using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Shapes;
using System.Xml.Linq;
using TeamAAS.Dialogs;
using TeamAAS.FlowEditor.Models;
using TeamAAS.FlowEditor.Plugins;
using TeamAAS.FlowEngine;

namespace TeamAAS.FlowEditor.Controls
{
    /// <summary>
    /// 流程编辑器画布 - 支持缩放、平移、拖拽节点、绘制连线、框选
    /// </summary>
    public class FlowCanvas : Canvas
    {
        #region 拖放坐标（高DPI安全）

        [System.Runtime.InteropServices.DllImport("user32.dll")]
        private static extern bool GetCursorPos(out POINT lpPoint);
        [System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
        private struct POINT { public int X; public int Y; }

        /// <summary>
        /// 用系统光标位置反推画布本地坐标。
        /// 不能用拖放事件的 e.GetPosition：PerMonitorV2 + 高 DPI 下 WPF 的拖放事件坐标
        /// 换算因子错误（已知问题），节点会落在光标旁边。
        /// 注意：PointFromScreen 的结果就是正确的 WPF 坐标，不要再乘 TransformToDevice——
        /// 进程按系统 DPI 虚拟化运行时，乘上去会造成预览超速偏移。
        /// </summary>
        public Point GetCursorCanvasPosition()
        {
            GetCursorPos(out POINT pt);
            var parent = (Visual)VisualTreeHelper.GetParent(this);
            var parentPt = parent.PointFromScreen(new Point(pt.X, pt.Y));
            // 逆画布 RenderTransform（缩放 + 平移）→ 画布本地坐标
            var t = RenderTransform;
            return t != null ? t.Inverse.Transform(parentPt) : parentPt;
        }

        #endregion

        #region 常量
        private const double MinZoom = 0.2;
        private const double MaxZoom = 3.0;
        private const double ZoomFactor = 1.15;
        #endregion

        #region 字段
        private readonly ScaleTransform _scale;
        private readonly TranslateTransform _translate;

        private FlowGraph _graph;
        private readonly Dictionary<string, NodeControl> _nodeControls = new Dictionary<string, NodeControl>();
        private readonly Dictionary<string, Path> _connectionPaths = new Dictionary<string, Path>();
        // 自动拉线预览（虚线）
        private Path _previewLine;

        // 平移状态
        private bool _isPanning;
        private Point _panStart;
        private Point _panOrigin;

        // 连线绘制状态
        private bool _isConnecting;
        private FlowNode _connectSourceNode;
        private PortSide _connectSourceSide;
        private Path _tempPath;

        // 框选状态
        private bool _isBoxSelecting;
        private Point _boxSelectStart;
        private Rectangle _selectionBox;

        // 选中项
        private FlowNode _selectedNode;
        private FlowConnection _selectedConnection;
        private readonly List<FlowNode> _selectedNodes = new List<FlowNode>();

        private const string ClipboardPrefix = "TeamAASFlow:";
        #endregion

        #region 事件
        public event Action<FlowNode> NodeDoubleClicked;
        public event Action<FlowNode> NodeSelected;
        public event Action<FlowConnection> ConnectionSelected;
        public event Action SelectionCleared;
        public event Action<double, double, NodePluginInfo> NodeDropRequested;
        public event Action<double> ZoomChanged;
        public event Action<FlowNode> NodeRunRequested;
        public event Action<FlowNode> NodeRunFromHereRequested;
        public event Action<FlowNode> NodePropertiesRequested;
        #endregion

        #region 属性
        public double Zoom => _scale.ScaleX;
        public double TranslateX => _translate.X;
        public double TranslateY => _translate.Y;

        public void SetTranslateX(double x) { _translate.X = x; }
        public void SetTranslateY(double y) { _translate.Y = y; }

        public Size ViewportSize => GetViewportSize();

        public FlowGraph Graph
        {
            get => _graph;
            set
            {
                if (_graph != null) UnsubscribeGraph();
                ClearCanvas();
                _graph = value;
                if (_graph != null) SubscribeGraph();
            }
        }

        /// <summary>流程运行中：锁定节点移动和双击编辑</summary>
        public static readonly DependencyProperty IsRunningProperty =
            DependencyProperty.Register(nameof(IsRunning), typeof(bool), typeof(FlowCanvas), new PropertyMetadata(false));

        public bool IsRunning
        {
            get => (bool)GetValue(IsRunningProperty);
            set => SetValue(IsRunningProperty, value);
        }

        /// <summary>只读模式（运行产品监控中）：允许选中节点查看结果，禁止一切修改操作</summary>
        public static readonly DependencyProperty IsReadOnlyProperty =
            DependencyProperty.Register(nameof(IsReadOnly), typeof(bool), typeof(FlowCanvas), new PropertyMetadata(false));

        public bool IsReadOnly
        {
            get => (bool)GetValue(IsReadOnlyProperty);
            set => SetValue(IsReadOnlyProperty, value);
        }
        #endregion

        #region 构造函数
        public FlowCanvas()
        {
            _scale = new ScaleTransform(1, 1);
            _translate = new TranslateTransform(0, 0);
            var group = new TransformGroup();
            group.Children.Add(_scale);
            group.Children.Add(_translate);
            RenderTransform = group;

            ClipToBounds = true;
            Focusable = true;
            Background = new SolidColorBrush(Colors.White);
            AllowDrop = true;

            // 初始画布尺寸
            Width = 5000;
            Height = 3500;

            // 初始偏移，显示画布的一部分
            _translate.X = 0;
            _translate.Y = 0;
        }
        #endregion

        #region Graph 订阅
        private void SubscribeGraph()
        {
            _graph.Nodes.CollectionChanged += OnNodesChanged;
            _graph.Connections.CollectionChanged += OnConnectionsChanged;

            foreach (var node in _graph.Nodes)
                AddNodeVisual(node);
            foreach (var conn in _graph.Connections)
                AddConnectionVisual(conn);
        }

        private void UnsubscribeGraph()
        {
            _graph.Nodes.CollectionChanged -= OnNodesChanged;
            _graph.Connections.CollectionChanged -= OnConnectionsChanged;
        }

        private void ClearCanvas()
        {
            foreach (var node in _nodeControls.Values)
            {
                if (node.DataContext is FlowNode fn)
                    fn.PropertyChanged -= OnNodePropertyChanged;
            }
            _nodeControls.Clear();
            _connectionPaths.Clear();
            Children.Clear();
        }

        private void OnNodesChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            // Clear()/整体替换会触发 Reset（NewItems/OldItems 均为 null），
            // 不处理会导致导入流程后旧节点可视化残留成“影子”。
            if (e.Action == NotifyCollectionChangedAction.Reset)
            {
                RebuildVisuals();
                return;
            }

            if (e.NewItems != null)
                foreach (FlowNode node in e.NewItems)
                    AddNodeVisual(node);

            if (e.OldItems != null)
                foreach (FlowNode node in e.OldItems)
                    RemoveNodeVisual(node);
        }

        private void OnConnectionsChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            if (e.Action == NotifyCollectionChangedAction.Reset)
            {
                RebuildVisuals();
                return;
            }

            if (e.NewItems != null)
                foreach (FlowConnection conn in e.NewItems)
                    AddConnectionVisual(conn);

            if (e.OldItems != null)
                foreach (FlowConnection conn in e.OldItems)
                    RemoveConnectionVisual(conn);
        }

        /// <summary>
        /// 集合被整体 Clear（Reset）时重建全部节点/连线可视化，避免旧图形残留（如导入流程后）。
        /// </summary>
        private void RebuildVisuals()
        {
            foreach (var kv in _nodeControls.ToList())
            {
                if (kv.Value.DataContext is FlowNode fn)
                    fn.PropertyChanged -= OnNodePropertyChanged;
                Children.Remove(kv.Value);
            }
            _nodeControls.Clear();

            foreach (var kv in _connectionPaths.ToList())
                Children.Remove(kv.Value);
            _connectionPaths.Clear();

            if (_graph == null) return;
            foreach (var node in _graph.Nodes)
                AddNodeVisual(node);
            foreach (var conn in _graph.Connections)
                AddConnectionVisual(conn);
        }
        #endregion

        #region 节点可视化
        private void AddNodeVisual(FlowNode node)
        {
            var ctrl = new NodeControl { DataContext = node };
            SetLeft(ctrl, node.X);
            SetTop(ctrl, node.Y);
            Children.Add(ctrl);
            _nodeControls[node.NodeId] = ctrl;

            // 节点渲染后更新实际尺寸，用于端口位置和碰撞检测
            ctrl.SizeChanged += (s, e) =>
            {
                node.NodeWidth = ctrl.ActualWidth;
                node.NodeHeight = ctrl.ActualHeight;
                UpdateConnectionsForNode(node.NodeId);
                UpdateCanvasSize();
            };

            node.PropertyChanged += OnNodePropertyChanged;
        }

        private void RemoveNodeVisual(FlowNode node)
        {
            if (_nodeControls.TryGetValue(node.NodeId, out var ctrl))
            {
                Children.Remove(ctrl);
                _nodeControls.Remove(node.NodeId);
                node.PropertyChanged -= OnNodePropertyChanged;
            }

