/* -*- mode: C++; indent-tabs-mode: nil; -*-

  *

  * This file is a part of LEMON, a generic C++ optimization library.

  *

  * Copyright (C) 2015-2017

  * EMAXA Kutato-fejleszto Kft. (EMAXA Research Ltd.)

  *

  * Permission to use, modify and distribute this software is granted

  * provided that this copyright notice appears in all copies. For

  * precise terms see the accompanying LICENSE file.

  *

  * This software is provided "AS IS" with no warranty of any kind,

  * express or implied, and with no claim as to its suitability for any

  * purpose.

  *

  */

 #ifndef LEMON_VF2_H

 #define LEMON_VF2_H

 ///\ingroup graph_properties

 ///\file

 ///\brief VF2 algorithm \cite cordella2004sub.

 #include <lemon/core.h>

 #include <lemon/concepts/graph.h>

 #include <lemon/bfs.h>

 #include <lemon/bits/vf2_internals.h>

 #include <vector>

 namespace lemon {

   namespace bits {

     namespace vf2 {

       class AlwaysEq {

       public:

         template<class T1, class T2>

         bool operator()(T1&, T2&) const {

           return true;

         }

       };

       template<class M1, class M2>

       class MapEq{

         const M1 &_m1;

         const M2 &_m2;

       public:

         MapEq(const M1 &m1, const M2 &m2) : _m1(m1), _m2(m2) { }

         bool operator()(typename M1::Key k1, typename M2::Key k2) const {

           return _m1[k1] == _m2[k2];

         }

       };

       template <class G>

       class BfsLeaveOrder : public BfsVisitor<G> {

         int i;

         const G &_g;

         std::vector<typename G::Node> &_order;

       public:

         BfsLeaveOrder(const G &g, std::vector<typename G::Node> &order)

           : i(0), _g(g), _order(order){

         }

         void process(const typename G::Node &node) {

           _order[i++]=node;

         }

       };

     }

   }

   ///%VF2 algorithm class.

   ///\ingroup graph_isomorphism This class provides an efficient

   ///implementation of the %VF2 algorithm \cite cordella2004sub

   ///for variants of the (Sub)graph Isomorphism problem.

   ///

   ///There is also a \ref vf2() "function-type interface" called \ref vf2()

   ///for the %VF2 algorithm, which is probably more convenient in most

   ///use cases.

   ///

   ///\tparam G1 The type of the graph to be embedded.

   ///The default type is \ref ListGraph.

   ///\tparam G2 The type of the graph g1 will be embedded into.

   ///The default type is \ref ListGraph.

   ///\tparam M The type of the NodeMap storing the mapping.

   ///By default, it is G1::NodeMap<G2::Node>

   ///\tparam NEQ A bool-valued binary functor determinining whether a node is

   ///mappable to another. By default, it is an always-true operator.

   ///

   ///\sa vf2()

 #ifdef DOXYGEN

   template<class G1, class G2, class M, class NEQ >

 #else

   template<class G1 = ListGraph,

            class G2 = ListGraph,

            class M = typename G1::template NodeMap<G2::Node>,

            class NEQ = bits::vf2::AlwaysEq >

 #endif

   class Vf2 {

     //The graph to be embedded

     const G1 &_g1;

     //The graph into which g1 is to be embedded

     const G2 &_g2;

     //Functor with bool operator()(G1::Node,G2::Node), which returns 1

     //if and only if the two nodes are equivalent

     NEQ _nEq;

     //Current depth in the search tree

     int _depth;

     //The current mapping. _mapping[v1]=v2 iff v1 has been mapped to v2,

     //where v1 is a node of G1 and v2 is a node of G2

     M &_mapping;

     //_order[i] is the node of g1 for which a pair is searched if depth=i

     std::vector<typename G1::Node> _order;

     //_conn[v2] = number of covered neighbours of v2

     typename G2::template NodeMap<int> _conn;

