/*    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):       David Salinas
 *
 *    Copyright (C) 2014  INRIA Sophia Antipolis-Mediterranee (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 SRC_SKELETON_BLOCKER_INCLUDE_GUDHI_SKELETON_BLOCKER_COMPLEX_H_
#define SRC_SKELETON_BLOCKER_INCLUDE_GUDHI_SKELETON_BLOCKER_COMPLEX_H_

#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/connected_components.hpp>
#include <boost/iterator/transform_iterator.hpp>
#include <boost/range/adaptor/map.hpp>

#include <iostream>
#include <fstream>
#include <sstream>
#include <memory>
#include <map>
#include <list>
#include <set>
#include <vector>
#include <string>
#include <algorithm>
#include <utility>

#include "gudhi/Skeleton_blocker/iterators/Skeleton_blockers_iterators.h"
#include "gudhi/Skeleton_blocker_link_complex.h"
#include "gudhi/Skeleton_blocker/Skeleton_blocker_link_superior.h"
#include "gudhi/Skeleton_blocker/Skeleton_blocker_sub_complex.h"
#include "gudhi/Skeleton_blocker/Skeleton_blocker_simplex.h"

#include "gudhi/Skeleton_blocker/Skeleton_blocker_complex_visitor.h"
#include "gudhi/Skeleton_blocker/internal/Top_faces.h"
#include "gudhi/Utils.h"

namespace Gudhi {

namespace skbl {

/**
 *@class Skeleton_blocker_complex
 *@brief Abstract Simplicial Complex represented with a skeleton/blockers pair.
 *@ingroup skbl
 */
template<class SkeletonBlockerDS>
class Skeleton_blocker_complex {
  template<class ComplexType> friend class Complex_vertex_iterator;
  template<class ComplexType> friend class Complex_neighbors_vertices_iterator;
  template<class ComplexType> friend class Complex_edge_iterator;
  template<class ComplexType> friend class Complex_edge_around_vertex_iterator;

  template<class ComplexType> friend class Skeleton_blocker_link_complex;
  template<class ComplexType> friend class Skeleton_blocker_link_superior;
  template<class ComplexType> friend class Skeleton_blocker_sub_complex;

 public:
  /**
   * @brief The type of stored vertex node, specified by the template SkeletonBlockerDS
   */
  typedef typename SkeletonBlockerDS::Graph_vertex Graph_vertex;

  /**
   * @brief The type of stored  edge node, specified by the template SkeletonBlockerDS
   */
  typedef typename SkeletonBlockerDS::Graph_edge Graph_edge;

  typedef typename SkeletonBlockerDS::Root_vertex_handle Root_vertex_handle;

  /**
   * @brief The type of an handle to a vertex of the complex.
   */
  typedef typename SkeletonBlockerDS::Vertex_handle Vertex_handle;
  typedef typename Root_vertex_handle::boost_vertex_handle boost_vertex_handle;

  /**
   * @brief A ordered set of integers that represents a simplex.
   */
  typedef Skeleton_blocker_simplex<Vertex_handle> Simplex_handle;
  typedef Skeleton_blocker_simplex<Root_vertex_handle> Root_simplex_handle;

  /**
   * @brief Handle to a blocker of the complex.
   */
  typedef Simplex_handle* Blocker_handle;

  typedef typename Root_simplex_handle::Simplex_vertex_const_iterator Root_simplex_iterator;
  typedef typename Simplex_handle::Simplex_vertex_const_iterator Simplex_handle_iterator;

 protected:
  typedef typename boost::adjacency_list<boost::setS,  // edges
      boost::vecS,  // vertices
      boost::undirectedS, Graph_vertex, Graph_edge> Graph;
  // todo/remark : edges are not sorted, it heavily penalizes computation for SuperiorLink
  // (eg Link with greater vertices)
  // that burdens simplex iteration / complex initialization via list of simplices.
  // to avoid that, one should modify the graph by storing two lists of adjacency for every
  // vertex, the one with superior and the one with lower vertices, that way there is
  // no more extra cost for computation of SuperiorLink
  typedef typename boost::graph_traits<Graph>::vertex_iterator boost_vertex_iterator;
  typedef typename boost::graph_traits<Graph>::edge_iterator boost_edge_iterator;

 protected:
  typedef typename boost::graph_traits<Graph>::adjacency_iterator boost_adjacency_iterator;

 public:
  /**
   * @brief Handle to an edge of the complex.
   */
  typedef typename boost::graph_traits<Graph>::edge_descriptor Edge_handle;

 protected:
  typedef std::multimap<Vertex_handle, Simplex_handle *> BlockerMap;
  typedef typename std::multimap<Vertex_handle, Simplex_handle *>::value_type BlockerPair;
  typedef typename std::multimap<Vertex_handle, Simplex_handle *>::iterator BlockerMapIterator;
  typedef typename std::multimap<Vertex_handle, Simplex_handle *>::const_iterator BlockerMapConstIterator;

 protected:
  int num_vertices_;
  int num_blockers_;

  typedef Skeleton_blocker_complex_visitor<Vertex_handle> Visitor;
  // typedef Visitor* Visitor_ptr;
  Visitor* visitor;

  /**
   * @details If 'x' is a Vertex_handle of a vertex in the complex then degree[x] = d is its degree.
   *
   * This quantity is updated when adding/removing edge.
   *
   * This is useful because the operation
   * list.size() is done in linear time.
   */
  std::vector<boost_vertex_handle> degree_;
  Graph skeleton; /** 1-skeleton of the simplicial complex. */

  // todo remove!!!

