Skeleton_blocker_contractor.h

/*    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 GUDHI_SKELETON_BLOCKER_CONTRACTOR_H_
#define GUDHI_SKELETON_BLOCKER_CONTRACTOR_H_

#include <memory>
#include <cassert>

// todo remove the queue to be independent from cgald
#include "gudhi/Contraction/CGAL_queue/Modifiable_priority_queue.h"


#include <list>
#include <boost/scoped_array.hpp>
#include <boost/scoped_ptr.hpp>


#include "gudhi/Contraction/Edge_profile.h"
#include "gudhi/Contraction/policies/Cost_policy.h"
#include "gudhi/Contraction/policies/Edge_length_cost.h"
#include "gudhi/Contraction/policies/Placement_policy.h"
#include "gudhi/Contraction/policies/First_vertex_placement.h"

#include "gudhi/Contraction/policies/Valid_contraction_policy.h"
#include "gudhi/Contraction/policies/Dummy_valid_contraction.h" //xxx remove
#include "gudhi/Contraction/policies/Link_condition_valid_contraction.h" //xxx remove

#include "gudhi/Contraction/policies/Contraction_visitor.h"

#include "gudhi/Skeleton_blocker/Skeleton_blocker_complex_visitor.h"

#include "gudhi/Utils.h"

namespace Gudhi{

namespace contraction {




template <class Profile>
Placement_policy<Profile>* make_first_vertex_placement(){
    return new First_vertex_placement<Profile>();
}

template <class Profile>
Valid_contraction_policy<Profile>* make_link_valid_contraction(){
    return new Link_condition_valid_contraction<Profile>();
}


template <class Profile>
class Contraction_visitor_remove_popable : public Contraction_visitor<Profile>{
public:
    typedef typename Profile::Point Point;
    typedef typename Profile::Complex Complex;
    typedef typename Complex::Vertex_handle Vertex_handle;

    //todo explore only neighborhood with stack
    void on_contracted(const Profile  &profile, boost::optional< Point > placement) override{
        std::list<Vertex_handle> vertex_to_check;
        vertex_to_check.push_front(profile.v0_handle());

        while(!vertex_to_check.empty()){
            Vertex_handle v = vertex_to_check.front();
            vertex_to_check.pop_front();

            bool blocker_popable_found=true;
            while (blocker_popable_found){
                blocker_popable_found = false;
                for(auto block : profile.complex().blocker_range(v)){
                    if (profile.complex().is_popable_blocker(block)) {
                        for(Vertex_handle nv : *block)
                            if(nv!=v) vertex_to_check.push_back(nv);
                        profile.complex().delete_blocker(block);
                        blocker_popable_found = true;
                        break;
                    }
                }
            }
        }
    }
};

template <class Profile>
Contraction_visitor<Profile>* make_remove_popable_blockers_visitor(){
    return new Contraction_visitor_remove_popable<Profile>();
}






template<
class GeometricSimplifiableComplex,
class EdgeProfile = Edge_profile<GeometricSimplifiableComplex>
>
class Skeleton_blocker_contractor : private skbl::Dummy_complex_visitor<typename GeometricSimplifiableComplex::Vertex_handle>{

    GeometricSimplifiableComplex& complex_;

public:
    typedef typename GeometricSimplifiableComplex::Graph_vertex Graph_vertex;
    typedef typename GeometricSimplifiableComplex::Vertex_handle Vertex_handle;
    typedef typename GeometricSimplifiableComplex::Simplex_handle Simplex_handle;
    typedef typename GeometricSimplifiableComplex::Simplex_handle_iterator Simplex_handle_iterator;



    typedef typename GeometricSimplifiableComplex::Root_vertex_handle Root_vertex_handle;

    typedef typename GeometricSimplifiableComplex::Graph_edge Graph_edge;
    typedef typename GeometricSimplifiableComplex::Edge_handle Edge_handle;
    typedef typename GeometricSimplifiableComplex::Point Point;

    typedef EdgeProfile  Profile;


    typedef Cost_policy<Profile> Cost_policy_;
    typedef Placement_policy<Profile> Placement_policy_;
    typedef Valid_contraction_policy<Profile> Valid_contraction_policy_;
    typedef Contraction_visitor<EdgeProfile> Contraction_visitor_;
    typedef Edge_profile_factory<EdgeProfile> Edge_profile_factory_;



    typedef boost::optional<double> Cost_type;
    typedef boost::optional<Point> Placement_type ;

    typedef size_t size_type;

    typedef Skeleton_blocker_contractor Self ;



private:

    struct Compare_id
    {
        Compare_id() : algorithm_(0) {}

        Compare_id( Self const* aAlgorithm ) : algorithm_(aAlgorithm) {}

        bool operator() ( Edge_handle a, Edge_handle b ) const
        {
            return algorithm_->get_undirected_edge_id(a) < algorithm_->get_undirected_edge_id(b);
        }

