/* -*- C++ -*-

 * src/lemon/dijkstra.h - Part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Combinatorial Optimization Research Group, EGRES).

 *

 * 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_DIJKSTRA_H

#define LEMON_DIJKSTRA_H

///\ingroup flowalgs

///\file

///\brief Dijkstra algorithm.

#include <lemon/list_graph.h>

#include <lemon/bin_heap.h>

#include <lemon/invalid.h>

#include <lemon/error.h>

#include <lemon/maps.h>

namespace lemon {

  class UninitializedData : public LogicError {};

/// \addtogroup flowalgs

/// @{

  ///Default traits class of Dijkstra class.

  ///Default traits class of Dijkstra class.

  ///\param GR Graph type.

  ///\param LM Type of length map.

  template<class GR, class LM>

  struct DijkstraDefaultTraits

  {

    ///The graph type the algorithm runs on. 

    typedef GR Graph;

    ///The type of the map that stores the edge lengths.

    ///It must meet the \ref concept::ReadMap "ReadMap" concept.

    ///

    typedef LM LengthMap;

    //The type of the length of the edges.

    typedef typename LM::Value Value;

    ///The heap type used by Dijkstra algorithm.

    ///The heap type used by Dijkstra algorithm.

    ///

    ///\sa BinHeap

    ///\sa Dijkstra

    typedef BinHeap<typename Graph::Node,

		    typename LM::Value,

		    typename GR::template NodeMap<int>,

		    std::less<Value> > Heap;

    ///\brief The type of the map that stores the last

    ///edges of the shortest paths.

    /// 

    ///It must meet the \ref concept::WriteMap "WriteMap" concept.

    ///

    typedef typename Graph::template NodeMap<typename GR::Edge> PredMap;

    ///Instantiates a PredMap.

    ///This function instantiates a \ref PredMap. 

    ///\param G is the graph, to which we would like to define the PredMap.

    ///\todo The graph alone may be insufficient for the initialization

    static PredMap *createPredMap(const GR &G) 

    {

      return new PredMap(G);

    }

    ///\brief The type of the map that stores the last but one

    ///nodes of the shortest paths.

    ///

    ///It must meet the \ref concept::WriteMap "WriteMap" concept.

    ///

    typedef typename Graph::template NodeMap<typename GR::Node> PredNodeMap;

    ///Instantiates a PredNodeMap.

    ///This function instantiates a \ref PredNodeMap. 

    ///\param G is the graph, to which we would like to define the \ref PredNodeMap

    static PredNodeMap *createPredNodeMap(const GR &G)

    {

      return new PredNodeMap(G);

    }

    ///The type of the map that stores whether a nodes is reached.

    ///It must meet the \ref concept::WriteMap "WriteMap" concept.

    ///By default it is a NullMap.

    ///\todo If it is set to a real map, Dijkstra::reached() should read this.

    ///\todo named parameter to set this type, function to read and write.

    typedef NullMap<typename Graph::Node,bool> ReachedMap;

    ///Instantiates a ReachedMap.

    ///This function instantiates a \ref ReachedMap. 

    ///\param G is the graph, to which we would like to define the \ref ReachedMap

    static ReachedMap *createReachedMap(const GR &G)

    {

      return new ReachedMap();

    }

    ///The type of the map that stores the dists of the nodes.

    ///It must meet the \ref concept::WriteMap "WriteMap" concept.

    ///

    typedef typename Graph::template NodeMap<typename LM::Value> DistMap;

    ///Instantiates a DistMap.

    ///This function instantiates a \ref DistMap. 

    ///\param G is the graph, to which we would like to define the \ref DistMap

    static DistMap *createDistMap(const GR &G)

    {

      return new DistMap(G);

    }

  };

  ///%Dijkstra algorithm class.

  ///This class provides an efficient implementation of %Dijkstra algorithm.

  ///The edge lengths are passed to the algorithm using a

  ///\ref concept::ReadMap "ReadMap",

  ///so it is easy to change it to any kind of length.

  ///

  ///The type of the length is determined by the

  ///\ref concept::ReadMap::Value "Value" of the length map.

  ///

  ///It is also possible to change the underlying priority heap.

  ///

  ///\param GR The graph type the algorithm runs on. The default value is

  ///\ref ListGraph. The value of GR is not used directly by Dijkstra, it

  ///is only passed to \ref DijkstraDefaultTraits.

