import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import '../models/record.dart';
import '../data/categories.dart';
import 'package:uuid/uuid.dart';
import 'package:decimal/decimal.dart';

class EditPage extends StatefulWidget {
  final Record? record;
  final Function(Record) onSave; // 添加保存回调

  const EditPage({
    Key? key,
    this.record,
    required this.onSave,
  }) : super(key: key);

  @override
  State<EditPage> createState() => _EditPageState();
}

class _EditPageState extends State<EditPage>
    with SingleTickerProviderStateMixin {
  late TabController _tabController;
  String? _selectedCategoryId;
  String _note = '';
  double _amount = 0.0;
  DateTime _selectedDate = DateTime.now();
  final _uuid = const Uuid();
  String _inputBuffer = '0.0'; // 用于显示的字符串
  String? _pendingOperation; // 等待执行的运算符
  String? _pendingValue; // 等待计算的第一个值
  String? _inputValue; // 当前输入的值

  final d = (String s) => Decimal.parse(s);

  @override
  void initState() {
    super.initState();
    // 先初始化 TabController
    _tabController = TabController(
      length: 2,
      vsync: this,
      initialIndex: widget.record?.type == RecordType.income ? 1 : 0,
    );
    _tabController.addListener(_onTabChanged);

    // 初始化数据
    if (widget.record != null) {
      // 编辑模式：初始化现有记录的数据
      _selectedCategoryId = widget.record!.categoryId;
      _note = widget.record!.note ?? '';
      _amount = widget.record!.amount;
      _selectedDate = widget.record!.createTime;
      // 设置输入缓冲区为当前金额的格式化字符串
      _inputValue = _formatNumberForDisplay(widget.record!.amount);
    } else {
      // 新建模式：默认选中第一个分类
      _selectedCategoryId = _currentCategories.first.id;
    }
  }

  /// 标签切换监听
  void _onTabChanged() {
    setState(() {
      // 切换类型时选中新类型的第一个分类
      _selectedCategoryId = _currentCategories.first.id;
    });
  }

  /// 获取当前记录类型
  RecordType get _currentType =>
      _tabController.index == 0 ? RecordType.expense : RecordType.income;

  /// 获取当前分类列表
  List<Category> get _currentCategories => CategoryConfig.getCategoriesByType(_currentType);

  /// 保存记录
  void _saveRecord() {
    if (_selectedCategoryId == null) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('请选择分类')),
      );
      return;
    }
    if (_amount <= 0) {
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('输入金额请大于0')),
      );
      return;
    }

    final record = Record(
      id: widget.record?.id ?? _uuid.v4(),
      type: _currentType,
      categoryId: _selectedCategoryId!,
      note: _note.isEmpty ? null : _note,
      amount: _amount,
      createTime: _selectedDate,
    );

    widget.onSave(record);
    Navigator.of(context).pop();
  }

  /// 显示金额
  String get _displayAmount {
    if (_pendingOperation != null ||
        _pendingValue != null ||
        _inputValue != null) {
      _inputBuffer =
          '${_pendingValue ?? ""} ${_pendingOperation ?? ""} ${_inputValue ?? ""}';
    } else {
      _inputBuffer = '0.0';
    }
    return _inputBuffer;
  }

  /// 处理数字输入
  void _handleNumber(String digit) {
    setState(() {
      if (_inputValue == '0' || _inputValue == null) {
        // 当前是0
        _inputValue = digit;
      } else {
        // 其他情况追加数字
        _inputValue = _inputValue! + digit;
      }
    });
  }

  /// 处理小数点
  void _handleDecimal() {
    setState(() {
      if (_inputValue == null || _inputValue == '0') {
        _inputValue = '0.';
      } else if (_inputValue!.contains('.')) {
        HapticFeedback.heavyImpact();
      } else {
        _inputValue = '$_inputValue.';
      }
    });
  }

  /// 处理删除
  void _handleDelete() {
    setState(() {
      if (_inputValue != null) {
        if (_inputValue!.length > 1) {
          _inputValue = _inputValue!.substring(0, _inputValue!.length - 1);
        } else {
          _inputValue = null;
        }
      } else if (_pendingOperation != null) {
        _pendingOperation = null;
        _inputValue = _pendingValue;
        _pendingValue = null;
      } else if (_pendingValue != null) {
        if (_pendingValue!.length > 1) {
          _pendingValue =
              _pendingValue!.substring(0, _pendingValue!.length - 1);
        } else {
          _pendingValue = null;
        }
      } else {
        _pendingValue = null;
      }
    });
  }

