/*
 * This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that
 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If
 * not, see <http://www.gnu.org/licenses/>.
 */
package silentium.gameserver.idfactory;

import java.util.BitSet;
import java.util.concurrent.atomic.AtomicInteger;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import silentium.commons.utils.PrimeFinder;
import silentium.gameserver.ThreadPoolManager;

public class BitSetIDFactory extends IdFactory
{
	private static Logger _log = LoggerFactory.getLogger(BitSetIDFactory.class.getName());

	private BitSet _freeIds;
	private AtomicInteger _freeIdCount;
	private AtomicInteger _nextFreeId;

	protected class BitSetCapacityCheck implements Runnable
	{
		@Override
		public void run()
		{
			synchronized (BitSetIDFactory.this)
			{
				if (reachingBitSetCapacity())
					increaseBitSetCapacity();
			}
		}
	}

	protected BitSetIDFactory()
	{
		super();
		synchronized (BitSetIDFactory.class)
		{
			ThreadPoolManager.getInstance().scheduleGeneralAtFixedRate(new BitSetCapacityCheck(), 30000, 30000);
			initialize();
		}
		_log.info("IDFactory: " + _freeIds.size() + " id's available.");
	}

	public void initialize()
	{
		try
		{
			_freeIds = new BitSet(PrimeFinder.nextPrime(100000));
			_freeIds.clear();
			_freeIdCount = new AtomicInteger(FREE_OBJECT_ID_SIZE);

			for (int usedObjectId : extractUsedObjectIDTable())
			{
				int objectID = usedObjectId - FIRST_OID;
				if (objectID < 0)
				{
					_log.warn("Object ID " + usedObjectId + " in DB is less than minimum ID of " + FIRST_OID);
					continue;
				}
				_freeIds.set(usedObjectId - FIRST_OID);
				_freeIdCount.decrementAndGet();
			}

			_nextFreeId = new AtomicInteger(_freeIds.nextClearBit(0));
			_initialized = true;
		}
		catch (Exception e)
		{
			_initialized = false;
			_log.error("BitSet ID Factory could not be initialized correctly: " + e.getMessage(), e);
		}
	}

	@Override
	public synchronized void releaseId(int objectID)
	{
		if ((objectID - FIRST_OID) > -1)
		{
			_freeIds.clear(objectID - FIRST_OID);
			_freeIdCount.incrementAndGet();
		}
		else
			_log.warn("BitSet ID Factory: release objectID " + objectID + " failed (< " + FIRST_OID + ")");
	}

	@Override
	public synchronized int getNextId()
	{
		int newID = _nextFreeId.get();
		_freeIds.set(newID);
		_freeIdCount.decrementAndGet();

		int nextFree = _freeIds.nextClearBit(newID);

		if (nextFree < 0)
			nextFree = _freeIds.nextClearBit(0);

		if (nextFree < 0)
		{
			if (_freeIds.size() < FREE_OBJECT_ID_SIZE)
				increaseBitSetCapacity();
			else
				throw new NullPointerException("Ran out of valid Id's.");
		}

		_nextFreeId.set(nextFree);

		return newID + FIRST_OID;
	}

	@Override
	public synchronized int size()
	{
		return _freeIdCount.get();
	}

	protected synchronized int usedIdCount()
	{
		return (size() - FIRST_OID);
	}

	protected synchronized boolean reachingBitSetCapacity()
	{
		return PrimeFinder.nextPrime(usedIdCount() * 11 / 10) > _freeIds.size();
	}

	protected synchronized void increaseBitSetCapacity()
	{
		BitSet newBitSet = new BitSet(PrimeFinder.nextPrime(usedIdCount() * 11 / 10));
		newBitSet.or(_freeIds);
		_freeIds = newBitSet;
	}
}