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#ifndef IFieldManager_h
#define IFieldManager_h 1

#include <vector>

#include "IElementField.hxx"
#include <IFieldDescription.hxx>
#include <IHandle.hxx>
#include <HEPUnits.hxx>

namespace COMET {

//  IFieldManager - handles the global ElectroMagnetic field
//
//  There is a single IFieldManager object.
//
//  The field from each individual beamline element is given by a
//  IElementField object. Any number of overlapping IElementField
//  objects can be added to the global field. Any element that
//  represents an element with an EM field will be added to the
//  IElementField list.

typedef std::vector<IElementField*> FieldList;

class IFieldManager {

    private:

        IFieldManager();
        IFieldManager(const IFieldManager&);

        ~IFieldManager();

        IFieldManager& operator=(const IFieldManager&);

        void setupArray();

    public:

        /// getObject() returns the single IFieldManager object.
        /// It is constructed, if necessary.
        static IFieldManager* getObject();

        /// GetFieldValue() returns the field value at a given point[].
        /// field is really field[6]: Bx,By,Bz,Ex,Ey,Ez.
        /// point[] is in global coordinates: x,y,z,t.
        void GetFieldValue(const Double_t* point, Double_t* field) const;

        /// addElementField() adds the IElementField object for a single
        /// element to the global field.
        void addElementField(IElementField* f) { if (fFields) fFields->push_back(f); }

        /// clear() removes all IElementField-s from the global object,
        /// and destroys them. Used before the geometry is completely
        /// re-created.
        void clear();

        /// updates all field tracking objects and clear()
        void updateField();

        /// Return the list of Element Fields
        FieldList* getFields() { return fFields; }

        COMET::IHandle<IFieldDescription> MakeDescription()const;

        static IFieldManager* Import(const char* filename);
        static IFieldManager* Import(TDirectory* directory);
        static IFieldManager* Import(){
            return Import(TDirectory::CurrentDirectory());
        }

    private:

        static IFieldManager* fObject;

        Int_t fNumFieldPointers;
        Bool_t fFirst;

        FieldList* fFields;

        const IElementField **fFieldPointers;

};
}
#endif