// Copyright: 	Matra-Datavision 1991
// File:	GraphTools_ReducedGraph.cxx
// Created:	Wed Oct 23 16:28:16 1991
// Author:	Denis PASCAL
//		<dp>

#include <Standard_NoMoreObject.hxx>
#include <Standard_NoSuchObject.hxx>
#include <GraphTools_RGNode.hxx>
#include <GraphTools_ListIteratorOfSCList.hxx>

static Standard_Boolean ContainsBack (const Handle(GraphTools_SC)& SC1,
			       const Handle(GraphTools_SC)& SC2)
{
  GraphTools_ListIteratorOfSCList it (SC1->GetBackSC());
  for (;it.More();it.Next()) {
    if (it.Value() == SC2) return Standard_True;
  }
  return Standard_False;
}

static Standard_Boolean ContainsFront (const Handle(GraphTools_SC)& SC1,
				const Handle(GraphTools_SC)& SC2)
{
  GraphTools_ListIteratorOfSCList it (SC1->GetFrontSC());
  for (;it.More();it.Next()) {
    if (it.Value() == SC2) return Standard_True;
  }
  return Standard_False;
}

//=======================================================================
//function : GraphTools_ReducedGraph
//purpose  : 
//=======================================================================

GraphTools_ReducedGraph::GraphTools_ReducedGraph () 
{
  performed = Standard_False;
}


//=======================================================================
//function : GraphTools_ReducedGraph
//purpose  : 
//=======================================================================

GraphTools_ReducedGraph::GraphTools_ReducedGraph 
  (const Graph& G) 
{
  FromGraph(G);
  Perform(G);
}


//=======================================================================
//function : FromGraph
//purpose  : 
//=======================================================================

void GraphTools_ReducedGraph::FromGraph (const Graph& G) 
{
  performed = Standard_False;
  for (GIterator itG (G); itG.More(); itG.Next() ) {
    GraphTools_RGNode newnode;
    myVertices.Add (itG.Value(),newnode);
  }
}


//=======================================================================
//function : FromVertex
//purpose  : 
//=======================================================================

void GraphTools_ReducedGraph::FromVertex (const Vertex& V) 
{
  performed = Standard_False;
  GraphTools_RGNode newnode;
  myVertices.Add(V,newnode);
}

//=======================================================================
//function : Perform
//purpose  : 
//=======================================================================

void GraphTools_ReducedGraph::Perform (const Graph& G)
{
  performed = Standard_True;
  myNowIndex = 0;
  myStack.Clear();
  mySort.Clear();
  Standard_Integer visited;
  Standard_Integer index = 1;
  while  (index <= myVertices.Extent()) {
    visited = myVertices(index).GetVisited();
    if (visited == 0) Visit(index,G);
    index++;
  }
  // front and back strong components  of a given one : Update
  Standard_Integer curV,nbV,adjV,nbadjV;
  Handle(GraphTools_SC) curSC,adjSC;
  GraphTools_ListIteratorOfSCList it;
  for (it.Initialize(mySort); it.More(); it.Next()) {
    curSC = it.Value();
    nbV   = curSC->NbVertices();
    for (Standard_Integer j = 1; j <= nbV; j++) {
      curV  = curSC->GetVertex(j);
      nbadjV = myVertices(curV).NbAdj();
      for (Standard_Integer k = 1; k <= nbadjV; k++) {
	adjV  = myVertices(curV).GetAdj(k);
	adjSC = myVertices(adjV).GetSC();
        if (adjSC != curSC) {
	  if (!ContainsFront(curSC,adjSC)) curSC->AddFrontSC (adjSC);
	  if (!ContainsBack(adjSC,curSC))  adjSC->AddBackSC  (curSC);
	}
      }
    }
  }
}


//=======================================================================
//function : Reset
//purpose  : 
//=======================================================================

void GraphTools_ReducedGraph::Reset ()
{
  performed = Standard_False;
  myVertices.Clear();
  myNowIndex = 0;
  myStack.Clear();
  mySort.Clear();
}


//=======================================================================
//function : IsRoot
//purpose  : 
//=======================================================================
Standard_Boolean GraphTools_ReducedGraph::IsRoot
  (const Handle(GraphTools_SC)& SC) const
{
  return (SC->GetBackSC().IsEmpty()); 
}                       


//=======================================================================
//function : IsLeaf
//purpose  : 
//=======================================================================
Standard_Boolean GraphTools_ReducedGraph::IsLeaf
  (const Handle(GraphTools_SC)& SC) const
{
  return (SC->GetFrontSC().IsEmpty());
} 


//=======================================================================
//function : NbVertices
//purpose  : 
//=======================================================================

Standard_Integer GraphTools_ReducedGraph::NbVertices
  (const Handle(GraphTools_SC)& SC) const
{
  return SC->NbVertices();
}


//=======================================================================
//function : GetVertex
//purpose  : 
//=======================================================================

const Vertex& GraphTools_ReducedGraph::GetVertex
  (const Handle(GraphTools_SC)& SC,
   const Standard_Integer index) const
{
  return myVertices.FindKey(SC->GetVertex(index));
}


//=======================================================================
//function : GetSC
//purpose  : 
//=======================================================================
Handle(GraphTools_SC) GraphTools_ReducedGraph::GetSC 
       (const Vertex& V) const
{
  if (!performed) Standard_DomainError::Raise();
  return myVertices.FindFromKey(V).GetSC();
}

 
//=======================================================================
//function : Visit
//purpose  : 
//=======================================================================

Standard_Integer GraphTools_ReducedGraph::Visit 
  (const Standard_Integer k, const Graph& G) 
{
  Standard_Integer MIN;
  Standard_Integer M;
  myNowIndex++; 
  myVertices(k).SetVisited(myNowIndex);
  MIN = myNowIndex;
  myStack.Push(k);
  Standard_Integer currentVisited;
  currentVisited = myVertices(k).GetVisited();
  Standard_Integer adjacentIndex;
  Standard_Integer adjacentVisited;
  for (VIterator itV (G,myVertices.FindKey(k)); itV.More(); itV.Next()) { 
    adjacentIndex = myVertices.FindIndex(itV.Value());
    if (adjacentIndex == 0) {
      GraphTools_RGNode newnode;
      adjacentIndex   = myVertices.Add (itV.Value(),newnode);
      adjacentVisited = 0;
    }
    else  adjacentVisited = myVertices(adjacentIndex).GetVisited();
    myVertices(k).AddAdj(adjacentIndex);
    if (adjacentVisited == 0) M = Visit (adjacentIndex,G);
    else M = adjacentVisited;
    if (M < MIN) MIN = M;
  }
  if (MIN == currentVisited) {
    Handle(GraphTools_SC) SC = new GraphTools_SC();
    Standard_Boolean more;
    do {
      SC->AddVertex(myStack.Top());
      myVertices(myStack.Top()).SetVisited(IntegerLast());
      myVertices(myStack.Top()).SetSC(SC);
      more = myStack.Top() != k;
      myStack.Pop() ; 
    }
    while (more);
    mySort.Prepend(SC);  
  }
  return MIN;
}