        Self const* algorithm_ ;
    } ;

    struct Compare_cost
    {
        Compare_cost() : algorithm_(0) {
        }

        Compare_cost( Self const* aAlgorithm ) : algorithm_(aAlgorithm) {
        }

        bool operator() ( Edge_handle a, Edge_handle b ) const
        {
            // NOTE: A cost is an optional<> value.
            // Absent optionals are ordered first; that is, "none < T" and "T > none" for any defined T != none.
            // In consequence, edges with undefined costs will be promoted to the top of the priority queue and poped out first.
            return algorithm_->get_data(a).cost() < algorithm_->get_data(b).cost();
        }

        Self const* algorithm_ ;

    } ;

    struct Undirected_edge_id : boost::put_get_helper<size_type, Undirected_edge_id>
    {
        typedef boost::readable_property_map_tag category;
        typedef size_type                        value_type;
        typedef size_type                        reference;
        typedef Edge_handle                  key_type;

        Undirected_edge_id() : algorithm_(0) {}

        Undirected_edge_id( Self const* aAlgorithm ) : algorithm_(aAlgorithm) {}

        size_type operator[] ( Edge_handle e ) const { return algorithm_->get_undirected_edge_id(e); }

        Self const* algorithm_ ;
    } ;

    typedef CGAL::Modifiable_priority_queue<Edge_handle,Compare_cost,Undirected_edge_id> PQ ;
    typedef typename PQ::handle pq_handle ;


    // An Edge_data is associated with EVERY edge in the complex (collapsible or not).
    // It relates the edge with the PQ-handle needed to update the priority queue
    // It also relates the edge with a policy-based cache
    class Edge_data
    {
    public :

        Edge_data() : PQHandle_(),cost_() {}

        Cost_type const& cost() const { return cost_ ; }
        Cost_type      & cost()       { return cost_ ; }

        pq_handle PQ_handle() const { return PQHandle_ ;}

        bool is_in_PQ() const { return PQHandle_ != PQ::null_handle() ; }

        void set_PQ_handle( pq_handle h ) { PQHandle_ = h ; }

        void reset_PQ_handle() { PQHandle_ = PQ::null_handle() ; }

    private:
        pq_handle PQHandle_ ;
        Cost_type cost_ ;

    } ;
    typedef Edge_data* Edge_data_ptr ;
    typedef boost::scoped_array<Edge_data> Edge_data_array ;


    int get_undirected_edge_id ( Edge_handle edge ) const {
        return complex_[edge].index() ;
    }


    const Edge_data& get_data ( Edge_handle edge ) const
    {
        return edge_data_array_[get_undirected_edge_id(edge)];
    }


    Edge_data& get_data ( Edge_handle edge )
    {
        return edge_data_array_[get_undirected_edge_id(edge)];
    }

    Cost_type get_cost(const Profile & profile) const{
        return (*cost_policy_)(profile,get_placement(profile));
    }

    Profile create_profile(Edge_handle edge) const{
        if(edge_profile_factory_)
            return edge_profile_factory_->make_profile(complex_,edge);
        else
            return Profile(complex_,edge);
    }


    void insert_in_PQ( Edge_handle edge, Edge_data& data )
    {
        data.set_PQ_handle(heap_PQ_->push(edge));
        ++current_num_edges_heap_;
    }

    void update_in_PQ( Edge_handle edge, Edge_data& data )
    {
        data.set_PQ_handle(heap_PQ_->update(edge,data.PQ_handle())) ;
    }

    void remove_from_PQ( Edge_handle edge, Edge_data& data )
    {
        data.set_PQ_handle(heap_PQ_->erase(edge,data.PQ_handle()));
        --current_num_edges_heap_;
    }

    boost::optional<Edge_handle> pop_from_PQ()  {
        boost::optional<Edge_handle> edge = heap_PQ_->extract_top();
        if ( edge )
        {
            get_data(*edge).reset_PQ_handle();
        }
        return edge ;
    }



private:

    void collect_edges(){
        //
        // Loop over all the edges in the complex in the heap
        //
        size_type size = complex_.num_edges();
        DBG("Collecting edges ...");
        DBGMSG("num edges :",size);

        edge_data_array_.reset( new Edge_data[size] ) ;

        heap_PQ_.reset( new PQ (size, Compare_cost(this), Undirected_edge_id(this) ) ) ;

        std::size_t id = 0 ;