  /** Each vertex can access to the blockers passing through it. */
  BlockerMap blocker_map_;

 public:
  /////////////////////////////////////////////////////////////////////////////
  /** @name Constructors, Destructors
   */
  //@{
  /**
   *@brief constructs a simplicial complex with a given number of vertices and a visitor.
   */
  explicit Skeleton_blocker_complex(int num_vertices_ = 0, Visitor* visitor_ = NULL)
      : visitor(visitor_) {
    clear();
    for (int i = 0; i < num_vertices_; ++i) {
      add_vertex();
    }
  }

 private:
  /**
   * 	this nested class is used for the next constructor that takes as an input a list of simplices.
   * 	It stores a vector where the ith cell contains a set of i-simplices
   *
   */
  class Simplices_sets_from_list {
   private:
    typedef std::set<Simplex_handle> Container_simplices;
    typedef typename Container_simplices::iterator Simplices_iterator;
    int dimension_;
    std::vector<Container_simplices> simplices_;

   public:
    explicit Simplices_sets_from_list(std::list<Simplex_handle>& simplices)
        : dimension_(-1) {
      assert(!simplices.empty());

      for (auto simplex = simplices.begin(); simplex != simplices.end();
          ++simplex) {
        dimension_ = std::max(dimension_, static_cast<int>(simplex->dimension()));
      }
      simplices_ = std::vector < Container_simplices > (dimension_ + 1);

      // compute k-simplices
      for (auto simplex = simplices.begin(); simplex != simplices.end();
          ++simplex) {
        simplices_[simplex->dimension()].insert(*simplex);
      }
    }

    Simplices_iterator begin(int k) {
      assert(0 <= k && k <= dimension_);
      return simplices_[k].begin();
    }

    Simplices_iterator end(int k) {
      assert(0 <= k && k <= dimension_);
      return simplices_[k].end();
    }

    Container_simplices& simplices(int k) {
      return simplices_[k];
    }

    int dimension() {
      return dimension_;
    }

    bool contains(const Simplex_handle& simplex) const {
      if (simplex.dimension() > dimension_)
        return false;
      else
        return simplices_[simplex.dimension()].find(simplex)
            != simplices_[simplex.dimension()].end();
    }

    void print() {
      for (int i = 0; i < dimension_; ++i) {
        std::cout << i << "-simplices" << std::endl;
        auto l = simplices_[i];
        for (auto s : l) {
          std::cout << s << std::endl;
        }
      }
    }
  };

  void compute_next_expand(Simplices_sets_from_list& simplices, int dim,
                           std::list<Simplex_handle>& next_expand) {
    next_expand.clear();

    // high_resolution_clock::time_point tbeginfor = high_resolution_clock::now();
    // auto durationlooplink = std::chrono::duration_cast<std::chrono::microseconds>( tbeginfor - tbeginfor ).count();

    for (auto sigma = simplices.begin(dim); sigma != simplices.end(dim);
        ++sigma) {
      // high_resolution_clock::time_point tbeg = high_resolution_clock::now();
      Simplex_handle t(*sigma);
      Skeleton_blocker_link_superior<Skeleton_blocker_complex> link(*this, t);
      // xxx all time here, most likely because accessing superior edges needs passing through lower one
      // currently

      // durationlooplink += std::chrono::duration_cast<std::chrono::microseconds>( high_resolution_clock::now() - tbeg ).count();

      for (auto v : link.vertex_range()) {
        Vertex_handle v_in_complex(*this->get_address(link.get_id(v)));
        t.add_vertex(v_in_complex);
        next_expand.push_back(t);
        t.remove_vertex(v_in_complex);
      }
    }
    // high_resolution_clock::time_point t2 = high_resolution_clock::now();
    // auto durationlooptotal = std::chrono::duration_cast<std::chrono::microseconds>( t2 - tbeginfor ).count();
    // DBGVALUE(durationlooptotal);
    // DBGVALUE(durationlooplink);
  }

 public:
  /**
   * @brief Constructor with a list of simplices.
   * @details The list of simplices must be the list
   * of simplices of a simplicial complex.
   */
  Skeleton_blocker_complex(std::list<Simplex_handle>& simplices,
                           Visitor* visitor_ = NULL)
      : num_vertices_(0),
        num_blockers_(0),
        visitor(visitor_) {
    Simplices_sets_from_list set_simplices(simplices);

    int dim = set_simplices.dimension();

    // add 1-skeleton to the complex
    for (auto v_it = set_simplices.begin(0); v_it != set_simplices.end(0);
        ++v_it)
      add_vertex();

    for (auto e_it = set_simplices.begin(1); e_it != set_simplices.end(1);
        ++e_it) {
      Vertex_handle a = e_it->first_vertex();
      Vertex_handle b = e_it->last_vertex();
      assert(contains_vertex(a) && contains_vertex(b));
      add_edge(a, b);
    }

    // then add blockers
    for (int current_dim = 1; current_dim <= dim; ++current_dim) {
      std::list<Simplex_handle> expansion_simplices;
      compute_next_expand(set_simplices, current_dim, expansion_simplices);

      for (const auto &simplex : expansion_simplices) {
        if (!set_simplices.contains(simplex)) {
          add_blocker(simplex);
        }
      }
    }
  }

  // We cannot use the default copy constructor since we need
  // to make a copy of each of the blockers
  Skeleton_blocker_complex(const Skeleton_blocker_complex& copy) {
    visitor = NULL;
    degree_ = copy.degree_;
    skeleton = Graph(copy.skeleton);
    num_vertices_ = copy.num_vertices_;

    num_blockers_ = 0;
    // we copy the blockers
    for (auto blocker : copy.const_blocker_range()) {
      add_blocker(*blocker);
    }
  }

