// -*- c++ -*- //

 #ifndef HUGO_KRUSKAL_H

 #define HUGO_KRUSKAL_H

 #include <algorithm>

 #include <unionfind.h>

 #include <for_each_macros.h>

 ///\file

 ///\brief Kruskal's algorithm to compute a minimum cost tree

 namespace hugo {

   /// Kruskal's algorithm to compute a minimum cost tree

   template <typename Graph, typename InputEdgeOrder, typename OutBoolMap>

   typename InputEdgeOrder::ValueType

   Kruskal(Graph const& G, InputEdgeOrder const& edges, 

 	  OutBoolMap& out_map)

   {

     typedef typename InputEdgeOrder::ValueType EdgeCost;

     typedef typename Graph::NodeMap<int> NodeIntMap;

     typedef typename Graph::Node Node;

     NodeIntMap comp_map(G, -1);

     UnionFind<Node,NodeIntMap> uf(comp_map); 

     EdgeCost tot_cost = 0;

     for (typename InputEdgeOrder::const_iterator p = edges.begin(); 

 	 p!=edges.end(); ++p ) {

       if ( uf.join(G.head(edges.first(p)),

 			     G.tail(edges.first(p))) ) {

 	out_map.set(edges.first(p), true);

 	tot_cost += edges.second(p);

       }

       else {

 	out_map.set(edges.first(p), false);

       }

     }

     return tot_cost;

   }

   /* A work-around for running Kruskal with const-reference bool maps... */

   template<typename Map>

   class NonConstMapWr {

     const Map &m;

   public:

     typedef typename Map::ValueType ValueType;

     NonConstMapWr(const Map &_m) : m(_m) {}

     template<typename KeyType>

     void set(KeyType const& k, ValueType const &v) const { m.set(k,v); }

   };

   template <typename Graph, typename InputEdgeOrder, typename OutBoolMap>

   inline

   typename InputEdgeOrder::ValueType

   Kruskal(Graph const& G, InputEdgeOrder const& edges, 

 	  OutBoolMap const& out_map)

   {

     NonConstMapWr<OutBoolMap> map_wr(out_map);

     return Kruskal(G, edges, map_wr);

   }  

   /* ** ** Output-objektumok: egyszeruen extra bool mapek ** ** */

   /// A writable bool-map that makes a sequence of "true" keys

   /// A writable bool-map that creates a sequence out of keys that receive

   /// the value "true".

   /// \warning Not a regular property map, as it doesn't know its KeyType

   template<typename Iterator>

   class SequenceOutput {

     mutable Iterator it;

   public:

     typedef bool ValueType;

     SequenceOutput(Iterator const &_it) : it(_it) {}

     template<typename KeyType>

     void set(KeyType const& k, bool v) const { if(v) {*it=k; ++it;} }

   };

   template<typename Iterator>

   inline

   SequenceOutput<Iterator>

   makeSequenceOutput(Iterator it) {

     return SequenceOutput<Iterator>(it);

   }

   /* ** ** InputSource -ok ** ** */

   template<typename Key, typename Val>

   class KruskalPairVec : public std::vector< std::pair<Key,Val> > {

   public:

     typedef std::vector< std::pair<Key,Val> > Parent;

     typedef Key KeyType;

     typedef Val ValueType;

     typedef std::pair<Key,Val> PairType;

     typedef typename Parent::iterator iterator;

     typedef typename Parent::const_iterator const_iterator;

   private:

     class comparePair {

     public:

       bool operator()(PairType const& a, PairType const& b) {

 	return a.second < b.second;

       }

     };

   public:

     // FIXME: kell ez?

     // KruskalPairVec(Parent const& p) : Parent(p) {}

     void sort() {

       std::sort(begin(), end(), comparePair());

     }

     // FIXME: nem nagyon illik ez ide...

     template<typename Graph, typename Map>

     KruskalPairVec(Graph const& G, Map const& m) {

       typedef typename Graph::EdgeIt EdgeIt;

       clear();

       FOR_EACH_LOC(EdgeIt, e, G) {

       // for (EdgeIt e=G.template first<EdgeIt>(); G.valid(e); G.next(e)) {

 	push_back(make_pair(e, m[e]));

       }

       sort();

     }

     Key const& first(const_iterator i) const { return i->first; }

     Key& first(iterator i) { return i->first; }

     Val const& second(const_iterator i) const { return i->second; }

     Val& second(iterator i) { return i->second; }

   };

   template <typename Map>

   class KruskalMapVec : public std::vector<typename Map::KeyType> {

   public:

     typedef typename Map::KeyType KeyType;

     typedef typename Map::ValueType ValueType;

     typedef typename std::vector<KeyType> Parent;

     typedef typename Parent::iterator iterator;

     typedef typename Parent::const_iterator const_iterator;

   private:

     const Map &m;

     class compareKeys {

       const Map &m;

     public:

       compareKeys(Map const &_m) : m(_m) {}

       bool operator()(KeyType const& a, KeyType const& b) {

 	return m[a] < m[b];

       }

     };

   public:

     KruskalMapVec(Map const& _m) : m(_m) {}

     void sort() {

       std::sort(begin(), end(), compareKeys(m));

     }

     // FIXME: nem nagyon illik ez ide...

     template<typename Graph>

     KruskalMapVec(Graph const& G, Map const& _m) : m(_m) {

       typedef typename Graph::EdgeIt EdgeIt;

       clear();

       FOR_EACH_LOC(EdgeIt, e, G) {

       // for (EdgeIt e=G.template first<EdgeIt>(); G.valid(e); G.next(e)) {

 	push_back(e);

       }

       sort();

     }

     KeyType const& first(const_iterator i) const { return *i; }

     KeyType& first(iterator i) { return *i; }

     ValueType const& second(const_iterator i) const { return m[*i]; }

     ValueType& second(iterator i) { return m[*i]; }

   };

   /* ** ** Wrapper fuggvenyek ** ** */

   /// \brief Wrapper to Kruskal().

   /// Input is from an EdgeMap, output is a plain boolmap.

   template <typename Graph, typename EdgeCostMap, typename RetEdgeBoolMap>

   inline

   typename EdgeCostMap::ValueType

   Kruskal_EdgeCostMapIn_BoolMapOut(Graph const& G,

 				   EdgeCostMap const& edge_costs,

 				   RetEdgeBoolMap &ret_bool_map) {

     typedef KruskalPairVec<typename Graph::Edge, typename EdgeCostMap::ValueType>

       InputVec;

     InputVec iv(G, edge_costs);

     return Kruskal(G, iv, ret_bool_map);

   }

   /// \brief Wrapper to Kruskal().

   /// Input is from an EdgeMap, output is to a sequence.

   template <typename Graph, typename EdgeCostMap, typename RetIterator>

   inline

   typename EdgeCostMap::ValueType

   Kruskal_EdgeCostMapIn_IteratorOut(Graph const& G,

 				    EdgeCostMap const& edge_costs,

 				    RetIterator ret_iterator) {

     typedef SequenceOutput<RetIterator> OutMap;

     OutMap out(ret_iterator);

     typedef KruskalPairVec<typename Graph::Edge, typename EdgeCostMap::ValueType>

       InputVec;

     InputVec iv(G, edge_costs);

     return Kruskal(G, iv, out);

   }

 } //namespace hugo

 #endif //HUGO_KRUSKAL_H