#ifndef HUGO_PREFLOW_PUSH_HH

#define HUGO_PREFLOW_PUSH_HH

//#include <algorithm>

#include <list>

#include <vector>

#include <queue>

//#include "pf_hiba.hh"

//#include <marci_list_graph.hh>

//#include <marci_graph_traits.hh>

#include <invalid.h>

#include <graph_wrapper.h>

//#include <reverse_bfs.hh>

using namespace std;

namespace hugo {

  template <typename Graph, typename T>

  class preflow_push {

    //Useful typedefs

    typedef typename Graph::Node Node;

    typedef typename Graph::NodeIt NodeIt;

    typedef typename Graph::Edge Edge;

    typedef typename Graph::OutEdgeIt OutEdgeIt;

    typedef typename Graph::InEdgeIt InEdgeIt;

    //---------------------------------------------

    //Parameters of the algorithm

    //---------------------------------------------

    //Fully examine an active node until excess becomes 0

    enum node_examination_t {examine_full, examine_to_relabel};

    //No more implemented yet:, examine_only_one_edge};

    node_examination_t node_examination;

    //Which implementation to be used

    enum implementation_t {impl_fifo, impl_highest_label};

    //No more implemented yet:};

    implementation_t implementation;

    //---------------------------------------------

    //Parameters of the algorithm

    //---------------------------------------------

  private:

    //input

    Graph& G;

    Node s;

    Node t;

    typename Graph::EdgeMap<T> &capacity;

    //output

    typename Graph::EdgeMap<T> preflow;

    T maxflow_value;

    //auxiliary variables for computation

    //The number of the nodes

    int number_of_nodes;

    //A nodemap for the level

    typename Graph::NodeMap<int> level;

    //A nodemap for the excess

    typename Graph::NodeMap<T> excess;

    //Number of nodes on each level

    vector<int> num_of_nodes_on_level;

    //For the FIFO implementation

    list<Node> fifo_nodes;

    //For 'highest label' implementation

    int highest_active;

    //int second_highest_active;

    vector< list<Node> > active_nodes;

  public:

    //Constructing the object using the graph, source, sink and capacity vector

    preflow_push(

		      Graph& _G, 

		      Node _s, 

		      Node _t, 

		      typename Graph::EdgeMap<T> & _capacity)

      : G(_G), s(_s), t(_t), 

	capacity(_capacity), 

	preflow(_G),

	//Counting the number of nodes

	//number_of_nodes(count(G.first<EachNodeIt>())),

	number_of_nodes(G.nodeNum()),

	level(_G),

	excess(_G)//,

        // Default constructor: active_nodes()

    { 

      //Simplest parameter settings

      node_examination = examine_full;//examine_to_relabel;//

      //Which implementation to be usedexamine_full

      implementation = impl_highest_label;//impl_fifo;

      //

      num_of_nodes_on_level.resize(2*number_of_nodes-1);

      num_of_nodes_on_level.clear();

      switch(implementation){

      case impl_highest_label :{

	active_nodes.clear();

	active_nodes.resize(2*number_of_nodes-1);

	break;

      }

      default:

	break;

      }

    }

    //Returns the value of a maximal flow 

    T run();

    typename Graph::EdgeMap<T>  getmaxflow(){

      return preflow;

    }

  private:

    //For testing purposes only

    //Lists the node_properties

    void write_property_vector(typename Graph::NodeMap<T> a,

			       //node_property_vector<Graph, T> a, 

			       char* prop_name="property"){

      for(NodeIt i=G.template first<NodeIt>(); G.valid(i); G.next(i)) {

	cout<<"Node id.: "<<G.id(i)<<", "<<prop_name<<" value: "<<a[i]<<endl;

      }

      cout<<endl;

    }

    //Modifies the excess of the node and makes sufficient changes

    void modify_excess(const Node& a ,T v){

      //T old_value=excess[a];

      excess[a] += v;

    }

    //This private procedure is supposed to modify the preflow on edge j

    //by value v (which can be positive or negative as well) 