  /**
   */
  Skeleton_blocker_complex& operator=(const Skeleton_blocker_complex& copy) {
    clear();
    visitor = NULL;
    degree_ = copy.degree_;
    skeleton = Graph(copy.skeleton);
    num_vertices_ = copy.num_vertices_;

    num_blockers_ = 0;
    // we copy the blockers
    for (auto blocker : copy.const_blocker_range())
      add_blocker(*blocker);
    return *this;
  }

  /**
   * The destructor delete all blockers allocated.
   */
  virtual ~Skeleton_blocker_complex() {
    clear();
  }

  /**
   * @details Clears the simplicial complex. After a call to this function,
   * blockers are destroyed. The 1-skeleton and the set of blockers
   * are both empty.
   */
  virtual void clear() {
    // xxx for now the responsabilty of freeing the visitor is for
    // the user
    visitor = NULL;

    degree_.clear();
    num_vertices_ = 0;

    remove_blockers();

    skeleton.clear();
  }

  /**
   *@brief allows to change the visitor.
   */
  void set_visitor(Visitor* other_visitor) {
    visitor = other_visitor;
  }

  //@}

  /////////////////////////////////////////////////////////////////////////////
  /** @name Vertices operations
   */
  //@{
 public:
  /**
   * @brief Return a local Vertex_handle of a vertex given a global one.
   * @remark Assume that the vertex is present in the complex.
   */
  Vertex_handle operator[](Root_vertex_handle global) const {
    auto local(get_address(global));
    assert(local);
    return *local;
  }

  /**
   * @brief Return the vertex node associated to local Vertex_handle.
   * @remark Assume that the vertex is present in the complex.
   */
  Graph_vertex& operator[](Vertex_handle address) {
    assert(
        0 <= address.vertex && address.vertex < boost::num_vertices(skeleton));
    return skeleton[address.vertex];
  }

  /**
   * @brief Return the vertex node associated to local Vertex_handle.
   * @remark Assume that the vertex is present in the complex.
   */
  const Graph_vertex& operator[](Vertex_handle address) const {
    assert(
        0 <= address.vertex && address.vertex < boost::num_vertices(skeleton));
    return skeleton[address.vertex];
  }

  /**
   * @brief Adds a vertex to the simplicial complex and returns its Vertex_handle.
   */
  Vertex_handle add_vertex() {
    Vertex_handle address(boost::add_vertex(skeleton));
    num_vertices_++;
    (*this)[address].activate();
    // safe since we now that we are in the root complex and the field 'address' and 'id'
    // are identical for every vertices
    (*this)[address].set_id(Root_vertex_handle(address.vertex));
    degree_.push_back(0);
    if (visitor)
      visitor->on_add_vertex(address);
    return address;
  }

  /**
   * @brief Remove a vertex from the simplicial complex
   * @remark It just deactivates the vertex with a boolean flag but does not
   * remove it from vertices from complexity issues.
   */
  void remove_vertex(Vertex_handle address) {
    assert(contains_vertex(address));
    // We remove b
    boost::clear_vertex(address.vertex, skeleton);
    (*this)[address].deactivate();
    num_vertices_--;
    degree_[address.vertex] = -1;
    if (visitor)
      visitor->on_remove_vertex(address);
  }

  /**
   */
  bool contains_vertex(Vertex_handle u) const {
    if (u.vertex < 0 || u.vertex >= boost::num_vertices(skeleton))
      return false;
    return (*this)[u].is_active();
  }

  /**
   */
  bool contains_vertex(Root_vertex_handle u) const {
    boost::optional<Vertex_handle> address = get_address(u);
    return address && (*this)[*address].is_active();
  }

  /**
   * @return true iff the simplicial complex contains all vertices
   * of simplex sigma
   */
  bool contains_vertices(const Simplex_handle & sigma) const {
    for (auto vertex : sigma)
      if (!contains_vertex(vertex))
        return false;
    return true;
  }

  /**
   * @brief Given an Id return the address of the vertex having this Id in the complex.
   * @remark For a simplicial complex, the address is the id but it may not be the case for a SubComplex.
   */
  virtual boost::optional<Vertex_handle> get_address(
      Root_vertex_handle id) const {
    boost::optional<Vertex_handle> res;
    if (id.vertex < boost::num_vertices(skeleton))
      res = Vertex_handle(id.vertex);  // xxx
    return res;
  }

  /**
   * return the id of a vertex of adress local present in the graph
   */
  Root_vertex_handle get_id(Vertex_handle local) const {
    assert(0 <= local.vertex && local.vertex < boost::num_vertices(skeleton));
    return (*this)[local].get_id();
  }

  /**
   * @brief Convert an address of a vertex of a complex to the address in
   * the current complex.
   * @details
   * If the current complex is a sub (or sup) complex of 'other', it converts
   * the address of a vertex v expressed in 'other' to the address of the vertex
   * v in the current one.
   * @remark this methods uses Root_vertex_handle to identify the vertex and
   * assumes the vertex is present in the current complex.
   */
  Vertex_handle convert_handle_from_another_complex(
      const Skeleton_blocker_complex& other, Vertex_handle vh_in_other) const {
    auto vh_in_current_complex = get_address(other.get_id(vh_in_other));
    assert(vh_in_current_complex);
    return *vh_in_current_complex;
  }