            // 移除相关连线可视化
            var toRemove = _connectionPaths
                .Where(kvp => kvp.Value.Tag is FlowConnection fc &&
                    (fc.SourceNodeId == node.NodeId || fc.TargetNodeId == node.NodeId))
                .ToList();
            foreach (var kvp in toRemove)
            {
                Children.Remove(kvp.Value);
                _connectionPaths.Remove(kvp.Key);
            }

            if (_selectedNode == node)
                _selectedNode = null;
            _selectedNodes.Remove(node);
        }

        private void OnNodePropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
        {
            var node = (FlowNode)sender;
            if (e.PropertyName == nameof(FlowNode.X) || e.PropertyName == nameof(FlowNode.Y))
            {
                if (_nodeControls.TryGetValue(node.NodeId, out var ctrl))
                {
                    SetLeft(ctrl, node.X);
                    SetTop(ctrl, node.Y);
                }
                UpdateConnectionsForNode(node.NodeId);
                UpdateCanvasSize();
            }
            else if (e.PropertyName == nameof(FlowNode.IsEnabled))
            {
                if (_nodeControls.TryGetValue(node.NodeId, out var ctrl))
                    ctrl.UpdateDisabledVisual();
            }
            else if (e.PropertyName == nameof(FlowNode.Status))
            {
                node.NotifyStatusChanged();
            }
        }
        #endregion

        #region 连线可视化
        private void AddConnectionVisual(FlowConnection conn)
        {
            var path = new Path
            {
                Stroke = new SolidColorBrush(Color.FromRgb(232, 145, 73)),
                StrokeThickness = 2,
                Fill = new SolidColorBrush(Color.FromRgb(232, 145, 73)),
                Tag = conn,
                Cursor = Cursors.Hand
            };

            UpdateConnectionPath(path, conn);
            Children.Insert(0, path);
            _connectionPaths[conn.ConnectionId] = path;

            path.MouseLeftButtonDown += (s, e) =>
            {
                SelectConnection(conn);
                e.Handled = true;
            };
        }

        private void RemoveConnectionVisual(FlowConnection conn)
        {
            if (_connectionPaths.TryGetValue(conn.ConnectionId, out var path))
            {
                Children.Remove(path);
                _connectionPaths.Remove(conn.ConnectionId);
            }
            if (_selectedConnection == conn)
                _selectedConnection = null;
        }

        private void UpdateConnectionPath(Path path, FlowConnection conn)
        {
            var sourceNode = _graph?.GetNode(conn.SourceNodeId);
            var targetNode = _graph?.GetNode(conn.TargetNodeId);
            if (sourceNode == null || targetNode == null) return;

            Point start = GetPortPosition(sourceNode, conn.SourceSide);
            Point end = GetPortPosition(targetNode, conn.TargetSide);

            path.Data = CreateConnectionGeometry(start, end, conn.SourceSide, conn.TargetSide);

            if (conn.IsSelected)
            {
                path.Stroke = Brushes.White;
                path.Fill = Brushes.White;
                path.StrokeThickness = 3;
            }
            else
            {
                // 连接到异常分支节点的线用红色，其余橙色
                bool isException = targetNode.Category == NodeCategory.ExceptionBranch;
                var color = isException
                    ? Color.FromRgb(0xB7, 0x1C, 0x1C)
                    : Color.FromRgb(232, 145, 73);
                path.Stroke = new SolidColorBrush(color);
                path.Fill = new SolidColorBrush(color);
                path.StrokeThickness = 2;
            }
        }

        private void UpdateConnectionsForNode(string nodeId)
        {
            foreach (var kvp in _connectionPaths)
            {
                if (kvp.Value.Tag is FlowConnection conn)
                {
                    if (conn.SourceNodeId == nodeId || conn.TargetNodeId == nodeId)
                        UpdateConnectionPath(kvp.Value, conn);
                }
            }
        }
        #endregion

        #region 端口位置 & 连线几何
        public static Point GetPortPosition(FlowNode node, PortDirection direction, int portIndex)
        {
            double w = node.NodeWidth;
            double h = node.NodeHeight;

            if (direction == PortDirection.Input)
            {
                // portIndex 0 = Left, 1 = Top
                if (portIndex == 0) return new Point(node.X, node.Y + h / 2);
                return new Point(node.X + w / 2, node.Y);
            }
            else // Output
            {
                // portIndex 0 = Right, 1 = Bottom
                if (portIndex == 0) return new Point(node.X + w, node.Y + h / 2);
                return new Point(node.X + w / 2, node.Y + h);
            }
        }

        /// <summary>
        /// 根据边获取端口位置（通用，不区分输入输出）
        /// </summary>
        public static Point GetPortPosition(FlowNode node, PortSide side)
        {
            double w = node.NodeWidth;
            double h = node.NodeHeight;
            switch (side)
            {
                case PortSide.Left: return new Point(node.X, node.Y + h / 2);
                case PortSide.Top: return new Point(node.X + w / 2, node.Y);
                case PortSide.Right: return new Point(node.X + w, node.Y + h / 2);
                case PortSide.Bottom: return new Point(node.X + w / 2, node.Y + h);
                default: return new Point(node.X, node.Y + h / 2);
            }
        }

        /// <summary>
        /// 根据端口方向和索引推断所在边
        /// </summary>
        public static PortSide GetPortSide(PortDirection direction, int portIndex)
        {
            if (direction == PortDirection.Input)
                return portIndex == 0 ? PortSide.Left : PortSide.Top;
            return portIndex == 0 ? PortSide.Right : PortSide.Bottom;
        }

        public static Geometry CreateConnectionGeometry(Point start, Point end, PortSide startSide = PortSide.Right, PortSide endSide = PortSide.Left)
        {
            // 偏移起止点，留出间距让箭头可见
            Point adjStart = OffsetPoint(start, startSide, 8);
            Point adjEnd = OffsetPoint(end, endSide, 12);

            var geo = new StreamGeometry();
            using (var ctx = geo.Open())
            {
                // 控制点方向（端口朝外方向）
                Vector startDir = GetSideDirection(startSide);
                Vector endDir = GetSideDirection(endSide);

                // 控制点偏移量：基于距离动态调整，保证曲度自然
                double dist = (adjEnd - adjStart).Length;
                double offset = Math.Max(50, dist * 0.4);

                Point cp1 = adjStart + startDir * offset;
                Point cp2 = adjEnd + endDir * offset;

                // 绘制平滑贝塞尔曲线
                ctx.BeginFigure(adjStart, false, false);
                ctx.BezierTo(cp1, cp2, adjEnd, true, false);

                // 箭头方向 = 贝塞尔终点切线 (end - cp2)
                double angle = Math.Atan2(adjEnd.Y - cp2.Y, adjEnd.X - cp2.X);
                double arrowSize = 7;
                var p1 = new Point(
                    adjEnd.X - arrowSize * Math.Cos(angle - Math.PI / 6),
                    adjEnd.Y - arrowSize * Math.Sin(angle - Math.PI / 6));
                var p2 = new Point(
                    adjEnd.X - arrowSize * Math.Cos(angle + Math.PI / 6),
                    adjEnd.Y - arrowSize * Math.Sin(angle + Math.PI / 6));
                ctx.BeginFigure(adjEnd, true, true);
                ctx.LineTo(p1, true, true);
                ctx.LineTo(p2, true, true);
            }
            geo.Freeze();
            return geo;
        }

        /// <summary>
        /// 端口朝外方向单位向量
        /// </summary>
        private static Vector GetSideDirection(PortSide side)
        {
            switch (side)
            {
                case PortSide.Left: return new Vector(-1, 0);
                case PortSide.Right: return new Vector(1, 0);
                case PortSide.Top: return new Vector(0, -1);
                case PortSide.Bottom: return new Vector(0, 1);
                default: return new Vector(1, 0);
            }
        }

        /// <summary>
        /// 根据鼠标位置推断目标端口边
        /// </summary>
        private static PortSide DetermineEndSide(Point start, Point end, PortSide startSide)
        {
            double dx = end.X - start.X;
            double dy = end.Y - start.Y;

            switch (startSide)
            {
                case PortSide.Right:
                    return dx >= 0 ? PortSide.Left : PortSide.Right;
                case PortSide.Bottom:
                    return dy >= 0 ? PortSide.Top : PortSide.Bottom;
                case PortSide.Left:
                    return dx <= 0 ? PortSide.Right : PortSide.Left;
                case PortSide.Top:
                    return dy <= 0 ? PortSide.Bottom : PortSide.Top;
                default:
                    return PortSide.Left;
            }
        }

        /// <summary>
        /// 沿端口方向偏移点，留出间距
        /// </summary>
        private static Point OffsetPoint(Point p, PortSide side, double offset)
        {
            switch (side)
            {
                case PortSide.Left: return new Point(p.X - offset, p.Y);
                case PortSide.Right: return new Point(p.X + offset, p.Y);
                case PortSide.Top: return new Point(p.X, p.Y - offset);
                case PortSide.Bottom: return new Point(p.X, p.Y + offset);
                default: return p;
            }
        }
        #endregion

