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#ifndef __RVLALG_VECTOR_TERMINATOR
#define __RVLALG_VECTOR_TERMINATOR

#include "functional.hh"
#include "ls.hh"
#include "alg.hh"

/**  vectorterm.H
     Terminators which involve manipulating Vectors.  Includes
     using the built-in Vector operations as well as passing vectors
     to other objects.
*/

namespace RVLAlg {
  using namespace RVL;
/** Terminator which takes a unary function object,
    a vector, and a tolerance.

    STOP: \f$f(x) < tol\f$
*/

template <class Scalar>
class UnaryThresholdTerminator: public Terminator {
  
public:
  UnaryThresholdTerminator( FunctionObjectScalarRedn<Scalar>& tf, 
			    Vector<Scalar> & tx,
			    Scalar ttol) 
    : f(tf), x(tx), tol(ttol) {}

  virtual bool query() { 
    x.eval(f);
    Scalar temp = f.getValue();
    return (temp < tol);
  }

protected:
  FunctionObjectScalarRedn<Scalar> & f;
  Vector<Scalar> & x;
  Scalar tol;
  
};

/** Terminator which takes a binary function object, two
    vectors, and a tolerance.

    STOP: \f$f(x,y) < tol\f$
*/

template <class Scalar>
class BinaryThresholdTerminator: public Terminator {
  
public:
  BinaryThresholdTerminator( FunctionObjectScalarRedn<Scalar>& tf, 
			     Vector<Scalar> & tx,
			     Vector<Scalar> & ty,
			     Scalar ttol) 
    : f(tf), x(tx), y(ty), tol(ttol) {}

  virtual bool query() { 
    Scalar temp;
    x.eval(f, y);
    temp = f.getValue();
    return (temp < tol);
  }

protected:
  FunctionObjectScalarRedn<Scalar> & f;
  Vector<Scalar> & x;
  Vector<Scalar> & y;
  Scalar tol;  
};

/** Terminator which takes a ternary function object, three
    vectors, and a tolerance.

    STOP: \f$f(x,y,z) < tol\f$
*/

template <class Scalar>
class TernaryThresholdTerminator: public Terminator {
  
public:
  TernaryThresholdTerminator( FunctionObjectScalarRedn<Scalar>& tf, 
			      Vector<Scalar> & tx,
			      Vector<Scalar> & ty,
			      Vector<Scalar> & tz,
			      Scalar ttol) 
    : f(tf), x(tx), y(ty), z(tz), tol(ttol) {}

  virtual bool query() { 
    Scalar temp;
    x.eval(f,y,z);
    temp = f.getValue();
    return (temp < tol);
  }

protected:
  FunctionObjectScalarRedn<Scalar> & f;
  Vector<Scalar> & x;
  Vector<Scalar> & y;
  Vector<Scalar> & z;
  Scalar tol;
};

/** Terminator which takes a vector and a tolerance.

    STOP: \f$\|\|x\|\| < tol\f$
*/

template< class Scalar >
class NormThresholdTerminator: public Terminator {
public:
  typedef typename ScalarFieldTraits<Scalar>::AbsType NormRetType;

  NormThresholdTerminator( const Vector<Scalar> & tx, NormRetType ttol): x(tx), tol(ttol) {}

  virtual bool query() {
    return (x.norm() < tol);
  }

protected:
  const Vector<Scalar> & x;
  NormRetType tol;
};

/** Terminator which takes a vector and a tolerance.

    STOP: \f$\|\|x\|\|^{2} < tol\f$

    note: this is slightly cheaper than finding ||x|| < tol 
*/

template< class Scalar >
class Norm2ThresholdTerminator: public Terminator {
public:
  typedef typename ScalarFieldTraits<Scalar>::AbsType NormRetType;

  Norm2ThresholdTerminator( Vector<Scalar> & tx, NormRetType ttol): x(tx), tol(ttol) {}

  virtual bool query() {
    return (x.norm2() < tol);
  }

protected:
  Vector<Scalar> & x;
  NormRetType tol;
};

/** Terminator which takes two vectors and a tolerance.

