//-------------------------------------------------------------------------
// Author:      Oliver Merle (Oliver.Merle@exp2.physik.uni-giessen.de)
// Changes:     Mustafa Schmidt (Mustafa.A.Schmidt@physik.uni-giessen.de)   
// Date:        30.11.2015
// Description: Class to handle tiled sensors
//-------------------------------------------------------------------------

#ifndef SensorGridPhotodetector_HH
#define SensorGridPhotodetector_HH


#include <vector>

namespace SensorGrid {

class SensorGridBase;
struct PixelInfo;


class SensorGridPhotodetector
{
private: struct PixelTraits;
public:
    SensorGridPhotodetector(SensorGridBase* sensor_grid_, bool per_pixel_traits_,
                       double const & pde_init, double const & noise_rate_init, double const & time_res_init);

protected:
    SensorGridPhotodetector() {} // for use in derived classes
    void Init(SensorGridBase* sensor_grid_, bool per_pixel_traits_, double const & efficiency_init, double const & noise_rate_init, double const & time_res_init);

public:
    // Per pixel data initialization:
    void SetPixel(int pixel_id, double efficiency, double noise_rate, double time_res_ns);
    void UseInhomogenityFactor(bool flag) { use_inhomogenity_factor=flag; }

    /// Handle photon detection:
    int  Detect(double const & hit_pos_x, double const & hit_pos_y, double const & hit_time_ns,
                double const & wavelength_nm, PixelInfo & pixel_info, double & smeared_time_ns) const;

    /// Generate noise hits
    void GenerateNoise(double const & time_start_ns, double const & time_window_ns, std::vector<std::pair<int, double> > & hits) const;

    /// Derived classes should override this function and return the average pde of the sensor.

    /// Per pixel deviations of the PDE can be taken into account by including them in
    /// a individual pixel efficiency.
    virtual double GetPDE(const double & wavelength_nm) const {return 1.0;}


    /// Derived classes should override this function to account for spatial PDE deviations (e.g. due to gain inhomgenity)

    /// This function is used to implement inhomogenitites over the whole sensor, which cannot
    /// be treated as single pixel efficiencies, e.g. if the pixels are large compared to the
    /// spatial deviation of the inhomogenity.
    virtual double GetInhomegenityFactor(double const & hit_pos_x, double const & hit_pos_y) const {return 1.0;}

    /// Apply time smearing
    double GetSmearedTime(double const & time_value, PixelInfo const & pixel_info) const;


    /// Reinit noise iterator and return number of noise hits.
    int GenerateNoise(double const & time_start_ns, double const & time_window_ns);

    /// Noise hit generator function which has to be called after GenerateNoise() to retrieve the noise hits.
    bool GetNoiseHit(int & pixel_number, double & hit_time_ns, double & smeared_time_ns);

    /// Set the dark count rate for all pixels to dcr_Hz
    void SetDCR(double const & dcr_Hz);

    const SensorGridBase * GetGrid() {return sensor_grid;}

protected:
    bool                     per_pixel_traits;
    bool                     use_inhomogenity_factor;
    PixelTraits*             pixel_traits;
    SensorGridBase*          sensor_grid;
    // state of noise generator:
    int                      noisegen_pixel_number;
    double                   noisegen_time_start_ns;
    double                   noisegen_time_window_ns;
    int                      noisegen_n_hits;
    int                      noisegen_current_hit;
    double                   noisegen_current_time_sigma;
};


} // namespace SensorGrid

#endif // SensorGridPhotodetector_HH