  ///\param LM This read-only

  ///EdgeMap

  ///determines the

  ///lengths of the edges. It is read once for each edge, so the map

  ///may involve in relatively time consuming process to compute the edge

  ///length if it is necessary. The default map type is

  ///\ref concept::StaticGraph::EdgeMap "Graph::EdgeMap<int>".

  ///The value of LM is not used directly by Dijkstra, it

  ///is only passed to \ref DijkstraDefaultTraits.

  ///\param TR Traits class to set various data types used by the algorithm.

  ///The default traits class is

  ///\ref DijkstraDefaultTraits "DijkstraDefaultTraits<GR,LM>".

  ///See \ref DijkstraDefaultTraits for the documentation of

  ///a Dijkstra traits class.

  ///

  ///\author Jacint Szabo and Alpar Juttner

  ///\todo We need a typedef-names should be standardized. (-:

#ifdef DOXYGEN

  template <typename GR,

	    typename LM,

	    typename TR>

#else

  template <typename GR=ListGraph,

	    typename LM=typename GR::template EdgeMap<int>,

	    typename TR=DijkstraDefaultTraits<GR,LM> >

#endif

  class Dijkstra {

  public:

    ///Exception thrown by dijkstra.

    class UninitializedData : public lemon::UninitializedData {};

    typedef TR Traits;

    ///The type of the underlying graph.

    typedef typename TR::Graph Graph;

    ///\e

    typedef typename Graph::Node Node;

    ///\e

    typedef typename Graph::NodeIt NodeIt;

    ///\e

    typedef typename Graph::Edge Edge;

    ///\e

    typedef typename Graph::OutEdgeIt OutEdgeIt;

    ///The type of the length of the edges.

    typedef typename TR::LengthMap::Value Value;

    ///The type of the map that stores the edge lengths.

    typedef typename TR::LengthMap LengthMap;

    ///\brief The type of the map that stores the last

    ///edges of the shortest paths.

    typedef typename TR::PredMap PredMap;

    ///\brief The type of the map that stores the last but one

    ///nodes of the shortest paths.

    typedef typename TR::PredNodeMap PredNodeMap;

    ///The type of the map indicating if a node is reached.

    typedef typename TR::ReachedMap ReachedMap;

    ///The type of the map that stores the dists of the nodes.

    typedef typename TR::DistMap DistMap;

    ///The heap type used by the dijkstra algorithm.

    typedef typename TR::Heap Heap;

  private:

    /// Pointer to the underlying graph.

    const Graph *G;

    /// Pointer to the length map

    const LengthMap *length;

    ///Pointer to the map of predecessors edges.

    PredMap *_pred;

    ///Indicates if \ref _pred is locally allocated (\c true) or not.

    bool local_pred;

    ///Pointer to the map of predecessors nodes.

    PredNodeMap *pred_node;

    ///Indicates if \ref pred_node is locally allocated (\c true) or not.

    bool local_pred_node;

    ///Pointer to the map of distances.

    DistMap *distance;

    ///Indicates if \ref distance is locally allocated (\c true) or not.

    bool local_distance;

    ///Pointer to the map of reached status of the nodes.

    ReachedMap *_reached;

    ///Indicates if \ref _reached is locally allocated (\c true) or not.

    bool local_reached;

    ///The source node of the last execution.

    Node source;

    ///Initializes the maps.

    ///\todo Error if \c G or are \c NULL. What about \c length?

    ///\todo Better memory allocation (instead of new).

    void init_maps() 

    {

      if(!_pred) {

	local_pred = true;

	_pred = Traits::createPredMap(*G);

      }

      if(!pred_node) {

	local_pred_node = true;

	pred_node = Traits::createPredNodeMap(*G);

      }

      if(!distance) {

	local_distance = true;

	distance = Traits::createDistMap(*G);

      }

      if(!_reached) {

	local_reached = true;

	_reached = Traits::createReachedMap(*G);

      }

    }

  public :

    template <class T>

    struct DefPredMapTraits : public Traits {

      typedef T PredMap;

      ///\todo An exception should be thrown.

      ///

      static PredMap *createPredMap(const Graph &G) 

      {

	throw UninitializedData();

      }

    };

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

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

    ///

    template <class T>

    class DefPredMap : public Dijkstra< Graph,

					LengthMap,

					DefPredMapTraits<T> > { };

    template <class T>

    struct DefPredNodeMapTraits : public Traits {

      typedef T PredNodeMap;

      ///\todo An exception should be thrown.

