/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

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

 *

 * Copyright (C) 2003-2009

 * 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 <lemon/concepts/digraph.h>

#include <lemon/smart_graph.h>

#include <lemon/list_graph.h>

#include <lemon/lgf_reader.h>

#include <lemon/bellman_ford.h>

#include <lemon/path.h>

#include "graph_test.h"

#include "test_tools.h"

using namespace lemon;

char test_lgf[] =

  "@nodes\n"

  "label\n"

  "0\n"

  "1\n"

  "2\n"

  "3\n"

  "4\n"

  "@arcs\n"

  "    length\n"

  "0 1 3\n"

  "1 2 -3\n"

  "1 2 -5\n"

  "1 3 -2\n"

  "0 2 -1\n"

  "1 2 -4\n"

  "0 3 2\n"

  "4 2 -5\n"

  "2 3 1\n"

  "@attributes\n"

  "source 0\n"

  "target 3\n";

void checkBellmanFordCompile()

{

  typedef int Value;

  typedef concepts::Digraph Digraph;

  typedef concepts::ReadMap<Digraph::Arc,Value> LengthMap;

  typedef BellmanFord<Digraph, LengthMap> BF;

  typedef Digraph::Node Node;

  typedef Digraph::Arc Arc;

  Digraph gr;

  Node s, t, n;

  Arc e;

  Value l;

  int k;

  bool b;

  BF::DistMap d(gr);

  BF::PredMap p(gr);

  LengthMap length;

  concepts::Path<Digraph> pp;

  {

    BF bf_test(gr,length);

    const BF& const_bf_test = bf_test;

    bf_test.run(s);

    bf_test.run(s,k);

    bf_test.init();

    bf_test.addSource(s);

    bf_test.addSource(s, 1);

    b = bf_test.processNextRound();

    b = bf_test.processNextWeakRound();

    bf_test.start();

    bf_test.checkedStart();

    bf_test.limitedStart(k);

    l  = const_bf_test.dist(t);

    e  = const_bf_test.predArc(t);

    s  = const_bf_test.predNode(t);

    b  = const_bf_test.reached(t);

    d  = const_bf_test.distMap();

    p  = const_bf_test.predMap();

    pp = const_bf_test.path(t);

    pp = const_bf_test.negativeCycle();

    for (BF::ActiveIt it(const_bf_test); it != INVALID; ++it) {}

  }

  {

    BF::SetPredMap<concepts::ReadWriteMap<Node,Arc> >

      ::SetDistMap<concepts::ReadWriteMap<Node,Value> >

      ::SetOperationTraits<BellmanFordDefaultOperationTraits<Value> >

      ::Create bf_test(gr,length);

    LengthMap length_map;

    concepts::ReadWriteMap<Node,Arc> pred_map;

    concepts::ReadWriteMap<Node,Value> dist_map;

    bf_test

      .lengthMap(length_map)

      .predMap(pred_map)

      .distMap(dist_map);

    bf_test.run(s);

    bf_test.run(s,k);

    bf_test.init();

    bf_test.addSource(s);

    bf_test.addSource(s, 1);

    b = bf_test.processNextRound();

    b = bf_test.processNextWeakRound();

    bf_test.start();

    bf_test.checkedStart();

    bf_test.limitedStart(k);

    l  = bf_test.dist(t);

    e  = bf_test.predArc(t);

    s  = bf_test.predNode(t);

    b  = bf_test.reached(t);

    pp = bf_test.path(t);

    pp = bf_test.negativeCycle();

  }

}

void checkBellmanFordFunctionCompile()

{

  typedef int Value;

  typedef concepts::Digraph Digraph;

  typedef Digraph::Arc Arc;

  typedef Digraph::Node Node;

  typedef concepts::ReadMap<Digraph::Arc,Value> LengthMap;

  Digraph g;

  bool b;

  bellmanFord(g,LengthMap()).run(Node());

  b = bellmanFord(g,LengthMap()).run(Node(),Node());

  bellmanFord(g,LengthMap())

    .predMap(concepts::ReadWriteMap<Node,Arc>())

    .distMap(concepts::ReadWriteMap<Node,Value>())

    .run(Node());

  b=bellmanFord(g,LengthMap())

    .predMap(concepts::ReadWriteMap<Node,Arc>())

    .distMap(concepts::ReadWriteMap<Node,Value>())