     //_currEdgeIts[i] is the last used edge iterator in the i-th

     //depth to find a pair for node _order[i]

     std::vector<typename G2::IncEdgeIt> _currEdgeIts;

     //lookup tables for cutting the searchtree

     typename G1::template NodeMap<int> _rNew1t, _rInOut1t;

     MappingType _mapping_type;

     bool _deallocMappingAfterUse;

     //cut the search tree

     template<MappingType MT>

     bool cut(const typename G1::Node n1,const typename G2::Node n2) const {

       int rNew2=0,rInOut2=0;

       for(typename G2::IncEdgeIt e2(_g2,n2); e2!=INVALID; ++e2) {

         const typename G2::Node currNode=_g2.oppositeNode(n2,e2);

         if(_conn[currNode]>0)

           ++rInOut2;

         else if(MT!=SUBGRAPH&&_conn[currNode]==0)

           ++rNew2;

       }

       switch(MT) {

       case INDUCED:

         return _rInOut1t[n1]<=rInOut2&&_rNew1t[n1]<=rNew2;

       case SUBGRAPH:

         return _rInOut1t[n1]<=rInOut2;

       case ISOMORPH:

         return _rInOut1t[n1]==rInOut2&&_rNew1t[n1]==rNew2;

       default:

         return false;

       }

     }

     template<MappingType MT>

     bool feas(const typename G1::Node n1,const typename G2::Node n2) {

       if(!_nEq(n1,n2))

         return 0;

       for(typename G1::IncEdgeIt e1(_g1,n1); e1!=INVALID; ++e1) {

         const typename G1::Node& currNode=_g1.oppositeNode(n1,e1);

         if(_mapping[currNode]!=INVALID)

           --_conn[_mapping[currNode]];

       }

       bool isIso=1;

       for(typename G2::IncEdgeIt e2(_g2,n2); e2!=INVALID; ++e2) {

         int& connCurrNode = _conn[_g2.oppositeNode(n2,e2)];

         if(connCurrNode<-1)

           ++connCurrNode;

         else if(MT!=SUBGRAPH&&connCurrNode==-1) {

           isIso=0;

           break;

         }

       }

       for(typename G1::IncEdgeIt e1(_g1,n1); e1!=INVALID; ++e1) {

         const typename G2::Node& currNodePair=_mapping[_g1.oppositeNode(n1,e1)];

         int& connCurrNodePair=_conn[currNodePair];

         if(currNodePair!=INVALID&&connCurrNodePair!=-1) {

           switch(MT) {

           case INDUCED:

           case ISOMORPH:

             isIso=0;

             break;

           case SUBGRAPH:

             if(connCurrNodePair<-1)

               isIso=0;

             break;

           }

           connCurrNodePair=-1;

         }

       }

       return isIso&&cut<MT>(n1,n2);

     }

     void addPair(const typename G1::Node n1,const typename G2::Node n2) {

       _conn[n2]=-1;

       _mapping.set(n1,n2);

       for(typename G2::IncEdgeIt e2(_g2,n2); e2!=INVALID; ++e2) {

         int& currConn = _conn[_g2.oppositeNode(n2,e2)];

         if(currConn!=-1)

           ++currConn;

       }

     }

     void subPair(const typename G1::Node n1,const typename G2::Node n2) {

       _conn[n2]=0;

       _mapping.set(n1,INVALID);

       for(typename G2::IncEdgeIt e2(_g2,n2); e2!=INVALID; ++e2) {

         int& currConn = _conn[_g2.oppositeNode(n2,e2)];

         if(currConn>0)

           --currConn;

         else if(currConn==-1)

           ++_conn[n2];

       }

     }

     void initOrder() {

       //determine the order in which we will find pairs for the nodes of g1

       //BFS order is more efficient in practice than DFS

       bits::vf2::BfsLeaveOrder<G1> v(_g1,_order);

       BfsVisit<G1,bits::vf2::BfsLeaveOrder<G1> > bfs(_g1, v);

       bfs.run();