    STOP: \f$\|\|x - y\|\| < tol\f$
*/


template< class Scalar >
class DiffThresholdTerminator: public Terminator {
public:
  typedef typename ScalarFieldTraits<Scalar>::AbsType NormRetType;

  DiffThresholdTerminator( Vector<Scalar> & tx, Vector<Scalar> & ty, NormRetType ttol)
    : x(tx), y(ty), tol(ttol) {
    if( ! x.inSameSpace(y) ) {
      RVLException e; e << "Error in DiffThresholdTerminator constructor: Vectors not in same space.";
      throw e;
    }
  }

  virtual bool query() {
    Vector<Scalar> temp(x.getSpace());
    temp.lincomb(1.0, x, -1.0, y);
    return (temp.norm() < tol);
  }

protected:
  Vector<Scalar> & x;
  Vector<Scalar> & y;
  NormRetType tol;
};


/** Terminator which takes two vectors and a tolerance.

    STOP: \f$\|\|x - y\|\|^{2} < tol\f$

    note: this is slightly cheaper than finding \f$\|\|x - y\|\| < tol\f$ 
*/


template< class Scalar >
class Diff2ThresholdTerminator: public Terminator {
public:
  typedef typename ScalarFieldTraits<Scalar>::AbsType NormRetType;

  Diff2ThresholdTerminator( Vector<Scalar> & tx, Vector<Scalar> & ty, NormRetType ttol)
    : x(tx), y(ty), tol(ttol) {
    if( ! x.inSameSpace(y) ) {
      RVLException e; e << "Error in DiffThresholdTerminator constructor: Vectors not in same space.";
      throw e;
    }
  }

  virtual bool query() {
    Vector<Scalar> temp(x.getSpace());
    temp.lincomb(1.0, x, -1.0, y);
    return (temp.norm2() < tol);
  }

protected:
  Vector<Scalar> & x;
  Vector<Scalar> & y;
  NormRetType tol;
};

/** Terminator which takes two vectors and a tolerance.

    STOP: \f$\left< x, y \right> < tol\f$
*/

template< class Scalar >
class IPThresholdTerminator: public Terminator {
public:
  IPThresholdTerminator( Vector<Scalar> & tx, Vector<Scalar> & ty, Scalar ttol)
    : x(tx), y(ty), tol(ttol) {
    if( ! x.inSameSpace(y) ) {
	RVLException e; e << "Error in DiffThresholdTerminator constructor: Vectors not in same space.";
      throw e;
    }
  }

  virtual bool query() {
    Scalar temp = x.inner(y);
    return (temp < tol);
  }

protected:
  Vector<Scalar> & x;
  Vector<Scalar> & y;
  Scalar tol;
};

/** Terminator which takes two vectors and a tolerance.

    STOP: \f$\| \left< x , y \right> \| < tol\f$
 */

template< class Scalar >
class AbsIPThresholdTerminator: public Terminator {
public:
  typedef typename ScalarFieldTraits<Scalar>::AbsType NormRetType;

  AbsIPThresholdTerminator( Vector<Scalar> & tx, Vector<Scalar> & ty, NormRetType ttol)
    : x(tx), y(ty), tol(ttol) {
    if( ! x.inSameSpace(y) ) {
      RVLException e; e << "Error in DiffThresholdTerminator constructor: Vectors not in same space.";
      throw e;
    }
  }
  ~AbsIPThresholdTerminator(){}

  virtual bool query() {
    Scalar temp = x.inner(y);
    return (fabs(temp) < tol);
  }

protected:
  Vector<Scalar> & x;
  Vector<Scalar> & y;
  NormRetType tol;
};

/** A terminator which checks for a stationary point in 
    a functional.  Stops when
\f[ \|\|\nabla f(x)\|\| <= tol \f]

    Note: For efficiency, we store \f$tol^2\f$ and compare it to
    the square of the norm, since this is ussually cheaper.
*/
template <class Scalar> 
class NormGradientTerminator: public Terminator {
public:
  typedef typename ScalarFieldTraits<Scalar>::AbsType NormRetType;  

  /** Takes the current x, the functional f, and the tolerance.  
      Notice that all inputs except for the tolerance are references,
      and similar internal data members are also references.  Thus, external
      changes to these objects will affect the terminator.  This
      is the intended behavior. 
      