        #region 坐标转换
        public Point ToCanvasPoint(Point screenPoint)
        {
            return new Point(
                (screenPoint.X - _translate.X) / _scale.ScaleX,
                (screenPoint.Y - _translate.Y) / _scale.ScaleY);
        }
        #endregion

        #region 缩放 & 平移
        public void ZoomAt(Point center, double newScale)
        {
            newScale = Math.Max(MinZoom, Math.Min(MaxZoom, newScale));
            if (Math.Abs(newScale - _scale.ScaleX) < 0.001) return;

            // center 是 GetPosition(this) 返回的画布本地坐标
            // 保持 center 对应的屏幕点不变：screen = center * oldScale + oldTranslate = center * newScale + newTranslate
            _translate.X = _translate.X + center.X * (_scale.ScaleX - newScale);
            _translate.Y = _translate.Y + center.Y * (_scale.ScaleY - newScale);
            _scale.ScaleX = newScale;
            _scale.ScaleY = newScale;
            ClampTranslate();
            ZoomChanged?.Invoke(newScale);
        }

        protected override void OnMouseWheel(MouseWheelEventArgs e)
        {
            if ((Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control)
            {
                // Ctrl + 滚轮 = 缩放
                var mousePos = e.GetPosition(this);
                double factor = e.Delta > 0 ? ZoomFactor : 1 / ZoomFactor;
                ZoomAt(mousePos, _scale.ScaleX * factor);
                e.Handled = true;
            }
            else if ((Keyboard.Modifiers & ModifierKeys.Shift) == ModifierKeys.Shift)
            {
                // Shift + 滚轮 = 水平平移
                _translate.X += e.Delta * 0.5;
                ClampTranslate();
                e.Handled = true;
            }
            else
            {
                // 滚轮 = 上下平移
                _translate.Y += e.Delta * 0.5;
                ClampTranslate();
                e.Handled = true;
            }
        }

        protected override void OnMouseDown(MouseButtonEventArgs e)
        {
            base.OnMouseDown(e);
            if (e.ChangedButton == MouseButton.Middle)
            {
                _isPanning = true;
                _panStart = e.GetPosition(Parent as IInputElement);
                _panOrigin = new Point(_translate.X, _translate.Y);
                CaptureMouse();
                e.Handled = true;
            }
        }

        protected override void OnMouseMove(MouseEventArgs e)
        {
            base.OnMouseMove(e);
            var pos = e.GetPosition(this);

            if (_isPanning)
            {
                var panPos = e.GetPosition(Parent as IInputElement);
                _translate.X = _panOrigin.X + (panPos.X - _panStart.X);
                _translate.Y = _panOrigin.Y + (panPos.Y - _panStart.Y);
                ClampTranslate();
            }
            else if (_isConnecting && _tempPath != null)
            {
                Point start = GetPortPosition(_connectSourceNode, _connectSourceSide);
                PortSide endSide = DetermineEndSide(start, pos, _connectSourceSide);
                _tempPath.Data = CreateConnectionGeometry(start, pos, _connectSourceSide, endSide);
            }
            else if (_isBoxSelecting)
            {
                UpdateSelectionBox(pos);
            }
        }

        protected override void OnMouseUp(MouseButtonEventArgs e)
        {
            base.OnMouseUp(e);
            if (e.ChangedButton == MouseButton.Middle)
            {
                _isPanning = false;
                ReleaseMouseCapture();
                e.Handled = true;
            }
        }
        #endregion

        #region 左键交互

        // 双击检测 + 单击选中都用 Preview（隧道事件），在 MoveThumb 捕获鼠标之前触发
        protected override void OnPreviewMouseLeftButtonDown(MouseButtonEventArgs e)
        {
            if (e.ClickCount == 2)
            {
                var dblNode = FindAncestor<NodeControl>(e.OriginalSource as DependencyObject);
                if (dblNode != null)
                {
                    // 流程运行中 / 只读监控模式禁止双击打开编辑器
                    if (IsRunning || IsReadOnly) { e.Handled = true; return; }
                    NodeDoubleClicked?.Invoke(dblNode.GetNode());
                    e.Handled = true;
                    return;
                }
            }
            else if (e.ClickCount == 1)
            {
                // 单击节点选中（在 MoveThumb 捕获鼠标之前处理）
                var nodeCtrl = FindAncestor<NodeControl>(e.OriginalSource as DependencyObject);
                if (nodeCtrl != null)
                {
                    Focus();
                    bool isCtrl = (Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control;
                    SelectNode(nodeCtrl.GetNode(), isCtrl);
                    // 不设 Handled，让 MoveThumb 继续处理拖拽
                }
            }
            base.OnPreviewMouseLeftButtonDown(e);
        }

        protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
        {
            base.OnMouseLeftButtonDown(e);
            Focus();

            var pos = e.GetPosition(this);
            var src = e.OriginalSource as DependencyObject;

            // 1. 检查连接点
            var connector = FindAncestor<ConnectorControl>(src);
            if (connector != null)
            {
                StartConnection(connector);
                e.Handled = true;
                return;
            }

            // 2. 检查连线（Path with FlowConnection Tag）
            if (src is Path path && path.Tag is FlowConnection conn)
            {
                SelectConnection(conn);
                e.Handled = true;
                return;
            }

            // 3. 检查节点
            var nodeCtrl = FindAncestor<NodeControl>(src);
            if (nodeCtrl != null)
            {
                bool isCtrl = (Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control;
                SelectNode(nodeCtrl.GetNode(), isCtrl);
                return; // 不设 Handled，让 MoveThumb 处理拖拽
            }

            // 4. 空白区域 - 框选
            ClearSelection();
            StartBoxSelect(pos);
            e.Handled = true;
        }

        protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
        {
            base.OnMouseLeftButtonUp(e);

            if (_isConnecting)
                EndConnection(e.GetPosition(this));

            if (_isBoxSelecting)
                EndBoxSelect();
        }

        #endregion

        #region 右键菜单

        protected override void OnMouseRightButtonDown(MouseButtonEventArgs e)
        {
            base.OnMouseRightButtonDown(e);
            Focus();
            var pos = e.GetPosition(this);
            var src = e.OriginalSource as DependencyObject;

            var nodeCtrl = FindAncestor<NodeControl>(src);
            if (nodeCtrl != null)
            {
                var node = nodeCtrl.GetNode();
                // 如果右键的节点不在已选列表中，单选它
                if (!_selectedNodes.Contains(node) && _selectedNode != node)
                    SelectNode(node, false);
                else if (_selectedNode == null && _selectedNodes.Count == 0)
                    SelectNode(node, false);
                ShowNodeContextMenu(node);
                e.Handled = true;
            }
            else
            {
                ShowCanvasContextMenu(pos);
                e.Handled = true;
            }
        }

        private void ShowNodeContextMenu(FlowNode node)
        {
            var menu = new ContextMenu();
            bool readOnly = IsReadOnly || IsRunning;

            // 复制
            var miCopy = new MenuItem { Header = "复制", IsEnabled = !readOnly };
            miCopy.Click += (s, e) => CopySelectedNodes();
            menu.Items.Add(miCopy);

            // 禁用/启用节点
            var miToggleEnabled = new MenuItem { Header = node.IsEnabled ? "禁用节点" : "启用节点", IsEnabled = !readOnly };
            miToggleEnabled.Click += (s, e) => ToggleNodeEnabled(node);
            menu.Items.Add(miToggleEnabled);

            menu.Items.Add(new Separator());

            // 删除节点
            var miDelNode = new MenuItem { Header = "删除节点", IsEnabled = !readOnly };
            miDelNode.Click += (s, e) => DeleteSelectedNodes();
            menu.Items.Add(miDelNode);

            // 删除连接线
            var miDelConn = new MenuItem { Header = "删除连接线", IsEnabled = !readOnly };
            miDelConn.Click += (s, e) => DeleteSelectedConnections();
            menu.Items.Add(miDelConn);

            // 运行和从此处运行：仅单选时显示（只读模式下不允许从编辑器发起运行）
            bool isSingle = _selectedNodes.Count <= 1 && _selectedNode != null;
            if (isSingle)
            {
                menu.Items.Add(new Separator());

                var miRun = new MenuItem { Header = "运行", IsEnabled = !readOnly };
                miRun.Click += (s, e) => NodeRunRequested?.Invoke(node);
                menu.Items.Add(miRun);

                var miRunFrom = new MenuItem { Header = "此处开始运行", IsEnabled = !readOnly };
                miRunFrom.Click += (s, e) => NodeRunFromHereRequested?.Invoke(node);
                menu.Items.Add(miRunFrom);

                menu.Items.Add(new Separator());

                var miProp = new MenuItem { Header = "属性", IsEnabled = !readOnly };
                miProp.Click += (s, e) => NodePropertiesRequested?.Invoke(node);
                menu.Items.Add(miProp);
            }

            menu.IsOpen = true;
        }

        /// <summary>
        /// 切换节点启用状态（禁用后不执行、背景变灰）
        /// </summary>
        private void ToggleNodeEnabled(FlowNode node)
        {
            if (node == null) return;
            node.IsEnabled = !node.IsEnabled;
        }

        private void ShowCanvasContextMenu(Point pos)
        {
            var menu = new ContextMenu();

            var miLayout = new MenuItem { Header = "自动排版" };
            miLayout.Click += (s, e) => AutoLayout();
            menu.Items.Add(miLayout);

            menu.Items.Add(new Separator());

            var miPaste = new MenuItem { Header = "粘贴" };
            miPaste.Click += (s, e) => PasteNodesAt(pos);
            miPaste.IsEnabled = !IsReadOnly && !IsRunning && HasClipboardData();
            menu.Items.Add(miPaste);

            menu.IsOpen = true;
        }

        #endregion

        #region 连线绘制
        private void StartConnection(ConnectorControl connector)
        {
            if (IsRunning || IsReadOnly) return; // 流程运行中 / 只读模式禁止新建连线

            var node = connector.GetNode();
            if (node == null) return;