     }

     template<MappingType MT>

     bool extMatch() {

       while(_depth>=0) {

         if(_depth==static_cast<int>(_order.size())) {

           //all nodes of g1 are mapped to nodes of g2

           --_depth;

           return true;

         }

         typename G1::Node& nodeOfDepth = _order[_depth];

         const typename G2::Node& pairOfNodeOfDepth = _mapping[nodeOfDepth];

         typename G2::IncEdgeIt &edgeItOfDepth = _currEdgeIts[_depth];

         //the node of g2 whose neighbours are the candidates for

         //the pair of nodeOfDepth

         typename G2::Node currPNode;

         if(edgeItOfDepth==INVALID) {

           typename G1::IncEdgeIt fstMatchedE(_g1,nodeOfDepth);

           //if pairOfNodeOfDepth!=INVALID, we don't use fstMatchedE

           if(pairOfNodeOfDepth==INVALID) {

             for(; fstMatchedE!=INVALID &&

                   _mapping[_g1.oppositeNode(nodeOfDepth,

                                             fstMatchedE)]==INVALID;

                 ++fstMatchedE) ; //find fstMatchedE

           }

           if(fstMatchedE==INVALID||pairOfNodeOfDepth!=INVALID) {

             //We found no covered neighbours, this means that

             //the graph is not connected (or _depth==0). Each

             //uncovered (and there are some other properties due

             //to the spec. problem types) node of g2 is

             //candidate. We can read the iterator of the last

             //tried node from the match if it is not the first

             //try (match[nodeOfDepth]!=INVALID)

             typename G2::NodeIt n2(_g2);

             //if it's not the first try

             if(pairOfNodeOfDepth!=INVALID) {

               n2=++typename G2::NodeIt(_g2,pairOfNodeOfDepth);

               subPair(nodeOfDepth,pairOfNodeOfDepth);

             }

             for(; n2!=INVALID; ++n2)

               if(MT!=SUBGRAPH) {

                 if(_conn[n2]==0&&feas<MT>(nodeOfDepth,n2))

                   break;

               }

               else if(_conn[n2]>=0&&feas<MT>(nodeOfDepth,n2))

                 break;

             // n2 is the next candidate

             if(n2!=INVALID){

               addPair(nodeOfDepth,n2);

               ++_depth;

             }

             else // there are no more candidates

               --_depth;

             continue;

           }

           else {

             currPNode=_mapping[_g1.oppositeNode(nodeOfDepth,

                                                 fstMatchedE)];

             edgeItOfDepth=typename G2::IncEdgeIt(_g2,currPNode);

           }

         }

         else {

           currPNode=_g2.oppositeNode(pairOfNodeOfDepth,

                                      edgeItOfDepth);

           subPair(nodeOfDepth,pairOfNodeOfDepth);

           ++edgeItOfDepth;

         }

         for(; edgeItOfDepth!=INVALID; ++edgeItOfDepth) {

           const typename G2::Node currNode =

             _g2.oppositeNode(currPNode, edgeItOfDepth);

           if(_conn[currNode]>0&&feas<MT>(nodeOfDepth,currNode)) {

             addPair(nodeOfDepth,currNode);

             break;

           }

         }

         edgeItOfDepth==INVALID?--_depth:++_depth;

       }

       return false;

     }

     //calculate the lookup table for cutting the search tree

     void initRNew1tRInOut1t() {

       typename G1::template NodeMap<int> tmp(_g1,0);

       for(unsigned int i=0; i<_order.size(); ++i) {

         const typename G1::Node& orderI = _order[i];

         tmp[orderI]=-1;

         for(typename G1::IncEdgeIt e1(_g1,orderI); e1!=INVALID; ++e1) {

           const typename G1::Node currNode=_g1.oppositeNode(orderI,e1);

           if(tmp[currNode]>0)

             ++_rInOut1t[orderI];

           else if(tmp[currNode]==0)

             ++_rNew1t[orderI];

         }

         for(typename G1::IncEdgeIt e1(_g1,orderI); e1!=INVALID; ++e1) {

           const typename G1::Node currNode=_g1.oppositeNode(orderI,e1);

           if(tmp[currNode]!=-1)

             ++tmp[currNode];

         }

       }

     }

   public:

     ///Constructor

     ///Constructor

     ///\param g1 The graph to be embedded into \e g2.

