/*
 * 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 com.l2jserver.gameserver.instancemanager;

import gnu.trove.map.hash.TIntObjectHashMap;
import gnu.trove.procedure.TObjectProcedure;

import java.util.Map;

import javolution.util.FastMap;

import com.l2jserver.Config;
import com.l2jserver.gameserver.model.actor.L2Character;
import com.l2jserver.gameserver.model.actor.instance.L2PcInstance;
import com.l2jserver.gameserver.network.L2GameClient;

public class AntiFeedManager
{
	public static final int GAME_ID = 0;
	public static final int OLYMPIAD_ID = 1;
	public static final int TVT_ID = 2;
	public static final int L2EVENT_ID = 3;

	private final Map<Integer,Long> _lastDeathTimes;
	private final TIntObjectHashMap<Map<Integer, Connections>> _eventIPs;

	public static final AntiFeedManager getInstance()
	{
		return SingletonHolder._instance;
	}
	
	protected AntiFeedManager()
	{
		_lastDeathTimes = new FastMap<Integer,Long>().shared();
		_eventIPs = new TIntObjectHashMap<>();
	}
	
	/**
	 * Set time of the last player's death to current
	 * @param objectId Player's objectId
	 */
	public final void setLastDeathTime(int objectId)
	{
		_lastDeathTimes.put(objectId, System.currentTimeMillis());
	}
	
	/**
	 * Check if current kill should be counted as non-feeded.
	 * @param attacker Attacker character
	 * @param target Target character
	 * @return True if kill is non-feeded.
	 */
	public final boolean check(L2Character attacker, L2Character target)
	{
		if (!Config.L2JMOD_ANTIFEED_ENABLE)
			return true;
		
		if (target == null)
			return false;
		
		final L2PcInstance targetPlayer = target.getActingPlayer();
		if (targetPlayer == null)
			return false;
		
		if (Config.L2JMOD_ANTIFEED_INTERVAL > 0
				&& _lastDeathTimes.containsKey(targetPlayer.getObjectId()))
			return (System.currentTimeMillis() - _lastDeathTimes.get(targetPlayer.getObjectId())) > Config.L2JMOD_ANTIFEED_INTERVAL;
			
			if (Config.L2JMOD_ANTIFEED_DUALBOX && attacker != null)
			{
				final L2PcInstance attackerPlayer = attacker.getActingPlayer();
				if (attackerPlayer == null)
					return false;
				
				final L2GameClient targetClient = targetPlayer.getClient();
				final L2GameClient attackerClient = attackerPlayer.getClient();
				if (targetClient == null
						|| attackerClient == null
						|| targetClient.isDetached()
						|| attackerClient.isDetached())
					// unable to check ip address
					return !Config.L2JMOD_ANTIFEED_DISCONNECTED_AS_DUALBOX;
				
				return !targetClient.getConnectionAddress().equals(attackerClient.getConnectionAddress());
			}
			
			return true;
	}
	
	/**
	 * Clears all timestamps
	 */
	public final void clear()
	{
		_lastDeathTimes.clear();
	}

	/**
	 * Register new event for dualbox check.
	 * Should be called only once.
	 * @param eventId
	 */
	public final void registerEvent(int eventId)
	{
		if (!_eventIPs.containsKey(eventId))
			_eventIPs.put(eventId, new FastMap<Integer, Connections>());
	}

	/**
	 * 
	 * @param eventId
	 * @param player
	 * @param max
	 * @return If number of all simultaneous connections from player's IP address lower than max
	 * then increment connection count and return true.<br>
	 * False if number of all simultaneous connections from player's IP address higher than max.
	 */
	public final boolean tryAddPlayer(int eventId, L2PcInstance player, int max)
	{
		return tryAddClient(eventId, player.getClient(), max);
	}

