import 'package:chicken_farm/components/vb_select.dart';
import 'package:chicken_farm/core/utils/logger.dart';
import 'package:flutter/material.dart';

/// 搜索API函数签名
/// T 为数据类型
typedef SearchApiFunction<T> =
    Future<Map<String, dynamic>> Function({
      required Map<String, dynamic> queryParams,
    });

/// 选项转换器，将数据类型T转换为SelectOption
typedef SelectOptionConverter<T> = SelectOption Function(T data);

/// 搜索选择组件
class VberSearchSelect<T> extends StatefulWidget {
  /// 搜索API函数
  final SearchApiFunction<T> searchApi;

  /// 数据转换方法，将原始数据转换为SelectOption
  final SelectOptionConverter<T> converter;

  /// 根据value获取对应label的函数
  final Future<String?> Function(String?)? getValueLabel;

  /// 当前选中的值
  final String? value;

  /// 值改变回调
  final ValueChanged<String?>? onChanged;

  /// 提示文字
  final String? hint;

  /// 是否启用
  final bool enabled;

  /// 每页数据条数
  final int pageSize;

  /// 额外参数，用于传递给搜索API
  final Map<String, dynamic>? extraParams;

  const VberSearchSelect({
    super.key,
    required this.searchApi,
    required this.converter,
    this.getValueLabel,
    this.value,
    this.onChanged,
    this.hint,
    this.enabled = true,
    this.pageSize = 3,
    this.extraParams,
  });

  @override
  State<VberSearchSelect<T>> createState() => _VberSearchSelectState<T>();
}

class _VberSearchSelectState<T> extends State<VberSearchSelect<T>>
    with SingleTickerProviderStateMixin {
  final TextEditingController _textController = TextEditingController();
  final TextEditingController _searchController = TextEditingController();
  final FocusNode _focusNode = FocusNode();
  final FocusNode _searchFocusNode = FocusNode(); // 添加搜索框的FocusNode
  final LayerLink _layerLink = LayerLink();
  OverlayEntry? _overlayEntry;
  List<T> _items = [];
  bool _isLoading = false;
  bool _isOverlayVisible = false;
  String? _selectedValue;
  SelectOption? _selectedOption; // 新增：用来存储选中的选项
  int _currentPage = 1;
  bool _hasMore = true;
  String _lastSearchText = '';

  @override
  void initState() {
    super.initState();
    _selectedValue = widget.value;
    _initTextController();
    _focusNode.addListener(_onFocusChange);
  }

  /// 初始化文本控制器
  void _initTextController() async {
    if (widget.value != null && widget.getValueLabel != null) {
      try {
        final label = await widget.getValueLabel!(widget.value);
        if (mounted) {
          setState(() {
            _textController.text = label ?? widget.value ?? '';
          });
        }
      } catch (e) {
        logger.e('Failed to get label for value: ${widget.value}', e);
      }
    }
  }

  @override
  void didUpdateWidget(covariant VberSearchSelect<T> oldWidget) {
    super.didUpdateWidget(oldWidget);
    // 当外部传入的value发生变化时，同步更新内部状态
    if (oldWidget.value != widget.value) {
      _syncValueAndText(widget.value);
    }
  }

  /// 同步外部value和内部_selectedValue以及_textController.text
  void _syncValueAndText(String? newValue) async {
    setState(() {
      _selectedValue = newValue;
    });

    // 优先使用存储的选项
    String? label;
    if (_selectedOption != null && _selectedOption!.value == newValue) {
      label = _selectedOption!.label;
    }

    // 尝试在现有选项中查找匹配的标签
    if (label == null && newValue != null) {
      for (var item in _items) {
        final option = widget.converter(item);
        if (option.value == newValue) {
          label = option.label;
          break;
        }
      }
    }

    // 如果在现有选项中没找到，且提供了getValueLabel函数，则尝试通过它获取
    if (label == null && newValue != null && widget.getValueLabel != null) {
      try {
        label = await widget.getValueLabel!(newValue);
      } catch (e) {
        logger.e('Failed to get label for value: $newValue', e);
      }
    }

    // 更新文本显示控件
    if (mounted) {
      setState(() {
        // 优先级: 找到的label > value本身 > 空字符串
        _textController.text = label ?? newValue ?? '';
      });
    }
  }