     ///\param g2 The graph \e g1 will be embedded into.

     ///\param m \ref concepts::ReadWriteMap "read-write" NodeMap

     ///storing the found mapping.

     ///\param neq A bool-valued binary functor determining whether a node is

     ///mappable to another. By default it is an always true operator.

     Vf2(const G1 &g1, const G2 &g2, M &m, const NEQ &neq = NEQ() ) :

       _g1(g1), _g2(g2), _nEq(neq), _depth(0), _mapping(m),

       _order(countNodes(g1)), _conn(g2,0),

       _currEdgeIts(countNodes(g1),INVALID), _rNew1t(g1,0), _rInOut1t(g1,0),

       _mapping_type(SUBGRAPH), _deallocMappingAfterUse(0)

     {

       initOrder();

       initRNew1tRInOut1t();

       for(typename G1::NodeIt n(g1);n!=INVALID;++n)

         m[n]=INVALID;

     }

     ///Destructor

     ///Destructor.

     ///

     ~Vf2(){

       if(_deallocMappingAfterUse)

         delete &_mapping;

     }

     ///Returns the current mapping type

     ///Returns the current mapping type

     ///

     MappingType mappingType() const {

       return _mapping_type;

     }

     ///Sets mapping type

     ///Sets mapping type.

     ///

     ///The mapping type is set to \ref SUBGRAPH by default.

     ///

     ///\sa See \ref MappingType for the possible values.

     void mappingType(MappingType m_type) {

       _mapping_type = m_type;

     }

     ///Finds a mapping

     ///It finds a mapping from g1 into g2 according to the mapping

     ///type set by \ref mappingType(MappingType) "mappingType()".

     ///

     ///By subsequent calls, it returns all possible mappings one-by-one.

     ///

     ///\retval true if a mapping is found.

     ///\retval false if there is no (more) mapping.

     bool find() {

       switch(_mapping_type) {

       case SUBGRAPH:

         return extMatch<SUBGRAPH>();

       case INDUCED:

         return extMatch<INDUCED>();

       case ISOMORPH:

         return extMatch<ISOMORPH>();

       default:

         return false;

       }

     }

   };

   template<class G1, class G2>

   class Vf2WizardBase {

   protected:

     typedef G1 Graph1;

     typedef G2 Graph2;

     const G1 &_g1;

     const G2 &_g2;

     MappingType _mapping_type;

     typedef typename G1::template NodeMap<typename G2::Node> Mapping;

     bool _local_mapping;

     void *_mapping;

     void createMapping() {

       _mapping = new Mapping(_g1);

     }

     void *myVf2; //used in Vf2Wizard::find

     typedef bits::vf2::AlwaysEq NodeEq;

     NodeEq _node_eq;

     Vf2WizardBase(const G1 &g1,const G2 &g2)

       : _g1(g1), _g2(g2), _mapping_type(SUBGRAPH), _local_mapping(true) { }

   };

   /// Auxiliary class for the function-type interface of %VF2 algorithm.

   ///

   /// This auxiliary class implements the named parameters of

   /// \ref vf2() "function-type interface" of \ref Vf2 algorithm.

   ///

   /// \warning This class is not to be used directly.