  /**
   * @brief return the graph degree of a vertex.
   */
  int degree(Vertex_handle local) const {
    assert(0 <= local.vertex && local.vertex < boost::num_vertices(skeleton));
    return degree_[local.vertex];
  }

  //@}

  /////////////////////////////////////////////////////////////////////////////
  /** @name Edges operations
   */
  //@{
 public:
  /**
   * @brief return an edge handle if the two vertices forms
   * an edge in the complex
   */
  boost::optional<Edge_handle> operator[](
      const std::pair<Vertex_handle, Vertex_handle>& ab) const {
    boost::optional<Edge_handle> res;
    std::pair<Edge_handle, bool> edge_pair(
        boost::edge(ab.first.vertex, ab.second.vertex, skeleton));
    if (edge_pair.second)
      res = edge_pair.first;
    return res;
  }

  /**
   * @brief returns the stored node associated to an edge
   */
  Graph_edge& operator[](Edge_handle edge_handle) {
    return skeleton[edge_handle];
  }

  /**
   * @brief returns the stored node associated to an edge
   */
  const Graph_edge& operator[](Edge_handle edge_handle) const {
    return skeleton[edge_handle];
  }

  /**
   * @brief returns the first vertex of an edge
   * @details it assumes that the edge is present in the complex
   */
  Vertex_handle first_vertex(Edge_handle edge_handle) const {
    return static_cast<Vertex_handle>(source(edge_handle, skeleton));
  }

  /**
   * @brief returns the first vertex of an edge
   * @details it assumes that the edge is present in the complex
   */
  Vertex_handle second_vertex(Edge_handle edge_handle) const {
    return static_cast<Vertex_handle>(target(edge_handle, skeleton));
  }

  /**
   * @brief returns the simplex made with the two vertices of the edge
   * @details it assumes that the edge is present in the complex

   */
  Simplex_handle get_vertices(Edge_handle edge_handle) const {
    auto edge((*this)[edge_handle]);
    return Simplex_handle((*this)[edge.first()], (*this)[edge.second()]);
  }

  /**
   * @brief Adds an edge between vertices a and b and all its cofaces.
   */
  Edge_handle add_edge(Vertex_handle a, Vertex_handle b) {
    assert(contains_vertex(a) && contains_vertex(b));
    assert(a != b);

    auto edge_handle((*this)[std::make_pair(a, b)]);
    // std::pair<Edge_handle,bool> pair_descr_bool = (*this)[std::make_pair(a,b)];
    // Edge_handle edge_descr;
    // bool edge_present = pair_descr_bool.second;
    if (!edge_handle) {
      edge_handle = boost::add_edge(a.vertex, b.vertex, skeleton).first;
      (*this)[*edge_handle].setId(get_id(a), get_id(b));
      degree_[a.vertex]++;
      degree_[b.vertex]++;
      if (visitor)
        visitor->on_add_edge(a, b);
    }
    return *edge_handle;
  }

  /**
   * @brief Adds all edges and their cofaces of a simplex to the simplicial complex.
   */
  void add_edges(const Simplex_handle & sigma) {
    Simplex_handle_iterator i, j;
    for (i = sigma.begin(); i != sigma.end(); ++i)
      for (j = i, j++; j != sigma.end(); ++j)
        add_edge(*i, *j);
  }

  /**
   * @brief Removes an edge from the simplicial complex and all its cofaces.
   * @details returns the former Edge_handle representing the edge
   */
  virtual Edge_handle remove_edge(Vertex_handle a, Vertex_handle b) {
    bool found;
    Edge_handle edge;
    tie(edge, found) = boost::edge(a.vertex, b.vertex, skeleton);
    if (found) {
      if (visitor)
        visitor->on_remove_edge(a, b);
      // if (heapCollapse.Contains(edge)) heapCollapse.Delete(edge);
      boost::remove_edge(a.vertex, b.vertex, skeleton);
      degree_[a.vertex]--;
      degree_[b.vertex]--;
    }
    return edge;
  }

  /**
   * @brief Removes edge and its cofaces from the simplicial complex.
   */
  void remove_edge(Edge_handle edge) {
    assert(contains_vertex(first_vertex(edge)));
    assert(contains_vertex(second_vertex(edge)));
    remove_edge(first_vertex(edge), second_vertex(edge));
  }

  /**
   * @brief The complex is reduced to its set of vertices.
   * All the edges and blockers are removed.
   */
  void keep_only_vertices() {
    remove_blockers();

    for (auto u : vertex_range()) {
      while (this->degree(u) > 0) {
        Vertex_handle v(*(adjacent_vertices(u.vertex, this->skeleton).first));
        this->remove_edge(u, v);
      }
    }
  }

  /**
   * @return true iff the simplicial complex contains an edge between
   * vertices a and b
   */
  bool contains_edge(Vertex_handle a, Vertex_handle b) const {
    // if (a.vertex<0 || b.vertex <0) return false;
    return boost::edge(a.vertex, b.vertex, skeleton).second;
  }

  /**
   * @return true iff the simplicial complex contains all vertices
   * and all edges of simplex sigma
   */
  bool contains_edges(const Simplex_handle & sigma) const {
    for (auto i = sigma.begin(); i != sigma.end(); ++i) {
      if (!contains_vertex(*i))
        return false;
      for (auto j = i; ++j != sigma.end();) {
        if (!contains_edge(*i, *j))
          return false;
      }
    }
    return true;
  }
  //@}

