#ifndef PREFLOW_PUSH_HH

#define PREFLOW_PUSH_HH

#include <algorithm>

#include <list>

#include <vector>

//#include "pf_hiba.hh"

//#include <marci_list_graph.hh>

#include <marci_graph_traits.hh>

#include "reverse_bfs.hh"

using namespace std;

namespace marci {

  template <typename graph_type, typename T>

  class preflow_push {

    //Hasznos typedef-ek

    typedef graph_traits<graph_type>::node_iterator node_iterator;

    typedef graph_traits<graph_type>::edge_iterator edge_iterator;

    typedef graph_traits<graph_type>::each_node_iterator each_node_iterator;

    typedef graph_traits<graph_type>::each_edge_iterator each_edge_iterator;

    typedef graph_traits<graph_type>::out_edge_iterator out_edge_iterator;

    typedef graph_traits<graph_type>::in_edge_iterator in_edge_iterator;

    typedef graph_traits<graph_type>::sym_edge_iterator sym_edge_iterator;

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

    //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_type& G;

    node_iterator s;

    node_iterator t;

    edge_property_vector<graph_type, T> &capacity;

    //output

    edge_property_vector<graph_type, T> preflow;

    T maxflow_value;

    //auxiliary variables for computation

    int number_of_nodes;

    node_property_vector<graph_type, int> level;

    node_property_vector<graph_type, T> excess;

    //Number of nodes on each level

    vector<int> num_of_nodes_on_level;

    //For the FIFO implementation

    list<node_iterator> fifo_nodes;

    //For 'highest label' implementation

    int highest_active;

    //int second_highest_active;

    vector< list<node_iterator> > active_nodes;

  public:

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

    preflow_push(

		      graph_type& _G, 

		      node_iterator _s, 

		      node_iterator _t, 

		      edge_property_vector<graph_type, T>& _capacity)

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

	capacity(_capacity), 

	preflow(_G),

	//Counting the number of nodes

	number_of_nodes(number_of(G.first_node())),

	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.resize(2*number_of_nodes-1);

	active_nodes.clear();

	break;

      }

      default:

	break;

      }

    }

    //Returns the value of a maximal flow 

    T run();

    edge_property_vector<graph_type, T> getmaxflow(){

      return preflow;

    }

  private:

    //For testing purposes only

    //Lists the node_properties

    void write_property_vector(node_property_vector<graph_type, T> a, 

			       char* prop_name="property"){

      for(each_node_iterator i=G.first_node(); i.valid(); ++i) {

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

      }

      cout<<endl;

    }

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

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

	T old_value=excess.get(a);

	excess.put(a,old_value+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_iterator j, const T& v){

      //Auxiliary variable

      T old_value;

      //Modifiyng the edge

      old_value=preflow.get(j);

      preflow.put(j,old_value+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_iterator get_active_node(){

      //cout<<highest_active<<endl;

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

	  active_nodes[highest_active].pop_front();

	  return a;

	}

	else {

	  return node_iterator();

	}

	break;

      }

      case impl_fifo : {

	if( ! fifo_nodes.empty() ) {

	  node_iterator a=fifo_nodes.front();

	  fifo_nodes.pop_front();

	  return a;

	}

	else {

	  return node_iterator();

	}

	break;

      }

      }

      //

      return node_iterator();

    }

    //Puts node 'a' among the active nodes

    void make_active(const node_iterator& a){

      //s and t never become active

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

	switch(implementation){

	case impl_highest_label :

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

	  break;

	case impl_fifo :

	  fifo_nodes.push_back(a);

	  break;

	}

      }

      //Update highest_active label

      if (highest_active<level.get(a)){

	highest_active=level.get(a);

      }

    }

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

    void change_level_to(node_iterator a, int new_value){

      int seged = level.get(a);

      level.put(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(each_node_iterator i=G.first_node(); i.valid(); ++i) {

        level.put(i,0);

        excess.put(i,0);

	for(out_edge_iterator j=G.first_out_edge(i); j.valid(); ++j) 

	  preflow.put(j, 0);

      }

      num_of_nodes_on_level[0]=number_of_nodes;

      highest_active=0;

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

      //Initialize parameters

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

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

      //This is the only part that uses BFS

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

      //Setting starting level values using reverse bfs

      reverse_bfs<graph_type> rev_bfs(G,t);

      rev_bfs.run();

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

      for(each_node_iterator i=G.first_node(); i.valid(); ++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(out_edge_iterator j=G.first_out_edge(s); j.valid(); ++j){ 

	modify_preflow(j,capacity.get(j) );

	make_active(G.head(j));

	int lev=level.get(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(out_edge_iterator j, int& new_level){

      if (capacity.get(j)>preflow.get(j)){

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

	  return true;

	}

	else{

	  if (level.get(G.head(j)) < new_level)

	    new_level=level.get(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(in_edge_iterator j, int& new_level){

      if (0<preflow.get(j)){

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

	  return true;

	}

	else{

	  if (level.get(G.tail(j)) < new_level)

	    new_level=level.get(G.tail(j));

	}

      }

      return false;

    }

  };  //class preflow_push  

  template<typename graph_type, typename T>

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

    preprocess();

    T e,v;

    node_iterator a;

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

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

      //write_property_vector(excess,"excess");

      //write_property_vector(level,"level");

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

      int new_level=2*number_of_nodes;

      bool go_to_next_node=false;

      e = excess.get(a);

      while (!go_to_next_node){

	//Out edges from node a

	{

	  out_edge_iterator j=G.first_out_edge(a);

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

	    if (is_admissible_forward_edge(j,new_level)){

	      v=min(e,capacity.get(j) - preflow.get(j));

	      e -= v;

	      //New node might become active

	      if (excess.get(G.head(j))==0){

		make_active(G.head(j));

	      }

	      modify_preflow(j,v);

	    }

	    ++j;

	  }

	}

	//In edges to node a

	{

	  in_edge_iterator j=G.first_in_edge(a);

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

	    if (is_admissible_backward_edge(j,new_level)){

	      v=min(e,preflow.get(j));

	      e -= v;

	      //New node might become active

	      if (excess.get(G.tail(j))==0){

		make_active(G.tail(j));

	      }

	      modify_preflow(j,-v);

	    }

	    ++j;

	  }

	}

	//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

	  //Level remains empty

	  if (num_of_nodes_on_level[level.get(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.get(t);

    return maxflow_value;

  }//run

}//namespace marci

#endif //PREFLOW_PUSH_HH