// Copyright 2019-2020 CERN and copyright holders of ALICE O2.
// See https://alice-o2.web.cern.ch/copyright for details of the copyright holders.
// All rights not expressly granted are reserved.
//
// This software is distributed under the terms of the GNU General Public
// License v3 (GPL Version 3), copied verbatim in the file "COPYING".
//
// In applying this license CERN does not waive the privileges and immunities
// granted to it by virtue of its status as an Intergovernmental Organization
// or submit itself to any jurisdiction.
///
/// \brief This task contains the individual steps that are to be taken
///        in the second part of the tutorial. These are 5 steps, and at the end,
///        the participant is expected to have a two-particle correlation spectrum.
/// \author
/// \since

#include "Framework/runDataProcessing.h"
#include "Framework/AnalysisTask.h"
#include "Common/DataModel/TrackSelectionTables.h"
#include "Framework/ASoAHelpers.h"

using namespace o2;
using namespace o2::framework;
using namespace o2::framework::expressions;

//This is an example of a conveient declaration of "using"
using MyCompleteTracks = soa::Join<aod::Tracks, aod::TracksExtra, aod::TracksDCA>;

//STEP 2: partition
//This is a plain partitioning example.
//Note that the subscription to tracks is actually unchanged,
//but the usage of a specific partition inside the process function can now be used.
//This is all pretty similar to PYTHON list handling.
struct partitionexample {
  Partition<MyCompleteTracks> leftTracks = aod::track::eta < 0.0f;
  Partition<MyCompleteTracks> rightTracks = aod::track::eta >= 0.0f;

  //Configurable for number of bins
  Configurable<int> nBins{"nBins", 100, "N bins in all histos"};

  // histogram defined with HistogramRegistry
  HistogramRegistry registry{
    "registry",
    {
      {"hVertexZ", "hVertexZ", {HistType::kTH1F, {{nBins, -15., 15.}}}},
      {"etaHistogramleft", "etaHistogramleft", {HistType::kTH1F, {{nBins, -1., +1}}}},
      {"ptHistogramleft", "ptHistogramleft", {HistType::kTH1F, {{nBins, 0., 10.0}}}},
      {"etaHistogramright", "etaHistogramright", {HistType::kTH1F, {{nBins, -1., +1}}}},
      {"ptHistogramright", "ptHistogramright", {HistType::kTH1F, {{nBins, 0., 10.0}}}}
      
    }
  };

  void process(aod::Collision const& collision, /*soa::Filtered<*/MyCompleteTracks/*>*/ const& tracks)
  {
    //Fill the event counter
    //check getter here: https://aliceo2group.github.io/analysis-framework/docs/datamodel/ao2dTables.html
    registry.get<TH1>(HIST("hVertexZ"))->Fill(collision.posZ());
    
    //partitions are not grouped by default
    auto leftTracksGrouped = leftTracks->sliceByCached(aod::track::collisionId, collision.globalIndex());
    auto rightTracksGrouped = rightTracks->sliceByCached(aod::track::collisionId, collision.globalIndex());
    
    //This will take place once per event!
    for (auto& track : leftTracksGrouped) { //<- only for a subset
      registry.get<TH1>(HIST("etaHistogramleft"))->Fill(track.eta()); //<- this should show the selection
      registry.get<TH1>(HIST("ptHistogramleft"))->Fill(track.pt());
    }
    for (auto& track : rightTracksGrouped) { //<- only for a subset
      registry.get<TH1>(HIST("etaHistogramright"))->Fill(track.eta()); //<- this should show the selection
      registry.get<TH1>(HIST("ptHistogramright"))->Fill(track.pt());
    }
  }
};

WorkflowSpec defineDataProcessing(ConfigContext const& cfgc)
{
  return WorkflowSpec{
    adaptAnalysisTask<partitionexample>(cfgc)
  };
}