MyAvaloniaDemo/AuroraDesk.Presentation/Views/Pages/NodeCanvasPageView.axaml.cs

using ReactiveUI.Avalonia;
using ReactiveUI;
using Avalonia.Markup.Xaml;
using Avalonia.Controls;
using Avalonia.Controls.Shapes;
using Avalonia.Input;
using Avalonia;
using Avalonia.Media;
using Avalonia.Collections;
using Avalonia.VisualTree;
using AuroraDesk.Presentation.ViewModels.Pages;
using AuroraDesk.Core.Entities;
using System.Linq;
using System.Reactive.Disposables;
using System;
using Avalonia.Layout;

namespace AuroraDesk.Presentation.Views.Pages;

public partial class NodeCanvasPageView : ReactiveUserControl<NodeCanvasPageViewModel>
{
    private Canvas? _canvasContainer;
    private Canvas? _gridBackgroundLayer;
    private ScrollViewer? _canvasScrollViewer;
    private Node? _draggedNode;
    private Point? _dragStartPoint;
    private ConnectionPoint? _hoveredConnectionPoint;
    private Path? _tempConnectionLine;
    private const double GridSize = 20;

    public NodeCanvasPageView()
    {
        InitializeComponent();
    }

    private void InitializeComponent()
    {
        AvaloniaXamlLoader.Load(this);
        
        // 延迟初始化，等待加载完成
        this.Loaded += (s, e) =>
        {
            _canvasContainer = this.FindControl<Canvas>("CanvasContainer");
            _gridBackgroundLayer = this.FindControl<Canvas>("GridBackgroundLayer");
            _canvasScrollViewer = this.FindControl<ScrollViewer>("CanvasScrollViewer");
            
            if (_canvasContainer != null)
            {
                _canvasContainer.PointerPressed += OnCanvasPointerPressed;
                _canvasContainer.PointerMoved += OnCanvasPointerMoved;
                _canvasContainer.PointerReleased += OnCanvasPointerReleased;
                
                // 在 Canvas 上添加拖拽事件
                _canvasContainer.AddHandler(DragDrop.DragOverEvent, OnCanvasDragOver);
                _canvasContainer.AddHandler(DragDrop.DropEvent, OnCanvasDrop);
                
                // 监听 Canvas 尺寸变化，更新网格
                _canvasContainer.SizeChanged += (sender, args) => DrawGridBackground();
            }
            
            // 在 ScrollViewer 上也添加拖拽事件，确保可以接收从左侧拖拽的组件
            if (_canvasScrollViewer != null)
            {
                _canvasScrollViewer.AddHandler(DragDrop.DragOverEvent, OnCanvasDragOver);
                _canvasScrollViewer.AddHandler(DragDrop.DropEvent, OnCanvasDrop);
            }

            // 设置组件库的拖拽支持
            SetupTemplateDragAndDrop();
            
            // 绘制网格背景
            DrawGridBackground();

            // 监听连接变化，更新连接线
            if (ViewModel != null)
            {
                ViewModel.WhenAnyValue(x => x.Connections)
                    .Subscribe(_ => UpdateConnectionLines());

                ViewModel.WhenAnyValue(x => x.Nodes)
                    .Subscribe(nodes => 
                    {
                        UpdateConnectionLines();
                        UpdateNodesOnCanvas(nodes);
                        // 调试：检查节点数量
                        System.Diagnostics.Debug.WriteLine($"节点数量: {nodes?.Count ?? 0}");
                        if (nodes != null)
                        {
                            foreach (var node in nodes)
                            {
                                System.Diagnostics.Debug.WriteLine($"节点: {node.Title}, 位置: ({node.X}, {node.Y})");
                            }
                        }
                    });

                ViewModel.WhenAnyValue(x => x.IsConnecting, x => x.ConnectingSourcePoint)
                    .Subscribe(_ => UpdateConnectionLines());
            }
        };
    }

    private void SetupTemplateDragAndDrop()
    {
        // 延迟设置，等待模板加载完成
        if (ViewModel != null)
        {
            ViewModel.WhenAnyValue(x => x.NodeTemplates)
                .Subscribe(_ =>
                {
                    // 使用延迟来确保UI已渲染
                    System.Threading.Tasks.Task.Delay(100).ContinueWith(_ =>
                    {
                        Avalonia.Threading.Dispatcher.UIThread.Post(() =>
                        {
                            SetupTemplateItems();
                        });
                    });
                });
        }
    }

