/*    This file is part of the Gudhi Library. The Gudhi library 
  *    (Geometric Understanding in Higher Dimensions) is a generic C++ 
  *    library for computational topology.
  *
  *    Author(s):       Clément Maria
  *
  *    Copyright (C) 2014  INRIA Sophia Antipolis-Méditerranée (France)
  *
  *    This program is free software: you can redistribute it and/or modify
  *    it under the terms of the GNU General Public License as published by
  *    the Free Software Foundation, either version 3 of the License, or
  *    (at your option) any later version.
  *
  *    This program 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 General Public License for more details.
  *
  *    You should have received a copy of the GNU General Public License
  *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */

#ifndef SIMPLEX_TREE_ITERATORS_H
#define SIMPLEX_TREE_ITERATORS_H

#include "boost/iterator/iterator_facade.hpp"

namespace Gudhi{

/* \addtogroup simplex_tree
  * Iterators and range types for the Simplex_tree.
  * @{
  */

/* \brief Iterator over the vertices of a simplex
  * in a SimplexTree.
  *
  * Forward iterator, 'value_type' is SimplexTree::Vertex_handle.*/
template < class SimplexTree >
class Simplex_tree_simplex_vertex_iterator 
: public boost::iterator_facade < Simplex_tree_simplex_vertex_iterator < SimplexTree >
                                , typename SimplexTree::Vertex_handle const
                                , boost::forward_traversal_tag
                                , typename SimplexTree::Vertex_handle const
                                >
{
public:
  typedef typename SimplexTree::Simplex_handle Simplex_handle;
  typedef typename SimplexTree::Siblings       Siblings;
  typedef typename SimplexTree::Vertex_handle  Vertex_handle;

  Simplex_tree_simplex_vertex_iterator (SimplexTree * st) :   //any end() iterator
  sib_(NULL), v_(st->null_vertex()) {}

  Simplex_tree_simplex_vertex_iterator( SimplexTree *  st,
                                        Simplex_handle sh) :
  sib_(st->self_siblings(sh)),
  v_(sh->first)    {}

private:
  friend class boost::iterator_core_access;

  bool equal (Simplex_tree_simplex_vertex_iterator const &other) const
  { return sib_ == other.sib_ && v_ == other.v_; }

  Vertex_handle const& dereference() const { return v_; }

  void increment () { v_ = sib_->parent(); sib_ = sib_->oncles();}

  Siblings *    sib_;
  Vertex_handle        v_;
};

/*---------------------------------------------------------------------------*/
/* \brief Iterator over the simplices of the boundary of a
  *  simplex.
  *
  * Forward iterator, value_type is SimplexTree::Simplex_handle.*/
template < class SimplexTree >
class Simplex_tree_boundary_simplex_iterator 
: public boost::iterator_facade < Simplex_tree_boundary_simplex_iterator< SimplexTree >
                                , typename SimplexTree::Simplex_handle const
                                , boost::forward_traversal_tag
                                >
{
public:
  typedef typename SimplexTree::Simplex_handle  Simplex_handle;
  typedef typename SimplexTree::Vertex_handle   Vertex_handle;
  typedef typename SimplexTree::Siblings        Siblings;

// any end() iterator
  Simplex_tree_boundary_simplex_iterator(SimplexTree * st) :
  last_(st->null_vertex()), sib_(NULL) {}

  Simplex_tree_boundary_simplex_iterator ( SimplexTree *  st,
                                           Simplex_handle sh ) :
  suffix_(), st_(st)
  { 
    last_          = sh->first;
    Siblings * sib = st->self_siblings(sh);
    next_          = sib->parent();
    sib_           = sib->oncles();       /* \todo check if NULL*/
    if(sib_ != NULL) { sh_ = sib_->find(next_); }
    else { last_ = st->null_vertex(); } // vertex: == end()
  }

private:
  friend class boost::iterator_core_access;
// valid when iterating along the SAME boundary.
  bool equal (Simplex_tree_boundary_simplex_iterator const& other) const
  { return (sib_ == other.sib_ && last_ == other.last_);}

  Simplex_handle const& dereference () const  { return sh_; }

  void increment()
  { 
    if(sib_ == NULL) { last_ = st_->null_vertex(); return; }
    
    Siblings * for_sib = sib_;
    for(typename std::vector< Vertex_handle >::reverse_iterator rit = suffix_.rbegin();
      rit != suffix_.rend(); ++rit)
    {
      sh_ = for_sib->find(*rit);
      for_sib =  sh_->second.children();
    } 
    sh_ = for_sib->find(last_); //sh_ points to the right simplex now
    suffix_.push_back(next_);
    next_ = sib_->parent();
    sib_ = sib_->oncles();
  }

