// Author: Enrico Guiraud, Danilo Piparo CERN  09/2018

/*************************************************************************
 * Copyright (C) 1995-2018, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

#ifndef ROOT_RJITTEDDEFINE
#define ROOT_RJITTEDDEFINE

#include "ROOT/RDF/RDefineBase.hxx"
#include "ROOT/RDF/RSampleInfo.hxx"
#include "ROOT/RDF/Utils.hxx" // TypeName2TypeID
#include <string_view>
#include "RtypesCore.h"

#include <memory>
#include <stdexcept>
#include <string>
#include <typeinfo>
#include <vector>

class TTreeReader;

namespace ROOT {
namespace Detail {
namespace RDF {

/// A wrapper around a concrete RDefine, which forwards all calls to it
/// RJittedDefine is a placeholder that is put in the collection of custom columns in place of a RDefine
/// that will be just-in-time compiled. Jitted code will assign the concrete RDefine to this RJittedDefine
/// before the event-loop starts.
class RJittedDefine : public RDefineBase {
   std::unique_ptr<RDefineBase> fConcreteDefine = nullptr;
   /// Type info obtained through TypeName2TypeID based on the column type name.
   /// The expectation is that this always compares equal to fConcreteDefine->GetTypeId() (which however is only
   /// available after jitting). It can be null if TypeName2TypeID failed to figure out this type.
   const std::type_info *fTypeId = nullptr;

public:
   RJittedDefine(std::string_view name, std::string_view type, RLoopManager &lm,
                 const RDFInternal::RColumnRegister &colRegister, const ColumnNames_t &columns)
      : RDefineBase(name, type, colRegister, lm, columns)
   {
      // try recovering the type_info of this type, no problem if we fail (as long as no one calls GetTypeId)
      try {
         fTypeId = &RDFInternal::TypeName2TypeID(std::string(type));
      } catch (const std::runtime_error &) {
      }
   }
   ~RJittedDefine();

   void SetDefine(std::unique_ptr<RDefineBase> c) { fConcreteDefine = std::move(c); }

   void InitSlot(TTreeReader *r, unsigned int slot) final;
   void *GetValuePtr(unsigned int slot) final;
   const std::type_info &GetTypeId() const final;
   void Update(unsigned int slot, Long64_t entry) final;
   void Update(unsigned int slot, const ROOT::RDF::RSampleInfo &id) final;
   void FinalizeSlot(unsigned int slot) final;
   void MakeVariations(const std::vector<std::string> &variations) final;
   RDefineBase &GetVariedDefine(const std::string &variationName) final;
};

} // ns RDF
} // ns Detail
} // ns ROOT

#endif // ROOT_RJITTEDDEFINE