  @override
  void dispose() {
    _textController.dispose();
    _searchController.dispose();
    _focusNode.removeListener(_onFocusChange);
    _focusNode.dispose();
    _searchFocusNode.dispose(); // 释放搜索框的FocusNode
    _overlayEntry?.remove();
    super.dispose();
  }

  void _onFocusChange() {
    // 只有当_focusNode获得焦点且组件启用时才显示弹出层
    if (_focusNode.hasFocus && widget.enabled) {
      // 添加一个微小的延迟，避免焦点竞争
      Future.microtask(() {
        if (_focusNode.hasFocus && mounted) {
          _showOverlay();
        }
      });
    }
  }

  void _showOverlay() {
    if (_isOverlayVisible) return;

    _overlayEntry = _createOverlayEntry();
    Overlay.of(context).insert(_overlayEntry!);
    _isOverlayVisible = true;

    // 清空搜索框
    _searchController.clear();
    _items.clear();
    _currentPage = 1;
    _hasMore = true;
    _lastSearchText = '';

    _performSearch('', (callback) => setState(() => callback()));

    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (_searchFocusNode.canRequestFocus && mounted) {
        _searchFocusNode.requestFocus();
      }
    });
  }

  void _hideOverlay() {
    _overlayEntry?.remove();
    _overlayEntry = null;
    _isOverlayVisible = false;
    _searchFocusNode.unfocus();
    _lastSearchText = '';
    _items.clear();
  }

  OverlayEntry _createOverlayEntry() {
    // 获取选择框的大小和位置
    final renderBox = context.findRenderObject() as RenderBox;
    final size = renderBox.size;
    final offset = renderBox.localToGlobal(Offset.zero);

    return OverlayEntry(
      builder: (context) => Positioned(
        left: offset.dx,
        top: offset.dy + size.height + 5,
        width: size.width,
        child: Material(
          elevation: 4,
          borderRadius: BorderRadius.circular(4),
          child: Container(
            constraints: BoxConstraints(
              maxHeight: MediaQuery.of(context).size.height * 0.4,
            ),
            child: StatefulBuilder(
              builder: (context, setState) {
                return Column(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Padding(
                      padding: const EdgeInsets.all(16.0),
                      child: TextField(
                        key: ValueKey('search_text_field_${widget.hint ?? ''}_${UniqueKey().toString()}'),
                        controller: _searchController,
                        focusNode: _searchFocusNode,
                        autofocus: false,
                        decoration: InputDecoration(
                          hintText: '请输入${widget.hint}搜索关键词',
                          contentPadding: EdgeInsets.symmetric(
                            horizontal: 12,
                            vertical: 8,
                          ),
                          border: OutlineInputBorder(
                            borderRadius: BorderRadius.circular(4),
                          ),
                          isDense: true,
                        ),
                        onChanged: (value) {
                          Future.delayed(const Duration(milliseconds: 300), () {
                            if (_lastSearchText != _searchController.text) {
                              _lastSearchText = _searchController.text;
                              _items.clear();
                              _currentPage = 1;
                              _hasMore = true;
                              _performSearch(_searchController.text, setState);
                            } else {}
                          });
                        },
                      ),
                    ),
                    if (_isLoading && _items.isEmpty)
                      Padding(
                        padding: const EdgeInsets.all(16.0),
                        child: Center(child: CircularProgressIndicator()),
                      )
                    else if (!_isLoading && _items.isEmpty)
                      Padding(
                        padding: const EdgeInsets.all(16.0),
                        child: Center(
                          child: Text(
                            '没有查询到结果',
                            style: TextStyle(color: Colors.grey, fontSize: 14),
                          ),
                        ),
                      )
                    else
                      Flexible(
                        child: NotificationListener<ScrollNotification>(
                          onNotification: (notification) {
                            if (notification.metrics.pixels ==
                                    notification.metrics.maxScrollExtent &&
                                _hasMore &&
                                !_isLoading) {
                              _loadMore(setState);
                              return true;
                            }
                            return false;
                          },
                          child: Builder(
                            builder: (BuildContext context) {
                              return ListView.builder(
                                padding: EdgeInsets.zero,
                                shrinkWrap: true,
                                itemCount: _items.length + (_hasMore ? 1 : 0),
                                itemBuilder: (context, index) {
                                  if (index == _items.length) {
                                    // 显示加载更多指示器
                                    return Padding(
                                      padding: const EdgeInsets.all(12.0),
                                      child: Center(
                                        child: _isLoading
                                            ? CircularProgressIndicator()
                                            : Text('上拉加载更多'),
                                      ),
                                    );
                                  }
                                  final item = _items[index];
                                  final option = widget.converter(item);
                                  return ListTile(
                                    title: Text(option.label),
                                    onTap: () => _selectItem(option, item),
                                    dense: true,
                                    contentPadding: EdgeInsets.symmetric(
                                      horizontal: 16,
                                      vertical: 4,
                                    ),
                                    visualDensity: VisualDensity.compact,
                                  );
                                },
                              );
                            },
                          ),
                        ),
                      ),
                  ],
                );
              },
            ),
          ),
        ),
      ),
    );
  }

