mathtool/lib/tools/vector_normal.dart

// tools/vector_normal.dart
import 'package:flutter/material.dart';
import 'package:rational/rational.dart';
import '../utils/rationalsqrt2.dart';

class VectorNormalPage extends StatefulWidget {
  @override
  _VectorNormalPageState createState() => _VectorNormalPageState();
}

class _VectorNormalPageState extends State<VectorNormalPage> {
  final List<TextEditingController> _controllers = List.generate(9, (_) => TextEditingController());
  final List<FocusNode> _focusNodes = List.generate(9, (_) => FocusNode());
  TextEditingController? _currentFocusedController;
  FocusNode? _currentFocusedNode;
  String _result = '';
  bool _isCalculating = false;

  @override
  void initState() {
    super.initState();
    // 为每个焦点节点添加监听器
    for (int i = 0; i < _focusNodes.length; i++) {
      _focusNodes[i].addListener(() {
        if (_focusNodes[i].hasFocus) {
          _setCurrentFocusedController(_controllers[i], _focusNodes[i]);
        }
      });
    }
  }

  @override
  void dispose() {
    for (var controller in _controllers) {
      controller.dispose();
    }
    for (var focusNode in _focusNodes) {
      focusNode.dispose();
    }
    super.dispose();
  }

  // 设置当前聚焦的控制器和焦点节点
  void _setCurrentFocusedController(TextEditingController controller, FocusNode focusNode) {
    setState(() {
      _currentFocusedController = controller;
      _currentFocusedNode = focusNode;
    });
  }

  // 插入根号到当前光标位置
  void _insertSqrt() {
    if (_currentFocusedController == null || _currentFocusedNode == null) return;
    
    final controller = _currentFocusedController!;
    final focusNode = _currentFocusedNode!;
    final text = controller.text;
    final selection = controller.selection;
    final newText = text.substring(0, selection.start) + '√' + text.substring(selection.end);
    final newCursorPosition = selection.start + 1;
    
    controller.value = TextEditingValue(
      text: newText,
      selection: TextSelection.collapsed(offset: newCursorPosition),
    );
    
    // 确保焦点保持在当前输入框
    if (!focusNode.hasFocus) {
      focusNode.requestFocus();
    }
    
    // 延迟设置光标位置，避免全选
    Future.delayed(Duration(milliseconds: 10), () {
      controller.selection = TextSelection.collapsed(offset: newCursorPosition);
    });
  }

  // 计算法向量
  void _calculateNormal() {
    setState(() {
      _isCalculating = true;
      _result = '';
    });

    try {
      // 解析三个点的坐标
      List<Vector3> points = [];
      for (int i = 0; i < 3; i++) {
        final x = RationalExtend.parse(_controllers[i * 3].text.isEmpty ? '0' : _controllers[i * 3].text);
        final y = RationalExtend.parse(_controllers[i * 3 + 1].text.isEmpty ? '0' : _controllers[i * 3 + 1].text);
        final z = RationalExtend.parse(_controllers[i * 3 + 2].text.isEmpty ? '0' : _controllers[i * 3 + 2].text);
        points.add(Vector3(x, y, z));
      }

      // 计算两个向量
      final vector1 = points[1] - points[0];
      final vector2 = points[2] - points[0];

      // 计算叉积（法向量）
      final normal = vector1.cross(vector2);

      setState(() {
        _result = '法向量：(${normal.x}, ${normal.y}, ${normal.z})';
      });
    } catch (e) {
      setState(() {
        _result = '计算错误：$e';
      });
    } finally {
      setState(() {
        _isCalculating = false;
      });
    }
  }

  // 清除所有输入
  void _clearAll() {
    for (var controller in _controllers) {
      controller.clear();
    }
    setState(() {
      _result = '';
      _currentFocusedController = null;
      _currentFocusedNode = null;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('三点法向量计算'),
        backgroundColor: Colors.white,
        elevation: 1,
      ),
      body: SingleChildScrollView(
        padding: EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            _buildInputSection('点A', 0),
            SizedBox(height: 16),
            _buildInputSection('点B', 3),
            SizedBox(height: 16),
            _buildInputSection('点C', 6),
            SizedBox(height: 24),
            _buildControlButtons(),
            SizedBox(height: 24),
            _buildResultSection(),
            SizedBox(height: 24),
            _buildInstructions(),
          ],
        ),
      ),
    );
  }