  /// 处理运算符
  void _handleOperator(String operator) {
    // 如果有待处理的运算，先计算结果
    if (_pendingOperation != null) {
      // 先保存当前运算符，因为计算可能会重置状态
      final newOperator = operator;
      _calculateResult();
      _pendingValue = _inputValue;
      _inputValue = null;

      // 计算完成后，设置新的运算符
      setState(() {
        // 如果计算导致重置（结果为0），不添加新的运算符
        if (_inputBuffer == '0.0') {
          return;
        } else {
          _pendingOperation = newOperator;
        }
      });
    } else if (_inputValue != null ) {
      // 正常设置运算符
      setState(() {
        _pendingOperation = operator;
        _pendingValue = _inputValue!;
        _inputValue = null;
      });
    } else {
      HapticFeedback.heavyImpact();
    }
  }

  /// 计算结果
  void _calculateResult() {

    double result = 0;
    if(_pendingValue == null && _inputValue== null){
      return;
    }
    else if (_pendingOperation != null &&
        _pendingValue != null &&
        _inputValue != null) {
    
      switch (_pendingOperation) {
        case '+':
          result = (d(_pendingValue!) + d(_inputValue!)).toDouble();
          if (result == 0) {
            _resetToDefault();
            return;
          }
          break;
        case '-':
          result = (d(_pendingValue!) - d(_inputValue!)).toDouble();
          if (result <= 0) {
            _resetToDefault();
            return;
          }
          break;
        default:
          return;
      }
    } else {
      result = double.parse(_inputValue ?? _pendingValue!);
    } 

    setState(() {
        // 格式化结果，去掉不必要的小数位
        _pendingValue = null;
        _amount = result;
        _pendingOperation = null;
        _inputValue = _formatNumberForDisplay(result);
      });
  }

  /// 重置到默认状态
  void _resetToDefault() {
    setState(() {
      _inputBuffer = '0.0';
      _amount = 0;
      _pendingOperation = null;
      _pendingValue = null;
      _inputValue = null;
    });
  }

  /// 格式化数字用于显示
  String _formatNumberForDisplay(double number) {
    // 如果是整数，直接返回整数部分
    if (number % 1 == 0) {
      return number.toInt().toString();
    }
    // 如果是小数，去掉末尾的0
    String numStr = number.toString();
    while (numStr.endsWith('0')) {
      numStr = numStr.substring(0, numStr.length - 1);
    }
    if (numStr.endsWith('.')) {
      numStr = numStr.substring(0, numStr.length - 1);
    }
    return numStr;
  }

  /// 修改键盘按钮处理逻辑
  void _onKeyboardButtonPressed(String value) {
    if (_inputBuffer.length >= 20 && value != '删除' && value != '保存'&& value != 'again'){
      ScaffoldMessenger.of(context).showSnackBar(
        const SnackBar(content: Text('输入数字过大')),
      );
      return;
    }
    switch (value) {
      case '删除':
        _handleDelete();
        break;
      case '保存':
        _calculateResult();
        _saveRecord();
        break;
      case 'again':
        // TODO: 实现again功能
        break;
      case '+':
      case '-':
        _handleOperator(value);
        break;
      case '.':
        _handleDecimal();
        break;
      default:
        _handleNumber(value);
    }
  }

  /// 格式化日期显示
  String _formatDate(DateTime date) {
    final now = DateTime.now();
    final today = DateTime(now.year, now.month, now.day);
    final dateToCheck = DateTime(date.year, date.month, date.day);
    final difference = today.difference(dateToCheck).inDays;

    // 检查是否是今天、昨天、前天
    switch (difference) {
      case 0:
        return '今天';
      case 1:
        return '昨天';
      case 2:
        return '前天';
      default:
        // 如果是当年
        if (date.year == now.year) {
          return '${date.month}/${date.day}';
        }
        // 不是当年
        return '${date.year}/${date.month}/${date.day}';
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: TabBar(
          controller: _tabController,
          tabs: const [
            Tab(text: '支出'),
            Tab(text: '收入'),
          ],
        ),
      ),
      body: Column(
        children: [
          // 分类网格
          Expanded(
            child: GridView.builder(
              padding: const EdgeInsets.all(16),
              gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
                crossAxisCount: 4,
                mainAxisSpacing: 16,
                crossAxisSpacing: 16,
              ),
              itemCount: _currentCategories.length,
              itemBuilder: (context, index) {
                final category = _currentCategories[index];
                final isSelected = category.id == _selectedCategoryId;
                return _buildCategoryItem(category, isSelected);
              },
            ),
          ),
          // 底部编辑区域
          _buildBottomEditor(),
        ],
      ),
    );
  }

