ASP.NET DaST to wrestle with MVC and WebForms

// ******************************************************************************
// ******************************************************************************
// ASP.NET DaST Rendering Engine
// Copyright (C) 2011 Roman Gubarenko
// Project Home: http://aspnetdast.sourceforge.net/
// ******************************************************************************
// ******************************************************************************
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
//
// ******************************************************************************
// Primary Contact: rgubarenko@gmail.com
// Learn More: http://aspnetdast.sourceforge.net/
// Project Repository: http://sourceforge.net/projects/aspnetdast/
// ******************************************************************************




using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using AspNetDaST.Web.Private;

namespace AspNetDaST.Web
{
  public class PathNavigator
  {
    internal ScopeTreeModel _scopeTree;
    internal ScopeController _controller;
    internal PathExact _origPath;

    // current navigation values
    private PathExact _currPath;
    private int? _savedAxis;
    private ScopeFacade _scope;


    internal PathNavigator(ScopeController controller, PathExact path)
    {
      _scopeTree = controller.TreeNode.ScopeTree;
      _controller = controller;
      _origPath = path;

      ResetNavigation();
    }

    internal void ResetNavigation()
    {
      _currPath = PathExact.Empty.Append(_origPath);
      _savedAxis = null;
      _scope = null;
    }


    #region Navigation Interface

    public ScopeFacade Scope 
    {
      get
      {
        var scopeData = _scopeTree.GetScopeDataBag(_currPath);
        return new ScopeFacade(_scopeTree, _currPath, scopeData);
      }
    }

    public PathNavigator Fwd(params object[] segments)
    {
      if (segments == null || segments.Length == 0) throw new DaSTException("Invalid path specification");

      int oldLength = _currPath.Length;

      _currPath = _currPath.Append(segments);

      if (_savedAxis.HasValue)
      {
        _currPath[oldLength].Axis = _savedAxis.Value;
      }

      EnsureValidCurrPath();

      return this;
    }

    public PathNavigator Rew(int countSteps)
    {
      if (countSteps <= 0 || countSteps > _currPath.Length) throw new DaSTException("Invalid number of steps");

      _savedAxis = _currPath[_currPath.Length - countSteps].Axis;

      _currPath = _currPath.Subpath(_currPath.Length - countSteps);

      EnsureValidCurrPath();

      return this;
    }

    private void EnsureValidCurrPath()
    {
      // make sure that selection does not go beyond current control
      var foundNode = _scopeTree.GetNode(_currPath);

      // ensure scope is accessible
      if(!ScopeTreeTools.Model.IsScopeAccessible(_controller, foundNode))
        throw new DaSTException("Cannot access scope beyond current controller");
    }
 
    #endregion

    public override string ToString()
    {
      return _currPath.ToString();
    }
  }
}