// -*- c++ -*-

 #ifndef HUGO_MINLENGTHPATHS_H

 #define HUGO_MINLENGTHPATHS_H

 ///\file

 ///\brief An algorithm for finding k paths of minimal total length.

 #include <iostream>

 #include <dijkstra.h>

 #include <graph_wrapper.h>

 #include <maps.h>

 namespace hugo {

 ///\brief Implementation of an algorithm for finding k paths between 2 nodes 

   /// of minimal total length 

 ///

 /// The class \ref hugo::MinLengthPaths "MinLengthPaths" implements

 /// an algorithm which finds k edge-disjoint paths

 /// from a given source node to a given target node in an

 /// edge-weighted directed graph having minimal total weigth (length).

 /// 

 /// 

   template <typename Graph, typename T, 

     typename LengthMap=typename Graph::EdgeMap<T> >

   class MinLengthPaths {

 //      class ConstMap {

 //      public :

 //        typedef int ValueType;

 //        typedef typename Graph::Edge KeyType;

 //        int operator[](typename Graph::Edge e) const { 

 //  	return 1;

 //        } 

 //      };

     typedef typename Graph::Node Node;

     typedef typename Graph::NodeIt NodeIt;

     typedef typename Graph::Edge Edge;

     typedef typename Graph::OutEdgeIt OutEdgeIt;

     typedef typename Graph::EdgeMap<int> EdgeIntMap;

     typedef ConstMap<Edge,int> ConstMap;

     typedef TrivGraphWrapper<const Graph> TrivGraphType;

     typedef ResGraphWrapper<TrivGraphType,int,EdgeIntMap,

       ConstMap> ResGraphType;

     //template <typename Graph, typename T>

     class ModLengthMap {   

       typedef typename ResGraphType::NodeMap<T> NodeMap;

       const ResGraphType& G;

       const EdgeIntMap& rev; 

       const LengthMap &ol;   

       const NodeMap &pot;     

     public :

       typedef typename LengthMap::KeyType KeyType;

       typedef typename LengthMap::ValueType ValueType;

       ValueType operator[](typename ResGraphType::Edge e) const {     

 	if ( (1-2*rev[e])*ol[e]-(pot[G.head(e)]-pot[G.tail(e)] ) <0 ){

 	  ///\TODO This has to be removed

 	  std::cout<<"Negative length!!"<<std::endl;

 	}

 	return (1-2*rev[e])*ol[e]-(pot[G.head(e)]-pot[G.tail(e)]);   

       }     

       ModLengthMap(  const ResGraphType& _G, const EdgeIntMap& _rev, 

 		     const LengthMap &o,  const NodeMap &p) : 

 	G(_G), rev(_rev), ol(o), pot(p){}; 

     };

     const Graph& G;

     const LengthMap& length;

     //auxiliary variable

     //The value is 1 iff the edge is reversed

     EdgeIntMap reversed; 

   public :

     MinLengthPaths(Graph& _G, LengthMap& _length) : G(_G), 

       length(_length), reversed(_G)/*, dijkstra_dist(_G)*/{ }

     ///Runs the algorithm

     ///Runs the algorithm

     ///Returns k if there are at least k edge-disjoint paths from s to t.

     ///Otherwise it returns the number of edge-disjoint paths from s to t.

     int run(Node s, Node t, int k) {

       ConstMap const1map(1);

       ResGraphType res_graph(G, reversed, const1map);

       //Initialize the copy of the Dijkstra potential to zero

       typename ResGraphType::NodeMap<T> dijkstra_dist(G);

       ModLengthMap mod_length( res_graph, reversed, length, dijkstra_dist);

       Dijkstra<ResGraphType, ModLengthMap> dijkstra(res_graph, mod_length);

       for (int i=0; i<k; ++i){

 	dijkstra.run(s);

 	if (!dijkstra.reached(t)){

 	  //There is no k path from s to t

 	  return ++i;

 	};

 	{

 	  //We have to copy the potential

 	  typename ResGraphType::NodeIt n;

 	  for ( res_graph.first(n) ; res_graph.valid(n) ; res_graph.next(n) ) {

 	      dijkstra_dist[n] += dijkstra.distMap()[n];

 	  }

 	}

 	/*

 	{

 	  //We have to copy the potential

 	  typename ResGraphType::EdgeIt e;

 	  for ( res_graph.first(e) ; res_graph.valid(e) ; res_graph.next(e) ) {

 	    //dijkstra_dist[e] = dijkstra.distMap()[e];

 	    mod_length_c[Edge(e)] = mod_length_c[Edge(e)] - 

 	      dijkstra.distMap()[res_graph.head(e)] +  

 	      dijkstra.distMap()[res_graph.tail(e)];

 	  }

 	}

 	*/

 	//Reversing the sortest path

 	Node n=t;

 	Edge e;

 	while (n!=s){

 	  e = dijkstra.pred(n);

 	  n = dijkstra.predNode(n);

 	  reversed[e] = 1-reversed[e];

 	}

       }

       return k;

     }

   };//class MinLengthPaths

 } //namespace hugo

 #endif //HUGO_MINLENGTHPATHS_H