  /// 构建分类项
  Widget _buildCategoryItem(Category category, bool isSelected) {
    return InkWell(
      onTap: () => setState(() => _selectedCategoryId = category.id),
      child: Container(
        decoration: BoxDecoration(
          color: isSelected
              ? Theme.of(context).primaryColor.withOpacity(0.1)
              : null,
          border: Border.all(
            color: isSelected ? Theme.of(context).primaryColor : Colors.grey,
          ),
          borderRadius: BorderRadius.circular(8),
        ),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Icon(
              category.icon,
              color: isSelected ? Theme.of(context).primaryColor : Colors.grey,
            ),
            const SizedBox(height: 4),
            Text(
              category.name,
              style: TextStyle(
                color:
                    isSelected ? Theme.of(context).primaryColor : Colors.grey,
              ),
            ),
          ],
        ),
      ),
    );
  }

  /// 构建底部编辑区域
  Widget _buildBottomEditor() {
    return Container(
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: Colors.white,
        boxShadow: [
          BoxShadow(
            color: Colors.black.withOpacity(0.1),
            blurRadius: 8,
            offset: const Offset(0, -2),
          ),
        ],
      ),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          // 备注和金额
          _buildNoteAndAmount(),
          // 配置按钮
          Row(
            children: [
              TextButton.icon(
                onPressed: () {
                  // TODO: 实现账户选择
                },
                icon: const Icon(Icons.account_balance_wallet),
                label: const Text('默认账户'),
              ),
              TextButton.icon(
                onPressed: () async {
                  final date = await showDatePicker(
                    context: context,
                    initialDate: _selectedDate,
                    firstDate: DateTime(2000),
                    lastDate: DateTime.now(),
                  );
                  if (date != null) {
                    setState(() => _selectedDate = date);
                  }
                },
                icon: const Icon(Icons.calendar_today),
                label: Text(_formatDate(_selectedDate)),
              ),
              TextButton.icon(
                onPressed: () {
                  // TODO: 实现图片选择
                },
                icon: const Icon(Icons.photo),
                label: const Text('图片'),
              ),
            ],
          ),
          // 数字键盘
          _buildNumberKeyboard(),
        ],
      ),
    );
  }

  /// 构建数字键盘
  Widget _buildNumberKeyboard() {
    return GridView.count(
      shrinkWrap: true,
      crossAxisCount: 4,
      childAspectRatio: 2,
      children: [
        _buildKeyboardButton('7'),
        _buildKeyboardButton('8'),
        _buildKeyboardButton('9'),
        _buildKeyboardButton('删除', isFunction: true),
        _buildKeyboardButton('4'),
        _buildKeyboardButton('5'),
        _buildKeyboardButton('6'),
        _buildKeyboardButton('+'),
        _buildKeyboardButton('1'),
        _buildKeyboardButton('2'),
        _buildKeyboardButton('3'),
        _buildKeyboardButton('-'),
        _buildKeyboardButton('again'),
        _buildKeyboardButton('0'),
        _buildKeyboardButton('.'),
        _buildKeyboardButton('保存', isFunction: true),
      ],
    );
  }

  /// 构建键盘按钮
  Widget _buildKeyboardButton(String text, {bool isFunction = false}) {
    return TextButton(
      onPressed: () => _onKeyboardButtonPressed(text),
      child: Text(
        text,
        style: TextStyle(
          fontSize: 20,
          color: isFunction ? Theme.of(context).primaryColor : Colors.black,
        ),
      ),
    );
  }

  /// 构建底部编辑区域中的备注和金额行
  Widget _buildNoteAndAmount() {
    return Row(
      children: [
        Expanded(
          child: TextField(
            controller: TextEditingController(text: _note), // 使用控制器设置初始值
            decoration: const InputDecoration(
              hintText: '添加备注',
              border: InputBorder.none,
            ),
            onChanged: (value) => setState(() => _note = value),
          ),
        ),
        Text(
          _displayAmount,
          style: const TextStyle(
            fontSize: 24,
            fontWeight: FontWeight.bold,
          ),
        ),
      ],
    );
  }

  @override
  void dispose() {
    _tabController.dispose();
    super.dispose();
  }
}