    private void SetupTemplateItems()
    {
        // 查找所有模板项
        var templateItems = this.GetVisualDescendants()
            .OfType<Border>()
            .Where(b => b.Name == "TemplateItem")
            .ToList();

        foreach (var item in templateItems)
        {
            SetupTemplateItemDrag(item);
        }
    }

    private void SetupTemplateItemDrag(Border item)
    {
        if (item.DataContext is NodeTemplate template)
        {
            item.PointerPressed += async (sender, args) =>
            {
                if (args.GetCurrentPoint(item).Properties.IsLeftButtonPressed)
                {
                    // 设置允许拖拽的光标
                    item.Cursor = new Cursor(StandardCursorType.DragMove);
                    
                    var dataTransfer = new DataObject();
                    dataTransfer.Set("NodeTemplate", template);
                    
                    // 执行拖拽操作
                    var result = await DragDrop.DoDragDrop(args, dataTransfer, DragDropEffects.Copy);
                    
                    // 恢复光标
                    item.Cursor = Cursor.Default;
                }
            };
        }
    }

    private void OnCanvasDragOver(object? sender, DragEventArgs e)
    {
        if (e.Data.GetDataFormats().Contains("NodeTemplate"))
        {
            e.DragEffects = DragDropEffects.Copy;
        }
    }

    private void OnCanvasDrop(object? sender, DragEventArgs e)
    {
        if (_canvasContainer == null || ViewModel == null) return;

        if (e.Data.GetDataFormats().Contains("NodeTemplate") && 
            e.Data.Get("NodeTemplate") is NodeTemplate template)
        {
            // 获取相对于 Canvas 的位置
            var point = e.GetPosition(_canvasContainer);
            ViewModel.AddNodeFromTemplateCommand.Execute((template, point.X, point.Y)).Subscribe();
            e.Handled = true;
        }
    }

    private void UpdateConnectionLines()
    {
        if (_canvasContainer == null || ViewModel == null) return;

        // 移除临时连接线
        if (_tempConnectionLine != null && _canvasContainer.Children.Contains(_tempConnectionLine))
        {
            _canvasContainer.Children.Remove(_tempConnectionLine);
            _tempConnectionLine = null;
        }

        // 更新所有连接线
        var connections = ViewModel.Connections.ToList();
        foreach (var connection in connections)
        {
            UpdateConnectionLine(connection);
        }

        // 如果正在连接，显示临时连接线
        if (ViewModel.IsConnecting && ViewModel.ConnectingSourcePoint != null)
        {
            ShowTempConnectionLine(ViewModel.ConnectingSourcePoint);
        }
    }

    private void UpdateConnectionLine(Connection connection)
    {
        if (_canvasContainer == null || connection.SourcePoint == null || connection.TargetPoint == null)
            return;

        var sourcePoint = GetConnectionPointPosition(connection.SourcePoint);
        var targetPoint = GetConnectionPointPosition(connection.TargetPoint);

        // 查找或创建连接线Path
        var path = _canvasContainer.Children.OfType<Path>()
            .FirstOrDefault(p => p.Tag == connection);

        if (path == null)
        {
            path = new Path
            {
                Stroke = new SolidColorBrush(Color.FromRgb(52, 152, 219)),
                StrokeThickness = 2,
                Tag = connection
            };
            _canvasContainer.Children.Add(path);
        }

        // 创建贝塞尔曲线
        var geometry = new PathGeometry();
        var figure = new PathFigure
        {
            StartPoint = sourcePoint
        };

        var controlPoint1 = new Point(sourcePoint.X + 50, sourcePoint.Y);
        var controlPoint2 = new Point(targetPoint.X - 50, targetPoint.Y);
        var bezierSegment = new BezierSegment
        {
            Point1 = controlPoint1,
            Point2 = controlPoint2,
            Point3 = targetPoint
        };

        figure.Segments.Add(bezierSegment);
        geometry.Figures.Add(figure);
        path.Data = geometry;
    }

    private void ShowTempConnectionLine(ConnectionPoint sourcePoint)
    {
        if (_canvasContainer == null) return;

        var startPoint = GetConnectionPointPosition(sourcePoint);
        var endPoint = new Point(startPoint.X + 100, startPoint.Y);

        if (_tempConnectionLine == null)
        {
            _tempConnectionLine = new Path
            {
                Stroke = new SolidColorBrush(Color.FromRgb(52, 152, 219)),
                StrokeThickness = 2,
                StrokeDashArray = new AvaloniaList<double> { 5, 5 }
            };
            _canvasContainer.Children.Add(_tempConnectionLine);
        }

        var geometry = new PathGeometry();
        var figure = new PathFigure { StartPoint = startPoint };
        var lineSegment = new LineSegment { Point = endPoint };
        figure.Segments.Add(lineSegment);
        geometry.Figures.Add(figure);
        _tempConnectionLine.Data = geometry;
    }

    private Point GetConnectionPointPosition(ConnectionPoint point)
    {
        if (point.Node == null || _canvasContainer == null)
            return new Point(0, 0);

        var nodeX = point.Node.X;
        var nodeY = point.Node.Y;
        var nodeHeight = point.Node.Height;