      ///

      static PredNodeMap *createPredNodeMap(const Graph &G) 

      {

	throw UninitializedData();

      }

    };

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

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

    ///

    template <class T>

    class DefPredNodeMap : public Dijkstra< Graph,

					    LengthMap,

					    DefPredNodeMapTraits<T> > { };

    template <class T>

    struct DefDistMapTraits : public Traits {

      typedef T DistMap;

      ///\todo An exception should be thrown.

      ///

      static DistMap *createDistMap(const Graph &G) 

      {

	throw UninitializedData();

      }

    };

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

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

    ///

    template <class T>

    class DefDistMap : public Dijkstra< Graph,

					LengthMap,

					DefDistMapTraits<T> > { };

    ///Constructor.

    ///\param _G the graph the algorithm will run on.

    ///\param _length the length map used by the algorithm.

    Dijkstra(const Graph& _G, const LengthMap& _length) :

      G(&_G), length(&_length),

      _pred(NULL), local_pred(false),

      pred_node(NULL), local_pred_node(false),

      distance(NULL), local_distance(false),

      _reached(NULL), local_reached(false)

    { }

    ///Destructor.

    ~Dijkstra() 

    {

      if(local_pred) delete _pred;

      if(local_pred_node) delete pred_node;

      if(local_distance) delete distance;

      if(local_reached) delete _reached;

    }

    ///Sets the length map.

    ///Sets the length map.

    ///\return <tt> (*this) </tt>

    Dijkstra &lengthMap(const LengthMap &m) 

    {

      length = &m;

      return *this;

    }

    ///Sets the map storing the predecessor edges.

    ///Sets the map storing the predecessor edges.

    ///If you don't use this function before calling \ref run(),

    ///it will allocate one. The destuctor deallocates this

    ///automatically allocated map, of course.

    ///\return <tt> (*this) </tt>

    Dijkstra &predMap(PredMap &m) 

    {

      if(local_pred) {

	delete _pred;

	local_pred=false;

      }

      _pred = &m;

      return *this;

    }

    ///Sets the map storing the predecessor nodes.

    ///Sets the map storing the predecessor nodes.

    ///If you don't use this function before calling \ref run(),

    ///it will allocate one. The destuctor deallocates this

    ///automatically allocated map, of course.

    ///\return <tt> (*this) </tt>

    Dijkstra &predNodeMap(PredNodeMap &m) 

    {

      if(local_pred_node) {

	delete pred_node;

	local_pred_node=false;

      }

      pred_node = &m;

      return *this;

    }

    ///Sets the map storing the distances calculated by the algorithm.

    ///Sets the map storing the distances calculated by the algorithm.

    ///If you don't use this function before calling \ref run(),

    ///it will allocate one. The destuctor deallocates this

    ///automatically allocated map, of course.

    ///\return <tt> (*this) </tt>

    Dijkstra &distMap(DistMap &m) 

    {

      if(local_distance) {

	delete distance;

	local_distance=false;

      }

      distance = &m;

      return *this;

    }

  ///Runs %Dijkstra algorithm from node \c s.

  ///This method runs the %Dijkstra algorithm from a root node \c s

  ///in order to

  ///compute the

  ///shortest path to each node. The algorithm computes

  ///- The shortest path tree.

  ///- The distance of each node from the root.

  ///\todo heap_map's type could also be in the traits class.

    void run(Node s) {

      init_maps();

      source = s;

      for ( NodeIt u(*G) ; u!=INVALID ; ++u ) {

	_pred->set(u,INVALID);

	pred_node->set(u,INVALID);

	///\todo *_reached is not set to false.

      }

      typename Graph::template NodeMap<int> heap_map(*G,-1);

      Heap heap(heap_map);

      heap.push(s,0); 

      while ( !heap.empty() ) {

	Node v=heap.top(); 

	_reached->set(v,true);

	Value oldvalue=heap[v];

	heap.pop();

	distance->set(v, oldvalue);

	for(OutEdgeIt e(*G,v); e!=INVALID; ++e) {

	  Node w=G->target(e); 

	  switch(heap.state(w)) {

	  case Heap::PRE_HEAP:

	    heap.push(w,oldvalue+(*length)[e]); 

	    _pred->set(w,e);

	    pred_node->set(w,v);

	    break;

	  case Heap::IN_HEAP:

	    if ( oldvalue+(*length)[e] < heap[w] ) {

	      heap.decrease(w, oldvalue+(*length)[e]); 

	      _pred->set(w,e);

	      pred_node->set(w,v);

	    }

	    break;

	  case Heap::POST_HEAP:

	    break;

	  }

	}

      }

    }

    ///The distance of a node from the root.

    ///Returns the distance of a node from the root.