        //xxx do a parralel for
        for(auto edge : complex_.edge_range()){
            //          Edge_handle edge = *edge_it;
            complex_[edge].index() = id++;
            Profile const& profile = create_profile(edge);
            Edge_data& data = get_data(edge);
            data.cost() = get_cost(profile) ;
            ++initial_num_edges_heap_;
            insert_in_PQ(edge,data);
            if(contraction_visitor_) contraction_visitor_->on_collected(profile,data.cost());
        }

        DBG("Edges collected.");

    }

    bool should_stop(double lCost,const Profile &profile) const{
        return false;
    }

    boost::optional<Point> get_placement(const Profile& profile) const{
        return (*placement_policy_)(profile);
    }

    bool is_contraction_valid( Profile const& profile, Placement_type placement ) const{
        return (*valid_contraction_policy_)(profile,placement);
    }


public:
    void contract_edges(int num_max_contractions=-1){

        DBG("\n\nContract edges");
        int num_contraction = 0 ;

        bool unspecified_num_contractions = (num_max_contractions == -1);
        //
        // Pops and processes each edge from the PQ
        //
        boost::optional<Edge_handle> edge ;
        while ( (edge = pop_from_PQ())&& ((num_contraction<num_max_contractions)||(unspecified_num_contractions)))
        {
            Profile const& profile = create_profile(*edge);
            Cost_type cost(get_data(*edge).cost());
            if(contraction_visitor_) contraction_visitor_->on_selected(profile,cost,0,0);

            DBGMSG("\n\n---- Pop edge - num vertices :",complex_.num_vertices());

            if (cost){
                DBGMSG("sqrt(cost):",std::sqrt(*cost));
                if (should_stop(*cost,profile) )
                {
                    if(contraction_visitor_) contraction_visitor_->on_stop_condition_reached();
                    DBG("should_stop");
                    break ;
                }
                Placement_type placement = get_placement(profile);
                if ( is_contraction_valid(profile,placement) && placement )
                {
                    DBG("contraction_valid");
                    contract_edge(profile,placement);
                    ++ num_contraction;
                }
                else
                {
                    DBG("contraction not valid");
                    if(contraction_visitor_) contraction_visitor_->on_non_valid(profile);
                }
            }
            else
            {
                DBG("uncomputable cost");
            }
        }
        if(contraction_visitor_) contraction_visitor_->on_stop_condition_reached();     
    }


    bool is_in_heap(Edge_handle edge) const{
        if(heap_PQ_->empty()) return false;
        else{
            return edge_data_array_[get_undirected_edge_id(edge)].is_in_PQ();
        }
    }

    bool is_heap_empty() const{
        return heap_PQ_->empty();
    }


    boost::optional<std::pair<Edge_handle,Placement_type > > top_edge(){
        boost::optional<std::pair<Edge_handle,Placement_type > > res;

        if(!heap_PQ_->empty()) {
            auto edge = heap_PQ_->top();
            Profile const& profile = create_profile(edge);
            Placement_type placement = get_placement(profile);
            res = make_pair(edge,placement);
            DBGMSG("top edge:",complex_[edge]);

        }
        return res;
    }


    Skeleton_blocker_contractor(GeometricSimplifiableComplex& complex)
    :complex_(complex),
     cost_policy_(new Edge_length_cost<Profile>),
     placement_policy_(new First_vertex_placement<Profile>),
     valid_contraction_policy_(new Link_condition_valid_contraction<Profile>),
     contraction_visitor_(new Contraction_visitor_()),
     edge_profile_factory_(0),
     initial_num_edges_heap_(0),
     current_num_edges_heap_(0)
    {
        complex_.set_visitor(this);
        if(contraction_visitor_) contraction_visitor_->on_started(complex);
        collect_edges();
    }

    Skeleton_blocker_contractor(GeometricSimplifiableComplex& complex,
            Cost_policy_ *cost_policy,
            Placement_policy_ * placement_policy = new First_vertex_placement<Profile>,
            Valid_contraction_policy_ * valid_contraction_policy = new Link_condition_valid_contraction<Profile>,
            Contraction_visitor_* contraction_visitor = new Contraction_visitor_(),
            Edge_profile_factory_* edge_profile_factory = NULL
    ):
        complex_(complex),
        cost_policy_(cost_policy),
        placement_policy_(placement_policy),
        valid_contraction_policy_(valid_contraction_policy),
        contraction_visitor_(contraction_visitor),
        edge_profile_factory_(edge_profile_factory),
        initial_num_edges_heap_(0),
        current_num_edges_heap_(0)
    {
        complex_.set_visitor(this);
        if(contraction_visitor) contraction_visitor->on_started(complex);
        collect_edges();
    }


