/* Copyright (c) 1997-2018
   Ewgenij Gawrilow, Michael Joswig (Technische Universitaet Berlin, Germany)
   http://www.polymake.org

   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 2, or (at your option) any
   later version: http://www.gnu.org/licenses/gpl.txt.

   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.
--------------------------------------------------------------------------------
*/

#include "polymake/client.h"
#include "polymake/Array.h"
#include "polymake/Set.h"
#include "polymake/Matrix.h"
#include "polymake/linalg.h"
#include "polymake/Rational.h"
#include "polymake/PowerSet.h"

namespace polymake { namespace matroid {

   Array<Set<int> > dual_bases_from_bases(int n_elements, const Array<Set<int> >&bases) {
      Array<Set<int> > result(bases.size());
      Set<int> total_set = sequence(0,n_elements);
      for(pm::ensure_features< Array< Set<int> >, pm::cons<pm::end_sensitive, pm::indexed> >::const_iterator b = ensure( bases, (pm::cons<pm::end_sensitive, pm::indexed>*)0).begin(); !b.at_end(); b++) {
         result[b.index()] = total_set - *b;
      }
      return result;
   }

   Array<Set<int> > dual_circuits_from_bases(const int n, const Array<Set<int> >& bases)
   {
      if(bases.empty()) {
         return Array<Set<int> >();
      }
      const int  r=bases[0].size();
      if (r==0) return Array<Set<int> >(0);
      if (r==n) {
         Array<Set<int> > c(n);
         for (int i=0; i<n;++i)
            c[i]=scalar2set(i);
         return c;
      } 
      int n_cocircuits=0;
      std::vector<Set<int> > cocircuits;
      for (int k=1; k<=n-r+1; ++k)
         for (Entire< Subsets_of_k<const sequence&> >::const_iterator j=entire(all_subsets_of_k(sequence(0,n),k));!j.at_end();++j) {
            bool is_cocircuit=true;
            for (Entire<std::vector<Set<int> > >::const_iterator i=entire(cocircuits); is_cocircuit&&!i.at_end();++i) 
               if (incl(*i,*j)<=0) is_cocircuit=false;
            for (Entire<Array<Set<int> > >::const_iterator i = entire(bases); is_cocircuit&&!i.at_end(); ++i){
               if (((*i)*(*j)).empty()) is_cocircuit=false;
            }
            if (is_cocircuit) {
               cocircuits.push_back(Set<int>(*j));
               ++n_cocircuits;
            }
         }
      return Array<Set<int> >(n_cocircuits,entire(cocircuits));
   }

	Array<Set<int> > bases_from_dual_circuits(const int n, const Array<Set<int> >& cocircuits)
	{
		if (cocircuits.empty()) return Array<Set<int> >(1);
		int n_bases=0;
		std::vector<Set<int> > bases;
		int r=n;
		for (int k=1; k<=r; ++k)
			for (Entire< Subsets_of_k<const sequence&> >::const_iterator j=entire(all_subsets_of_k(sequence(0,n),k));!j.at_end();++j) {
				bool is_basis=true;
				for (Entire<Array<Set<int> > >::const_iterator i = entire(cocircuits); is_basis&&!i.at_end(); ++i){
					if (((*i)*(*j)).empty()) is_basis=false;
				}
				if (is_basis) {
					bases.push_back(Set<int>(*j));
					++n_bases;
					r=k;
				}
			}
		return Array<Set<int> >(n_bases,entire(bases));
	}


	Array<Set<int> > bases_from_dual_circuits_and_rank(const int n, const int rank, const Array<Set<int> >& cocircuits)
	{
		if (cocircuits.empty()) return Array<Set<int> >(1);
		int n_bases=0;
		std::vector<Set<int> > bases;
		for (Entire< Subsets_of_k<const sequence&> >::const_iterator j=entire(all_subsets_of_k(sequence(0,n),rank));!j.at_end();++j) {
			bool is_basis=true;
			for (Entire<Array<Set<int> > >::const_iterator i = entire(cocircuits); is_basis&&!i.at_end(); ++i){
				if (((*i)*(*j)).empty()) is_basis=false;
			}
			if (is_basis) {
				bases.push_back(Set<int>(*j));
				++n_bases;
			}
		}
		return Array<Set<int> >(n_bases,entire(bases));
	}



   Function4perl(&dual_bases_from_bases, "dual_bases_from_bases");
   Function4perl(&dual_circuits_from_bases, "dual_circuits_from_bases");
   Function4perl(&bases_from_dual_circuits, "bases_from_dual_circuits");
   Function4perl(&bases_from_dual_circuits_and_rank, "bases_from_dual_circuits_and_rank");

} }

// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