    //and maintain the excess on the head and tail

    //Here we do not check whether this is possible or not

    void modify_preflow(Edge j, const T& v){

      //Modifiyng the edge

      preflow[j] += v;

      //Modifiyng the head

      modify_excess(G.head(j),v);

      //Modifiyng the tail

      modify_excess(G.tail(j),-v);

    }

    //Gives the active node to work with 

    //(depending on the implementation to be used)

    Node get_active_node(){

      switch(implementation) {

      case impl_highest_label : {

	//First need to find the highest label for which there's an active node

	while( highest_active>=0 && active_nodes[highest_active].empty() ){ 

	  --highest_active;

	}

	if( highest_active>=0) {

	  Node a=active_nodes[highest_active].front();

	  active_nodes[highest_active].pop_front();

	  return a;

	}

	else {

	  return INVALID;

	}

	break;

      }

      case impl_fifo : {

	if( ! fifo_nodes.empty() ) {

	  Node a=fifo_nodes.front();

	  fifo_nodes.pop_front();

	  return a;

	}

	else {

	  return INVALID;

	}

	break;

      }

      }

      //

      return INVALID;

    }

    //Puts node 'a' among the active nodes

    void make_active(const Node& a){

      //s and t never become active

      if (a!=s && a!= t){

	switch(implementation){

	case impl_highest_label :

	  active_nodes[level[a]].push_back(a);

	  break;

	case impl_fifo :

	  fifo_nodes.push_back(a);

	  break;

	}

      }

      //Update highest_active label

      if (highest_active<level[a]){

	highest_active=level[a];

      }

    }

    //Changes the level of node a and make sufficent changes

    void change_level_to(Node a, int new_value){

      int seged = level[a];

      level.set(a,new_value);

      --num_of_nodes_on_level[seged];

      ++num_of_nodes_on_level[new_value];

    }

    //Collection of things useful (or necessary) to do before running

    void preprocess(){

      //---------------------------------------

      //Initialize parameters

      //---------------------------------------

      //Setting starting preflow, level and excess values to zero

      //This can be important, if the algorithm is run more then once

      for(NodeIt i=G.template first<NodeIt>(); G.valid(i); G.next(i)) {

        level.set(i,0);

        excess.set(i,0);

	for(OutEdgeIt j=G.template first<OutEdgeIt>(i); G.valid(j); G.next(j)) 

	  preflow.set(j, 0);

      }

      num_of_nodes_on_level[0]=number_of_nodes;

      highest_active=0;

      //---------------------------------------

      //Initialize parameters

      //---------------------------------------

      //------------------------------------

      //This is the only part that uses BFS

      //------------------------------------

      /*Reverse_bfs from t, to find the starting level.*/

      //Copyright: Jacint

      change_level_to(t,0);

      std::queue<Node> bfs_queue;

      bfs_queue.push(t);

      while (!bfs_queue.empty()) {

	Node v=bfs_queue.front();	

	bfs_queue.pop();

	int l=level[v]+1;

	InEdgeIt e;

	for(G.first(e,v); G.valid(e); G.next(e)) {

	  Node w=G.tail(e);

	  if ( level[w] == number_of_nodes && w != s ) {

	    bfs_queue.push(w);

	    //Node first=level_list[l];

	    //if ( G.valid(first) ) left.set(first,w);

	    //right.set(w,first);

	    //level_list[l]=w;

	    change_level_to(w, l);

	    //level.set(w, l);

	  }

	}

      }

      change_level_to(s,number_of_nodes);

      //level.set(s,number_of_nodes);

      /*

      //Setting starting level values using reverse bfs

      reverse_bfs<Graph> rev_bfs(G,t);

      rev_bfs.run();

      //write_property_vector(rev_bfs.dist,"rev_bfs");

      for(NodeIt i=G.template first<NodeIt>(); G.valid(i); G.next(i)) {

        change_level_to(i,rev_bfs.dist(i));

