////////////////////////////////////////////////////////////////////////////////
// 
// Flip.cc
//
//    produced: 18/06/98 jr
// 
////////////////////////////////////////////////////////////////////////////////
#include <iostream>
#include <assert.h>
#include <vector>

#include "LabelSet.hh"
#include "Circuits.hh"
#include "Flip.hh"
#include "TriangNode.hh"

namespace topcom {

  // class FlipRep:
  // constructors:
  FlipRep::FlipRep(const Chirotope& chiro, const dependent_set_type& ds, const TriangNode& tn) :
    fliprep_type() {
    MessageStreams::debug() << "\t\t constructing a flip representation from dependent set " << ds
					<< " in " << tn << " in rank " << tn.rank() << " ..." << std::endl;
    const Circuit circuit(chiro, ds);
    MessageStreams::debug() << "\t\t\t induced circuit is " << circuit << std::endl;
    const Simplex c_support(circuit.support());
    if (c_support.card() == tn.rank() + 1) {

      // general position circuit:
      if (tn.containment_ok(circuit)) {
	first = circuit.first;
	second = circuit.second;
      }
      else if (tn.containment_ok(circuit.inverse())) {
	first = circuit.second;
	second = circuit.first;
      }
    }
    else {

      // special position circuit:
      if (tn.link_ok(circuit)) {
	first = circuit.first;
	second = circuit.second;
      }
      else if (tn.link_ok(circuit.inverse())) {
	first = circuit.second;
	second = circuit.first;
      }
    }
    MessageStreams::debug() << "\t\t induced flip representation is " << *this << "." << std::endl;
  }

  // class Flip:
  // internal algorithms:
  void Flip::_construct(const TriangNode& tn, const Circuit& circuit) {
    Simplex simp(circuit.support());

    // general position circuit:
    if (simp.card() == tn.rank() + 1) {
      for (LabelSet::const_iterator iter = circuit.first.begin();
	   iter != circuit.first.end();
	   ++iter) {
	simp -= *iter;
	first += simp;
	simp += *iter;
      }
      for (LabelSet::const_iterator iter = circuit.second.begin();
	   iter != circuit.second.end();
	   ++iter) {
	simp -= *iter;
	second += simp;
	simp += *iter;
      }
    }
    else {

      // special position circuit:
      std::vector<Simplex> common_link;
      LabelSet::const_iterator first_iter = circuit.first.begin();
      simp -= *first_iter;
      for (SimplicialComplex::const_iterator tn_iter = tn.begin();
	   tn_iter != tn.end();
	   ++tn_iter) {
	if (tn_iter->superset(simp)) {
	  first += *tn_iter;
	  common_link.push_back(*tn_iter - simp);
	}
      }
      simp += *first_iter;
      while (++first_iter != circuit.first.end()) {
	simp -= *first_iter;
	for (size_type i = 0; i < common_link.size(); ++i) {
	  first += (simp + common_link[i]);
	}
	simp += *first_iter;
      }
      for (LabelSet::const_iterator second_iter = circuit.second.begin();
	   second_iter != circuit.second.end();
	   ++second_iter) {
	simp -= *second_iter;
	for (size_type i = 0; i < common_link.size(); ++i) {
	  second += (simp + common_link[i]);
	}
	simp += *second_iter;
      }
    }
  }

  void Flip::_construct(const Chirotope& chiro, const TriangNode& tn, const dependent_set_type& ds) {
    const Circuit circuit(chiro, ds);
    _construct(tn, circuit);
  }

}; // namespace topcom

// eof Flip.cc
