#ifndef CLASSIC_PlanarArcGeometry_HH
#define CLASSIC_PlanarArcGeometry_HH

// ------------------------------------------------------------------------
// $RCSfile: PlanarArcGeometry.h,v $
// ------------------------------------------------------------------------
// $Revision: 1.1.1.1 $
// ------------------------------------------------------------------------
// Copyright: see Copyright.readme
// ------------------------------------------------------------------------
//
// Class: PlanarArcGeometry
//
// ------------------------------------------------------------------------
// Class category: BeamlineGeometry
// ------------------------------------------------------------------------
//
// $Date: 2000/03/27 09:32:34 $
// $Author: fci $
//
// ------------------------------------------------------------------------

#include "BeamlineGeometry/Geometry.h"

// Class PlanarArcGeometry
// ------------------------------------------------------------------------
/// A simple arc in the XZ plane.
//  A PlanarArcGeometry object represents a Geometry which is as simple
//  circular arc in the local XZ plane with no torsion. The origin is
//  defined at the centre of the geometry, and the geometry extends
//  from -length/2 to +length/2. Transformations generated by this
//  geometry are characterised by a displacement in the XZ plane and a
//  pure Y rotation.
//  [p]
//  This geometry can have two states:
//  [ul]
//  [li]Length L is non-zero:
//  The geometry is defined as a finite arc in the XZ plane.
//  In this state, the following changes are allowed:
//  [ul]
//  [li]Setting the angle phi: recompute the curvature as phi / L.
//  [li]Setting the curvature h: recompute the angle as h * L.
//  [li]Setting the length: if non-zero, recompute the angle as h * L,
//  otherwise set h to zero.
//  [/ul]
//  [li]Length is zero, implying curvature also zero:
//  The geometry is defined as sharp bend by phi in the XZ plane.
//  In this state, the following changes are allowed:
//  [ul]
//  [li]Setting the angle phi: leave both h and L as zero.
//  [li]Setting the curvature h: not accepted.
//  [li]Setting the length: if non-zero, recompute the angle as h * L.
//  [/ul]
//  [/ul]

class PlanarArcGeometry : public BGeometryBase {
public:

    /// Constructor.
    //  Build PlanarArcGeometry from length [b]l[/b] and curvature [b]h[/b].
    PlanarArcGeometry(double l, double h);

    /// Constructor.
    //  Build PlanarArcGeometry from length zero and angle [b]phi[/b].
    PlanarArcGeometry(double phi);

    PlanarArcGeometry(const PlanarArcGeometry &);
    virtual ~PlanarArcGeometry();
    const PlanarArcGeometry &operator=(const PlanarArcGeometry &);

    /// Get arc length.
    //  Return arc length along the design arc.
    virtual double getArcLength() const;

    /// Get element length.
    //  Return element length measured along the design arc.
    virtual double getElementLength() const;

    /// Get angle.
    double getBendAngle() const;

    /// Get curvature.
    double getCurvature() const;

    /// Set angle.
    virtual void setBendAngle(double);

    /// Set curvature.
    void setCurvature(double);

    /// Set length.
    //  Assign the arc length for this class.
    virtual void setElementLength(double);

    /// Get origin.
    //  Return the distance from the entrance of the geometry to the origin
    //  (non-negative).
    virtual double getOrigin() const;

    /// Get entrance.
    //  Return the arc length from the origin to the entrance of the
    //  geometry (non-positive).
    double getEntrance() const;

    /// Get exit.
    //  Return the arc length from the origin to the exit of the
    //  geometry (non-negative).
    double getExit() const;

    /// Get transform.
    //  Return the transform of the local coordinate system from the
    //  position [b]fromS[/b] to the position [b]toS[/b].
    virtual Euclid3D getTransform(double fromS, double toS) const;

    /// Get transform.
    //  Equivalent to getTransform(0.0, s).
    //  Return the transform of the local coordinate system from the
    //  origin and [b]s[/b].
    virtual Euclid3D getTransform(double s) const;

    /// Get transform.
    //  Equivalent to getTransform(getEntrance(), getExit()).
    //  Return the transform of the local coordinate system from the
    //  entrance to the exit of the element.
    virtual Euclid3D getTotalTransform() const;

    /// Get transform.
    //  Equivalent to getTransform(0.0, getEntrance()).
    //  Return the transform of the local coordinate system from the
    //  origin to the entrance of the element.
    Euclid3D getEntranceFrame() const;

    /// Get transform.
    //  Equivalent to getTransform(0.0, getExit()).
    //  Return the transform of the local coordinate system from the
    //  origin to the exit of the element.
    Euclid3D getExitFrame()     const;

private:

    double len;
    double h;
    double angle;
};

// inlined (trivial) member functions

inline PlanarArcGeometry::PlanarArcGeometry(double l, double hh):
    len(l), h(hh), angle(hh *l)
{}


inline PlanarArcGeometry::PlanarArcGeometry(double phi):
    len(0.0), h(0.0), angle(phi)
{}


inline PlanarArcGeometry::PlanarArcGeometry(const PlanarArcGeometry &rhs):
    BGeometryBase(rhs),len(rhs.len), h(rhs.h), angle(rhs.angle)
{}


inline const PlanarArcGeometry &PlanarArcGeometry::operator=
(const PlanarArcGeometry &rhs) {
    len = rhs.len;
    h = rhs.h;
    angle = rhs.angle;
    return *this;
}

#endif // CLASSIC_PlanarArcGeometry_HH