AvalonStudio.TextEditor.Document.TextAnchorTree.FixTreeOnDelete C# (CSharp) Method

		private void FixTreeOnDelete(TextAnchorNode node, TextAnchorNode parentNode)
		{
			Debug.Assert(node == null || node.parent == parentNode);
			if (parentNode == null)
				return;

			// warning: node may be null
			var sibling = Sibling(node, parentNode);
			if (sibling.color == RED)
			{
				parentNode.color = RED;
				sibling.color = BLACK;
				if (node == parentNode.left)
				{
					RotateLeft(parentNode);
				}
				else
				{
					RotateRight(parentNode);
				}

				sibling = Sibling(node, parentNode); // update value of sibling after rotation
			}

			if (parentNode.color == BLACK
			    && sibling.color == BLACK
			    && GetColor(sibling.left) == BLACK
			    && GetColor(sibling.right) == BLACK)
			{
				sibling.color = RED;
				FixTreeOnDelete(parentNode, parentNode.parent);
				return;
			}

			if (parentNode.color == RED
			    && sibling.color == BLACK
			    && GetColor(sibling.left) == BLACK
			    && GetColor(sibling.right) == BLACK)
			{
				sibling.color = RED;
				parentNode.color = BLACK;
				return;
			}

			if (node == parentNode.left &&
			    sibling.color == BLACK &&
			    GetColor(sibling.left) == RED &&
			    GetColor(sibling.right) == BLACK)
			{
				sibling.color = RED;
				sibling.left.color = BLACK;
				RotateRight(sibling);
			}
			else if (node == parentNode.right &&
			         sibling.color == BLACK &&
			         GetColor(sibling.right) == RED &&
			         GetColor(sibling.left) == BLACK)
			{
				sibling.color = RED;
				sibling.right.color = BLACK;
				RotateLeft(sibling);
			}
			sibling = Sibling(node, parentNode); // update value of sibling after rotation

			sibling.color = parentNode.color;
			parentNode.color = BLACK;
			if (node == parentNode.left)
			{
				if (sibling.right != null)
				{
					Debug.Assert(sibling.right.color == RED);
					sibling.right.color = BLACK;
				}
				RotateLeft(parentNode);
			}
			else
			{
				if (sibling.left != null)
				{
					Debug.Assert(sibling.left.color == RED);
					sibling.left.color = BLACK;
				}
				RotateRight(parentNode);
			}
		}