// ============================================================================
// ==                                                                        ==
// == AMDiS - Adaptive multidimensional simulations                          ==
// ==                                                                        ==
// ==  http://www.amdis-fem.org                                              ==
// ==                                                                        ==
// ============================================================================
//
// Software License for AMDiS
//
// Copyright (c) 2010 Dresden University of Technology 
// All rights reserved.
// Authors: Simon Vey, Thomas Witkowski et al.
//
// This file is part of AMDiS
//
// See also license.opensource.txt in the distribution.



/** \file DualTraverse.h */

#ifndef AMDIS_DUALTRAVERSE_H
#define AMDIS_DUALTRAVERSE_H

#include "Traverse.h"
#include "Flag.h"
#include "AMDiS_fwd.h"

namespace AMDiS {

  /** \brief
   * Stores the four pointers to element info structures, that are required for the
   * dual mesh traverse.
   */
  struct DualElInfo 
  {
    ElInfo *rowElInfo;
    ElInfo *colElInfo;
    ElInfo *smallElInfo;
    ElInfo *largeElInfo;
  };

  /// Parallel traversal of two meshes. 
  class DualTraverse
  {
  public:
    DualTraverse() 
      : fillSubElemMat(false),
	basisFcts(NULL)
    {}

    virtual ~DualTraverse() {}

    /// Start dual traversal
    bool traverseFirst(Mesh *mesh1, 
		       Mesh *mesh2, 
		       int level1, 
		       int level2, 
		       Flag flag1,
		       Flag flag2,
		       ElInfo **elInfo1,
		       ElInfo **elInfo2,
		       ElInfo **elInfoSmall,
		       ElInfo **elInfoLarge);

    /// Alternative use for starting dual traversal.
    inline bool traverseFirst(Mesh *mesh1, Mesh *mesh2,
			      int level1, int level2,
			      Flag flag1, Flag flag2,
			      DualElInfo &dualElInfo)
    {
      return traverseFirst(mesh1, mesh2, level1, level2, flag1, flag2,
			   &(dualElInfo.rowElInfo), 
			   &(dualElInfo.colElInfo),
			   &(dualElInfo.smallElInfo),
			   &(dualElInfo.largeElInfo));
    }

    /// Get next ElInfo combination
    bool traverseNext(ElInfo **elInfoNext1,
		      ElInfo **elInfoNext2,
		      ElInfo **elInfoSmall,
		      ElInfo **elInfoLarge);

    /// Alternative use for getting the next elements in the dual traversal.
    inline bool traverseNext(DualElInfo &dualElInfo)
    {
      return traverseNext(&(dualElInfo.rowElInfo), 
			  &(dualElInfo.colElInfo),
			  &(dualElInfo.smallElInfo),
			  &(dualElInfo.largeElInfo));
    }

    bool check(ElInfo **elInfo1,
	       ElInfo **elInfo2,
	       ElInfo **elInfoSmall,
	       ElInfo **elInfoLarge) 
    {
      prepareNextStep(elInfo1, elInfo2, elInfoSmall, elInfoLarge);
      return true;
    }
    
    virtual bool skipEl1(ElInfo *elInfo) 
    {
      return false;
    }

    virtual bool skipEl2(ElInfo *elInfo) 
    {
      return false;
    }
    
    inline void setFillSubElemMat(bool b, const BasisFunction *fcts) 
    {
      fillSubElemMat = b;
      basisFcts = fcts;
    }

    /** \brief
     * Checks if the small element has an edge/face which is part of a given edge/face
     * of the large element. If this is the case, it returns the local number of the 
     * small edge/face, and -1 otherwise.
     *
     * \param[in]  dualElInfo    Dual element info with large and small element infos.
     * \param[in]  largeFace     A local edge/face number on the large element.
     */
    static int getFace(DualElInfo *dualElInfo, int largeFace);    
      
  protected:
    /** \brief
     * Determines smaller and larger element, determines which element(s) has to 
     * be incremented in the next step 
     */
    void prepareNextStep(ElInfo **elInfo1,
			 ElInfo **elInfo2,
			 ElInfo **elInfoSmall,
			 ElInfo **elInfoLarge);

    void fillSubElInfo(ElInfo *elInfo1, 
		       ElInfo *elInfo2,
		       ElInfo *elInfoSmall,
		       ElInfo *elInfoLarge);

  protected:
    /// Stack for mesh 1
    TraverseStack stack1;

    /// Stack for mesh 2
    TraverseStack stack2;

    /** \brief
     * used to determine whether all small elements belonging to the large
     * element are traversed.
     */
    double rest;

    /// true if element 1 should be incremented (set in prepareNextStep())
    bool inc1;

    /// true if element 2 should be incremented (set in prepareNextStep())
    bool inc2;

    /// for level traverse of mesh 1
    int level1_;

    /// for level traverse of mesh 2
    int level2_;

    /// for leaf element level traverse of mesh 1
    bool callLeafElLevel1_;

    /// for leaf element level traverse of mesh 2
    bool callLeafElLevel2_;

    /** \brief
     * If true, during dual mesh traverse for the smaller element the transformation
     * matrix will be computed. This matrix defines the transformation mapping for 
     * points defined on the larger element to the coordinates of the smaller element.
     */
    bool fillSubElemMat;

    /** \brief
     * If \ref fillSubElemMat is set to true, the corresponding transformation
     * matrices are computed. These depend on the basis functions that are used.
     */
    const BasisFunction *basisFcts;
  };

}

#endif