	/**
	 * 
	 * @param eventId
	 * @param client
	 * @param max
	 * @return If number of all simultaneous connections from player's IP address lower than max then increment connection count and return true.<br>
	 * False if number of all simultaneous connections from player's IP address higher than max.
	 */
	public final boolean tryAddClient(int eventId, L2GameClient client, int max)
	{
		if (client == null)
			return false; // unable to determine IP address

		final Map<Integer, Connections> event = _eventIPs.get(eventId);
		if (event == null)
			return false; // no such event registered

		final Integer addrHash = Integer.valueOf(client.getConnectionAddress().hashCode());
		int limit = Config.L2JMOD_DUALBOX_CHECK_WHITELIST.get(addrHash);
		limit = limit < 0 ? Integer.MAX_VALUE : limit + max;

		Connections conns;
		synchronized (event)
		{
			conns = event.get(addrHash);
			if (conns == null)
			{
				conns = new Connections();
				event.put(addrHash, conns);
			}
		}

		return conns.testAndIncrement(limit);
	}

	/**
	 * Decreasing number of active connection from player's IP address
	 * @param eventId
	 * @param player
	 * @return true if success and false if any problem detected.
	 */
	public final boolean removePlayer(int eventId, L2PcInstance player)
	{
		final L2GameClient client = player.getClient();
		if (client == null)
			return false; // unable to determine IP address

		final Map<Integer, Connections> event = _eventIPs.get(eventId);
		if (event == null)
			return false; // no such event registered

		final Integer addrHash = Integer.valueOf(client.getConnectionAddress().hashCode());
		Connections conns = event.get(addrHash);
		if (conns == null)
			return false; // address not registered

		synchronized (event)
		{
			if (conns.testAndDecrement())
				event.remove(addrHash);
		}

		return true;
	}

	/**
	 * Remove player connection IP address from all registered events lists.
	 * @param client
	 */
	public final void onDisconnect(L2GameClient client)
	{
		if (client == null)
			return;

		final Integer addrHash = Integer.valueOf(client.getConnectionAddress().hashCode());
		_eventIPs.forEachValue(new DisconnectProcedure(addrHash));
	}

	/**
	 * Clear all entries for this eventId.
	 * @param eventId
	 */
	public final void clear(int eventId)
	{
		final Map<Integer, Connections> event = _eventIPs.get(eventId);
		if (event != null)
			event.clear();
	}

	/**
	 * @param player
	 * @param max
	 * @return maximum number of allowed connections (whitelist + max)
	 */
	public final int getLimit(L2PcInstance player, int max)
	{
		return getLimit(player.getClient(), max);
	}

	/**
	 * @param client
	 * @param max
	 * @return maximum number of allowed connections (whitelist + max)
	 */
	public final int getLimit(L2GameClient client, int max)
	{
		if (client == null)
			return max;

		final Integer addrHash = Integer.valueOf(client.getConnectionAddress().hashCode());
		final int limit = Config.L2JMOD_DUALBOX_CHECK_WHITELIST.get(addrHash);
		return limit < 0 ? 0 : limit + max;
	}

	protected static final class Connections
	{
		private int _num = 0;

		/**
		 * and false if maximum number is reached.
		 * @param max 
		 * @return true if successfully incremented number of connections
		 */
		public final synchronized boolean testAndIncrement(int max)
		{
			if (_num < max)
			{
				_num++;
				return true;
			}
			return false;
		}

		/**
		 * @return true if all connections are removed
		 */
		public final synchronized boolean testAndDecrement()
		{
			if (_num > 0)
				_num--;

			return _num == 0;
		}
	}

	private static final class DisconnectProcedure implements TObjectProcedure<Map<Integer, Connections>>
	{
		private final Integer _addrHash;

		public DisconnectProcedure(Integer addrHash)
		{
			_addrHash = addrHash;
		}

		@Override
		public final boolean execute(Map<Integer, Connections> event)
		{
			final Connections conns = event.get(_addrHash);
			if (conns != null)
			{
				synchronized (event)
				{
					if (conns.testAndDecrement())
						event.remove(_addrHash);
				}
			}
			return true;
		}
	}
	
	private static class SingletonHolder
	{
		protected static final AntiFeedManager _instance = new AntiFeedManager();
	}
}