  void _loadMore(StateSetter overlaySetState) async {
    if (!_hasMore || _isLoading) return;

    overlaySetState(() {
      _isLoading = true;
    });

    try {
      _currentPage++;

      final result = await _fetchData(_currentPage);

      final List<dynamic> rows = result['rows'] is List ? result['rows'] : [];
      final int total = result['total'] is int ? result['total'] : 0;
      final newItems = rows.cast<T>().toList();

      if (mounted) {
        overlaySetState(() {
          _items.addAll(newItems);
          _hasMore = _items.length < total;
          _isLoading = false;
        });
      }
    } catch (e) {
      logger.e('加载更多失败：$e');
      if (mounted) {
        overlaySetState(() {
          _currentPage--; // 回退页码
          _isLoading = false;
        });
      }
    }
  }

  void _performSearch(String keyword, StateSetter overlaySetState) async {
    overlaySetState(() {
      _isLoading = true;
    });

    try {
      _currentPage = 1;
      _hasMore = true;

      final result = await _fetchData(_currentPage, keyword: keyword);

      final List<dynamic> rows = result['rows'] is List ? result['rows'] : [];
      final int total = result['total'] is int ? result['total'] : 0;
      final newItems = rows.cast<T>().toList();

      if (mounted) {
        overlaySetState(() {
          _items = newItems;
          _hasMore = _items.length < total;
          _isLoading = false;
        });
      }
    } catch (e) {
      logger.e('搜索失败：$e');
      if (mounted) {
        overlaySetState(() {
          _items = [];
          _hasMore = false;
          _isLoading = false;
        });
      }
    }
  }

  Future<Map<String, dynamic>> _fetchData(
    int pageNum, {
    String? keyword,
  }) async {
    final Map<String, dynamic> queryParams = {
      'pageSize': widget.pageSize,
      'pageNum': pageNum,
    };

    if (keyword != null) {
      queryParams['keyword'] = keyword;
    } else if (keyword == null && _searchController.text.isNotEmpty) {
      // 如果keyword参数为null但_searchController中有内容，则使用该内容
      queryParams['keyword'] = _searchController.text;
    }

    if (widget.extraParams != null) {
      queryParams.addAll(widget.extraParams!);
    }

    final r = await widget.searchApi(queryParams: queryParams);
    return r;
  }

  void _selectItem(SelectOption option, T item) {
    setState(() {
      _textController.text = option.label;
      _selectedValue = option.value;
      _selectedOption = option; // 保存选中的选项
      
      // 检查当前选中的项是否已经在列表中，如果不在则添加到列表开头
      // 这样可以在后续通过value同步label时找到对应的项
      bool itemExists = _items.any((element) {
        final elementOption = widget.converter(element);
        return elementOption.value == option.value;
      });
      
      if (!itemExists) {
        // 将选中项插入到列表开头，方便快速查找
        _items.insert(0, item);
      }
    });

    widget.onChanged?.call(option.value);
    _hideOverlay();
    // 不需要在下一帧失去焦点，立即失去焦点可能会导致一些问题
    // 使用post frame callback确保overlay完全隐藏后再失去焦点
    WidgetsBinding.instance.addPostFrameCallback((_) {
      if (mounted) {
        _focusNode.unfocus();
      }
    });
  }

  void _clearSelection() {
    setState(() {
      _textController.clear();
      _selectedValue = null;
      _selectedOption = null; // 清除保存的选项
    });

    widget.onChanged?.call(null);
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onTap: () {
        // 点击时请求焦点
        if (widget.enabled) {
          _focusNode.requestFocus();
        }
      },
      child: CompositedTransformTarget(
        link: _layerLink,
        child: TextField(
          controller: _textController,
          focusNode: _focusNode,
          readOnly: true,
          enabled: widget.enabled,
          decoration: InputDecoration(
            hintText: '请选择${widget.hint ?? ""}...',
            suffixIcon: _selectedValue != null
                ? IconButton(
                    icon: Icon(Icons.clear, size: 20),
                    onPressed: _clearSelection,
                  )
                : Icon(Icons.arrow_drop_down),
          ),
        ),
      ),
    );
  }
}