   ///

   /// \tparam TR The traits class that defines various types used by the

   /// algorithm.

   template<class TR>

   class Vf2Wizard : public TR {

     typedef TR Base;

     typedef typename TR::Graph1 Graph1;

     typedef typename TR::Graph2 Graph2;

     typedef typename TR::Mapping Mapping;

     typedef typename TR::NodeEq NodeEq;

     using TR::_g1;

     using TR::_g2;

     using TR::_mapping_type;

     using TR::_mapping;

     using TR::_node_eq;

   public:

     ///Constructor

     Vf2Wizard(const Graph1 &g1,const Graph2 &g2) : Base(g1,g2) {}

     ///Copy constructor

     Vf2Wizard(const Base &b) : Base(b) {}

     ///Copy constructor

     Vf2Wizard(const Vf2Wizard &b) : Base(b) {}

     template<class T>

     struct SetMappingBase : public Base{

       typedef T Mapping;

       SetMappingBase(const Base &b) : Base(b) {}

     };

     ///\brief \ref named-templ-param "Named parameter" for setting

     ///the mapping.

     ///

     ///\ref named-templ-param "Named parameter" function for setting

     ///the map that stores the found embedding.

     template<class T>

     Vf2Wizard< SetMappingBase<T> > mapping(const T &t) {

       Base::_mapping=reinterpret_cast<void*>(const_cast<T*>(&t));

       Base::_local_mapping = false;

       return Vf2Wizard<SetMappingBase<T> >(*this);

     }

     template<class NE>

     struct SetNodeEqBase : public Base {

       typedef NE NodeEq;

       NodeEq _node_eq;

       SetNodeEqBase(const Base &b, const NE &node_eq)

         : Base(b), _node_eq(node_eq){

       }

     };

     ///\brief \ref named-templ-param "Named parameter" for setting

     ///the node equivalence relation.

     ///

     ///\ref named-templ-param "Named parameter" function for setting

     ///the equivalence relation between the nodes.

     ///

     ///\param node_eq A bool-valued binary functor determinining

     ///whether a node is mappable to another. By default it is an

     ///always true operator.

     template<class T>

     Vf2Wizard< SetNodeEqBase<T> > nodeEq(const T &node_eq) {

       return Vf2Wizard<SetNodeEqBase<T> >(SetNodeEqBase<T>(*this,node_eq));

     }

     ///\brief \ref named-templ-param "Named parameter" for setting

     ///the node labels.

     ///

     ///\ref named-templ-param "Named parameter" function for setting

     ///the node labels defining equivalence relation between them.

     ///

     ///\param m1 An arbitrary \ref concepts::ReadMap "readable node map"

     ///of g1.

     ///\param m2 An arbitrary \ref concepts::ReadMap "readable node map"

     ///of g2.

     ///

     ///The value type of these maps must be equal comparable.

     template<class M1, class M2>

     Vf2Wizard< SetNodeEqBase<bits::vf2::MapEq<M1,M2> > >

     nodeLabels(const M1 &m1,const M2 &m2){

       return nodeEq(bits::vf2::MapEq<M1,M2>(m1,m2));

     }

     ///\brief \ref named-templ-param "Named parameter" for setting

     ///the mapping type.

     ///

     ///\ref named-templ-param "Named parameter" for setting

     ///the mapping type.

     ///

     ///The mapping type is set to \ref SUBGRAPH by default.

     ///

     ///\sa See \ref MappingType for the possible values.

     Vf2Wizard<Base> &mappingType(MappingType m_type) {

       _mapping_type = m_type;

       return *this;

     }

     ///\brief \ref named-templ-param "Named parameter" for setting

     ///the mapping type to \ref INDUCED.

     ///

     ///\ref named-templ-param "Named parameter" for setting

     ///the mapping type to \ref INDUCED.

     Vf2Wizard<Base> &induced() {

       _mapping_type = INDUCED;

       return *this;

     }

     ///\brief \ref named-templ-param "Named parameter" for setting

     ///the mapping type to \ref ISOMORPH.

     ///

     ///\ref named-templ-param "Named parameter" for setting

     ///the mapping type to \ref ISOMORPH.