    ~Skeleton_blocker_contractor(){
        complex_.set_visitor(0);
    }

private:


    void contract_edge(const Profile& profile, Placement_type placement ) {
        if(contraction_visitor_) contraction_visitor_->on_contracting(profile,placement);

        assert(complex_.contains_vertex(profile.v0_handle()));
        assert(complex_.contains_vertex(profile.v1_handle()));
        assert(placement);

        profile.complex().point(profile.v0_handle()) = *placement;

        // remark : this is not necessary since v1 will be deactivated
        //  profile.complex().point(profile.v1_handle()) = *placement;

        complex_.contract_edge(profile.v0_handle(),profile.v1_handle());

        assert(complex_.contains_vertex(profile.v0_handle()));
        assert(!complex_.contains_vertex(profile.v1_handle()));

        update_changed_edges();

        // the visitor could do something as complex_.remove_popable_blockers();
        if(contraction_visitor_) contraction_visitor_->on_contracted(profile,placement);
    }

private:

    // every time the visitor's method on_changed_edge is called, it adds an
    // edge to changed_edges_
    std::vector< Edge_handle > changed_edges_;

    inline void on_changed_edge(Vertex_handle a,Vertex_handle b) override{
        boost::optional<Edge_handle> ab(complex_[std::make_pair(a,b)]);
        assert(ab);
        changed_edges_.push_back(*ab);
    }

    void update_changed_edges(){
        //xxx do a parralel for

        DBG("update edges");

        //      sequential loop
        for(auto ab : changed_edges_){
            //1-get the Edge_handle corresponding to ab
            //2-change the data in mEdgeArray[ab.id()]
            //3-update the heap
            Edge_data& data = get_data(ab);
            Profile const& profile = create_profile(ab);
            data.cost() = get_cost(profile) ;
            if ( data.is_in_PQ()){
                update_in_PQ(ab,data);
            }
            else{
                insert_in_PQ(ab,data);
            }
        }
        changed_edges_.clear();
    }


private:
    void on_remove_edge(Vertex_handle a,Vertex_handle b) override{

        boost::optional<Edge_handle> ab((complex_[std::make_pair(a,b)]));
        assert(ab);
        Edge_data& lData = get_data(*ab) ;
        if ( lData.is_in_PQ() )
        {
            remove_from_PQ(*ab,lData) ;
        }
    }
private:
    void on_swaped_edge(Vertex_handle a,Vertex_handle b,Vertex_handle x) override{
        boost::optional<Edge_handle> ax(complex_[std::make_pair(a,x)]);
        boost::optional<Edge_handle> bx(complex_[std::make_pair(b,x)]);
        assert(ax&& bx);
        complex_[*ax].index() =complex_[*bx].index();
    }
private:
    void on_delete_blocker(const Simplex_handle * blocker) override{
        // we go for all pairs xy that belongs to the blocker
        // note that such pairs xy are necessarily edges of the complex
        // by definition of a blocker

        // todo uniqument utile pour la link condition
        // laisser à l'utilisateur? booleen update_heap_on_removed_blocker?
        Simplex_handle blocker_copy(*blocker);
        for (auto x = blocker_copy.begin(); x!= blocker_copy.end(); ++x){
            for(auto y=x ; ++y != blocker_copy.end(); ){
                auto edge_descr(complex_[std::make_pair(*x,*y)]);
                assert(edge_descr);
                Edge_data& data = get_data(*edge_descr);
                Profile const& profile = create_profile(*edge_descr);
                data.cost() = get_cost(profile) ;

                // If the edge is already in the heap
                // its priority has not changed.
                // If the edge is not present, we reinsert it
                // remark : we could also reinsert the edge
                // only if it is valid
                if ( !data.is_in_PQ() ){
                    insert_in_PQ(*edge_descr,data);
                }
            }
        }
    }


private:
    std::shared_ptr<Cost_policy_> cost_policy_;
    std::shared_ptr<Placement_policy_> placement_policy_;
    std::shared_ptr<Valid_contraction_policy_> valid_contraction_policy_;
    std::shared_ptr<Contraction_visitor_> contraction_visitor_;

    //in case the user wants to do something special when the edge profile
    //are created (for instance add some info)
    std::shared_ptr<Edge_profile_factory_> edge_profile_factory_;
    Edge_data_array edge_data_array_ ;

    boost::scoped_ptr<PQ> heap_PQ_ ;
    int initial_num_edges_heap_;
    int current_num_edges_heap_;

};

}  // namespace contraction
} // namespace GUDHI

#endif /* GUDHI_SKELETON_BLOCKER_CONTRACTOR_H_ */