  Widget _buildInputSection(String title, int startIndex) {
    return Card(
      elevation: 2,
      child: Padding(
        padding: EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              title,
              style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
            ),
            SizedBox(height: 12),
            Row(
              children: [
                _buildCoordinateInput('x', _controllers[startIndex], _focusNodes[startIndex]),
                SizedBox(width: 12),
                _buildCoordinateInput('y', _controllers[startIndex + 1], _focusNodes[startIndex + 1]),
                SizedBox(width: 12),
                _buildCoordinateInput('z', _controllers[startIndex + 2], _focusNodes[startIndex + 2]),
              ],
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildCoordinateInput(String label, TextEditingController controller, FocusNode focusNode) {
    return Expanded(
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Text(
            label,
            style: TextStyle(fontSize: 14, color: Colors.grey[600]),
          ),
          SizedBox(height: 4),
          TextField(
            controller: controller,
            focusNode: focusNode,
            decoration: InputDecoration(
              hintText: '0',
              border: OutlineInputBorder(),
              contentPadding: EdgeInsets.symmetric(horizontal: 12, vertical: 8),
            ),
            keyboardType: TextInputType.number,
          ),
        ],
      ),
    );
  }

  Widget _buildControlButtons() {
    return Row(
      children: [
        Expanded(
          flex: 3,
          child: ElevatedButton(
            onPressed: _isCalculating ? null : _calculateNormal,
            style: ElevatedButton.styleFrom(
              backgroundColor: Colors.blue,
              padding: EdgeInsets.symmetric(vertical: 12),
            ),
            child: _isCalculating
            ? SizedBox(
              width: 20,
              height: 20,
              child: CircularProgressIndicator(
                strokeWidth: 2,
                valueColor: AlwaysStoppedAnimation(Colors.white),
              ),
            )
            : Text(
              '计算法向量',
              style: TextStyle(fontSize: 16, color: Colors.white),
            ),
          ),
        ),
        SizedBox(width: 12),
        Expanded(
          flex: 2,
          child: OutlinedButton(
            onPressed: _clearAll,
            style: OutlinedButton.styleFrom(
              padding: EdgeInsets.symmetric(vertical: 12),
            ),
            child: Text('清除', style: TextStyle(fontSize: 16)),
          ),
        ),
        SizedBox(width: 12),
        // 使用 GestureDetector 而不是 ElevatedButton 来避免焦点转移
        GestureDetector(
          onTap: _insertSqrt,
          child: Container(
            width: 60,
            padding: EdgeInsets.symmetric(vertical: 12),
            decoration: BoxDecoration(
              color: Colors.blue,
              borderRadius: BorderRadius.circular(4),
            ),
            child: Text(
              '√',
              style: TextStyle(fontSize: 18, color: Colors.white),
              textAlign: TextAlign.center,
            ),
          ),
        ),
      ],
    );
  }

  Widget _buildResultSection() {
    if (_result.isEmpty) return SizedBox();

    return Card(
      color: Colors.grey[50],
      elevation: 2,
      child: Padding(
        padding: EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              '计算结果',
              style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
            ),
            SizedBox(height: 12),
            Text(
              _result,
              style: TextStyle(fontSize: 16, color: Colors.blue[700]),
            ),
            SizedBox(height: 8),
            Text(
              '说明：法向量是通过向量AB和向量AC的叉积计算得到',
              style: TextStyle(fontSize: 12, color: Colors.grey[600]),
            ),
          ],
        ),
      ),
    );
  }

  Widget _buildInstructions() {
    return Card(
      color: Colors.grey[50],
      elevation: 2,
      child: Padding(
        padding: EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              '使用说明',
              style: TextStyle(fontSize: 18, fontWeight: FontWeight.bold),
            ),
            SizedBox(height: 12),
            Text(
              '√2/2请输入为1/2√2\n'
              '如果已知两向量坐标，将一个点设为原点即可',
              style: TextStyle(fontSize: 14, color: Colors.grey[700]),
            ),
          ],
        ),
      ),
    );
  }
}

// 三维向量类，使用RationalExtend进行计算
class Vector3 {
  final RationalExtend x, y, z;

  Vector3(this.x, this.y, this.z);

  // 向量减法
  Vector3 operator -(Vector3 other) {
    return Vector3(x - other.x, y - other.y, z - other.z);
  }

  // 向量叉积
  Vector3 cross(Vector3 other) {
    final newX = y * other.z - z * other.y;
    final newY = z * other.x - x * other.z;
    final newZ = x * other.y - y * other.x;
    return Vector3(newX, newY, newZ);
  }

  @override
  String toString() {
    return '($x, $y, $z)';
  }
}