/*
 * 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 net.sf.l2j.gameserver;

import java.lang.Thread.UncaughtExceptionHandler;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.RunnableScheduledFuture;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Logger;

import net.sf.l2j.Config;
import net.sf.l2j.util.StringUtil;

/**
 * <p>
 * This class is made to handle all the ThreadPools used in L2j.
 * </p>
 * <p>
 * Scheduled Tasks can either be sent to a {@link #_generalScheduledThreadPool "general"} or {@link #_effectsScheduledThreadPool "effects"} {@link ScheduledThreadPoolExecutor ScheduledThreadPool}: The "effects" one is used for every effects (skills, hp/mp regen ...) while the "general" one is used
 * for everything else that needs to be scheduled.<br>
 * There also is an {@link #_aiScheduledThreadPool "ai"} {@link ScheduledThreadPoolExecutor ScheduledThreadPool} used for AI Tasks.
 * </p>
 * <p>
 * Tasks can be sent to {@link ScheduledThreadPoolExecutor ScheduledThreadPool} either with:
 * <ul>
 * <li>{@link #scheduleEffect(Runnable, long)} : for effects Tasks that needs to be executed only once.</li>
 * <li>{@link #scheduleGeneral(Runnable, long)} : for scheduled Tasks that needs to be executed once.</li>
 * <li>{@link #scheduleAi(Runnable, long)} : for AI Tasks that needs to be executed once</li>
 * </ul>
 * or
 * <ul>
 * <li>{@link #scheduleEffectAtFixedRate(Runnable, long, long)} : for effects Tasks that needs to be executed periodicaly.</li>
 * <li>{@link #scheduleGeneralAtFixedRate(Runnable, long, long)} : for scheduled Tasks that needs to be executed periodicaly.</li>
 * <li>{@link #scheduleAiAtFixedRate(Runnable, long, long)} : for AI Tasks that needs to be executed periodicaly</li>
 * </ul>
 * </p>
 * <p>
 * For all Tasks that should be executed with no delay asynchronously in a ThreadPool there also are usual {@link ThreadPoolExecutor ThreadPools} that can grow/shrink according to their load.:
 * <ul>
 * <li>{@link #_generalPacketsThreadPool GeneralPackets} where most packets handler are executed.</li>
 * <li>
 * {@link #_ioPacketsThreadPool I/O Packets} where all the i/o packets are executed.</li>
 * <li>There will be an AI ThreadPool where AI events should be executed</li>
 * <li>A general ThreadPool where everything else that needs to run asynchronously with no delay should be executed ( {@link net.sf.l2j.gameserver.model.actor.knownlist KnownList} updates, SQL updates/inserts...)?</li>
 * </ul>
 * </p>
 * @author -Wooden-
 */
public class ThreadPoolManager
{
	protected static final Logger _log = Logger.getLogger(ThreadPoolManager.class.getName());
	
	private static final class RunnableWrapper implements Runnable
	{
		private final Runnable _r;
		
		public RunnableWrapper(final Runnable r)
		{
			_r = r;
		}
		
		@Override
		public final void run()
		{
			try
			{
				_r.run();
			}
			catch (final Throwable e)
			{
				final Thread t = Thread.currentThread();
				final UncaughtExceptionHandler h = t.getUncaughtExceptionHandler();
				if (h != null)
					h.uncaughtException(t, e);
			}
		}
	}
	
	protected ScheduledThreadPoolExecutor _effectsScheduledThreadPool;
	protected ScheduledThreadPoolExecutor _generalScheduledThreadPool;
	protected ScheduledThreadPoolExecutor _aiScheduledThreadPool;
	private final ThreadPoolExecutor _generalPacketsThreadPool;
	private final ThreadPoolExecutor _ioPacketsThreadPool;
	private final ThreadPoolExecutor _generalThreadPool;
	