    .path(concepts::Path<Digraph>())

    .dist(Value())

    .run(Node(),Node());

}

template <typename Digraph, typename Value>

void checkBellmanFord() {

  TEMPLATE_DIGRAPH_TYPEDEFS(Digraph);

  typedef typename Digraph::template ArcMap<Value> LengthMap;

  Digraph gr;

  Node s, t;

  LengthMap length(gr);

  std::istringstream input(test_lgf);

  digraphReader(gr, input).

    arcMap("length", length).

    node("source", s).

    node("target", t).

    run();

  BellmanFord<Digraph, LengthMap>

    bf(gr, length);

  bf.run(s);

  Path<Digraph> p = bf.path(t);

  check(bf.reached(t) && bf.dist(t) == -1, "Bellman-Ford found a wrong path.");

  check(p.length() == 3, "path() found a wrong path.");

  check(checkPath(gr, p), "path() found a wrong path.");

  check(pathSource(gr, p) == s, "path() found a wrong path.");

  check(pathTarget(gr, p) == t, "path() found a wrong path.");

  ListPath<Digraph> path;

  Value dist;

  bool reached = bellmanFord(gr,length).path(path).dist(dist).run(s,t);

  check(reached && dist == -1, "Bellman-Ford found a wrong path.");

  check(path.length() == 3, "path() found a wrong path.");

  check(checkPath(gr, path), "path() found a wrong path.");

  check(pathSource(gr, path) == s, "path() found a wrong path.");

  check(pathTarget(gr, path) == t, "path() found a wrong path.");

  for(ArcIt e(gr); e!=INVALID; ++e) {

    Node u=gr.source(e);

    Node v=gr.target(e);

    check(!bf.reached(u) || (bf.dist(v) - bf.dist(u) <= length[e]),

          "Wrong output. dist(target)-dist(source)-arc_length=" <<

          bf.dist(v) - bf.dist(u) - length[e]);

  }

  for(NodeIt v(gr); v!=INVALID; ++v) {

    if (bf.reached(v)) {

      check(v==s || bf.predArc(v)!=INVALID, "Wrong tree.");

      if (bf.predArc(v)!=INVALID ) {

        Arc e=bf.predArc(v);

        Node u=gr.source(e);

        check(u==bf.predNode(v),"Wrong tree.");

        check(bf.dist(v) - bf.dist(u) == length[e],

              "Wrong distance! Difference: " <<

              bf.dist(v) - bf.dist(u) - length[e]);

      }

    }

  }

}

void checkBellmanFordNegativeCycle() {

  DIGRAPH_TYPEDEFS(SmartDigraph);

  SmartDigraph gr;

  IntArcMap length(gr);

  Node n1 = gr.addNode();

  Node n2 = gr.addNode();

  Node n3 = gr.addNode();

  Node n4 = gr.addNode();

  Arc a1 = gr.addArc(n1, n2);

  Arc a2 = gr.addArc(n2, n2);

  length[a1] = 2;

  length[a2] = -1;

  {

    BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);

    bf.run(n1);

    StaticPath<SmartDigraph> p = bf.negativeCycle();

    check(p.length() == 1 && p.front() == p.back() && p.front() == a2,

          "Wrong negative cycle.");

  }

  length[a2] = 0;

  {

    BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);

    bf.run(n1);

    check(bf.negativeCycle().empty(),

          "Negative cycle should not be found.");

  }

  length[gr.addArc(n1, n3)] = 5;

  length[gr.addArc(n4, n3)] = 1;

  length[gr.addArc(n2, n4)] = 2;

  length[gr.addArc(n3, n2)] = -4;

  {

    BellmanFord<SmartDigraph, IntArcMap> bf(gr, length);

    bf.init();

    bf.addSource(n1);

    for (int i = 0; i < 4; ++i) {

      check(bf.negativeCycle().empty(),

            "Negative cycle should not be found.");

      bf.processNextRound();

    }

    StaticPath<SmartDigraph> p = bf.negativeCycle();

    check(p.length() == 3, "Wrong negative cycle.");

    check(length[p.nth(0)] + length[p.nth(1)] + length[p.nth(2)] == -1,

          "Wrong negative cycle.");

  }

}

int main() {

  checkBellmanFord<ListDigraph, int>();

  checkBellmanFord<SmartDigraph, double>();

  checkBellmanFordNegativeCycle();

  return 0;

}