  Vertex_handle                   last_   ; //last vertex of the simplex
  Vertex_handle                   next_   ; //next vertex to push in suffix_
  std::vector< Vertex_handle >    suffix_ ;
  Siblings *                      sib_    ; //where the next search will start from
  Simplex_handle                  sh_     ; //current Simplex_handle in the boundary
  SimplexTree *                   st_     ; //simplex containing the simplicial complex
};
/*---------------------------------------------------------------------------*/
/* \brief Iterator over the simplices of a simplicial complex.
  *
  * Forward iterator, value_type is SimplexTree::Simplex_handle.*/
template < class SimplexTree >
class Simplex_tree_complex_simplex_iterator 
: public boost::iterator_facade < Simplex_tree_complex_simplex_iterator< SimplexTree >
                                , typename SimplexTree::Simplex_handle const 
                                , boost::forward_traversal_tag
                                >
{
public:
  typedef typename SimplexTree::Simplex_handle Simplex_handle;
  typedef typename SimplexTree::Siblings       Siblings;
  typedef typename SimplexTree::Vertex_handle  Vertex_handle;

//any end() iterator
  Simplex_tree_complex_simplex_iterator() : st_(NULL) {}

  Simplex_tree_complex_simplex_iterator(SimplexTree * st) :
  st_(st) 
  {
    if(st == NULL || st->root() == NULL || st->root()->members().empty())  { st_ = NULL; }
    else
   {
    sh_ = st->root()->members().begin();
    sib_ = st->root();
    while(st->has_children(sh_)) 
      { sib_ = sh_->second.children();
        sh_ = sib_->members().begin(); }
    }
  }
private:
  friend class boost::iterator_core_access;

// valid when iterating along the SAME boundary.
  bool equal (Simplex_tree_complex_simplex_iterator const& other) const
  {
    if(other.st_ == NULL) { return (st_ == NULL); }
    if(st_ == NULL) { return false; }
    return (&(sh_->second) == &(other.sh_->second));
  }

  Simplex_handle const& dereference () const { return sh_; }

// Depth first traversal.
  void increment ()
  {
    ++sh_;
    if(sh_ == sib_->members().end())
    {
      if(sib_->oncles() == NULL) { st_ = NULL; return; } //reach the end
      sh_ = sib_->oncles()->members().find(sib_->parent());
      sib_ = sib_->oncles();    
      return; 
    }
    while(st_->has_children(sh_)) 
    {
     sib_ = sh_->second.children();
     sh_ = sib_->members().begin(); 
    }
  }

  Simplex_handle     sh_;
  Siblings *         sib_;
  SimplexTree *      st_;
};

/* \brief Iterator over the simplices of the skeleton of a given
  * dimension of the simplicial complex.
  *
  * Forward iterator, value_type is SimplexTree::Simplex_handle.*/
template < class SimplexTree >
class Simplex_tree_skeleton_simplex_iterator 
: public boost::iterator_facade < Simplex_tree_skeleton_simplex_iterator< SimplexTree >
                                , typename SimplexTree::Simplex_handle const 
                                , boost::forward_traversal_tag
                                >
{
public:
  typedef typename SimplexTree::Simplex_handle Simplex_handle;
  typedef typename SimplexTree::Siblings       Siblings;
  typedef typename SimplexTree::Vertex_handle  Vertex_handle;

//any end() iterator
  Simplex_tree_skeleton_simplex_iterator() : st_(NULL) {}

  Simplex_tree_skeleton_simplex_iterator( SimplexTree * st
                                        , int dim_skel ) 
  : st_(st) 
  , dim_skel_(dim_skel)
  , curr_dim_(0)
  {
    if(st == NULL || st->root() == NULL || st->root()->members().empty())  { st_ = NULL; }
    else
   {
    sh_ = st->root()->members().begin();
    sib_ = st->root();
    while(st->has_children(sh_) && curr_dim_ < dim_skel_) 
      { sib_ = sh_->second.children();
        sh_ = sib_->members().begin();
        ++curr_dim_; }
    }
  }
private:
  friend class boost::iterator_core_access;

// valid when iterating along the SAME boundary.
  bool equal (Simplex_tree_skeleton_simplex_iterator const& other) const
  {
    if(other.st_ == NULL) { return (st_ == NULL); }
    if(st_ == NULL)       { return false; }
    return (&(sh_->second) == &(other.sh_->second));
  }

  Simplex_handle const& dereference () const { return sh_; }

// Depth first traversal of the skeleton.
  void increment ()
  {
    ++sh_;
    if(sh_ == sib_->members().end())
    {
      if(sib_->oncles() == NULL) { st_ = NULL; return; } //reach the end
      sh_ = sib_->oncles()->members().find(sib_->parent());
      sib_ = sib_->oncles();
      --curr_dim_;    
      return; 
    }
    while(st_->has_children(sh_) && curr_dim_ < dim_skel_) 
    {
     sib_ = sh_->second.children();
     sh_ = sib_->members().begin(); 
     ++curr_dim_;
    }
  }

  Simplex_handle     sh_;
  Siblings *         sib_;
  SimplexTree *      st_;
  int                dim_skel_;
  int                curr_dim_;
};

/* @} */ //end addtogroup simplex_tree

}  // namespace GUDHI

#endif // SIMPLEX_TREE_ITERATORS_H