  /////////////////////////////////////////////////////////////////////////////
  /** @name Blockers operations
   */
  //@{
  /**
   * @brief Adds the simplex to the set of blockers and
   * returns a Blocker_handle toward it if was not present before and 0 otherwise.
   */
  Blocker_handle add_blocker(const Simplex_handle& blocker) {
    assert(blocker.dimension() > 1);
    if (contains_blocker(blocker)) {
      // std::cerr << "ATTEMPT TO ADD A BLOCKER ALREADY THERE ---> BLOCKER IGNORED" << endl;
      return 0;
    } else {
      if (visitor)
        visitor->on_add_blocker(blocker);
      Blocker_handle blocker_pt = new Simplex_handle(blocker);
      num_blockers_++;
      auto vertex = blocker_pt->begin();
      while (vertex != blocker_pt->end()) {
        blocker_map_.insert(BlockerPair(*vertex, blocker_pt));
        ++vertex;
      }
      return blocker_pt;
    }
  }

 protected:
  /**
   * @brief Adds the simplex to the set of blockers
   */
  void add_blocker(Blocker_handle blocker) {
    if (contains_blocker(*blocker)) {
      // std::cerr << "ATTEMPT TO ADD A BLOCKER ALREADY THERE ---> BLOCKER IGNORED" << endl;
      return;
    } else {
      if (visitor)
        visitor->on_add_blocker(*blocker);
      num_blockers_++;
      auto vertex = blocker->begin();
      while (vertex != blocker->end()) {
        blocker_map_.insert(BlockerPair(*vertex, blocker));
        ++vertex;
      }
    }
  }

 protected:
  /**
   * Removes sigma from the blocker map of vertex v
   */
  void remove_blocker(const Blocker_handle sigma, Vertex_handle v) {
    Complex_blocker_around_vertex_iterator blocker;
    for (blocker = blocker_range(v).begin(); blocker != blocker_range(v).end();
        ++blocker) {
      if (*blocker == sigma)
        break;
    }
    if (*blocker != sigma) {
      std::cerr
          << "bug ((*blocker).second == sigma) ie try to remove a blocker not present\n";
      assert(false);
    } else {
      blocker_map_.erase(blocker.current_position());
    }
  }

 public:
  /**
   * @brief Removes the simplex from the set of blockers.
   * @remark sigma has to belongs to the set of blockers
   */
  void remove_blocker(const Blocker_handle sigma) {
    for (auto vertex : *sigma) {
      remove_blocker(sigma, vertex);
    }
    num_blockers_--;
  }

  /**
   * @brief Remove all blockers, in other words, it expand the simplicial
   * complex to the smallest flag complex that contains it.
   */
  void remove_blockers() {
    // Desallocate the blockers
    while (!blocker_map_.empty()) {
      delete_blocker(blocker_map_.begin()->second);
    }
    num_blockers_ = 0;
    blocker_map_.clear();
  }

 protected:
  /**
   * Removes the simplex sigma from the set of blockers.
   * sigma has to belongs to the set of blockers
   *
   * @remark contrarily to delete_blockers does not call the destructor
   */
  void remove_blocker(const Simplex_handle& sigma) {
    assert(contains_blocker(sigma));
    for (auto vertex : sigma)
      remove_blocker(sigma, vertex);
    num_blockers_--;
  }

 public:
  /**
   * Removes the simplex s from the set of blockers
   * and desallocate s.
   */
  void delete_blocker(Blocker_handle sigma) {
    if (visitor)
      visitor->on_delete_blocker(sigma);
    remove_blocker(sigma);
    delete sigma;
  }

  /**
   * @return true iff s is a blocker of the simplicial complex
   */
  bool contains_blocker(const Blocker_handle s) const {
    if (s->dimension() < 2)
      return false;

    Vertex_handle a = s->first_vertex();

    for (auto blocker : const_blocker_range(a)) {
      if (s == *blocker)
        return true;
    }
    return false;
  }

  /**
   * @return true iff s is a blocker of the simplicial complex
   */
  bool contains_blocker(const Simplex_handle & s) const {
    if (s.dimension() < 2)
      return false;

    Vertex_handle a = s.first_vertex();

    for (auto blocker : const_blocker_range(a)) {
      if (s == *blocker)
        return true;
    }
    return false;
  }

 private:
  /**
   * @return true iff a blocker of the simplicial complex
   * is a face of sigma.
   */
  bool blocks(const Simplex_handle & sigma) const {
    for (auto blocker : const_blocker_range()) {
      if (sigma.contains(*blocker))
        return true;
    }
    return false;
  }

  //@}

 protected:
  /**
   * @details Adds to simplex the neighbours of v e.g. \f$ n \leftarrow n \cup N(v) \f$.
   * If keep_only_superior is true then only vertices that are greater than v are added.
   */
  virtual void add_neighbours(Vertex_handle v, Simplex_handle & n,
                              bool keep_only_superior = false) const {
    boost_adjacency_iterator ai, ai_end;
    for (tie(ai, ai_end) = adjacent_vertices(v.vertex, skeleton); ai != ai_end;
        ++ai) {
      if (keep_only_superior) {
        if (*ai > v.vertex) {
          n.add_vertex(Vertex_handle(*ai));
        }
      } else {
        n.add_vertex(Vertex_handle(*ai));
      }
    }
  }

  /**
   * @details Add to simplex res all vertices which are
   * neighbours of alpha: ie \f$ res \leftarrow res \cup N(alpha) \f$.
   *
   * If 'keep_only_superior' is true then only vertices that are greater than alpha are added.
   * todo revoir
   *
   */
  virtual void add_neighbours(const Simplex_handle &alpha, Simplex_handle & res,
                              bool keep_only_superior = false) const {
    res.clear();
    auto alpha_vertex = alpha.begin();
    add_neighbours(*alpha_vertex, res, keep_only_superior);
    for (alpha_vertex = (alpha.begin())++; alpha_vertex != alpha.end();
        ++alpha_vertex)
      keep_neighbours(*alpha_vertex, res, keep_only_superior);
  }

