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

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

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

/// 选择结果（多选）
class MultiPickerResult<T> {
  final List<T> values;
  final List<int> indices;

  MultiPickerResult(this.values, this.indices);
}

/// 显示样式
enum BottomPickerStyle {
  wheel,
  list,
}

/// 通用底部弹窗选择器
class BottomPicker {
  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,
        bool withIndex = false,
        BottomPickerStyle style = BottomPickerStyle.wheel,
        bool multiSelect = false,
        List<int>? initialSelectedIndices,

        /// 新增：列表样式标题
        String title = '请选择',

        String cancelText = '取消',
        String confirmText = '确定',
        int maxLines = 3,
      }) {
    if (items.isEmpty) return Future.value(null);

    final safeIndex = initialIndex.clamp(0, items.length - 1);
    final initialMulti = (initialSelectedIndices ?? const <int>[])
        .where((e) => e >= 0 && e < items.length)
        .toSet();

    if (style == BottomPickerStyle.wheel) {
      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: [
                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: Text(
                          cancelText,
                          style: const TextStyle(
                            color: Colors.black54,
                            fontSize: 16,
                          ),
                        ),
                      ),
                      TextButton(
                        onPressed: () {
                          FocusScope.of(context).unfocus();
                          if (withIndex) {
                            Navigator.of(ctx).pop(
                              PickerResult<T>(selected, selectedIndex),
                            );
                          } else {
                            Navigator.of(ctx).pop(selected);
                          }
                        },
                        child: Text(
                          confirmText,
                          style: const TextStyle(
                            color: Colors.blue,
                            fontSize: 16,
                          ),
                        ),
                      ),
                    ],
                  ),
                ),
                const Divider(height: 1),
                Expanded(
                  child: CupertinoPicker(
                    scrollController: FixedExtentScrollController(
                      initialItem: safeIndex,
                    ),
                    itemExtent: itemExtent,
                    onSelectedItemChanged: (index) {
                      selected = items[index];
                      selectedIndex = index;
                    },
                    children: items.map((item) {
                      return Center(
                        child: SizedBox(
                          width: double.infinity,
                          child: DefaultTextStyle.merge(
                            style: const TextStyle(fontSize: 16),
                            child: itemBuilder(item),
                          ),
                        ),
                      );
                    }).toList(),
                  ),
                ),
              ],
            ),
          );
        },
      );
    }

    // 列表样式
    return showModalBottomSheet<dynamic>(
      context: context,
      isScrollControlled: true,
      backgroundColor: Colors.white,
      shape: const RoundedRectangleBorder(
        borderRadius: BorderRadius.vertical(top: Radius.circular(12)),
      ),
      builder: (ctx) {
        int selectedIndex = safeIndex;
        final Set<int> selectedIndices = Set<int>.from(initialMulti);

        if (!multiSelect && selectedIndices.isEmpty) {
          selectedIndices.add(safeIndex);
        }

        T currentSingleValue = items[selectedIndex];

        return SafeArea(
          child: SizedBox(
            height: height,
            child: StatefulBuilder(
              builder: (context, setState) {
                return Column(
                  children: [
                    Padding(
                      padding: const EdgeInsets.symmetric(
                        horizontal: 16,
                        vertical: 10,
                      ),
                      child: Row(
                        children: [
                          Expanded(
                            child: Text(
                              title,
                              style: const TextStyle(
                                fontSize: 16,
                                fontWeight: FontWeight.w600,
                              ),
                            ),
                          ),
                          TextButton(
                            onPressed: () {
                              FocusScope.of(context).unfocus();
                              Navigator.of(ctx).pop();
                            },
                            child: Text(
                              cancelText,
                              style: const TextStyle(
                                color: Colors.black54,
                                fontSize: 16,
                              ),
                            ),
                          ),
                          TextButton(
                            onPressed: () {
                              FocusScope.of(context).unfocus();

                              if (multiSelect) {
                                final indices = selectedIndices.toList()..sort();
                                final values = indices.map((e) => items[e]).toList();

                                if (withIndex) {
                                  Navigator.of(ctx).pop(
                                    MultiPickerResult<T>(values, indices),
                                  );
                                } else {
                                  Navigator.of(ctx).pop(values);
                                }
                              } else {
                                if (withIndex) {
                                  Navigator.of(ctx).pop(
                                    PickerResult<T>(currentSingleValue, selectedIndex),
                                  );
                                } else {
                                  Navigator.of(ctx).pop(currentSingleValue);
                                }
                              }
                            },
                            child: Text(
                              confirmText,
                              style: const TextStyle(
                                color: Colors.blue,
                                fontSize: 16,
                              ),
                            ),
                          ),
                        ],
                      ),
                    ),
                    const Divider(height: 1),
                    Expanded(
                      child: ListView.separated(
                        padding: const EdgeInsets.symmetric(vertical: 8),
                        itemCount: items.length,
                        separatorBuilder: (_, __) => const Divider(height: 1),
                        itemBuilder: (context, index) {
                          final item = items[index];
                          final isSelected = multiSelect
                              ? selectedIndices.contains(index)
                              : selectedIndex == index;
                          return InkWell(
                            onTap: () {
                              setState(() {
                                if (multiSelect) {
                                  if (selectedIndices.contains(index)) {
                                    selectedIndices.remove(index);
                                  } else {
                                    selectedIndices.add(index);
                                  }
                                } else {
                                  selectedIndex = index;
                                  currentSingleValue = item;
                                }
                              });
                            },
                            child: Padding(
                              padding: const EdgeInsets.symmetric(
                                horizontal: 16,
                                vertical: 12,
                              ),
                              child: Row(
                                crossAxisAlignment: CrossAxisAlignment.start,
                                children: [
                                  if (multiSelect)
                                    Padding(
                                      padding: const EdgeInsets.only(top: 2),
                                      child: Icon(
                                        isSelected
                                            ? Icons.check_box
                                            : Icons.check_box_outline_blank,
                                        color: isSelected ? Colors.blue : Colors.grey,
                                        size: 22,
                                      ),
                                    )
                                  else
                                    Padding(
                                      padding: const EdgeInsets.only(top: 2),
                                      child: Icon(
                                        isSelected
                                            ? Icons.radio_button_checked
                                            : Icons.radio_button_off,
                                        color: isSelected ? Colors.blue : Colors.grey,
                                        size: 22,
                                      ),
                                    ),
                                  const SizedBox(width: 12),
                                  Expanded(
                                    child: DefaultTextStyle.merge(
                                      style: const TextStyle(
                                        fontSize: 16,
                                        color: Colors.black87,
                                        height: 1.35,
                                      ),
                                      child: itemBuilder(item),
                                    ),
                                  ),
                                ],
                              ),
                            ),
                          );
                        },
                      ),
                    ),
                  ],
                );
              },
            ),
          ),
        );
      },
    );
  }
}