#include <stdlib.h>

#include <array.h>

#include "cg3.h"

///////////////////////////////////////////////////////////
// TList
///////////////////////////////////////////////////////////

class TList : public TContainer
{           
  enum { MAX_SKIP = 8192 };

  struct TList_object : public TObject
  { 
    TObject* _obj;
    TList_object* _next;
    TList_object* _prev;
  };

  TList_object** _skip;
  long _items, _current;
  long _step, _last_skip;

protected:
  // @cmember Ritorna un puntatore al primo oggetto del contenitore
  virtual TObject* first_item( );
  // @cmember Ritorna un puntatore all'ultimo oggetto del contenitore
  virtual TObject* last_item( );
  // @cmember Ritorna un puntatore all'oggetto successivo all'oggetto corrente
  virtual TObject* succ_item( );
  // @cmember Ritorna un puntatore all'oggetto che precede l'oggetto corrente
  virtual TObject* pred_item( );
  // @cmember Ritorna il numero di oggetti nel contenitore
  virtual long objects( );

protected:
  TList_object* detach_lstobj(long index);
  TList_object* lstobjptr(long index);
  void change_step(long step);
  
public:
  
  TObject* TList::objptr(long index);
  
  void destroy();
  long insert(TObject* obj, long pos);
  long add(TObject* obj, long pos = -1);
  
  TObject* detach(long pos);
  bool remove(long pos);

  TList(long expected_size);
  virtual ~TList();
};

TList::TList(long expected_size)
          : _items(0), _current(0)
{
  _step = expected_size / MAX_SKIP + 1;
  _last_skip = 0;
 
  _skip = new TList_object*[MAX_SKIP];
  _skip[0] = NULL;
}

TList::~TList()
{
  destroy();
  delete [] _skip;
} 

long TList::objects( )
{
  return _items;
}

TObject* TList::first_item()
{
  return objptr(_current = 0);
}

TObject* TList::succ_item()
{
  return objptr(++_current);
}

TObject* TList::pred_item()
{
  return objptr(_current++);
}

TObject* TList::last_item()
{
  return objptr(_current = _items-1);
}

void TList::destroy() 
{
  TList_object* head = _skip[0];
  while (head)
  {
    TList_object* next = head->_next;
    if (head->_obj)
      delete head->_obj;
    delete head;
    head = next;
  }
  _items = _current = _last_skip = 0;
  _skip[0] = NULL;
}

TList::TList_object* TList::lstobjptr(long index) 
{
  TList_object* lstobj = NULL;
  const ldiv_t p = ldiv(index, _step);
  if (p.quot >= 0 && p.quot < _last_skip)
  {
    TList_object* lo = _skip[p.quot];
    for (long s = p.rem; lo && s > 0; s--)
      lo = lo->_next;

    lstobj = lo;
  }
  return lstobj;
}

TObject* TList::objptr(long index) 
{
  TList_object* lo = lstobjptr(index);
  return lo ? lo->_obj : NULL;
}

void TList::change_step(long step)
{
  CHECKD(step > 0 && step <= 16384, "Bad list step ", step);
  _step = step;
  _last_skip = 0;
  
  step = 0;       
  for (TList_object* lo = _skip[0]; lo; lo = lo->_next, step--)
  {
    if (step == 0)
    {
      CHECK(_last_skip < MAX_SKIP, "Too many items");
      _skip[_last_skip++] = lo;
      step = _step; 
    }
  }
}
             
long TList::insert(TObject* obj, long index)
{
  if (index < 0)
    index = 0;
  else  
  {
    if (index > _items) 
      index = _items;
  }    
  const long pred = index-1;
  
  TList_object* newobj = new TList_object;
  newobj->_obj = obj;  
  
  if (pred < 0)
  {               
    newobj->_prev = NULL;
    newobj->_next = _skip[0];
    if (_skip[0])
      _skip[0]->_prev = newobj;
  }  
  else
  {
    TList_object* lo = lstobjptr(pred);
    CHECK(lo, "NULL insertion point");
    newobj->_next = lo->_next;
    newobj->_prev = lo;
    if (lo->_next)
      lo->_next->_prev = newobj;
    lo->_next = newobj;
  }
  _items++;
  
  ldiv_t p = ldiv(index, _step);
  if (p.rem == 0 && p.quot < MAX_SKIP)    // Cambia il capolista
    _skip[p.quot] = newobj;

  for (long i = p.quot + 1; i < _last_skip; i++)
    _skip[i] = _skip[i]->_prev;           // Aggiorna capilista successivi
  
  // Siamo andati oltre l'ultimo skip
  const long s = (_items - 1) / _step + 1; 
  if (s > _last_skip)
  {
    if (s > MAX_SKIP)
      change_step(_step+1);
    else
      _last_skip++;
  }   
  
  return index;
}

long TList::add(TObject* obj, long index)
{
  if (index < 0 || index >= _items) 
  {
    index = insert(obj, _items);
  }  
  else
  {
    TList_object* lo = lstobjptr(index);
    CHECK(lo, "NULL list object");
    delete lo->_obj;
    lo->_obj = obj;
  }
  return index;  
}

TList::TList_object* TList::detach_lstobj(long index)
{
  TList_object* lo = lstobjptr(index);
  if (lo)
  {
    if (lo->_prev)
      lo->_prev->_next = lo->_next;
    if (lo->_next)
      lo->_next->_prev = lo->_prev;
    ldiv_t res = ldiv(index, _step);
    if (res.rem == 0)
      _skip[res.quot] = lo->_next;
    long p;
    for (p = res.quot + 1; p < _last_skip; p++)
      _skip[p] = _skip[p]->_next;
      
    _items--;
  
    p = (_items - 1) / _step + 1; 
    if (p < _last_skip)
    {                 
      _last_skip--;
      _skip[_last_skip] = NULL;
    }  
  } 
  
  return lo;
}

TObject* TList::detach(long index)
{
  TList_object* lo = detach_lstobj(index);
  TObject* obj;
  if (lo)
  {
    obj = lo->_obj;
    delete lo;
  }  
  else
    obj = NULL;
  return obj;
}

bool TList::remove(long index)
{
  TObject* o = detach(index);
  if (o)
    delete o;
  return o != NULL;
}   

#include <time.h>

int cg3600(int argc, char* argv[])
{          
  long max = 100000L;
  TList l(max);             
  const clock_t start = clock();
  
  for (long i = 0; i < max; i++)
    l.add(NULL);
  
  const clock_t end = clock()-start;  
  
  return 0;
}