  /**
   * @details Remove from simplex n all vertices which are
   * not neighbours of v e.g. \f$ res \leftarrow res \cap N(v) \f$.
   * If 'keep_only_superior' is true then only vertices that are greater than v are keeped.
   */
  virtual void keep_neighbours(Vertex_handle v, Simplex_handle& res,
                               bool keep_only_superior = false) const {
    Simplex_handle nv;
    add_neighbours(v, nv, keep_only_superior);
    res.intersection(nv);
  }

  /**
   * @details Remove from simplex all vertices which are
   * neighbours of v eg \f$ res \leftarrow res \setminus N(v) \f$.
   * If 'keep_only_superior' is true then only vertices that are greater than v are added.
   */
  virtual void remove_neighbours(Vertex_handle v, Simplex_handle & res,
                                 bool keep_only_superior = false) const {
    Simplex_handle nv;
    add_neighbours(v, nv, keep_only_superior);
    res.difference(nv);
  }

 public:
  /**
   * @brief Compute the local vertices of 's' in the current complex
   * If one of them is not present in the complex then the return value is uninitialized.
   *
   *
   */
  // xxx rename get_address et place un using dans sub_complex
  boost::optional<Simplex_handle> get_simplex_address(
      const Root_simplex_handle& s) const {
    boost::optional<Simplex_handle> res;

    Simplex_handle s_address;
    // Root_simplex_const_iterator i;
    for (auto i = s.begin(); i != s.end(); ++i) {
      boost::optional<Vertex_handle> address = get_address(*i);
      if (!address)
        return res;
      else
        s_address.add_vertex(*address);
    }
    res = s_address;
    return res;
  }

  /**
   * @brief returns a simplex with vertices which are the id of vertices of the
   * argument.
   */
  Root_simplex_handle get_id(const Simplex_handle& local_simplex) const {
    Root_simplex_handle global_simplex;
    for (auto x = local_simplex.begin(); x != local_simplex.end(); ++x) {
      global_simplex.add_vertex(get_id(*x));
    }
    return global_simplex;
  }

  /**
   * @brief returns true iff the simplex s belongs to the simplicial
   * complex.
   */
  virtual bool contains(const Simplex_handle & s) const {
    if (s.dimension() == -1) {
      return false;
    } else if (s.dimension() == 0) {
      return contains_vertex(s.first_vertex());
    } else {
      return (contains_edges(s) && !blocks(s));
    }
  }

  /*
   * @brief returnrs true iff the complex is empty.
   */
  bool empty() const {
    return num_vertices() == 0;
  }

  /*
   * @brief returns the number of vertices in the complex.
   */
  int num_vertices() const {
    // remark boost::num_vertices(skeleton) counts deactivated vertices
    return num_vertices_;
  }

  /*
   * @brief returns the number of edges in the complex.
   * @details currently in O(n)
   */
  // todo cache the value
  int num_edges() const {
    return boost::num_edges(skeleton);
  }

  /*
   * @brief returns the number of blockers in the complex.
   */
  int num_blockers() const {
    return num_blockers_;
  }

  /*
   * @brief returns true iff the graph of the 1-skeleton of the complex is complete.
   */
  bool complete() const {
    return (num_vertices() * (num_vertices() - 1)) / 2 == num_edges();
  }

  /**
   * @brief returns the number of connected components in the graph of the 1-skeleton.
   */
  int num_connected_components() const {
    int num_vert_collapsed = skeleton.vertex_set().size() - num_vertices();
    std::vector<int> component(skeleton.vertex_set().size());
    return boost::connected_components(this->skeleton, &component[0])
        - num_vert_collapsed;
  }

  /**
   * @brief %Test if the complex is a cone.
   * @details Runs in O(n) where n is the number of vertices.
   */
  bool is_cone() const {
    if (num_vertices() == 0)
      return false;
    if (num_vertices() == 1)
      return true;
    for (auto vi : vertex_range()) {
      // xxx todo faire une methode bool is_in_blocker(Vertex_handle)
      if (blocker_map_.find(vi) == blocker_map_.end()) {
        // no blocker passes through the vertex, we just need to
        // check if the current vertex is linked to all others vertices of the complex
        if (degree_[vi.vertex] == num_vertices() - 1)
          return true;
      }
    }
    return false;
  }

  //@}

  /////////////////////////////////////////////////////////////////////////////
  /** @name Vertex iterators
   */
  //@{
  typedef Complex_vertex_iterator<Skeleton_blocker_complex> CVI;  // todo rename

  //
  // @brief Range over the vertices of the simplicial complex.
  // Methods .begin() and .end() return a Complex_vertex_iterator.
  //
  typedef boost::iterator_range<
      Complex_vertex_iterator<Skeleton_blocker_complex> > Complex_vertex_range;

  /**
   * @brief Returns a Complex_vertex_range over all vertices of the complex
   */
  Complex_vertex_range vertex_range() const {
    auto begin = Complex_vertex_iterator<Skeleton_blocker_complex>(this);
    auto end = Complex_vertex_iterator<Skeleton_blocker_complex>(this, 0);
    return Complex_vertex_range(begin, end);
  }

  typedef boost::iterator_range<
      Complex_neighbors_vertices_iterator<Skeleton_blocker_complex> > Complex_neighbors_vertices_range;