            _isConnecting = true;
            _connectSourceNode = node;
            _connectSourceSide = connector.Side;

            _tempPath = new Path
            {
                Stroke = new SolidColorBrush(Color.FromRgb(232, 145, 73)),
                StrokeThickness = 2,
                StrokeDashArray = new DoubleCollection { 4, 2 },
                IsHitTestVisible = false
            };
            Children.Add(_tempPath);
            CaptureMouse();
        }

        private void EndConnection(Point mousePos)
        {
            _isConnecting = false;
            ReleaseMouseCapture();

            if (_tempPath != null)
            {
                Children.Remove(_tempPath);
                _tempPath = null;
            }

            if (_connectSourceNode == null || _graph == null) return;

            // 手动命中检测：遍历所有节点的4个端口，找到最近的
            const double hitRadius = 22.0;
            double minDist = double.MaxValue;
            FlowNode targetNode = null;
            PortSide targetSide = PortSide.Left;

            var sides = new[] { PortSide.Left, PortSide.Top, PortSide.Right, PortSide.Bottom };

            foreach (var node in _graph.Nodes)
            {
                if (node.NodeId == _connectSourceNode.NodeId) continue;

                foreach (var side in sides)
                {
                    var pos = GetPortPosition(node, side);
                    double d = PointDist(pos, mousePos);
                    if (d < hitRadius && d < minDist)
                    {
                        minDist = d;
                        targetNode = node;
                        targetSide = side;
                    }
                }
            }

            if (targetNode == null) { _connectSourceNode = null; return; }

            // 源 = 拖出端，目标 = 放入端。不检查方向类型。
            var conn = new FlowConnection
            {
                SourceNodeId = _connectSourceNode.NodeId,
                SourceSide = _connectSourceSide,
                TargetNodeId = targetNode.NodeId,
                TargetSide = targetSide
            };
            _graph?.TryAddConnection(conn);

            _connectSourceNode = null;
        }

        private static double PointDist(Point a, Point b)
        {
            double dx = a.X - b.X;
            double dy = a.Y - b.Y;
            return Math.Sqrt(dx * dx + dy * dy);
        }
        #endregion

        #region 框选
        private void StartBoxSelect(Point pos)
        {
            _isBoxSelecting = true;
            _boxSelectStart = pos;
            _selectionBox = new Rectangle
            {
                Stroke = new SolidColorBrush(Color.FromArgb(100, 0, 122, 204)),
                Fill = new SolidColorBrush(Color.FromArgb(30, 0, 122, 204)),
                StrokeThickness = 1,
                IsHitTestVisible = false
            };
            Children.Add(_selectionBox);
            CaptureMouse();
        }

        private void UpdateSelectionBox(Point pos)
        {
            if (_selectionBox == null) return;
            double x = Math.Min(_boxSelectStart.X, pos.X);
            double y = Math.Min(_boxSelectStart.Y, pos.Y);
            double w = Math.Abs(pos.X - _boxSelectStart.X);
            double h = Math.Abs(pos.Y - _boxSelectStart.Y);
            SetLeft(_selectionBox, x);
            SetTop(_selectionBox, y);
            _selectionBox.Width = w;
            _selectionBox.Height = h;
        }

        private void EndBoxSelect()
        {
            _isBoxSelecting = false;
            ReleaseMouseCapture();

            if (_selectionBox != null)
            {
                double x = GetLeft(_selectionBox);
                double y = GetTop(_selectionBox);
                double w = _selectionBox.Width;
                double h = _selectionBox.Height;
                var rect = new Rect(x, y, w, h);

                // 清除旧选择
                foreach (var n in _selectedNodes)
                    n.IsSelected = false;
                _selectedNodes.Clear();

                // 多选模式：选中框选范围内的所有节点
                foreach (var node in _graph?.Nodes ?? Enumerable.Empty<FlowNode>())
                {
                    var nodeRect = new Rect(node.X, node.Y, node.NodeWidth, node.NodeHeight);
                    if (rect.IntersectsWith(nodeRect))
                    {
                        node.IsSelected = true;
                        _selectedNodes.Add(node);
                    }
                }

                if (_selectedNodes.Count > 0)
                {
                    _selectedNode = _selectedNodes[_selectedNodes.Count - 1];
                    NodeSelected?.Invoke(_selectedNode);
                }

                Children.Remove(_selectionBox);
                _selectionBox = null;
            }
        }
        #endregion

        #region 选择
        public void SelectNode(FlowNode node, bool isMultiSelect = false)
        {
            if (isMultiSelect && node != null)
            {
                // Ctrl+Click: 切换该节点的选中状态
                if (_selectedNodes.Contains(node))
                {
                    _selectedNodes.Remove(node);
                    node.IsSelected = false;
                }
                else
                {
                    _selectedNodes.Add(node);
                    node.IsSelected = true;
                }
                _selectedNode = node;
                if (_selectedConnection != null)
                {
                    _selectedConnection.IsSelected = false;
                    if (_connectionPaths.TryGetValue(_selectedConnection.ConnectionId, out var p))
                        UpdateConnectionPath(p, _selectedConnection);
                    _selectedConnection = null;
                }
                NodeSelected?.Invoke(node);
                return;
            }

            // 普通点击：如果点击的节点已在多选列表中，保持多选不变（用于拖拽）
            if (node != null && _selectedNodes.Contains(node))
            {
                _selectedNode = node;
                if (_selectedConnection != null)
                {
                    _selectedConnection.IsSelected = false;
                    if (_connectionPaths.TryGetValue(_selectedConnection.ConnectionId, out var p))
                        UpdateConnectionPath(p, _selectedConnection);
                    _selectedConnection = null;
                }
                NodeSelected?.Invoke(node);
                return;
            }

            // 否则清除多选，单选
            foreach (var n in _selectedNodes)
                n.IsSelected = false;
            _selectedNodes.Clear();

            if (_selectedNode == node && _selectedConnection == null) return;

            if (_selectedNode != null)
                _selectedNode.IsSelected = false;
            if (_selectedConnection != null)
            {
                _selectedConnection.IsSelected = false;
                if (_connectionPaths.TryGetValue(_selectedConnection.ConnectionId, out var p))
                    UpdateConnectionPath(p, _selectedConnection);
            }

            _selectedNode = node;
            _selectedConnection = null;

            if (node != null)
                node.IsSelected = true;

            NodeSelected?.Invoke(node);
        }

        private void SelectConnection(FlowConnection conn)
        {
            foreach (var n in _selectedNodes)
                n.IsSelected = false;
            _selectedNodes.Clear();

            if (_selectedNode != null)
                _selectedNode.IsSelected = false;
            if (_selectedConnection != null)
            {
                _selectedConnection.IsSelected = false;
                if (_connectionPaths.TryGetValue(_selectedConnection.ConnectionId, out var p))
                    UpdateConnectionPath(p, _selectedConnection);
            }

            _selectedNode = null;
            _selectedConnection = conn;

            if (conn != null)
            {
                conn.IsSelected = true;
                if (_connectionPaths.TryGetValue(conn.ConnectionId, out var p))
                    UpdateConnectionPath(p, conn);
            }

            ConnectionSelected?.Invoke(conn);
        }

        public void ClearSelection()
        {
            foreach (var n in _selectedNodes)
                n.IsSelected = false;
            _selectedNodes.Clear();

            if (_selectedNode != null)
                _selectedNode.IsSelected = false;
            if (_selectedConnection != null)
            {
                _selectedConnection.IsSelected = false;
                if (_connectionPaths.TryGetValue(_selectedConnection.ConnectionId, out var p))
                    UpdateConnectionPath(p, _selectedConnection);
            }

            _selectedNode = null;
            _selectedConnection = null;
            SelectionCleared?.Invoke();
        }
        #endregion

        #region 拖放
        protected override void OnDrop(DragEventArgs e)
        {
            base.OnDrop(e);

            NodePluginInfo pluginInfo = null;