	//level.put(i,rev_bfs.dist.get(i));

      }

      */

      //------------------------------------

      //This is the only part that uses BFS

      //------------------------------------

      //Starting level of s

      change_level_to(s,number_of_nodes);

      //level.put(s,number_of_nodes);

      //we push as much preflow from s as possible to start with

      for(OutEdgeIt j=G.template first<OutEdgeIt>(s); G.valid(j); G.next(j)){ 

	modify_preflow(j,capacity[j] );

	make_active(G.head(j));

	int lev=level[G.head(j)];

	if(highest_active<lev){

	  highest_active=lev;

	}

      }

      //cout<<highest_active<<endl;

    } 

    //If the preflow is less than the capacity on the given edge

    //then it is an edge in the residual graph

    bool is_admissible_forward_edge(Edge j, int& new_level){

      if (capacity[j]>preflow[j]){

	if(level[G.tail(j)]==level[G.head(j)]+1){

	  return true;

	}

	else{

	  if (level[G.head(j)] < new_level)

	    new_level=level[G.head(j)];

	}

      }

      return false;

    }

    //If the preflow is greater than 0 on the given edge

    //then the edge reversd is an edge in the residual graph

    bool is_admissible_backward_edge(Edge j, int& new_level){

      if (0<preflow[j]){

	if(level[G.tail(j)]==level[G.head(j)]-1){

	  return true;

	}

	else{

	  if (level[G.tail(j)] < new_level)

	    new_level=level[G.tail(j)];

	}

      }

      return false;

    }

  };  //class preflow_push  

  template<typename Graph, typename T>

    T preflow_push<Graph, T>::run() {

    //We need a residual graph

    ResGraphType res_graph(G, preflow, capacity);

    preprocess();

    //write_property_vector(level,"level");

    T e,v;

    Node a;

    while (a=get_active_node(), G.valid(a)){

      bool go_to_next_node=false;

      e = excess[a];

      while (!go_to_next_node){

	//Initial value for the new level for the active node we are dealing with

	int new_level=2*number_of_nodes;

	//Out edges from node a

	{

	  OutEdgeIt j=G.template first<OutEdgeIt>(a);

	  while (G.valid(j) && e){

	    if (is_admissible_forward_edge(j,new_level)){

	      v=min(e,capacity[j] - preflow[j]);

	      e -= v;

	      //New node might become active

	      if (excess[G.head(j)]==0){

		make_active(G.head(j));

	      }

	      modify_preflow(j,v);

	    }

	    G.next(j);

	  }

	}

	//In edges to node a

	{

	  InEdgeIt j=G.template first<InEdgeIt>(a);

	  while (G.valid(j) && e){

	    if (is_admissible_backward_edge(j,new_level)){

	      v=min(e,preflow[j]);

	      e -= v;

	      //New node might become active

	      if (excess[G.tail(j)]==0){

		make_active(G.tail(j));

	      }

	      modify_preflow(j,-v);

	    }

	    G.next(j);

	  }

	}

	//if (G.id(a)==999)

	//cout<<new_level<<" e: "<<e<<endl;

	//cout<<G.id(a)<<" "<<new_level<<endl;

	if (0==e){

	  //Saturating push

	  go_to_next_node=true;

	}

	else{//If there is still excess in node a

	  //change_level_to(a,new_level+1);

	  //Level remains empty

	  if (num_of_nodes_on_level[level[a]]==1){

	    change_level_to(a,number_of_nodes);

	    //go_to_next_node=True;

	  }

	  else{

	    change_level_to(a,new_level+1);

	    //increase_level(a);

	  }

	  switch(node_examination){

	  case examine_to_relabel:

	    make_active(a);

	    go_to_next_node = true;

	    break;

	  default:

	    break;

	  }

	}//if (0==e)

      }

    }

    maxflow_value = excess[t];

    return maxflow_value;

  }//run

}//namespace hugo

#endif //PREFLOW_PUSH_HH