	/** temp workaround for VM issue */
	private static final long MAX_DELAY = Long.MAX_VALUE / 1000000 / 2;
	
	private boolean _shutdown;
	
	public static ThreadPoolManager getInstance()
	{
		return SingletonHolder._instance;
	}
	
	protected ThreadPoolManager()
	{
		_effectsScheduledThreadPool = new ScheduledThreadPoolExecutor(Config.THREAD_P_EFFECTS, new PriorityThreadFactory("EffectsSTPool", Thread.NORM_PRIORITY));
		_generalScheduledThreadPool = new ScheduledThreadPoolExecutor(Config.THREAD_P_GENERAL, new PriorityThreadFactory("GeneralSTPool", Thread.NORM_PRIORITY));
		_ioPacketsThreadPool = new ThreadPoolExecutor(Config.IO_PACKET_THREAD_CORE_SIZE, Integer.MAX_VALUE, 5L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(), new PriorityThreadFactory("I/O Packet Pool", Thread.NORM_PRIORITY + 1));
		_generalPacketsThreadPool = new ThreadPoolExecutor(Config.GENERAL_PACKET_THREAD_CORE_SIZE, Config.GENERAL_PACKET_THREAD_CORE_SIZE + 2, 15L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(), new PriorityThreadFactory("Normal Packet Pool", Thread.NORM_PRIORITY + 1));
		_generalThreadPool = new ThreadPoolExecutor(Config.GENERAL_THREAD_CORE_SIZE, Config.GENERAL_THREAD_CORE_SIZE + 2, 5L, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(), new PriorityThreadFactory("General Pool", Thread.NORM_PRIORITY));
		_aiScheduledThreadPool = new ScheduledThreadPoolExecutor(Config.AI_MAX_THREAD, new PriorityThreadFactory("AISTPool", Thread.NORM_PRIORITY));
		
		scheduleGeneralAtFixedRate(new PurgeTask(), 10 * 60 * 1000l, 5 * 60 * 1000l);
	}
	
	public static long validateDelay(long delay)
	{
		if (delay < 0)
			delay = 0;
		else if (delay > MAX_DELAY)
			delay = MAX_DELAY;
		return delay;
	}
	
	public ScheduledFuture<?> scheduleEffect(Runnable r, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			return _effectsScheduledThreadPool.schedule(new RunnableWrapper(r), delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			return null;
		}
	}
	
	public ScheduledFuture<?> scheduleEffectAtFixedRate(Runnable r, long initial, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			initial = ThreadPoolManager.validateDelay(initial);
			return _effectsScheduledThreadPool.scheduleAtFixedRate(new RunnableWrapper(r), initial, delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			return null; /* shutdown, ignore */
		}
	}
	
	@Deprecated
	public boolean removeEffect(RunnableScheduledFuture<?> r)
	{
		return _effectsScheduledThreadPool.remove(r);
	}
	
	public ScheduledFuture<?> scheduleGeneral(Runnable r, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			return _generalScheduledThreadPool.schedule(new RunnableWrapper(r), delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			return null; /* shutdown, ignore */
		}
	}
	
	public ScheduledFuture<?> scheduleGeneralAtFixedRate(Runnable r, long initial, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			initial = ThreadPoolManager.validateDelay(initial);
			return _generalScheduledThreadPool.scheduleAtFixedRate(new RunnableWrapper(r), initial, delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			return null; /* shutdown, ignore */
		}
	}
	
	@Deprecated
	public boolean removeGeneral(RunnableScheduledFuture<?> r)
	{
		return _generalScheduledThreadPool.remove(r);
	}
	
	public ScheduledFuture<?> scheduleAi(Runnable r, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			return _aiScheduledThreadPool.schedule(new RunnableWrapper(r), delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			return null; /* shutdown, ignore */
		}
	}
	
	public ScheduledFuture<?> scheduleAiAtFixedRate(Runnable r, long initial, long delay)
	{
		try
		{
			delay = ThreadPoolManager.validateDelay(delay);
			initial = ThreadPoolManager.validateDelay(initial);
			return _aiScheduledThreadPool.scheduleAtFixedRate(new RunnableWrapper(r), initial, delay, TimeUnit.MILLISECONDS);
		}
		catch (RejectedExecutionException e)
		{
			return null; /* shutdown, ignore */
		}
	}
	
	public void executePacket(Runnable pkt)
	{
		_generalPacketsThreadPool.execute(pkt);
	}
	
	public void executeCommunityPacket(Runnable r)
	{
		_generalPacketsThreadPool.execute(r);
	}
	
	public void executeIOPacket(Runnable pkt)
	{
		_ioPacketsThreadPool.execute(pkt);
	}
	
	public void executeTask(Runnable r)
	{
		_generalThreadPool.execute(r);
	}
	
	public void executeAi(Runnable r)
	{
		_aiScheduledThreadPool.execute(new RunnableWrapper(r));
	}
	
	private static class PriorityThreadFactory implements ThreadFactory
	{
		private final int _prio;
		private final String _name;
		private final AtomicInteger _threadNumber = new AtomicInteger(1);
		private final ThreadGroup _group;
		
		public PriorityThreadFactory(String name, int prio)
		{
			_prio = prio;
			_name = name;
			_group = new ThreadGroup(_name);
		}
		