            // 尝试从 DataObject 获取插件信息
            if (e.Data.GetDataPresent(typeof(NodePluginInfo)))
            {
                pluginInfo = e.Data.GetData(typeof(NodePluginInfo)) as NodePluginInfo;
            }
            else if (e.Data.GetDataPresent(DataFormats.StringFormat))
            {
                var str = e.Data.GetData(DataFormats.StringFormat) as string;
                if (!string.IsNullOrEmpty(str))
                    pluginInfo = PluginLoader.Instance.GetPluginInfo(str);
            }

            if (pluginInfo != null)
            {
                if (IsRunning || IsReadOnly)
                {
                    e.Handled = true; // 流程运行中 / 只读模式禁止添加插件
                    return;
                }

                // 预览与放置共用 e.GetPosition（实测正确）；不用 GetCursorPos/PointFromScreen
                //（其内部窗口原点与 PointToScreen 不一致，PerMonitorV2 下会算出错误位置）
                var pos = e.GetPosition(this);
                double dropX = pos.X - NodeControl.DefaultWidth / 2;
                double dropY = pos.Y - NodeControl.DefaultHeight / 2;

                // 避免与现有节点重叠
                var freePos = FindFreePosition(dropX, dropY);
                NodeDropRequested?.Invoke(freePos.X, freePos.Y, pluginInfo);
                UpdateCanvasSize();
                e.Handled = true;
            }
        }
        #endregion

        #region 键盘
        protected override void OnKeyDown(KeyEventArgs e)
        {
            base.OnKeyDown(e);

            if (e.Key == Key.Delete || e.Key == Key.Back)
            {
                if (IsRunning || IsReadOnly)
                {
                    e.Handled = true;
                    return;
                }

                // 批量删除多选节点
                if (_selectedNodes.Count > 0)
                {
                    foreach (var node in _selectedNodes.ToList())
                        _graph?.RemoveNode(node.NodeId);
                    _selectedNodes.Clear();
                    _selectedNode = null;
                    e.Handled = true;
                }
                else if (_selectedNode != null)
                {
                    _graph?.RemoveNode(_selectedNode.NodeId);
                    _selectedNode = null;
                    e.Handled = true;
                }
                else if (_selectedConnection != null)
                {
                    _graph?.RemoveConnection(_selectedConnection.ConnectionId);
                    _selectedConnection = null;
                    e.Handled = true;
                }
            }
            else if (e.Key == Key.C && (Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control)
            {
                if (IsRunning || IsReadOnly)
                {
                    e.Handled = true;
                    return;
                }
                CopySelectedNodes();
                e.Handled = true;
            }
            else if (e.Key == Key.V && (Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control)
            {
                if (IsRunning || IsReadOnly)
                {
                    e.Handled = true;
                    return;
                }
                PasteNodes();
                e.Handled = true;
            }
            else if (e.Key == Key.A && (Keyboard.Modifiers & ModifierKeys.Control) == ModifierKeys.Control)
            {
                SelectAllNodes();
                e.Handled = true;
            }
        }
        #endregion

        #region 复制粘贴
        /// <summary>
        /// 获取当前选中的节点列表（供 MoveThumb 多选拖拽使用）
        /// </summary>
        public List<FlowNode> GetSelectedNodes() => _selectedNodes;

        /// <summary>
        /// 全选所有节点
        /// </summary>
        private void SelectAllNodes()
        {
            foreach (var n in _selectedNodes)
                n.IsSelected = false;
            _selectedNodes.Clear();

            foreach (var node in _graph?.Nodes ?? Enumerable.Empty<FlowNode>())
            {
                node.IsSelected = true;
                _selectedNodes.Add(node);
            }

            if (_selectedNodes.Count > 0)
            {
                _selectedNode = _selectedNodes[_selectedNodes.Count - 1];
                NodeSelected?.Invoke(_selectedNode);
            }
        }

        private bool HasClipboardData()
        {
            try
            {
                var text = System.Windows.Clipboard.GetText();
                return !string.IsNullOrEmpty(text) && text.StartsWith(ClipboardPrefix);
            }
            catch { return false; }
        }

        private void CopySelectedNodes()
        {
            // 如果多选列表为空但单选不为空，将单选加入多选列表
            if (_selectedNodes.Count == 0 && _selectedNode != null)
            {
                _selectedNode.IsSelected = true;
                _selectedNodes.Add(_selectedNode);
            }

            if (_selectedNodes.Count == 0) return;

            var nodes = new List<FlowNode>();
            var idMap = new Dictionary<string, string>();
            foreach (var node in _selectedNodes)
            {
                var clone = CloneNode(node);
                clone.NodeId = System.Guid.NewGuid().ToString("N");
                idMap[node.NodeId] = clone.NodeId;
                nodes.Add(clone);
            }

            // 复制选中节点之间的连接线（映射到剪贴板节点的ID）
            var nodeIds = new HashSet<string>(_selectedNodes.Select(n => n.NodeId));
            var connections = _graph?.Connections
                .Where(c => nodeIds.Contains(c.SourceNodeId) && nodeIds.Contains(c.TargetNodeId))
                .Select(c => new FlowConnection
                {
                    SourceNodeId = idMap[c.SourceNodeId],
                    SourceSide = c.SourceSide,
                    TargetNodeId = idMap[c.TargetNodeId],
                    TargetSide = c.TargetSide,
                    BranchCondition = c.BranchCondition
                })
                .ToList();

            // 序列化到系统剪贴板
            try
            {
                var data = new ClipboardData { Nodes = nodes, Connections = connections };
                var formatter = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
                using (var ms = new System.IO.MemoryStream())
                {
                    formatter.Serialize(ms, data);
                    var base64 = Convert.ToBase64String(ms.ToArray());
                    System.Windows.Clipboard.SetText(ClipboardPrefix + base64);
                }
            }
            catch { }
        }

        private void PasteNodes()
        {
            PasteNodesAt(Mouse.GetPosition(this));
        }

        /// <summary>
        /// 在指定位置粘贴节点
        /// </summary>
        public void PasteNodesAt(Point pos)
        {
            if (_graph == null || IsRunning || IsReadOnly) return;

            // 从系统剪贴板读取
            List<FlowNode> clipNodes = null;
            List<FlowConnection> clipConns = null;
            try
            {
                var text = System.Windows.Clipboard.GetText();
                if (!string.IsNullOrEmpty(text) && text.StartsWith(ClipboardPrefix))
                {
                    var bytes = Convert.FromBase64String(text.Substring(ClipboardPrefix.Length));
                    var formatter = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
                    using (var ms = new System.IO.MemoryStream(bytes))
                    {
                        var data = (ClipboardData)formatter.Deserialize(ms);
                        clipNodes = data.Nodes;
                        clipConns = data.Connections;
                    }
                }
            }
            catch { return; }

            if (clipNodes == null || clipNodes.Count == 0) return;

            ClearSelection();

            // 计算偏移：让剪贴板内容的左上角对齐到鼠标位置
            double minX = double.MaxValue, minY = double.MaxValue;
            foreach (var data in clipNodes)
            {
                if (data.X < minX) minX = data.X;
                if (data.Y < minY) minY = data.Y;
            }
            double offsetX = pos.X - minX;
            double offsetY = pos.Y - minY;

            var newNodes = new List<FlowNode>();

            foreach (var data in clipNodes)
            {
                var newNode = CloneNode(data);
                newNode.X = data.X + offsetX;
                newNode.Y = data.Y + offsetY;
                newNode.IsSelected = true;
                int suffix = 1;
                while (Graph.Nodes.Any(n => n.NodeName == newNode.NodeName))
                    newNode.NodeName = $"{newNode.PluginModel.GetModel.ToolName}{++suffix}";
                // 重新初始化所有ID（FlowId/FlowName/NodeId/PluginModel/Group子节点）
                newNode.InitializeNode(_graph.GraphId, _graph.GraphName, _graph.Registry);

                _graph.AddNode(newNode);
                newNodes.Add(newNode);
            }

            _selectedNodes.AddRange(newNodes);
            if (newNodes.Count > 0)
                _selectedNode = newNodes[0];

            // 复制连接线
            if (clipConns != null && clipConns.Count > 0)
            {
                var idMap = new Dictionary<string, string>();
                for (int i = 0; i < clipNodes.Count && i < newNodes.Count; i++)
                    idMap[clipNodes[i].NodeId] = newNodes[i].NodeId;

                foreach (var conn in clipConns)
                {
                    if (idMap.TryGetValue(conn.SourceNodeId, out var newSrcId) &&
                        idMap.TryGetValue(conn.TargetNodeId, out var newTgtId))
                    {
                        _graph.TryAddConnection(new FlowConnection
                        {
                            SourceNodeId = newSrcId,
                            SourceSide = conn.SourceSide,
                            TargetNodeId = newTgtId,
                            TargetSide = conn.TargetSide,
                            BranchCondition = conn.BranchCondition
                        });
                    }
                }
            }

            UpdateCanvasSize();
        }

        /// <summary>
        /// 删除所有选中节点
        /// </summary>
        public void DeleteSelectedNodes()
        {
            if (_graph == null || IsRunning || IsReadOnly) return;

            if (_selectedNodes.Count > 0)
            {
                foreach (var node in _selectedNodes.ToList())
                    _graph.RemoveNode(node.NodeId);
                _selectedNodes.Clear();
                _selectedNode = null;
            }
            else if (_selectedNode != null)
            {
                _graph.RemoveNode(_selectedNode.NodeId);
                _selectedNode = null;
            }
        }

