import 'package:flutter/material.dart';

/// 原理图编辑器页面
/// 核心功能：支持 1000+ 元件流畅编辑、手势操作
class SchematicEditorScreen extends StatefulWidget {
  final String? projectId;
  
  const SchematicEditorScreen({super.key, this.projectId});

  @override
  State<SchematicEditorScreen> createState() => _SchematicEditorScreenState();
}

class _SchematicEditorScreenState extends State<SchematicEditorScreen> {
  // 当前缩放级别
  double _zoomLevel = 1.0;
  
  // 画布偏移
  Offset _offset = Offset.zero;
  
  // 是否正在拖拽
  bool _isPanning = false;
  
  // 上次触摸位置
  Offset? _lastPanPosition;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('原理图编辑器'),
        actions: [
          IconButton(
            icon: const Icon(Icons.save),
            onPressed: _saveProject,
            tooltip: '保存',
          ),
          IconButton(
            icon: const Icon(Icons.zoom_in),
            onPressed: () => _zoom(0.1),
            tooltip: '放大',
          ),
          IconButton(
            icon: const Icon(Icons.zoom_out),
            onPressed: () => _zoom(-0.1),
            tooltip: '缩小',
          ),
          IconButton(
            icon: const Icon(Icons.fit_screen),
            onPressed: _fitToScreen,
            tooltip: '适应屏幕',
          ),
        ],
      ),
      body: GestureDetector(
        // 双指缩放
        onScaleStart: _handleScaleStart,
        onScaleUpdate: _handleScaleUpdate,
        onScaleEnd: _handleScaleEnd,
        
        // 单指拖拽
        onPanStart: _handlePanStart,
        onPanUpdate: _handlePanUpdate,
        onPanEnd: _handlePanEnd,
        
        // 长按菜单
        onLongPress: _showContextMenu,
        
        child: Container(
          color: const Color(0xFFFAFAFA),
          child: CustomPaint(
            size: Size.infinite,
            painter: SchematicCanvasPainter(
              zoomLevel: _zoomLevel,
              offset: _offset,
            ),
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _addComponent,
        child: const Icon(Icons.add),
        tooltip: '添加元件',
      ),
    );
  }
  
  // 缩放处理
  void _handleScaleStart(ScaleStartDetails details) {
    _lastPanPosition = details.focalPoint;
  }
  
  void _handleScaleUpdate(ScaleUpdateDetails details) {
    setState(() {
      // 更新缩放级别（限制范围）
      _zoomLevel = (_zoomLevel * details.scale).clamp(0.1, 10.0);
      
      // 更新偏移
      if (_lastPanPosition != null) {
        _offset += details.focalPoint - _lastPanPosition!;
      }
      _lastPanPosition = details.focalPoint;
    });
  }
  
  void _handleScaleEnd(ScaleEndDetails details) {
    _lastPanPosition = null;
  }
  
  // 拖拽处理
  void _handlePanStart(DragStartDetails details) {
    _isPanning = true;
    _lastPanPosition = details.globalPosition;
  }
  
  void _handlePanUpdate(DragUpdateDetails details) {
    if (_isPanning && _lastPanPosition != null) {
      setState(() {
        _offset += details.delta;
      });
    }
  }
  
  void _handlePanEnd(DragEndDetails details) {
    _isPanning = false;
    _lastPanPosition = null;
  }
  
  // 手动缩放
  void _zoom(double delta) {
    setState(() {
      _zoomLevel = (_zoomLevel + delta).clamp(0.1, 10.0);
    });
  }
  
  // 适应屏幕
  void _fitToScreen() {
    setState(() {
      _zoomLevel = 1.0;
      _offset = Offset.zero;
    });
  }
  
  // 显示上下文菜单
  void _showContextMenu() {
    showModalBottomSheet(
      context: context,
      builder: (context) => SafeArea(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            ListTile(
              leading: const Icon(Icons.add),
              title: const Text('添加元件'),
              onTap: () {
                Navigator.pop(context);
                _addComponent();
              },
            ),
            ListTile(
              leading: const Icon(Icons.content_cut),
              title: const Text('剪切'),
              onTap: () => Navigator.pop(context),
            ),
            ListTile(
              leading: const Icon(Icons.content_copy),
              title: const Text('复制'),
              onTap: () => Navigator.pop(context),
            ),
            ListTile(
              leading: const Icon(Icons.delete),
              title: const Text('删除'),
              onTap: () => Navigator.pop(context),
            ),
          ],
        ),
      ),
    );
  }
  
  // 添加元件
  void _addComponent() {
    // TODO: 实现元件添加逻辑
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(content: Text('添加元件功能开发中...')),
    );
  }
  
  // 保存项目
  void _saveProject() {
    // TODO: 实现保存逻辑
    ScaffoldMessenger.of(context).showSnackBar(
      const SnackBar(content: Text('保存功能开发中...')),
    );
  }
}

/// 原理图画布绘制器
class SchematicCanvasPainter extends CustomPainter {
  final double zoomLevel;
  final Offset offset;
  
  SchematicCanvasPainter({
    required this.zoomLevel,
    required this.offset,
  });
  
  @override
  void paint(Canvas canvas, Size size) {
    // 保存画布状态
    canvas.save();
    
    // 应用变换
    canvas.translate(offset.dx, offset.dy);
    canvas.scale(zoomLevel);
    
    // 绘制网格
    _drawGrid(canvas, size);
    
    // TODO: 绘制元件（1000+ 元件场景）
    // _drawComponents(canvas);
    
    // 恢复画布状态
    canvas.restore();
  }
  
  void _drawGrid(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = const Color(0xFFE0E0E0)
      ..strokeWidth = 0.5;
    
    const gridSize = 50.0;
    
    // 计算可见区域
    final startX = (-offset.dx / zoomLevel).clamp(-1000.0, size.width);
    final startY = (-offset.dy / zoomLevel).clamp(-1000.0, size.height);
    
    // 绘制垂直线
    for (double x = startX; x < size.width; x += gridSize) {
      canvas.drawLine(
        Offset(x, 0),
        Offset(x, size.height),
        paint,
      );
    }
    
    // 绘制水平线
    for (double y = startY; y < size.height; y += gridSize) {
      canvas.drawLine(
        Offset(0, y),
        Offset(size.width, y),
        paint,
      );
    }
  }
  
  @override
  bool shouldRepaint(SchematicCanvasPainter oldDelegate) {
    return oldDelegate.zoomLevel != zoomLevel || 
           oldDelegate.offset != offset;
  }
}