// -------------------------------------------------------------------------
// -----          FairEvtFilterOnParticleDist header file              -----
// -------------------------------------------------------------------------

/** FairEvtFilterOnParticleDist.h
 * @author A. Goerres <a.goerres@fz-juelich.de>
 * @date February 2015
 * @brief Enables filtering generated events based on probability functions.
 *
 * This class offers a filter for the FairEvtFilter to filter based on a
 * probability function. This function may be applied to different geometrical
 * parameters such as cos(theta).
 *
 */

#ifndef FairEvtFilterOnParticleDist_H_
#define FairEvtFilterOnParticleDist_H_

#include "FairEvtFilter.h"
#include "TParticle.h"
#include "TF1.h"
#include "TMath.h"
#include "TRandom3.h"
#include "RhoHistogram/RhoTuple.h"


std::ostream& operator <<(std::ostream& os, const std::pair< std::pair<Int_t, Int_t>, TF1 >& gd);
std::ostream& operator <<(std::ostream& os, const std::vector< std::pair< std::pair<Int_t, Int_t>, TF1 > >& gd);


class FairEvtFilterOnParticleDist : public FairEvtFilter
{

public:

    /**
     * A list of possible geometries to apply distribtutions to.
     */
    enum GeomFilter {kTheta=0, kCosTheta, kPhi, kVertexZ, kVertexRho, kVertexRadius};

    /**
     * Make a type for the list of geometry distributions.
     */
    typedef std::pair< std::pair<Int_t, Int_t>, TF1 > GeomDist;


    /**
     * Default constructor
     */
    FairEvtFilterOnParticleDist(const Float_t mom);

    /**
     * Constructor with name and title
     */
    FairEvtFilterOnParticleDist(const char* name, const Float_t mom, const char* title="FairEvtFilterOnParticleDist");

    /**
     * Destructor
     */
    virtual ~FairEvtFilterOnParticleDist();


    ///
    /// User Interface
    ///

    /**
     * @brief Adds a filter for the cos(theta) distribution of a particle
     *
     * @param func Pointer to the TF1 that is used as a probability distribution
     * @param pdgCode Integer with the pdgCode to apply the function to
     * @return kTRUE if event matches, kFALSE otherwise
     */
    Bool_t AddCosThetaDist(TF1 * func, Int_t pdgCode) {
        return AndGeomDist(func, pdgCode, kCosTheta);
    };

    /**
     * @brief Checks if the particles in the event suit the filter settings
     * @return kTRUE if event matches, kFALSE otherwise
     */
    Bool_t EventMatches(Int_t evtNr);

    /**
     * @brief Get the current filter status
     * @return kTRUE if filter is activated
     */
    Bool_t FilterActive() {
        return ( fDistFilterActive );
    };

    /**
     * @brief Write the filter statistics tuple to the output file
     */
    void WriteEvtFilterStatsToRootFile();


private:

    ///
    /// Private Methods
    ///

    /**
     * Initialize class parameters
     */
    void InitParameters(const Float_t mom);


    /**
     * Print the header containing class title and instance name
     */
    void PrintVerboseOutputHeader(TString extraText);


    /**
     * General function to add a geometry distribution
     */
    Bool_t AndGeomDist(TF1 * func, Int_t pdgCode, GeomFilter geom);


    /**
     * Get the geometrical value of the particle
     */
    Float_t GetGeomValue(TParticle * par, GeomFilter geom);


    /**
     * Does the given distribution filter out the current particle?
     */
    Bool_t RejectFromDist(TParticle * particle, Int_t evtNr, Int_t trkNr);


    ///
    /// Some internal variables/constants
    ///

    // is a distribution filter active
    Bool_t fDistFilterActive;

    // the vector of distribution filters
    std::vector<GeomDist> fGeomDist;

    // the lorentz vector of the pbarpSystem's CMS
    TLorentzVector fPbarpCMS;
    TVector3 fPbarpCMSboost;

    // a random number generator
    TRandom3 fRnd;

    // collect some statistics
    RhoTuple * fFilterStats;


    ClassDef(FairEvtFilterOnParticleDist,1);

};


#endif /* FairEvtFilterOnParticleDist_H_ */