        // 计算连接点在Canvas上的绝对位置
        if (point.Type == ConnectionPointType.Input)
        {
            // 输入点在左侧，垂直居中
            var inputIndex = point.Node.ConnectionPoints
                .Where(p => p.Type == ConnectionPointType.Input)
                .OrderBy(p => p.Index)
                .ToList()
                .IndexOf(point);
            
            var spacing = nodeHeight / (point.Node.ConnectionPoints.Count(p => p.Type == ConnectionPointType.Input) + 1);
            return new Point(nodeX, nodeY + spacing * (inputIndex + 1));
        }
        else
        {
            // 输出点在右侧，垂直排列
            var outputIndex = point.Node.ConnectionPoints
                .Where(p => p.Type == ConnectionPointType.Output)
                .OrderBy(p => p.Index)
                .ToList()
                .IndexOf(point);
            
            var spacing = nodeHeight / (point.Node.ConnectionPoints.Count(p => p.Type == ConnectionPointType.Output) + 1);
            return new Point(nodeX + point.Node.Width, nodeY + spacing * (outputIndex + 1));
        }
    }

    private void OnCanvasPointerPressed(object? sender, PointerPressedEventArgs e)
    {
        if (_canvasContainer == null || ViewModel == null) return;

        var point = e.GetPosition(_canvasContainer);
        var source = e.Source as Control;

        // 检查是否点击了连接点
        var connectionPoint = FindConnectionPoint(source);
        if (connectionPoint != null)
        {
            HandleConnectionPointClick(connectionPoint);
            e.Handled = true;
            return;
        }

        // 检查是否点击了节点（但不是连接点）
        var node = FindNode(source);
        if (node != null && connectionPoint == null)
        {
            ViewModel.SelectedNode = node;
            _draggedNode = node;
            _dragStartPoint = point;
            e.Handled = true;
            return;
        }

        // 点击空白区域，取消选中和连接
        ViewModel.SelectedNode = null;
        ViewModel.CancelConnection();

        // 在点击位置添加新节点（仅在左键点击时）
        if (e.GetCurrentPoint(_canvasContainer).Properties.IsLeftButtonPressed)
        {
            // 调试：输出点击位置
            System.Diagnostics.Debug.WriteLine($"点击位置: ({point.X}, {point.Y})");
            System.Diagnostics.Debug.WriteLine($"Canvas大小: {_canvasContainer.Bounds.Width} x {_canvasContainer.Bounds.Height}");
            
            ViewModel.AddNodeCommand.Execute((point.X, point.Y)).Subscribe();
        }
    }

    private void OnCanvasPointerMoved(object? sender, PointerEventArgs e)
    {
        if (_canvasContainer == null || ViewModel == null) return;

        var point = e.GetPosition(_canvasContainer);

        // 拖拽节点
        if (_draggedNode != null && _dragStartPoint.HasValue)
        {
            var deltaX = point.X - _dragStartPoint.Value.X;
            var deltaY = point.Y - _dragStartPoint.Value.Y;
            ViewModel.UpdateNodePosition(_draggedNode, 
                _draggedNode.X + deltaX, 
                _draggedNode.Y + deltaY);
            _dragStartPoint = point;
        }

