#ifndef __JCOMPAREHISTOGRAMS__JTESTZERO_T__
#define __JCOMPAREHISTOGRAMS__JTESTZERO_T__

#include <istream>
#include <ostream>

#include "TMath.h"

#include "Math/Math.h"
#include "Math/Error.h"
#include "Math/ProbFuncMathCore.h"
#include "Math/SpecFuncMathCore.h"

#include "JCompareHistograms/JTest_t.hh"
#include "JCompareHistograms/JResultTitle.hh"


/**
 * \author rgruiz
 */
namespace JCOMPAREHISTOGRAMS {

  using JGIZMO::JRootObjectID;

  /**
   * Implementation of the Zeros test for histograms with expected low bin contents.
   */
  class JTestZero_t
  {
  public:
  
    /**
     * Default constructor.
     */    
    JTestZero_t(){}
  
    /**
     * Bin-by-Bin test for 2D histograms where a very low number of entries is expected.\n
     * The test loops over all the bins of both histograms and performs the following operations.\n 
     * -Calculates the probability that the observed bin content for histogram A is obtained from a Poisson of parameter 1.\n
     * -Compares the previous result with the threshold value given as an input parameter. The result is true if the probability is higher than the threshold.\n
     * -Calculates the probability that the observed bin content for histogram B is obtained from a Poisson of parameter 1.\n
     * -Compares the previous result with the threshold value given as an input parameter. The result is true if the probability is higher than the threshold.\n
     * -Compares the results from both bins: If both are true, or both are false, the test is passed. If one is true and the other is false, the test is failed.\n
     * At the end of the loop, a failure fraction is computed and compared to the outliersThreshold parameter. If the failure fraction is above the threshold, the test is failed.\n
     * 
     * \param h1 First object
     * \param h2 Second object
     * \param outliersThreshold Fraction of incompatible bins allowed.
     * \param threshold Poisson p-value
     * \param parameterName Name of the parameter used to test the histograms
     * \param testName Name of the test used to compare the histograms
     */
    JTestResult JTestZero_2D(TH2* h1, TH2* h2, double outliersThreshold, double threshold, std::string testName, std::string parameterName) {    

      using namespace std;
      using namespace JPP;
    
      int nx1 = h1->GetNbinsX();
      int nx2 = h2->GetNbinsX();      
      int ny1 = h1->GetNbinsY();
      int ny2 = h2->GetNbinsY();

      if(nx1 != nx2 || ny1 != ny2)
	ERROR("Histograms with different binning. The objects: " << h1->GetName() << " can not be compared." << endl);
        
      TH2D* h3 = (TH2D*)h1->Clone(h1->GetName()==h2->GetName() ?
				  MAKE_CSTRING(to_string(h1->GetName())) :
				  MAKE_CSTRING(to_string(h1->GetName()) + "_VS_" + to_string(h2->GetName())));
      h3->Reset();

      double failures = 0;
    
      for (int i=1 ; i<nx1+1 ; ++i){
	for (int j=1 ; j<ny1+1 ; ++j){
	
	  double m = h1 -> GetBinContent(i,j);
	  double n = h2 -> GetBinContent(i,j);
	
	  double p1 = 1 - ROOT::Math::poisson_cdf(m,1);
	  double p2 = 1 - ROOT::Math::poisson_cdf(n,1); 	

	  if ((p1 > threshold && p2 < threshold) || 
	      (p1 < threshold && p2 > threshold)){
	    h3->Fill(i,j);
	    failures+=1./(nx1*ny1);
	  }	 
	}
      }

      bool passed;
    
      (failures > outliersThreshold ? passed = false : passed = true);
    
      JResultTitle title(testName, parameterName, passed , failures);
    
      h3->SetTitle(title.getTitle().c_str());
    
      JTestResult r (testName,
		     JRootObjectID(MAKE_STRING(h1->GetDirectory()->GetPath() << h1->GetName())),
		     JRootObjectID(MAKE_STRING(h2->GetDirectory()->GetPath() << h1->GetName())),
		     parameterName, failures, threshold, h3, passed);

      return r;      
    };
  };
}
  
#endif