  /**
   * @brief Returns a Complex_edge_range over all edges of the simplicial complex that passes trough v
   */
  Complex_neighbors_vertices_range vertex_range(Vertex_handle v) const {
    auto begin = Complex_neighbors_vertices_iterator<Skeleton_blocker_complex>(
        this, v);
    auto end = Complex_neighbors_vertices_iterator<Skeleton_blocker_complex>(
        this, v, 0);
    return Complex_neighbors_vertices_range(begin, end);
  }

  //@}

  /** @name Edge iterators
   */
  //@{

  typedef boost::iterator_range<
      Complex_edge_iterator<Skeleton_blocker_complex<SkeletonBlockerDS>>> Complex_edge_range;

  /**
   * @brief Returns a Complex_edge_range over all edges of the simplicial complex
   */
  Complex_edge_range edge_range() const {
    auto begin = Complex_edge_iterator<Skeleton_blocker_complex<SkeletonBlockerDS>>(this);
    auto end = Complex_edge_iterator<Skeleton_blocker_complex<SkeletonBlockerDS>>(this, 0);
    return Complex_edge_range(begin, end);
  }

  typedef boost::iterator_range <Complex_edge_around_vertex_iterator<Skeleton_blocker_complex<SkeletonBlockerDS>>>
  Complex_edge_around_vertex_range;
  /**
   * @brief Returns a Complex_edge_range over all edges of the simplicial complex that passes
   * through 'v'
   */
  Complex_edge_around_vertex_range edge_range(Vertex_handle v) const {
    auto begin = Complex_edge_around_vertex_iterator<Skeleton_blocker_complex<SkeletonBlockerDS>>(this, v);
    auto end = Complex_edge_around_vertex_iterator<Skeleton_blocker_complex<SkeletonBlockerDS>>(this, v, 0);
    return Complex_edge_around_vertex_range(begin, end);
  }

  //@}

  /** @name Triangles iterators
   */
  //@{
 private:
  typedef Skeleton_blocker_link_complex<Skeleton_blocker_complex<SkeletonBlockerDS> > Link;
  typedef Skeleton_blocker_link_superior<Skeleton_blocker_complex<SkeletonBlockerDS> > Superior_link;

 public:
  typedef Triangle_around_vertex_iterator<Skeleton_blocker_complex, Superior_link> Superior_triangle_around_vertex_iterator;

  typedef boost::iterator_range < Triangle_around_vertex_iterator<Skeleton_blocker_complex, Link> > Complex_triangle_around_vertex_range;

  /**
   * @brief Range over triangles around a vertex of the simplicial complex.
   * Methods .begin() and .end() return a Triangle_around_vertex_iterator.
   *
   */
  Complex_triangle_around_vertex_range triangle_range(Vertex_handle v) const {
    auto begin = Triangle_around_vertex_iterator<Skeleton_blocker_complex, Link>(this, v);
    auto end = Triangle_around_vertex_iterator<Skeleton_blocker_complex, Link>(this, v, 0);
    return Complex_triangle_around_vertex_range(begin, end);
  }

  typedef boost::iterator_range<Triangle_iterator<Skeleton_blocker_complex> > Complex_triangle_range;

  /**
   * @brief Range over triangles of the simplicial complex.
   * Methods .begin() and .end() return a Triangle_around_vertex_iterator.
   *
   */
  Complex_triangle_range triangle_range() const {
    auto end = Triangle_iterator<Skeleton_blocker_complex>(this, 0);
    if (empty()) {
      return Complex_triangle_range(end, end);
    } else {
      auto begin = Triangle_iterator<Skeleton_blocker_complex>(this);
      return Complex_triangle_range(begin, end);
    }
  }

  //@}

  /** @name Simplices iterators
   */
  //@{
  typedef Simplex_around_vertex_iterator<Skeleton_blocker_complex, Link> Complex_simplex_around_vertex_iterator;

  /**
   * @brief Range over the simplices of the simplicial complex around a vertex.
   * Methods .begin() and .end() return a Complex_simplex_around_vertex_iterator.
   */
  typedef boost::iterator_range < Complex_simplex_around_vertex_iterator > Complex_simplex_around_vertex_range;

  /**
   * @brief Returns a Complex_simplex_around_vertex_range over all the simplices around a vertex of the complex
   */
  Complex_simplex_around_vertex_range simplex_range(Vertex_handle v) const {
    assert(contains_vertex(v));
    return Complex_simplex_around_vertex_range(
        Complex_simplex_around_vertex_iterator(this, v),
        Complex_simplex_around_vertex_iterator(this, v, true));
  }

  // typedef Simplex_iterator<Skeleton_blocker_complex,Superior_link> Complex_simplex_iterator;
  typedef Simplex_iterator<Skeleton_blocker_complex> Complex_simplex_iterator;

  typedef boost::iterator_range < Complex_simplex_iterator > Complex_simplex_range;

  /**
   * @brief Returns a Complex_simplex_range over all the simplices of the complex
   */
  Complex_simplex_range simplex_range() const {
    Complex_simplex_iterator end(this, true);
    if (empty()) {
      return Complex_simplex_range(end, end);
    } else {
      Complex_simplex_iterator begin(this);
      return Complex_simplex_range(begin, end);
    }
  }

  //@}

  /** @name Blockers iterators
   */
  //@{
 private:
  /**
   * @brief Iterator over the blockers adjacent to a vertex
   */
  typedef Blocker_iterator_around_vertex_internal<
  typename std::multimap<Vertex_handle, Simplex_handle *>::iterator,
  Blocker_handle>
  Complex_blocker_around_vertex_iterator;

