#ifndef OAEVENT_IFIELDDESCRIPTION_HXX
#define OAEVENT_IFIELDDESCRIPTION_HXX

#include "IDatum.hxx"
#include "IHandle.hxx"
#include "TRotation.h"
#include "TVector3.h"

namespace COMET{
    class IFieldDescription;
    class IElementFieldDescription;
    class IElementField;
}

/// An abstract base class for an individual element of the magnetic field
class COMET::IElementFieldDescription:public COMET::IDatum{
    public:
        IElementFieldDescription(const TRotation* rotation=NULL, 
                                 const TVector3* translation=NULL):
            COMET::IDatum("","Field element"),
            fTranslation(NULL), 
            fRotation(NULL){
                // Constructs from pointers so we can optionally not have 
                // a rotation
                SetRotation(rotation);
                SetTranslation(translation);
            }
        /// Copy constructor to handle owned pointers
        IElementFieldDescription(const IElementFieldDescription& rhs);
        // Swap function for copy-and-swap idiom
        friend void swap(IElementFieldDescription& aDescr, 
                         IElementFieldDescription& bDescr){
            using std::swap;
            swap(aDescr.fTranslation, bDescr.fTranslation);
            swap(aDescr.fRotation, bDescr.fRotation);
        }
        /// Desturctor
        virtual ~IElementFieldDescription();


        virtual void ls(Option_t* opt = "") const=0;

        /// Rebuild the field represented by this component
        /// Note that this class will be deleted once this task is finished, so 
        /// derived classes should give up ownership of all objects needed to
        /// describe the field.
        //virtual COMET::IElementField* Recreate()const=0;

        ClassDef(IElementFieldDescription,4);

        /// Get the translation of the field map element
        const TVector3* Translation()const{return fTranslation;}
        /// Get the rotation of the field map element
        const TRotation* Rotation()const{return fRotation;}
        /// Set center of field element
        void SetTranslation(const TVector3& trans){ 
            // Delete it if its been set
            if (fTranslation) delete fTranslation;
            // Make  a new one
            fTranslation = new TVector3(trans);
        };
        /// Set the center of field element
        void SetTranslation(const TVector3* trans){
            if (trans) SetTranslation(*trans);
        }
        /// Set the rotation field element
        void SetRotation(const TRotation& trans){ 
            // Delete it if its been set
            if (fRotation) delete fRotation;
            // Make  a new one
            fRotation = new TRotation(trans);
        };
        /// Set the rotation of field element
        void SetRotation(const TRotation* rotation){
            if (rotation) SetRotation(*rotation);
        }

    protected:
        /// The translation of the field map
        TVector3* fTranslation;
        /// The rotation of the field map
        TRotation* fRotation;
};

/// A persistable list of field components that built up a complete description
/// of the field across the detector
class COMET::IFieldDescription:public COMET::IDatum{
    public:
        IFieldDescription():COMET::IDatum("field_description","Description of electromagnetic field"){}
        virtual ~IFieldDescription(){}

        void AddElement(const COMET::IElementFieldDescription*);
        /// Rebuild the field represented by this description.
        /// Calls IElementField::Recreate on all elements in fDescriptionList
        ///
        /// @return true if successfully created all elements, false otherwise
        //bool Recreate()const;
        virtual void ls(Option_t* opt = "") const;

        size_t GetNumElements()const{return fDescriptionList.size();}
        const IElementFieldDescription&  GetElement(int index)const{return *fDescriptionList.at(index);}

    private:
        typedef std::vector<const IElementFieldDescription*> DescriptionList;
        std::vector<const IElementFieldDescription* > fDescriptionList;
        
        ClassDef(IFieldDescription,3);
};

#endif // OAEVENT_IFIELDDESCRIPTION_HXX