMultiPicker {
  static Future<List<T>?> show<T>(
    BuildContext context, {
    required List<T> items,
    required Widget Function(T item) itemBuilder,
    List<int>? initialSelectedIndices,
    int? maxSelection,
    bool allowEmpty = false,
    double itemHeight = 52,
    double maxHeightFactor = 0.75, // 屏幕高度的最大占比
    String? title,
  }) {
    if (items.isEmpty) return Future.value(null);

    // 安全化初始索引
    final initialSet = <int>{};
    if (initialSelectedIndices != null) {
      for (final i in initialSelectedIndices) {
        // if (i >= 0 && i < items.length) initialSet.add(i);
      }
    }

    return showDialog<List<T>?>(
      context: context,
      barrierDismissible: true,
      builder: (ctx) {
        return Dialog(
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(12),
          ),
          insetPadding: const EdgeInsets.symmetric(
            horizontal: 24,
            vertical: 24,
          ),
          child: _CenterMultiPickerBody<T>(
            items: items,
            itemBuilder: itemBuilder,
            initialSelected: initialSet,
            maxSelection: maxSelection,
            allowEmpty: allowEmpty,
            itemHeight: itemHeight,
            maxHeightFactor: maxHeightFactor,
            title: title,
          ),
        );
      },
    );
  }
}

class _CenterMultiPickerBody<T> extends StatefulWidget {
  const _CenterMultiPickerBody({
    Key? key,
    required this.items,
    required this.itemBuilder,
    required this.initialSelected,
    required this.maxSelection,
    required this.allowEmpty,
    required this.itemHeight,
    required this.maxHeightFactor,
    this.title,
  }) : super(key: key);

  final List<T> items;
  final Widget Function(T item) itemBuilder;
  final Set<int> initialSelected;
  final int? maxSelection;
  final bool allowEmpty;
  final double itemHeight;
  final double maxHeightFactor;
  final String? title;

  @override
  State<_CenterMultiPickerBody<T>> createState() =>
      _CenterMultiPickerBodyState<T>();
}

class _CenterMultiPickerBodyState<T> extends State<_CenterMultiPickerBody<T>> {
  late Set<int> _selected;

  // 固定的 header / footer 高度估算
  static const double _headerHeight = 56;
  static const double _footerHeight = 58;
  static const double _verticalPadding = 16; // Dialog 内上下 padding

  @override
  void initState() {
    super.initState();
    _selected = Set<int>.from(widget.initialSelected);
  }

  void _toggle(int idx) {
    setState(() {
      if (_selected.contains(idx)) {
        _selected.remove(idx);
      } else {
        if (widget.maxSelection != null &&
            _selected.length >= widget.maxSelection!) {
          ToastUtil.showNormal(context, '最多可选择 ${widget.maxSelection} 项');
          return;
        }
        _selected.add(idx);
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    final items = widget.items;
    final screenH = MediaQuery.of(context).size.height;
    final contentHeight =
        items.length * widget.itemHeight +
        _headerHeight +
        _footerHeight +
        _verticalPadding * 2;
    final maxAllowed = screenH * widget.maxHeightFactor;
    final dialogHeight =
        contentHeight <= maxAllowed ? contentHeight : maxAllowed;

    return Container(
      decoration: BoxDecoration(
          color: Colors.white,
          borderRadius: BorderRadius.circular(10)
      ),
      width: double.infinity,
      height: dialogHeight,
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.center,
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          // header
          Container(
            height: _headerHeight,
            padding: const EdgeInsets.symmetric(horizontal: 16),
            alignment: Alignment.centerLeft,
            child: Row(
              children: [
                if (widget.title != null)
                  Expanded(
                    child: Text(
                      widget.title!,
                      style: const TextStyle(
                        fontSize: 15,
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                  )
                else
                  Expanded(
                    child: Text(
                      '已选 ${_selected.length}${widget.maxSelection != null ? '/${widget.maxSelection}' : ''}',
                      style: const TextStyle(fontSize: 15),
                    ),
                  ),
                // 可将一些快捷按钮放在右侧（如全选/反选），这里暂不显示
              ],
            ),
          ),
          const Divider(height: 1),
          // 列表区域（可滚动）
          Expanded(
            child: Container(
              padding: const EdgeInsets.symmetric(vertical: 8),
              child: Scrollbar(
                thumbVisibility: true,
                child: ListView.separated(
                  physics: const BouncingScrollPhysics(),
                  itemCount: items.length,
                  separatorBuilder: (_, __) => const Divider(height: 1),
                  itemBuilder: (ctx, idx) {
                    final isSelected = _selected.contains(idx);
                    return InkWell(
                      onTap: () => _toggle(idx),
                      child: Container(
                        height: widget.itemHeight,
                        padding: const EdgeInsets.symmetric(
                          horizontal: 14,
                          vertical: 6,
                        ),
                        child: Row(
                          children: [
                            Container(
                              width: 22,
                              height: 22,
                              decoration: BoxDecoration(
                                color:
                                    isSelected
                                        ? Colors.blue
                                        : Colors.transparent,
                                border: Border.all(
                                  color:
                                      isSelected ? Colors.blue : Colors.black26,
                                ),
                                borderRadius: BorderRadius.circular(4),
                              ),
                              child:
                                  isSelected
                                      ? const Icon(
                                        Icons.check,
                                        size: 18,
                                        color: Colors.white,
                                      )
                                      : null,
                            ),
                            const SizedBox(width: 12),
                            Expanded(child: widget.itemBuilder(items[idx])),
                          ],
                        ),
                      ),
                    );
                  },
                ),
              ),
            ),
          ),
          const Divider(height: 1),
          // footer: 取消 / 确定（固定在底部）
          Container(
            height: _footerHeight,
            padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 8),
            child: Row(
              children: [
                Expanded(
                  child: CustomButton(
                    text: '取消',
                    backgroundColor: Colors.grey.shade200,
                    textStyle: TextStyle(fontSize: 14, color: Colors.black),
                    onPressed: () {
                      Navigator.of(context).pop(null);
                    },
                  ),
                ),
                const SizedBox(width: 12),
                Expanded(
                  child: CustomButton(
                    text: '确定',
                    backgroundColor: Colors.blue,
                    onPressed: () {
                      if (!widget.allowEmpty && _selected.isEmpty) {
                        ToastUtil.showNormal(context, '请至少选择一项');
                        return;
                      }
                      final result = _selected
                          .map((i) => items[i])
                          .toList(growable: false);
                      Navigator.of(context).pop(result);
                    },
                  ),
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}