        /// <summary>
        /// 删除选中节点的所有连接线
        /// </summary>
        public void DeleteSelectedConnections()
        {
            if (_graph == null || IsRunning || IsReadOnly) return;

            var nodes = _selectedNodes.Count > 0 ? _selectedNodes.ToList() :
                        (_selectedNode != null ? new List<FlowNode> { _selectedNode } : new List<FlowNode>());

            if (nodes.Count == 0) return;

            var nodeIds = new HashSet<string>(nodes.Select(n => n.NodeId));
            var connectionsToRemove = _graph.Connections
                .Where(c => nodeIds.Contains(c.SourceNodeId) || nodeIds.Contains(c.TargetNodeId))
                .ToList();

            foreach (var conn in connectionsToRemove)
                _graph.RemoveConnection(conn.ConnectionId);
        }

        /// <summary>
        /// 深拷贝节点（使用 BinaryFormatter，完整复制 PluginModel）
        /// </summary>
        private static FlowNode CloneNode(FlowNode source)
        {
            try
            {
#pragma warning disable SYSLIB0011
                var formatter = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
                using (var stream = new System.IO.MemoryStream())
                {
                    formatter.Serialize(stream, source);
                    stream.Position = 0;
                    return (FlowNode)formatter.Deserialize(stream);
                }
#pragma warning restore SYSLIB0011
            }
            catch(Exception ex)
            {
                System.Diagnostics.Debug.WriteLine($"[CloneNode] 序列化失败: {ex}");
                DialogHelper.Error($"节点复制失败: {ex.Message}");
                return default;
            }
        }
        #endregion

        [System.Serializable]
        private class ClipboardData
        {
            public List<FlowNode> Nodes;
            public List<FlowConnection> Connections;
        }

        #region 辅助
        private static T FindAncestor<T>(DependencyObject current) where T : DependencyObject
        {
            while (current != null && !(current is T))
                current = VisualTreeHelper.GetParent(current);
            return current as T;
        }
        #endregion

        #region 节点碰撞检测
        /// <summary>
        /// 检查指定位置是否会与其他节点碰撞
        /// </summary>
        public bool CheckNodeCollision(FlowNode draggingNode, double newX, double newY)
        {
            return CheckNodeCollision(draggingNode, newX, newY, null);
        }

        /// <summary>
        /// 检查指定位置是否会与其他节点碰撞。
        /// ignoreNodes 中的节点视为"与拖拽节点同步移动"（多选拖拽的同组成员）：
        /// 它们相对位置不变、不会与拖拽成员相撞，因此不作为障碍参与检测。
        /// </summary>
        public bool CheckNodeCollision(FlowNode draggingNode, double newX, double newY, System.Collections.Generic.ICollection<FlowNode> ignoreNodes)
        {
            if (_graph?.Nodes == null) return false;
            var newRect = new Rect(newX, newY, draggingNode.NodeWidth, draggingNode.NodeHeight);
            foreach (var node in _graph.Nodes)
            {
                if (node.NodeId == draggingNode.NodeId) continue;
                if (ignoreNodes != null && ignoreNodes.Contains(node)) continue;
                var nodeRect = new Rect(node.X, node.Y, node.NodeWidth, node.NodeHeight);
                if (newRect.IntersectsWith(nodeRect))
                    return true;
            }
            return false;
        }

        /// <summary>
        /// 从指定位置开始查找不与任何节点重叠的空闲位置
        /// </summary>
        public Point FindFreePosition(double startX, double startY)
        {
            double x = startX, y = startY;
            if (_graph?.Nodes == null) return new Point(x, y);

            bool collision;
            do
            {
                collision = false;
                var dropRect = new Rect(x, y, NodeControl.DefaultWidth, NodeControl.DefaultHeight);
                foreach (var node in _graph.Nodes)
                {
                    var nodeRect = new Rect(node.X, node.Y, node.NodeWidth, node.NodeHeight);
                    if (nodeRect.IntersectsWith(dropRect))
                    {
                        x += 20;
                        y += 20;
                        collision = true;
                        break;
                    }
                }
            } while (collision);

            return new Point(x, y);
        }
        #endregion

        #region 自动拉线

        /// <summary>
        /// 自动拉线 - 单节点拖拽结束时，若节点贴近其他节点则自动建立连接。
        /// 规则：靠下和靠右时其他节点当头（本节点作目标）；靠上和靠左时本节点当头（本节点作源）。
        /// 阈值：贴边距离 40px 内，且对应方向重叠量达到较小节点尺寸的 80%。
        /// 拖拽过程中通过 UpdateAutoConnectPreview 显示虚线预览，拉远自动消失。
        /// </summary>
        public void TryAutoConnect(FlowNode node)
        {
            if (node == null || _graph == null || _graph.Nodes == null || _graph.Connections == null)
            {
                ClearPreviewLine();
                return;
            }

            const double threshold = 40; // 贴边距离阈值(px)
            var pos = GetNodeVisualBounds(node);

            foreach (var other in _graph.Nodes)
            {
                if (other == node) continue;
                var oPos = GetNodeVisualBounds(other);

                // 1. 本节点在 other 正下方 → 上连下（other.Bottom → node.Top）
                if (HorizontalOverlap(pos, oPos) && VerticalGap(pos.Top, oPos.Bottom) <= threshold)
                {
                    if (TryAutoAdd(other, PortSide.Bottom, node, PortSide.Top))
                    {
                        ClearPreviewLine();
                        return; // 每次拖拽只自动连一条
                    }
                }

                // 2. 本节点在 other 正上方 → 本节点当头（node.Bottom → other.Top）
                if (HorizontalOverlap(pos, oPos) && VerticalGap(oPos.Top, pos.Bottom) <= threshold)
                {
                    if (TryAutoAdd(node, PortSide.Bottom, other, PortSide.Top))
                    {
                        ClearPreviewLine();
                        return;
                    }
                }

                // 3. 本节点在 other 正右方 →（other.Right → node.Left）
                if (VerticalOverlap(pos, oPos) && HorizontalGap(pos.Left, oPos.Right) <= threshold)
                {
                    if (TryAutoAdd(other, PortSide.Right, node, PortSide.Left))
                    {
                        ClearPreviewLine();
                        return;
                    }
                }

                // 4. 本节点在 other 正左方 → 本节点当头（node.Right → other.Left）
                if (VerticalOverlap(pos, oPos) && HorizontalGap(oPos.Left, pos.Right) <= threshold)
                {
                    if (TryAutoAdd(node, PortSide.Right, other, PortSide.Left))
                    {
                        ClearPreviewLine();
                        return;
                    }
                }
            }

            // 没有成功连接 → 清除预览
            ClearPreviewLine();
        }

        /// <summary>
        /// 拖拽过程中更新自动拉线虚线预览；靠近且可连接时显示，否则清除
        /// </summary>
        public void UpdateAutoConnectPreview(FlowNode node)
        {
            ClearPreviewLine();

            if (node == null || _graph == null || _graph.Nodes == null || _graph.Connections == null)
                return;

            const double threshold = 40; // 贴边距离阈值(px)
            var pos = GetNodeVisualBounds(node);

            foreach (var other in _graph.Nodes)
            {
                if (other == node) continue;
                var oPos = GetNodeVisualBounds(other);

                FlowNode source = null;
                PortSide sourceSide = PortSide.Bottom;
                FlowNode target = null;
                PortSide targetSide = PortSide.Top;

                // 1. 本节点在 other 正下方 → 上连下（other.Bottom → node.Top）
                if (HorizontalOverlap(pos, oPos) && VerticalGap(pos.Top, oPos.Bottom) <= threshold)
                {
                    source = other; sourceSide = PortSide.Bottom;
                    target = node; targetSide = PortSide.Top;
                }
                // 2. 本节点在 other 正上方 → 本节点当头（node.Bottom → other.Top）
                else if (HorizontalOverlap(pos, oPos) && VerticalGap(oPos.Top, pos.Bottom) <= threshold)
                {
                    source = node; sourceSide = PortSide.Bottom;
                    target = other; targetSide = PortSide.Top;
                }
                // 3. 本节点在 other 正右方 →（other.Right → node.Left）
                else if (VerticalOverlap(pos, oPos) && HorizontalGap(pos.Left, oPos.Right) <= threshold)
                {
                    source = other; sourceSide = PortSide.Right;
                    target = node; targetSide = PortSide.Left;
                }
                // 4. 本节点在 other 正左方 → 本节点当头（node.Right → other.Left）
                else if (VerticalOverlap(pos, oPos) && HorizontalGap(oPos.Left, pos.Right) <= threshold)
                {
                    source = node; sourceSide = PortSide.Right;
                    target = other; targetSide = PortSide.Left;
                }

                if (source == null) continue;

                // 预检：能连才显示预览（复用防重/防环逻辑）
                var connection = new FlowConnection
                {
                    SourceNodeId = source.NodeId,
                    SourceSide = sourceSide,
                    TargetNodeId = target.NodeId,
                    TargetSide = targetSide
                };
                if (!_graph.CanConnect(connection))
                    continue;