    ///\pre \ref run() must be called before using this function.

    ///\warning If node \c v in unreachable from the root the return value

    ///of this funcion is undefined.

    Value dist(Node v) const { return (*distance)[v]; }

    ///Returns the 'previous edge' of the shortest path tree.

    ///For a node \c v it returns the 'previous edge' of the shortest path tree,

    ///i.e. it returns the last edge of a shortest path from the root to \c

    ///v. It is \ref INVALID

    ///if \c v is unreachable from the root or if \c v=s. The

    ///shortest path tree used here is equal to the shortest path tree used in

    ///\ref predNode(Node v).  \pre \ref run() must be called before using

    ///this function.

    ///\todo predEdge could be a better name.

    Edge pred(Node v) const { return (*_pred)[v]; }

    ///Returns the 'previous node' of the shortest path tree.

    ///For a node \c v it returns the 'previous node' of the shortest path tree,

    ///i.e. it returns the last but one node from a shortest path from the

    ///root to \c /v. It is INVALID if \c v is unreachable from the root or if

    ///\c v=s. The shortest path tree used here is equal to the shortest path

    ///tree used in \ref pred(Node v).  \pre \ref run() must be called before

    ///using this function.

    Node predNode(Node v) const { return (*pred_node)[v]; }

    ///Returns a reference to the NodeMap of distances.

    ///Returns a reference to the NodeMap of distances. \pre \ref run() must

    ///be called before using this function.

    const DistMap &distMap() const { return *distance;}

    ///Returns a reference to the shortest path tree map.

    ///Returns a reference to the NodeMap of the edges of the

    ///shortest path tree.

    ///\pre \ref run() must be called before using this function.

    const PredMap &predMap() const { return *_pred;}

    ///Returns a reference to the map of nodes of shortest paths.

    ///Returns a reference to the NodeMap of the last but one nodes of the

    ///shortest path tree.

    ///\pre \ref run() must be called before using this function.

    const PredNodeMap &predNodeMap() const { return *pred_node;}

    ///Checks if a node is reachable from the root.

    ///Returns \c true if \c v is reachable from the root.

    ///\note The root node is reported to be reached!

    ///\pre \ref run() must be called before using this function.

    ///

    bool reached(Node v) { return v==source || (*_pred)[v]!=INVALID; }

  };

  /// Default traits used by \ref DijkstraWizard

  /// To make it easier to use Dijkstra algorithm we created a wizard class.

  /// This \ref DijkstraWizard class also needs default traits.

  /// The \ref DijkstraWizardBase is a class to be the default traits of the

  /// \ref DijkstraWizard class.

  template<class GR,class LM>

  class DijkstraWizardBase : public DijkstraDefaultTraits<GR,LM>

  {

    typedef DijkstraDefaultTraits<GR,LM> Base;

  protected:

    /// Pointer to the underlying graph.

    void *_g;

    /// Pointer to the length map

    void *_length;

    ///Pointer to the map of predecessors edges.

    void *_pred;

    ///Pointer to the map of predecessors nodes.

    void *_predNode;

    ///Pointer to the map of distances.

    void *_dist;

    ///Pointer to the source node.

    void *_source;

    /// Type of the nodes in the graph.

    typedef typename Base::Graph::Node Node;

    public:

    /// Constructor.

    /// This constructor does not require parameters, therefore it initiates

    /// all of the attributes to default values (0, INVALID).

    DijkstraWizardBase() : _g(0), _length(0), _pred(0), _predNode(0),

		       _dist(0), _source(INVALID) {}

    /// Constructor.

    /// This constructor requires some parameters, listed in the parameters list.

    /// Others are initiated to 0.

    /// \param g is the initial value of  \ref _g

    /// \param l is the initial value of  \ref _length

    /// \param s is the initial value of  \ref _source

    DijkstraWizardBase(const GR &g,const LM &l, Node s=INVALID) :

      _g((void *)&g), _length((void *)&l), _pred(0), _predNode(0),

		  _dist(0), _source((void *)&s) {}

  };

  /// A class to make easier the usage of Dijkstra algorithm

  /// This class is created to make it easier to use Dijkstra algorithm.

  /// It uses the functions and features of the plain \ref Dijkstra,

  /// but it is much more simple to use it.

  ///

  /// Simplicity means that the way to change the types defined

  /// in the traits class is based on functions that returns the new class

  /// and not on templatable built-in classes. When using the plain \Dijkstra

  /// the new class with the modified type comes from the original by using the ::

  /// operator. In this case only a function have to be called and it will

  /// return the needed class.

