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#ifndef OAEMFIELD_IFIELDMANAGER_HXX
#define OAEMFIELD_IFIELDMANAGER_HXX

#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 {

    friend void COMET::IElementField::addElementField();

    private:

        IFieldManager();
        IFieldManager(const IFieldManager&);

        ~IFieldManager();

        IFieldManager& operator=(const IFieldManager&);

        void SetupArray();

        static bool Recreate(const IFieldDescription& description);

    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;

        /// clear all field tracking objects and clear()
        void ClearField();

        /// update field objects, import field for the first only once, 
        //  check is not implemented yet!
        void UpdateField();

        /// Set the NoField flag to true so that the GetFieldValue function can work even no field is provided (return value = 0)
        void SetNoField();

        /// prints the field map to a file as a grid map
        bool WriteToFile(std::string& fileName, double x0, double y0, double z0, 
                                                double dX, double dY, double dZ, 
                                                   int nX,    int nY,    int nZ);

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

        static IFieldManager* Import(const char* filename);
        static IFieldManager* Import(TDirectory* directory);
        static IFieldManager* Import(const IFieldDescription* description);
        static IFieldManager* Import();

        void SetUniformed() { fUniformed = true; }

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


        static IFieldManager* fObject;

        Int_t fNumFieldPointers;
        Bool_t fFirst;
        Bool_t fFirstImport;
        Bool_t fUniformed;
        static Bool_t fNoField;

        FieldList* fFields;

        const IElementField **fFieldPointers;

};
}
#endif