  */
  NormGradientTerminator( Vector<Scalar> & x, 
			  Functional<Scalar> & f, 
			  NormRetType tol) 
    : tol_(tol*tol), fx_(f,x)
  {}

  /** Returns true when norm of the gradient is less than tol */
  bool query() {
    return( fx_.getGradient().norm2() <= tol_ );
  }

protected:
  NormRetType tol_; 
  FunctionalEvaluation<Scalar>  fx_;
};


/** Terminator which takes vectors x0 and x and a max for the norm difference r. Returns false if

    \f$\|x - x0\| < r\f$

    Returns true otherwise, <i>and</i> projects x onto the ball of
    radius r centered at x0, that is, replaces x by

    \f$ x \leftarrow x0 + \frac{r}{\|x-x_0\|}(x-x_0) \f$

    In order to avoid possible false positive return due to roundoff
    when query() is called repeatedly on the same data, scale
    \f$x-x_0\f$ by slightly smaller factor than returned by floating
    point division.
 */

template< class Scalar >
class DiffBallProjTerminator: public Terminator {
public:
  typedef typename ScalarFieldTraits<Scalar>::AbsType NormRetType;

  DiffBallProjTerminator( Vector<Scalar> const & tx, Vector<Scalar> & ty, NormRetType _maxstep, ostream & _str = cout)
    : x(tx), y(ty), maxstep(_maxstep), str(_str), res(false) {
    if( ! x.inSameSpace(y) ) {
      RVLException e; e << "Error in DiffBallProjTerminator constructor: Vectors not in same space.";
      throw e;
    }
  }

  virtual bool query() {
    Vector<Scalar> temp(x.getSpace());
    temp.copy(y);
    temp.linComb(-1.0,x);
    NormRetType tn = temp.norm();
    res = (tn > maxstep);
    if (res) {
      NormRetType scfac=ScalarFieldTraits<NormRetType>::One();
      if (ProtectedDivision(maxstep,tn,scfac)) {
	RVLException e; 
	e<<"Error: zerodivide in DiffBalProjTerminator::query\n";
	e<<"maxstep = "<<maxstep<<"\n";
	e<<"temp.norm() = "<<tn<<"\n";
	throw e;
      }
	  
      temp.scale((ScalarFieldTraits<NormRetType>::One() - 100*numeric_limits<NormRetType>::epsilon())*scfac);
      y.copy(x);
      y.linComb(1.0,temp);
    }
    return res;
  }

  /** for post facto use - access to result without recomputation */
  bool static_query() { return res; }

protected:
  Vector<Scalar> const & x;
  Vector<Scalar> & y;
  NormRetType maxstep;
  bool res;
  ostream & str;
};

/** Terminator which takes x and a max for the norm r. Returns false if

    \f$\|x\| < r\f$

    Returns true otherwise, <i>and</i> projects x onto the ball of
    radius r centered at 0, that is, replaces x by

    \f$ x \leftarrow \frac{r}{\|x\|}x \f$

    Special case of DiffBallProjTerminator with x0=0.

    In order to avoid possible false positive return due to roundoff
    when query() is called repeatedly on the same data, scale
    \f$x\f$ by slightly smaller factor than returned by floating
    point division.
 */

template< class Scalar >
class BallProjTerminator: public Terminator {
public:
  typedef typename ScalarFieldTraits<Scalar>::AbsType NormRetType;

  BallProjTerminator(Vector<Scalar> & ty, NormRetType _maxstep,
		     ostream & _str = cout)
    : y(ty), maxstep(_maxstep), queryres(false), str(_str) {}

  virtual bool query() {
    if (queryres) return true;
    NormRetType tn = y.norm();
    bool res = (tn > maxstep);
    if (res) {
      NormRetType scfac=ScalarFieldTraits<NormRetType>::One();
      if (ProtectedDivision(maxstep,tn,scfac)) {
	RVLException e; 
	e<<"Error: zerodivide in DiffBalProjTerminator::query\n";
	e<<"maxstep = "<<maxstep<<"\n";
	e<<"temp.norm() = "<<tn<<"\n";
	throw e;
      }
      y.scale((ScalarFieldTraits<NormRetType>::One() - 100*numeric_limits<NormRetType>::epsilon())*scfac);
      str<<"RVLAlg::BallProjTerminator::query: trust region truncation applied\n";
      str<<"  untruncated solution norm = "<<tn<<" trust radius = "<<maxstep<<"\n";      
    }
    queryres=res;
    return res;
  }

protected:
  Vector<Scalar> & y;
  NormRetType maxstep;
  mutable bool queryres;
  ostream & str;
};


}

#endif