  ///

  /// It does not have own \ref run method. When its \ref run method is called

  /// it initiates a plain \ref Dijkstra class, and calls the \ref Dijkstra::run

  /// method of it.

  template<class TR>

  class DijkstraWizard : public TR

  {

    typedef TR Base;

    ///The type of the underlying graph.

    typedef typename TR::Graph Graph;

    //\e

    typedef typename Graph::Node Node;

    //\e

    typedef typename Graph::NodeIt NodeIt;

    //\e

    typedef typename Graph::Edge Edge;

    //\e

    typedef typename Graph::OutEdgeIt OutEdgeIt;

    ///The type of the map that stores the edge lengths.

    typedef typename TR::LengthMap LengthMap;

    ///The type of the length of the edges.

    typedef typename LengthMap::Value Value;

    ///\brief The type of the map that stores the last

    ///edges of the shortest paths.

    typedef typename TR::PredMap PredMap;

    ///\brief The type of the map that stores the last but one

    ///nodes of the shortest paths.

    typedef typename TR::PredNodeMap PredNodeMap;

    ///The type of the map that stores the dists of the nodes.

    typedef typename TR::DistMap DistMap;

    ///The heap type used by the dijkstra algorithm.

    typedef typename TR::Heap Heap;

public:

    /// Constructor.

    DijkstraWizard() : TR() {}

    /// Constructor that requires parameters.

    /// These parameters will be the default values for the traits class.

    DijkstraWizard(const Graph &g,const LengthMap &l, Node s=INVALID) :

      TR(g,l,s) {}

    ///Copy constructor

    DijkstraWizard(const TR &b) : TR(b) {}

    ~DijkstraWizard() {}

    ///Runs Dijkstra algorithm from a given node.

    ///Runs Dijkstra algorithm from a given node.

    ///The node can be given by the \ref source function.

    void run()

    {

      if(_source==0) throw UninitializedData();

      Dijkstra<Graph,LengthMap,TR> Dij(*(Graph*)_g,*(LengthMap*)_length);

      if(_pred) Dij.predMap(*(PredMap*)_pred);

      if(_predNode) Dij.predNodeMap(*(PredNodeMap*)_predNode);

      if(_dist) Dij.distMap(*(DistMap*)_dist);

      Dij.run(*(Node*)_source);

    }

    ///Runs Dijkstra algorithm from a given node.

    ///Runs Dijkstra algorithm from a given node.

    ///\param s is the given source.

    void run(Node s)

    {

      _source=(void *)&s;

      run();

    }

    template<class T>

    struct DefPredMapBase : public Base {

      typedef T PredMap;

      static PredMap *createPredMap(const Graph &G) { return 0; };

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

    };

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

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

    template<class T>

    DijkstraWizard<DefPredMapBase<T> > predMap(const T &t) 

    {

      _pred=(void *)&t;

      return DijkstraWizard<DefPredMapBase<T> >(*this);

    }

    template<class T>

    struct DefPredNodeMapBase : public Base {

      typedef T PredNodeMap;

      static PredNodeMap *createPredNodeMap(const Graph &G) { return 0; };

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

    };

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

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

    template<class T>

    DijkstraWizard<DefPredNodeMapBase<T> > predNodeMap(const T &t) 

    {

      _predNode=(void *)&t;

      return DijkstraWizard<DefPredNodeMapBase<T> >(*this);

    }

    template<class T>

    struct DefDistMapBase : public Base {

      typedef T DistMap;

      static DistMap *createDistMap(const Graph &G) { return 0; };

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

    };

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

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

    template<class T>

    DijkstraWizard<DefDistMapBase<T> > distMap(const T &t) 

    {

      _dist=(void *)&t;

      return DijkstraWizard<DefDistMapBase<T> >(*this);

    }

    /// Sets the source node, from which the Dijkstra algorithm runs.

    /// Sets the source node, from which the Dijkstra algorithm runs.

    /// \param s is the source node.

    DijkstraWizard<TR> &source(Node s) 

    {

      source=(void *)&s;

      return *this;

    }

  };

  ///\e

  ///\todo Please document...

  ///

  template<class GR, class LM>

  DijkstraWizard<DijkstraWizardBase<GR,LM> >

  dijkstra(const GR &g,const LM &l,typename GR::Node s=INVALID)

  {

    return DijkstraWizard<DijkstraWizardBase<GR,LM> >(g,l,s);

  }

/// @}

} //END OF NAMESPACE LEMON

#endif