                Point start = GetPortPosition(source, sourceSide);
                Point end = GetPortPosition(target, targetSide);

                if (_previewLine == null)
                {
                    _previewLine = new Path
                    {
                        Stroke = new SolidColorBrush(Color.FromRgb(232, 145, 73)),
                        StrokeThickness = 2,
                        StrokeDashArray = new DoubleCollection { 4, 3 },
                        IsHitTestVisible = false
                    };
                    Panel.SetZIndex(_previewLine, 10000);
                    Children.Add(_previewLine);
                }

                _previewLine.Data = CreateConnectionGeometry(start, end, sourceSide, targetSide);
                return;
            }
        }

        /// <summary>
        /// 清除自动拉线虚线预览
        /// </summary>
        public void ClearPreviewLine()
        {
            if (_previewLine != null)
            {
                Children.Remove(_previewLine);
                _previewLine = null;
            }
        }

        /// <summary>
        /// 构造连线并交给 Graph 添加（复用已有防重/防环逻辑）
        /// </summary>
        private bool TryAutoAdd(FlowNode source, PortSide sourceSide, FlowNode target, PortSide targetSide)
        {
            var connection = new FlowConnection
            {
                SourceNodeId = source.NodeId,
                SourceSide = sourceSide,
                TargetNodeId = target.NodeId,
                TargetSide = targetSide
            };

            // 预检：能连才添加（复用防重/防环逻辑）
            if (!_graph.CanConnect(connection))
                return false;

            return _graph.TryAddConnection(connection);
        }

        private Rect GetNodeVisualBounds(FlowNode node)
        {
            double left = node.X;
            double top = node.Y;
            double w = NodeControl.DefaultWidth;
            double h = NodeControl.DefaultHeight;
            return new Rect(left, top, w, h);
        }

        private static bool HorizontalOverlap(Rect a, Rect b)
        {
            double overlap = Math.Min(a.Right, b.Right) - Math.Max(a.Left, b.Left);
            double minW = Math.Min(a.Width, b.Width);
            return minW > 0 && overlap >= minW * 0.8;
        }

        private static bool VerticalOverlap(Rect a, Rect b)
        {
            double overlap = Math.Min(a.Bottom, b.Bottom) - Math.Max(a.Top, b.Top);
            double minH = Math.Min(a.Height, b.Height);
            return minH > 0 && overlap >= minH * 0.8;
        }

        private static double VerticalGap(double aBottom, double bTop)
        {
            return Math.Abs(bTop - aBottom);
        }

        private static double HorizontalGap(double aRight, double bLeft)
        {
            return Math.Abs(bLeft - aRight);
        }

        #endregion

        #region 鸟瞰图支持
        /// <summary>
        /// 动态更新画布大小，使内容超出时自动扩展
        /// </summary>
        public void UpdateCanvasSize()
        {
            if (_graph?.Nodes == null || _graph.Nodes.Count == 0) return;

            var bounds = GetContentBounds();
            double minW = ActualWidth > 0 ? ActualWidth : 800;
            double minH = ActualHeight > 0 ? ActualHeight : 600;
            double newW = Math.Max(bounds.Right + 300, minW);
            double newH = Math.Max(bounds.Bottom + 300, minH);

            if (Math.Abs(Width - newW) > 1 || Math.Abs(Height - newH) > 1)
            {
                Width = newW;
                Height = newH;
            }
        }

        /// <summary>
        /// 适应内容 - 计算所有节点边界，缩放平移使内容完整显示并居中
        /// </summary>
        public void FitToContent()
        {
            var bounds = GetContentBounds();
            var vp = GetViewportSize();

            if (bounds.Width <= 0 || bounds.Height <= 0 || vp.Width <= 0 || vp.Height <= 0)
            {
                // 无内容或视口异常：复位 100% 原点
                _scale.ScaleX = 1.0;
                _scale.ScaleY = 1.0;
                _translate.X = 0;
                _translate.Y = 0;
                ZoomChanged?.Invoke(1.0);
                return;
            }

            const double padding = 50; // 四周留白
            double scaleX = (vp.Width - padding * 2) / bounds.Width;
            double scaleY = (vp.Height - padding * 2) / bounds.Height;
            double newScale = Math.Min(scaleX, scaleY);
            newScale = Math.Max(MinZoom, Math.Min(1.0, newScale)); // 内容小时不放大超过100%

            _scale.ScaleX = newScale;
            _scale.ScaleY = newScale;

            // 居中：内容中心对齐视口中心，但 0,0 原点固定在左上角（不跑到画布外）
            double centerX = bounds.X + bounds.Width / 2;
            double centerY = bounds.Y + bounds.Height / 2;
            _translate.X = Math.Min(0, vp.Width / 2 - centerX * newScale);
            _translate.Y = Math.Min(0, vp.Height / 2 - centerY * newScale);

            ZoomChanged?.Invoke(newScale);
        }

        /// <summary>
        /// 获取所有节点的内容边界
        /// </summary>
        public Rect GetContentBounds()
        {
            if (_graph?.Nodes == null || _graph.Nodes.Count == 0)
                return new Rect(0, 0, 0, 0);

            double minX = double.MaxValue, minY = double.MaxValue;
            double maxX = double.MinValue, maxY = double.MinValue;

            foreach (var node in _graph.Nodes)
            {
                minX = Math.Min(minX, node.X);
                minY = Math.Min(minY, node.Y);
                maxX = Math.Max(maxX, node.X + node.NodeWidth);
                maxY = Math.Max(maxY, node.Y + node.NodeHeight);
            }

            return new Rect(minX, minY, maxX - minX, maxY - minY);
        }

        /// <summary>
        /// 获取当前视口（画布坐标空间中的可见区域）
        /// </summary>
        public Rect GetViewport()
        {
            var vp = GetViewportSize();
            double x = -_translate.X / _scale.ScaleX;
            double y = -_translate.Y / _scale.ScaleY;
            double w = vp.Width / _scale.ScaleX;
            double h = vp.Height / _scale.ScaleY;
            return new Rect(x, y, w, h);
        }

        /// <summary>
        /// 获取可视区域大小（屏幕像素）- 取父容器的实际尺寸
        /// </summary>
        private Size GetViewportSize()
        {
            var parent = System.Windows.Media.VisualTreeHelper.GetParent(this) as FrameworkElement;
            if (parent != null && parent.ActualWidth > 0 && parent.ActualHeight > 0)
                return new Size(parent.ActualWidth, parent.ActualHeight);
            return new Size(800, 600);
        }

        /// <summary>
        /// 将画布视口居中到指定画布坐标点
        /// </summary>
        public void CenterOn(Point canvasPoint)
        {
            var vp = GetViewportSize();
            _translate.X = vp.Width / 2 - canvasPoint.X * _scale.ScaleX;
            _translate.Y = vp.Height / 2 - canvasPoint.Y * _scale.ScaleY;
            ClampTranslate();
        }
        #endregion

        #region 自动排版
        /// <summary>
        /// 层次化自动排版：从左到右分层，同层从上到下排列，最小化连线交叉。
        /// 算法：拓扑排序分层 → 重心启发式排序 → 居中对齐 → 连线方向归一化
        /// </summary>
        public void AutoLayout()
        {
            if (_graph == null || _graph.Nodes.Count == 0) return;
            if (IsRunning || IsReadOnly) return;

            var nodes = _graph.Nodes.ToList();
            var conns = _graph.Connections.ToList();
            var nodeIds = nodes.Select(n => n.NodeId).ToHashSet();

            // 1. 构建邻接表
            var succ = new Dictionary<string, List<string>>();
            var pred = new Dictionary<string, List<string>>();
            foreach (var n in nodes)
            {
                succ[n.NodeId] = new List<string>();
                pred[n.NodeId] = new List<string>();
            }
            foreach (var c in conns)
            {
                if (nodeIds.Contains(c.SourceNodeId) && nodeIds.Contains(c.TargetNodeId))
                {
                    succ[c.SourceNodeId].Add(c.TargetNodeId);
                    pred[c.TargetNodeId].Add(c.SourceNodeId);
                }
            }

            // 2. 层次分配（最长路径：node.layer = max(前驱 layer) + 1）
            var layer = new Dictionary<string, int>();
            var inDeg = nodes.ToDictionary(n => n.NodeId, n => pred[n.NodeId].Count);
            var queue = new Queue<string>();
            foreach (var n in nodes)
                if (inDeg[n.NodeId] == 0) queue.Enqueue(n.NodeId);

            while (queue.Count > 0)
            {
                var id = queue.Dequeue();
                int maxPred = -1;
                foreach (var p in pred[id])
                    if (layer.TryGetValue(p, out var pl)) maxPred = Math.Max(maxPred, pl);
                layer[id] = maxPred + 1;
                foreach (var s in succ[id])
                    if (--inDeg[s] == 0) queue.Enqueue(s);
            }
            // 未分配（孤立节点）放第 0 层
            foreach (var n in nodes)
                if (!layer.ContainsKey(n.NodeId)) layer[n.NodeId] = 0;

