// @(#)root/base:$Id$
// Author: Rene Brun    06/07/2002

/*************************************************************************
 * Copyright (C) 1995-2001, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

/** \class TProcessUUID
This class is a specialized TProcessID managing the list of UUIDs.
In addition to TProcessID, this object has the following members:

  - fUUIDs  : a THashList of TUUIDs in string format (using a TObjString)
  - fActive : a TBits table with one bit per TUUID in the table

When a new TUUID is entered into the list fUUIDs, it is assigned
the first free slot in the list of bits and the TUUID UUIDNumber
is set to this slot number.

When a TUUID is removed from the list, the corresponding bit
is reset in fActive.

The object corresponding to a TUUID at slot I can be found
via fObjects->At(I).

One can use two mechanisms to find the object corresponding to a TUUID:

 1. the input is the TUUID.AsString. One can find the corresponding
    TObjString object objs in fUUIDs via THashList::FindObject(name).
    The slot number is then objs->GetUniqueID().
 2. The input is the UUIDNumber. The slot number is UIUIDNumber

When a TRef points to an object having a TUUID, both the TRef and the
referenced object have their bit kHasUUID set. In this case, the pointer
TProcessID *fPID in TRef points to the unique object TProcessUUID.
The TRef uniqueID is directly the UUIDNumber=slot number.
*/

#include "TROOT.h"
#include "TProcessUUID.h"
#include "THashList.h"
#include "TBits.h"
#include "TObjString.h"
#include "TUUID.h"

ClassImp(TProcessUUID)

////////////////////////////////////////////////////////////////////////////////
/// Default constructor.

TProcessUUID::TProcessUUID() : TProcessID()
{
   fUUIDs   = new THashList(100,3);
   fActive  = new TBits(100);
   IncrementCount();
}

////////////////////////////////////////////////////////////////////////////////
/// Destructor.

TProcessUUID::~TProcessUUID()
{
   fUUIDs->Delete();
   delete fUUIDs;  fUUIDs  = 0;
   delete fActive; fActive = 0;
}

////////////////////////////////////////////////////////////////////////////////
/// Add uuid to the table of UUIDs
/// The TObject *obj has its uniqueID set to the UUID number
/// return entry number in the table

UInt_t TProcessUUID::AddUUID(TUUID &uuid, TObject *obj)
{
   UInt_t number;
   const char *uuids = uuid.AsString();
   TObjString *objs = (TObjString*)fUUIDs->FindObject(uuids);
   if (objs) {
      number = objs->GetUniqueID();
      uuid.SetUUIDNumber(number);
      objs->SetUniqueID(number);
      obj->SetUniqueID(number);
      obj->SetBit(kHasUUID);
      if (number >= (UInt_t)fObjects->GetSize()) fObjects->AddAtAndExpand(obj,number);
      if (fObjects->UncheckedAt(number) == 0) fObjects->AddAt(obj,number);
      return number;
   }

   objs = new TObjString(uuids);
   fUUIDs->Add(objs);
   number = fActive->FirstNullBit();
   uuid.SetUUIDNumber(number);
   objs->SetUniqueID(number);
   obj->SetUniqueID(number);
   obj->SetBit(kHasUUID);
   fActive->SetBitNumber(number);
   fObjects->AddAtAndExpand(obj,number);
   return number;
}

////////////////////////////////////////////////////////////////////////////////
/// Add uuid with name uuids to the table of UUIDs
/// return entry number in the table

UInt_t TProcessUUID::AddUUID(const char *uuids)
{

   TObjString *objs = (TObjString*)fUUIDs->FindObject(uuids);
   if (objs) return objs->GetUniqueID();

   UInt_t number;
   objs = new TObjString(uuids);
   fUUIDs->Add(objs);
   number = fActive->FirstNullBit();
   objs->SetUniqueID(number);
   fActive->SetBitNumber(number);
   return number;
}

////////////////////////////////////////////////////////////////////////////////
/// Find the TObjString by slot number

TObjString *TProcessUUID::FindUUID(UInt_t number) const
{
   TObjLink *lnk = fUUIDs->FirstLink();
   while (lnk) {
      TObject *obj = lnk->GetObject();
      if (obj->GetUniqueID() == number) return (TObjString*)obj;
      lnk = lnk->Next();
   }
   return 0;
}

////////////////////////////////////////////////////////////////////////////////
/// Remove entry number in the list of uuids

void TProcessUUID::RemoveUUID(UInt_t number)
{
   if (number > (UInt_t)fObjects->GetSize()) return;
   TObjLink *lnk = fUUIDs->FirstLink();
   while (lnk) {
      TObject *obj = lnk->GetObject();
      if (obj->GetUniqueID() == number) {
         fUUIDs->Remove(lnk);
         delete obj;
         fActive->ResetBit(number);
         fObjects->AddAt(0,number);
         return;
      }
      lnk = lnk->Next();
   }
}