     Vf2Wizard<Base> &iso() {

       _mapping_type = ISOMORPH;

       return *this;

     }

     ///Runs VF2 algorithm.

     ///This method runs VF2 algorithm.

     ///

     ///\retval true if a mapping is found.

     ///\retval false if there is no mapping.

     bool run(){

       if(Base::_local_mapping)

         Base::createMapping();

       Vf2<Graph1, Graph2, Mapping, NodeEq >

         alg(_g1, _g2, *reinterpret_cast<Mapping*>(_mapping), _node_eq);

       alg.mappingType(_mapping_type);

       bool ret = alg.find();

       if(Base::_local_mapping)

         delete reinterpret_cast<Mapping*>(_mapping);

       return ret;

     }

     ///Get a pointer to the generated Vf2 object.

     ///Gives a pointer to the generated Vf2 object.

     ///

     ///\return Pointer to the generated Vf2 object.

     ///\warning Don't forget to delete the referred Vf2 object after use.

     Vf2<Graph1, Graph2, Mapping, NodeEq >* getPtrToVf2Object() {

       if(Base::_local_mapping)

         Base::createMapping();

       Vf2<Graph1, Graph2, Mapping, NodeEq >* ptr =

         new Vf2<Graph1, Graph2, Mapping, NodeEq>

         (_g1, _g2, *reinterpret_cast<Mapping*>(_mapping), _node_eq);

       ptr->mappingType(_mapping_type);

       if(Base::_local_mapping)

         ptr->_deallocMappingAfterUse = true;

       return ptr;

     }

     ///Counts the number of mappings.

     ///This method counts the number of mappings.

     ///

     /// \return The number of mappings.

     int count() {

       if(Base::_local_mapping)

         Base::createMapping();

       Vf2<Graph1, Graph2, Mapping, NodeEq>

         alg(_g1, _g2, *reinterpret_cast<Mapping*>(_mapping), _node_eq);

       if(Base::_local_mapping)

         alg._deallocMappingAfterUse = true;

       alg.mappingType(_mapping_type);

       int ret = 0;

       while(alg.find())

         ++ret;

       return ret;

     }

   };

   ///Function-type interface for VF2 algorithm.

   /// \ingroup graph_isomorphism

   ///Function-type interface for VF2 algorithm \cite cordella2004sub.

   ///

   ///This function has several \ref named-func-param "named parameters"

   ///declared as the members of class \ref Vf2Wizard.

   ///The following examples show how to use these parameters.

   ///\code

   ///  // Find an embedding of graph g1 into graph g2

   ///  ListGraph::NodeMap<ListGraph::Node> m(g);

   ///  vf2(g1,g2).mapping(m).run();

   ///

   ///  // Check whether graphs g1 and g2 are isomorphic

   ///  bool is_iso = vf2(g1,g2).iso().run();

   ///

   ///  // Count the number of isomorphisms

   ///  int num_isos = vf2(g1,g2).iso().count();

   ///

   ///  // Iterate through all the induced subgraph mappings of graph g1 into g2

   ///  auto* myVf2 = vf2(g1,g2).mapping(m).nodeLabels(c1,c2)

   ///  .induced().getPtrToVf2Object();

   ///  while(myVf2->find()){

   ///    //process the current mapping m

   ///  }

   ///  delete myVf22;

   ///\endcode

   ///\warning Don't forget to put the \ref Vf2Wizard::run() "run()",

   ///\ref Vf2Wizard::count() "count()" or

   ///the \ref Vf2Wizard::getPtrToVf2Object() "getPtrToVf2Object()"

   ///to the end of the expression.

   ///\sa Vf2Wizard

   ///\sa Vf2

   template<class G1, class G2>

   Vf2Wizard<Vf2WizardBase<G1,G2> > vf2(const G1 &g1, const G2 &g2) {

     return Vf2Wizard<Vf2WizardBase<G1,G2> >(g1,g2);

   }

 }

 #endif