//
// ********************************************************************
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//
//
// $Id: G4ReduciblePolygon.hh,v 1.6 2003/11/03 18:39:55 gcosmo Exp $
// GEANT4 tag $Name: geant4-06-00-patch-01 $
//
// 
// --------------------------------------------------------------------
// GEANT 4 class header file
//
//
// G4ReduciblePolygon.hh
//
// Class description:
//
//   Utility class used to specify, test, reduce, and/or otherwise
//   manipulate a 2D polygon.
//
//   For this class, a polygon consists of n > 2 points in 2D
//   space (a,b). The polygon is always closed by connecting the
//   last point to the first. A G4ReduciblePolygon is guaranteed
//   to fulfill this definition in all instances. 
//
//   Illegal manipulations (such that a valid polygon would be
//   produced) result in an error return if possible and 
//   otherwise a G4Exception.
//
//   The set of manipulations is limited currently to what
//   is needed for G4Polycone and G4Polyhedra.

// Author: 
//   David C. Williams (davidw@scipp.ucsc.edu)
// --------------------------------------------------------------------
#ifndef G4ReduciblePolygon_hh
#define G4ReduciblePolygon_hh

#include "G4Types.hh"

class G4ReduciblePolygon
{
  friend class G4ReduciblePolygonIterator;

  public:
  //
  // Creator: via simple a/b arrays
  //
  G4ReduciblePolygon( const G4double a[], const G4double b[], G4int n );
  
  //
  // Creator: a special version for G4Polygon and G4Polycone
  // that takes two a points at planes of b
  // (where a==r and b==z for the GEANT3 classic PCON and PGON)
  //
  G4ReduciblePolygon( const G4double rmin[], const G4double rmax[],
                      const G4double z[], G4int n );
  
  virtual ~G4ReduciblePolygon();
  
  //
  // Queries
  //
  inline G4int NumVertices() const { return numVertices; }
  
  inline G4double Amin() const { return aMin; }
  inline G4double Amax() const { return aMax; }
  inline G4double Bmin() const { return bMin; }
  inline G4double Bmax() const { return bMax; }
  
  void CopyVertices( G4double a[], G4double b[] ) const;

  //
  // Manipulations
  //
  void ScaleA( G4double scale );
  void ScaleB( G4double scale );
  
  G4bool RemoveDuplicateVertices( G4double tolerance );
  G4bool RemoveRedundantVertices( G4double tolerance );
  
  void ReverseOrder();

  //
  // Tests
  //
  G4double Area();
  G4bool CrossesItself( G4double tolerance );
  G4bool BisectedBy( G4double a1, G4double b1,
         G4double a2, G4double b2, G4double tolerance );
  
  void Print();  // Debugging only
  
  protected:
  
  void Create( const G4double a[], const G4double b[], G4int n );
  
  void CalculateMaxMin();
  
  //
  // Below are member values that are *always* kept up to date (please!)
  //
  G4double aMin, aMax, bMin, bMax;
  G4int   numVertices;
  
  //
  // A subclass which holds the vertices in a single-linked list
  //
  // Yeah, call me an old-fashioned c hacker, but I cannot make
  // myself use the rogue tools for this trivial list.
  //
  struct ABVertex;
  friend struct ABVertex;
  struct ABVertex
  {
    G4double a, b;
    ABVertex *next;
  };
  
  ABVertex *vertexHead;

  private:

    G4ReduciblePolygon(const G4ReduciblePolygon&);
    G4ReduciblePolygon& operator=(const G4ReduciblePolygon&);
    // Private copy constructor and assignment operator.
};


//
// A companion class for iterating over the vertices of our polygon.
// It is simple enough that all routines are declared inline here.
//
class G4ReduciblePolygonIterator
{
  public:

  G4ReduciblePolygonIterator( const G4ReduciblePolygon *theSubject )
   { subject = theSubject; current=0; }
  
  void  Begin() { current = subject->vertexHead; }  
  G4bool  Next()  { if (current) current=current->next; return Valid(); }
  
  G4bool  Valid() const { return current!=0; }  
  
  G4double GetA() const { return current->a; }
  G4double GetB() const { return current->b; }
  
  protected:

  const G4ReduciblePolygon  *subject;      // Who are we iterating over
  G4ReduciblePolygon::ABVertex  *current;  // Current vertex
};

#endif