// -*- c++ -*-

#ifndef HUGO_DIMACS_H

#define HUGO_DIMACS_H

#include <iostream>

#include <string>

#include <vector>

namespace hugo {

  /// Dimacs flow files.

  /// This function reads a flow instance from dimacs flow format.

  /// At the beginning \c g is destroyed by \c g.clear().

  /// If the data coming from \c is is a max flow innstance, then 

  /// \c s and \t will be respectively the source and target nodes 

  /// and \c capacity will contain the edge capacities.

  /// If the data is a shortest path problem then \c s will be the 

  /// source node and \capacity will contain the edge lengths.

  template<typename Graph, typename CapacityMap>

  void readDimacsMaxFlow(std::istream& is, Graph &g, typename Graph::Node &s, typename Graph::Node &t, CapacityMap& capacity) {

    g.clear();

    int cap;

    char d;

    std::string problem;

    char c;

    int i, j;

    std::string str;

    int n, m; 

    typename Graph::Edge e;

    std::vector<typename Graph::Node> nodes;

    while (is>>c) {

      switch (c) {

      case 'c': //comment

	getline(is, str);

	break;

      case 'p': //problem definition

	is >> problem >> n >> m;

	getline(is, str);

	nodes.resize(n+1);

	for (int k=1; k<=n; ++k) nodes[k]=g.addNode();

	break;

      case 'n': //node definition

	if (problem=="sp") { //shortest path problem

	  is >> i;

	  getline(is, str);

	  s=nodes[i];

	}

	if (problem=="max") { //max flow problem

	  is >> i >> d;

	  getline(is, str);

	  if (d=='s') s=nodes[i];

	  if (d=='t') t=nodes[i];

	}

	break;

      case 'a':

	is >> i >> j >> cap;

	getline(is, str);

	e=g.addEdge(nodes[i], nodes[j]);

	capacity.update();

	capacity.set(e, cap);

	break;

      }

    }

  }

} //namespace hugo

#endif //HUGO_DIMACS_H