ME3Explorer.PackageEditor.treeView1_DragDrop C# (CSharp) Method

        private void treeView1_DragDrop(object sender, DragEventArgs e)
        {
            TreeNode sourceNode;

            if (e.Data.GetDataPresent("System.Windows.Forms.TreeNode", false))
            {
                Point pt = ((TreeView)sender).PointToClient(new Point(e.X, e.Y));
                TreeNode DestinationNode = ((TreeView)sender).GetNodeAt(pt);
                sourceNode = (TreeNode)e.Data.GetData("System.Windows.Forms.TreeNode");
                if (DestinationNode.TreeView != sourceNode.TreeView)
                {
                    IMEPackage importpcc = sourceNode.TreeView.Tag as IMEPackage;
                    if (importpcc == null)
                    {
                        return;
                    }

                    int n = Convert.ToInt32(sourceNode.Name);
                    int link;
                    if (DestinationNode.Name == "")
                    {
                        link = 0;
                    }
                    else
                    {
                        link = Convert.ToInt32(DestinationNode.Name);
                        link = link >= 0 ? link + 1 : link;
                    }
                    int nextIndex;
                    if (n >= 0)
                    {
                        if (!importExport(importpcc, n, link))
                        {
                            return;
                        }
                        nextIndex = pcc.ExportCount;
                    }
                    else
                    {
                        importImport(importpcc, -n - 1, link);
                        nextIndex = -pcc.ImportCount;
                    }
                    if (sourceNode.Nodes.Count > 0)
                    {
                        importTree(sourceNode, importpcc, nextIndex);
                    }

                    RefreshView();
                    goToNumber(n >= 0 ? pcc.ExportCount - 1 : -pcc.ImportCount);
                }
            }
        }