        // 如果正在连接，更新临时连接线
        if (ViewModel.IsConnecting && ViewModel.ConnectingSourcePoint != null)
        {
            var sourcePos = GetConnectionPointPosition(ViewModel.ConnectingSourcePoint);
            if (_tempConnectionLine != null)
            {
                var geometry = new PathGeometry();
                var figure = new PathFigure { StartPoint = sourcePos };
                var lineSegment = new LineSegment { Point = point };
                figure.Segments.Add(lineSegment);
                geometry.Figures.Add(figure);
                _tempConnectionLine.Data = geometry;
            }
        }
    }

    private void OnCanvasPointerReleased(object? sender, PointerReleasedEventArgs e)
    {
        _draggedNode = null;
        _dragStartPoint = null;
    }

    private void HandleConnectionPointClick(ConnectionPoint connectionPoint)
    {
        if (ViewModel == null) return;

        if (ViewModel.IsConnecting)
        {
            // 完成连接
            if (connectionPoint.Type == ConnectionPointType.Input)
            {
                ViewModel.CompleteConnectionCommand.Execute(connectionPoint).Subscribe();
            }
            else
            {
                // 取消当前连接，开始新连接
                ViewModel.CancelConnection();
                ViewModel.StartConnectionCommand.Execute(connectionPoint).Subscribe();
            }
        }
        else
        {
            // 开始连接
            if (connectionPoint.Type == ConnectionPointType.Output)
            {
                ViewModel.StartConnectionCommand.Execute(connectionPoint).Subscribe();
            }
        }
    }

    private Node? FindNode(Control? control)
    {
        if (control == null || ViewModel == null) return null;

        // 向上查找直到找到包含Node的容器
        var current = control;
        while (current != null)
        {
            if (current.DataContext is Node node && ViewModel.Nodes.Contains(node))
            {
                return node;
            }
            current = current.Parent as Control;
        }

        return null;
    }

    private ConnectionPoint? FindConnectionPoint(Control? control)
    {
        if (control == null) return null;

        var current = control;
        while (current != null)
        {
            if (current.DataContext is ConnectionPoint point)
            {
                return point;
            }
            current = current.Parent as Control;
        }

        return null;
    }

    private void DrawGridBackground()
    {
        if (_gridBackgroundLayer == null || _canvasContainer == null) return;

        // 清空之前的网格线
        _gridBackgroundLayer.Children.Clear();

        var width = _canvasContainer.Bounds.Width > 0 ? _canvasContainer.Bounds.Width : 2000;
        var height = _canvasContainer.Bounds.Height > 0 ? _canvasContainer.Bounds.Height : 2000;

        // 创建网格线画笔
        var gridBrush = new SolidColorBrush(Color.FromRgb(224, 224, 224)); // #E0E0E0

        // 绘制垂直线
        for (double x = 0; x <= width; x += GridSize)
        {
            var line = new Line
            {
                StartPoint = new Point(x, 0),
                EndPoint = new Point(x, height),
                Stroke = gridBrush,
                StrokeThickness = 0.5
            };
            _gridBackgroundLayer.Children.Add(line);
        }

        // 绘制水平线
        for (double y = 0; y <= height; y += GridSize)
        {
            var line = new Line
            {
                StartPoint = new Point(0, y),
                EndPoint = new Point(width, y),
                Stroke = gridBrush,
                StrokeThickness = 0.5
            };
            _gridBackgroundLayer.Children.Add(line);
        }
    }

    private void UpdateNodesOnCanvas(System.Collections.ObjectModel.ObservableCollection<Node>? nodes)
    {
        if (_canvasContainer == null || nodes == null) return;

        // 查找 ItemsControl
        var itemsControl = this.FindControl<ItemsControl>("NodesItemsControl");
        if (itemsControl == null)
        {
            itemsControl = _canvasContainer.GetVisualDescendants()
                .OfType<ItemsControl>()
                .FirstOrDefault();
        }

        if (itemsControl != null)
        {
            // 强制更新 ItemsControl 的布局
            itemsControl.InvalidateMeasure();
            itemsControl.InvalidateArrange();
            
            // 延迟更新，确保容器已生成
            Avalonia.Threading.Dispatcher.UIThread.Post(() =>
            {
                try
                {
                    foreach (var item in itemsControl.Items)
                    {
                        if (item is Node node)
                        {
                            // 在 Avalonia 中，通过遍历视觉树来查找对应的容器
                            var container = itemsControl.GetVisualDescendants()
                                .OfType<ContentControl>()
                                .FirstOrDefault(cc => cc.Content == node);
                            
                            if (container is ContentControl contentControl)
                            {
                                Canvas.SetLeft(contentControl, node.X);
                                Canvas.SetTop(contentControl, node.Y);
                                System.Diagnostics.Debug.WriteLine($"设置节点 {node.Title} 位置: ({node.X}, {node.Y})");
                            }
                        }
                    }
                }
                catch (Exception ex)
                {
                    System.Diagnostics.Debug.WriteLine($"更新节点位置时出错: {ex.Message}");
                }
            }, Avalonia.Threading.DispatcherPriority.Normal);
        }
    }
}