/* -*- C++ -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library

 *

 * Copyright (C) 2003-2008

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

#include <fstream>

#include <string>

#include "test_tools.h"

#include <lemon/smart_graph.h>

#include <lemon/dimacs.h>

#include <lemon/preflow.h>

#include <lemon/concepts/graph.h>

#include <lemon/concepts/maps.h>

using namespace lemon;

void checkPreflow() 

{

  typedef int VType;

  typedef concepts::Graph Graph;

  typedef Graph::Node Node;

  typedef Graph::Edge Edge;

  typedef concepts::ReadMap<Edge,VType> CapMap;

  typedef concepts::ReadWriteMap<Edge,VType> FlowMap;

  typedef concepts::WriteMap<Node,bool> CutMap;

  Graph g;

  Node n;

  Edge e;

  CapMap cap;

  FlowMap flow;

  CutMap cut;

  Preflow<Graph, CapMap>::DefFlowMap<FlowMap>::Create preflow_test(g,cap,n,n);

  preflow_test.capacityMap(cap);

  flow = preflow_test.flowMap();

  preflow_test.flowMap(flow);

  preflow_test.source(n);

  preflow_test.target(n);

  preflow_test.init();

  preflow_test.flowInit(cap);

  preflow_test.startFirstPhase();

  preflow_test.startSecondPhase();

  preflow_test.run();

  preflow_test.runMinCut();

  preflow_test.flowValue();

  preflow_test.minCut(n);

  preflow_test.minCutMap(cut);

  preflow_test.flow(e);

}

int cutValue (const SmartGraph& g, 

	      const SmartGraph::NodeMap<bool>& cut, 

	      const SmartGraph::EdgeMap<int>& cap) {

  int c=0;

  for(SmartGraph::EdgeIt e(g); e!=INVALID; ++e) {

    if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];

  }

  return c;

}

bool checkFlow(const SmartGraph& g, 

	       const SmartGraph::EdgeMap<int>& flow, 

	       const SmartGraph::EdgeMap<int>& cap, 

	       SmartGraph::Node s, SmartGraph::Node t) {

  for (SmartGraph::EdgeIt e(g); e != INVALID; ++e) {

    if (flow[e] < 0 || flow[e] > cap[e]) return false;

  }

  for (SmartGraph::NodeIt n(g); n != INVALID; ++n) {

    if (n == s || n == t) continue;

    int sum = 0;

    for (SmartGraph::OutEdgeIt e(g, n); e != INVALID; ++e) {

      sum += flow[e];

    }

    for (SmartGraph::InEdgeIt e(g, n); e != INVALID; ++e) {

      sum -= flow[e];

    }

    if (sum != 0) return false;

  }

  return true;

}

int main() {

  typedef SmartGraph Graph;

  typedef Graph::Node Node;

  typedef Graph::NodeIt NodeIt;

  typedef Graph::EdgeIt EdgeIt;

  typedef Graph::EdgeMap<int> CapMap;

  typedef Graph::EdgeMap<int> FlowMap;

  typedef Graph::NodeMap<bool> CutMap;

  typedef Preflow<Graph, CapMap> PType;

  std::string f_name;

  if( getenv("srcdir") )

    f_name = std::string(getenv("srcdir"));

  else f_name = ".";

  f_name += "/test/preflow_graph.dim";

  std::ifstream file(f_name.c_str());

  check(file, "Input file '" << f_name << "' not found.");

  Graph g;

  Node s, t;

  CapMap cap(g);

  readDimacs(file, g, cap, s, t);

  PType preflow_test(g, cap, s, t);

  preflow_test.run();

  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),

	"The flow is not feasible.");

  CutMap min_cut(g);

  preflow_test.minCutMap(min_cut); 

  int min_cut_value=cutValue(g,min_cut,cap);

  check(preflow_test.flowValue() == min_cut_value,

	"The max flow value is not equal to the three min cut values.");

  FlowMap flow(g);

  flow = preflow_test.flowMap();

  int flow_value=preflow_test.flowValue();

  for(EdgeIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e]; 

  preflow_test.flowInit(flow);

  preflow_test.startFirstPhase();

  CutMap min_cut1(g);

  preflow_test.minCutMap(min_cut1); 

  min_cut_value=cutValue(g,min_cut1,cap);

  check(preflow_test.flowValue() == min_cut_value &&

	min_cut_value == 2*flow_value,

	"The max flow value or the min cut value is wrong.");

  preflow_test.startSecondPhase();

  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),

	"The flow is not feasible.");

  CutMap min_cut2(g);

  preflow_test.minCutMap(min_cut2); 

  min_cut_value=cutValue(g,min_cut2,cap);

  check(preflow_test.flowValue() == min_cut_value &&

	min_cut_value == 2*flow_value,

	"The max flow value or the three min cut values were not doubled");

  preflow_test.flowMap(flow); 

  NodeIt tmp1(g,s);

  ++tmp1;

  if ( tmp1 != INVALID ) s=tmp1;

  NodeIt tmp2(g,t);

  ++tmp2;

  if ( tmp2 != INVALID ) t=tmp2;

  preflow_test.source(s);

  preflow_test.target(t); 

  preflow_test.run();

  CutMap min_cut3(g);

  preflow_test.minCutMap(min_cut3); 

  min_cut_value=cutValue(g,min_cut3,cap);

  check(preflow_test.flowValue() == min_cut_value,

	"The max flow value or the three min cut values are incorrect.");

  return 0;

}