#include "DrawResBase.h"

/** 
 * @defgroup pwg2_forward_analysis_scripts PWG2 Forward analysis - scripts
 *
 * @ingroup pwg2_forward_analysis
 */
/** 
 * Example macro to loop over the event-by-event 2D histogram of 
 * @f[
 *   \frac{d^{2}N_{ch}}{d\eta\,d\phi}
 * @f]
 * stored in an AOD.  
 * 
 * The class needs the files &lt;<i>base</i>&gt;<tt>_hists.root</tt> 
 * containing the histograms generated by AliForwardMultiplicity and 
 * the file &lt;<i>base</i>&gt;<tt>_aods.root</tt> containing the tree 
 * with AliAODEvent objects where AliAODForwardMult objects have been 
 * added to in the branch <tt>Forward</tt>
 * 
 * @ingroup pwg2_forward_analysis_scripts
 */
class DrawRes2D : public DrawResBase
{
public:
  /** 
   * Constructor 
   * 
   * @param special If true, add to the list of 'specials'
   */
  DrawRes2D()
    : fTotal2D(0)
  {
  }
  //__________________________________________________________________
  virtual void Clear(Option_t* option) 
  {
    DrawResBase::Clear(option);
    if (fTotal2D) delete fTotal2D;
    fTotal2D = 0;
  }
  //__________________________________________________________________
  Bool_t IsInit() const { return fTotal2D; }
  //__________________________________________________________________
  /** 
   * Utility function to set-up histograms based on the input 
   * @f$ dd^{2}N_{ch}/d\eta\,d\phi@f$ histogram.   This member function 
   * is called on the first event so that we have the proper binning 
   * 
   * @param templ Input histogram
   * 
   * @return true on succcess
   */
  Bool_t FirstEvent(const TH2D& templ) 
  { 
    if (!DrawResBase::FirstEvent(templ)) return kFALSE;

    const TAxis* etaAxis = templ.GetXaxis();
    const TAxis* phiAxis = templ.GetYaxis();
    
    // Generate sum histograms. 
    // - fTotal2D will be the direct sum of the input histograms. 
    fTotal2D = new TH2D("d2ndetadphi", "1/N dN^{2}_{ch}/d#etad#phi", 
			etaAxis->GetNbins(),
			etaAxis->GetXmin(),
			etaAxis->GetXmax(),
			phiAxis->GetNbins(),
			phiAxis->GetXmin(),
			phiAxis->GetXmax());
    fTotal2D->SetXTitle("#eta");
    fTotal2D->SetYTitle("#varphi [radians]");
    fTotal2D->SetZTitle(fTotal2D->GetTitle());
    fTotal2D->Sumw2();
    fTotal2D->SetStats(0);
    fTotal2D->SetDirectory(0);

    return kTRUE;
  }


  //__________________________________________________________________
  /** 
   * Process the events 
   * 
   * 
   * @return true on success, false otherwise 
   */
  void AddContrib(const TH2D& hist, Int_t) 
  {
    fTotal2D->Add(&hist);
  }
  //__________________________________________________________________
  /** 
   * Process the events 
   * 
   * 
   * @return true on success, false otherwise 
   */
  TH1D* GetResult()
  {
    // Do not sum underflow bins!
    TH1D* proj = fTotal2D->ProjectionX("dndeta_proj", 1, -1, "e");
    TH1D* norm = fTotal2D->ProjectionX("norm", 0, 1, "");
    proj->SetTitle("1/N dN_{ch}/d#eta");
    proj->Divide(norm);
    proj->Scale(1., "width");
    return proj;
  }
  /** 
   * Browse this object 
   * 
   * @param b Browser to use 
   */
  void Browse(TBrowser* b) 
  {
    if (fTotal2D) b->Add(fTotal2D);
    DrawResBase::Browse(b);
  }
  /** 
   * Create a new object of this class, and add it to the list of 
   * specials, and create a browse and browse to this object 
   * 
   * @return Newly created object
   */
  static DrawResBase* Create() 
  {
    DrawRes2D* dr = new DrawRes2D;
    gROOT->GetListOfSpecials()->Add(dr);
    TBrowser* b = new TBrowser("b");
    b->BrowseObject(gROOT->GetListOfSpecials());
    return dr;
  }
protected:
  TH2D*              fTotal2D;   // Direct sum of input histograms

  ClassDef(DrawRes2D,0)
};

//
// EOF
//