  /**
   * @brief Iterator over (constant) blockers adjacent to a vertex
   */
  typedef Blocker_iterator_around_vertex_internal<
  typename std::multimap<Vertex_handle, Simplex_handle *>::const_iterator,
  const Blocker_handle>
  Const_complex_blocker_around_vertex_iterator;

  typedef boost::iterator_range <Complex_blocker_around_vertex_iterator> Complex_blocker_around_vertex_range;
  typedef boost::iterator_range <Const_complex_blocker_around_vertex_iterator> Const_complex_blocker_around_vertex_range;

 public:
  /**
   * @brief Returns a range of the blockers of the complex passing through a vertex
   */
  Complex_blocker_around_vertex_range blocker_range(Vertex_handle v) {
    auto begin = Complex_blocker_around_vertex_iterator(blocker_map_.lower_bound(v));
    auto end = Complex_blocker_around_vertex_iterator(blocker_map_.upper_bound(v));
    return Complex_blocker_around_vertex_range(begin, end);
  }

  /**
   * @brief Returns a range of the blockers of the complex passing through a vertex
   */
  Const_complex_blocker_around_vertex_range const_blocker_range(Vertex_handle v) const {
    auto begin = Const_complex_blocker_around_vertex_iterator(blocker_map_.lower_bound(v));
    auto end = Const_complex_blocker_around_vertex_iterator(blocker_map_.upper_bound(v));
    return Const_complex_blocker_around_vertex_range(begin, end);
  }

 private:
  /**
   * @brief Iterator over the blockers.
   */
  typedef Blocker_iterator_internal<
  typename std::multimap<Vertex_handle,Simplex_handle *>::iterator,
  Blocker_handle>
  Complex_blocker_iterator;

  /**
   * @brief Iterator over the (constant) blockers.
   */
  typedef Blocker_iterator_internal<
  typename std::multimap<Vertex_handle,Simplex_handle *>::const_iterator,
  const Blocker_handle>
  Const_complex_blocker_iterator;

  typedef boost::iterator_range <Complex_blocker_iterator> Complex_blocker_range;
  typedef boost::iterator_range <Const_complex_blocker_iterator> Const_complex_blocker_range;

 public:
  /**
   * @brief Returns a range of the blockers of the complex
   */
  Complex_blocker_range blocker_range() {
    auto begin = Complex_blocker_iterator(blocker_map_.begin(), blocker_map_.end() );
    auto end = Complex_blocker_iterator(blocker_map_.end() , blocker_map_.end() );
    return Complex_blocker_range(begin, end);
  }

  /**
   * @brief Returns a range of the blockers of the complex
   */
  Const_complex_blocker_range const_blocker_range() const {
    auto begin = Const_complex_blocker_iterator(blocker_map_.begin(), blocker_map_.end() );
    auto end = Const_complex_blocker_iterator(blocker_map_.end(), blocker_map_.end() );
    return Const_complex_blocker_range(begin, end);
  }

  //@}

  /////////////////////////////////////////////////////////////////////////////
  /** @name Print and IO methods
   */
  //@{
 public:
  std::string to_string() const {
    std::ostringstream stream;
    stream << num_vertices() << " vertices:\n" << vertices_to_string() << std::endl;
    stream << num_edges() << " edges:\n" << edges_to_string() << std::endl;
    stream << num_blockers() << " blockers:\n" << blockers_to_string() << std::endl;
    return stream.str();
  }

  std::string vertices_to_string() const {
    std::ostringstream stream;
    for (auto vertex : vertex_range()) {
      stream << "(" << (*this)[vertex].get_id() << "),";
    }
    stream << std::endl;
    return stream.str();
  }

  std::string edges_to_string() const {
    std::ostringstream stream;
    for (auto edge : edge_range()) {
      stream << "(" << (*this)[edge].first() << "," << (*this)[edge].second() << ")" << " id = " << (*this)[edge].index() << std::endl;
    }
    stream << std::endl;
    return stream.str();
  }

  std::string blockers_to_string() const {
    std::ostringstream stream;
    for (auto bl : blocker_map_) {
      stream << bl.first << " => " << bl.second << ":" << *bl.second << std::endl;
    }
    return stream.str();
  }

  //@}
};

/**
 * build a simplicial complex from a collection
 * of top faces.
 */
template<typename Complex, typename SimplexHandleIterator>
unsigned make_complex_from_top_faces(Complex& complex,
                                     SimplexHandleIterator begin,
                                     SimplexHandleIterator end) {
  typedef typename Complex::Simplex_handle Simplex_handle;

  int dimension = 0;
  for (auto top_face = begin; top_face != end; ++top_face)
    dimension = std::max(dimension, top_face->dimension());

  std::vector < std::set<Simplex_handle>
      > simplices_per_dimension(dimension + 1);

  for (auto top_face = begin; top_face != end; ++top_face) {
    register_faces(simplices_per_dimension, *top_face);
  }

  // compute list of simplices
  std::list<Simplex_handle> simplices;
  for (int dim = 0; dim <= dimension; ++dim) {
    std::copy(simplices_per_dimension[dim].begin(),
              simplices_per_dimension[dim].end(),
              std::back_inserter(simplices));
  }
  complex = Complex(simplices);
  return simplices.size();
}

}  // namespace skbl

}  // namespace Gudhi

#endif  // SRC_SKELETON_BLOCKER_INCLUDE_GUDHI_SKELETON_BLOCKER_COMPLEX_H_