            // 3. 按层分组
            int maxLayer = layer.Values.Max();
            var layers = new List<List<string>>();
            for (int i = 0; i <= maxLayer; i++) layers.Add(new List<string>());
            foreach (var kv in layer) layers[kv.Value].Add(kv.Key);

            // 4. 层内排序：重心启发式（按前驱 Y 中位数排序，减少交叉）
            const double layerGap = 300;  // 层间距（水平）
            const double nodeGap = 50;    // 同层节点间距（垂直）
            const double startX = 40;
            const double startY = 40;

            var yPos = new Dictionary<string, double>();

            for (int li = 0; li < layers.Count; li++)
            {
                var layerNodes = layers[li];
                if (li > 0 && layerNodes.Count > 1)
                {
                    layerNodes.Sort((a, b) =>
                    {
                        double ma = MedianY(pred[a], yPos);
                        double mb = MedianY(pred[b], yPos);
                        return ma.CompareTo(mb);
                    });
                }

                double y = startY;
                foreach (var id in layerNodes)
                {
                    var node = _graph.GetNode(id);
                    if (node == null) continue;
                    node.X = startX + li * layerGap;
                    node.Y = y;
                    yPos[id] = y;
                    y += node.NodeHeight + nodeGap;
                }
            }

            // 5. 各层垂直居中
            double maxLayerH = 0;
            var layerHeights = new double[layers.Count];
            for (int li = 0; li < layers.Count; li++)
            {
                var ln = layers[li];
                if (ln.Count == 0) continue;
                var first = _graph.GetNode(ln[0]);
                var last = _graph.GetNode(ln[ln.Count - 1]);
                if (first == null || last == null) continue;
                double h = (last.Y + last.NodeHeight) - first.Y;
                layerHeights[li] = h;
                maxLayerH = Math.Max(maxLayerH, h);
            }
            for (int li = 0; li < layers.Count; li++)
            {
                double offset = (maxLayerH - layerHeights[li]) / 2;
                if (offset <= 0) continue;
                foreach (var id in layers[li])
                {
                    var node = _graph.GetNode(id);
                    if (node != null) node.Y += offset;
                }
            }

            // 6. 连线方向归一化：跨层 Right→Left，同层 Bottom→Top
            foreach (var c in conns)
            {
                var src = _graph.GetNode(c.SourceNodeId);
                var tgt = _graph.GetNode(c.TargetNodeId);
                if (src == null || tgt == null) continue;
                if (layer.TryGetValue(c.SourceNodeId, out var sl) &&
                    layer.TryGetValue(c.TargetNodeId, out var tl) && sl == tl)
                {
                    c.SourceSide = PortSide.Bottom;
                    c.TargetSide = PortSide.Top;
                }
                else
                {
                    c.SourceSide = PortSide.Right;
                    c.TargetSide = PortSide.Left;
                }
            }

            // 7. 刷新视觉
            foreach (var node in nodes)
            {
                if (_nodeControls.TryGetValue(node.NodeId, out var ctrl))
                {
                    SetLeft(ctrl, node.X);
                    SetTop(ctrl, node.Y);
                }
            }
            foreach (var kvp in _connectionPaths)
                if (kvp.Value.Tag is FlowConnection fc) UpdateConnectionPath(kvp.Value, fc);

            // 8. 适应内容
            UpdateCanvasSize();
            FitToContent();
        }

        private static double MedianY(List<string> predIds, Dictionary<string, double> yPos)
        {
            var ys = predIds.Where(yPos.ContainsKey).Select(id => yPos[id]).OrderBy(v => v).ToList();
            if (ys.Count == 0) return 0;
            int mid = ys.Count / 2;
            return ys.Count % 2 == 0 ? (ys[mid - 1] + ys[mid]) / 2 : ys[mid];
        }
        #endregion

        #region 平移限制
        /// <summary>
        /// 限制平移范围，确保不会看到内容区域之外
        /// </summary>
        private void ClampTranslate()
        {
            // 原点固定，不超出画布边界
            var vp = GetViewportSize();
            // 用画布尺寸判断平移范围，而非节点范围
            double canvasW = (Width > 0 ? Width : 5000) * _scale.ScaleX;
            double canvasH = (Height > 0 ? Height : 3500) * _scale.ScaleY;

            // X 轴：原点不动，不超出右下边界
            if (canvasW <= vp.Width)
                _translate.X = 0;
            else
            {
                double minX = vp.Width - canvasW;
                if (_translate.X < minX) _translate.X = minX;
                if (_translate.X > 0) _translate.X = 0;
            }

            // Y 轴
            if (canvasH <= vp.Height)
                _translate.Y = 0;
            else
            {
                double minY = vp.Height - canvasH;
                if (_translate.Y < minY) _translate.Y = minY;
                if (_translate.Y > 0) _translate.Y = 0;
            }
        }
        #endregion

        #region 对齐引导线
        private readonly List<System.Windows.Documents.Adorner> _alignLines = new List<System.Windows.Documents.Adorner>();

        public void AddAlignLine(Point start, Point end)
        {
            var layer = System.Windows.Documents.AdornerLayer.GetAdornerLayer(this);
            if (layer == null) return;

            // Adorner 坐标空间与画布布局坐标空间一致，直接传画布坐标
            var line = new SelectionAlignLine(this, start, end);
            layer.Add(line);
            _alignLines.Add(line);
        }

        public void ClearAlignLines()
        {
            var layer = System.Windows.Documents.AdornerLayer.GetAdornerLayer(this);
            if (layer != null)
            {
                foreach (var line in _alignLines)
                    layer.Remove(line);
            }
            _alignLines.Clear();
        }

        /// <summary>
        /// 检查节点对齐并返回对齐偏移量
        /// </summary>
        public void CheckAlignment(FlowNode draggingNode, ref double x, ref double y)
        {
            ClearAlignLines();

            const double threshold = 5.0;
            double nodeLeft = x;
            double nodeTop = y;
            double nodeRight = x + draggingNode.NodeWidth;
            double nodeBottom = y + draggingNode.NodeHeight;
            double nodeCenterX = x + draggingNode.NodeWidth / 2;
            double nodeCenterY = y + draggingNode.NodeHeight / 2;

            double snapX = double.NaN;
            double snapY = double.NaN;

            if (_graph?.Nodes == null) return;

            foreach (var other in _graph.Nodes)
            {
                if (other.NodeId == draggingNode.NodeId) continue;

                double otherLeft = other.X;
                double otherTop = other.Y;
                double otherRight = other.X + other.NodeWidth;
                double otherBottom = other.Y + other.NodeHeight;
                double otherCenterX = other.X + other.NodeWidth / 2;
                double otherCenterY = other.Y + other.NodeHeight / 2;

                // 垂直对齐检测（显示垂直引导线，调整 X）
                if (!double.IsNaN(snapX))
                {
                    // 已有 X 对齐，只检查 Y
                }
                else if (Math.Abs(nodeLeft - otherLeft) < threshold)
                {
                    snapX = otherLeft;
                    AddAlignLine(new Point(otherLeft, Math.Min(nodeTop, otherTop)),
                                 new Point(otherLeft, Math.Max(nodeBottom, otherBottom)));
                }
                else if (Math.Abs(nodeRight - otherRight) < threshold)
                {
                    snapX = otherRight - draggingNode.NodeWidth;
                    AddAlignLine(new Point(otherRight, Math.Min(nodeTop, otherTop)),
                                 new Point(otherRight, Math.Max(nodeBottom, otherBottom)));
                }
                else if (Math.Abs(nodeCenterX - otherCenterX) < threshold)
                {
                    snapX = otherCenterX - draggingNode.NodeWidth / 2;
                    AddAlignLine(new Point(otherCenterX, Math.Min(nodeTop, otherTop)),
                                 new Point(otherCenterX, Math.Max(nodeBottom, otherBottom)));
                }

                // 水平对齐检测（显示水平引导线，调整 Y）
                if (!double.IsNaN(snapY))
                {
                    // 已有 Y 对齐
                }
                else if (Math.Abs(nodeTop - otherTop) < threshold)
                {
                    snapY = otherTop;
                    AddAlignLine(new Point(Math.Min(nodeLeft, otherLeft), otherTop),
                                 new Point(Math.Max(nodeRight, otherRight), otherTop));
                }
                else if (Math.Abs(nodeBottom - otherBottom) < threshold)
                {
                    snapY = otherBottom - draggingNode.NodeHeight;
                    AddAlignLine(new Point(Math.Min(nodeLeft, otherLeft), otherBottom),
                                 new Point(Math.Max(nodeRight, otherRight), otherBottom));
                }
                else if (Math.Abs(nodeCenterY - otherCenterY) < threshold)
                {
                    snapY = otherCenterY - draggingNode.NodeHeight / 2;
                    AddAlignLine(new Point(Math.Min(nodeLeft, otherLeft), otherCenterY),
                                 new Point(Math.Max(nodeRight, otherRight), otherCenterY));
                }
            }

            if (!double.IsNaN(snapX)) x = snapX;
            if (!double.IsNaN(snapY)) y = snapY;
        }
        #endregion
    }
}