		@Override
		public Thread newThread(Runnable r)
		{
			Thread t = new Thread(_group, r);
			t.setName(_name + "-" + _threadNumber.getAndIncrement());
			t.setPriority(_prio);
			return t;
		}
		
		public ThreadGroup getGroup()
		{
			return _group;
		}
	}
	
	public void shutdown()
	{
		_shutdown = true;
		
		_effectsScheduledThreadPool.shutdown();
		_generalScheduledThreadPool.shutdown();
		_generalPacketsThreadPool.shutdown();
		_ioPacketsThreadPool.shutdown();
		_generalThreadPool.shutdown();
		
		_log.info("All ThreadPools are now stopped.");
	}
	
	public boolean isShutdown()
	{
		return _shutdown;
	}
	
	public void purge()
	{
		_effectsScheduledThreadPool.purge();
		_generalScheduledThreadPool.purge();
		_aiScheduledThreadPool.purge();
		_ioPacketsThreadPool.purge();
		_generalPacketsThreadPool.purge();
		_generalThreadPool.purge();
	}
	
	public String getPacketStats()
	{
		final StringBuilder sb = new StringBuilder(1000);
		ThreadFactory tf = _generalPacketsThreadPool.getThreadFactory();
		if (tf instanceof PriorityThreadFactory)
		{
			PriorityThreadFactory ptf = (PriorityThreadFactory) tf;
			int count = ptf.getGroup().activeCount();
			Thread[] threads = new Thread[count + 2];
			ptf.getGroup().enumerate(threads);
			StringUtil.append(sb, "General Packet Thread Pool:\r\n" + "Tasks in the queue: ", String.valueOf(_generalPacketsThreadPool.getQueue().size()), "\r\n" + "Showing threads stack trace:\r\n" + "There should be ", String.valueOf(count), " Threads\r\n");
			for (Thread t : threads)
			{
				if (t == null)
					continue;
				
				StringUtil.append(sb, t.getName(), "\r\n");
				for (StackTraceElement ste : t.getStackTrace())
				{
					StringUtil.append(sb, ste.toString(), "\r\n");
				}
			}
		}
		
		sb.append("Packet Tp stack traces printed.\r\n");
		
		return sb.toString();
	}
	
	public String getIOPacketStats()
	{
		final StringBuilder sb = new StringBuilder(1000);
		ThreadFactory tf = _ioPacketsThreadPool.getThreadFactory();
		
		if (tf instanceof PriorityThreadFactory)
		{
			PriorityThreadFactory ptf = (PriorityThreadFactory) tf;
			int count = ptf.getGroup().activeCount();
			Thread[] threads = new Thread[count + 2];
			ptf.getGroup().enumerate(threads);
			StringUtil.append(sb, "I/O Packet Thread Pool:\r\n" + "Tasks in the queue: ", String.valueOf(_ioPacketsThreadPool.getQueue().size()), "\r\n" + "Showing threads stack trace:\r\n" + "There should be ", String.valueOf(count), " Threads\r\n");
			
			for (Thread t : threads)
			{
				if (t == null)
					continue;
				
				StringUtil.append(sb, t.getName(), "\r\n");
				
				for (StackTraceElement ste : t.getStackTrace())
				{
					StringUtil.append(sb, ste.toString(), "\r\n");
				}
			}
		}
		
		sb.append("Packet Tp stack traces printed.\r\n");
		
		return sb.toString();
	}
	
	public String getGeneralStats()
	{
		final StringBuilder sb = new StringBuilder(1000);
		ThreadFactory tf = _generalThreadPool.getThreadFactory();
		
		if (tf instanceof PriorityThreadFactory)
		{
			PriorityThreadFactory ptf = (PriorityThreadFactory) tf;
			int count = ptf.getGroup().activeCount();
			Thread[] threads = new Thread[count + 2];
			ptf.getGroup().enumerate(threads);
			StringUtil.append(sb, "General Thread Pool:\r\n" + "Tasks in the queue: ", String.valueOf(_generalThreadPool.getQueue().size()), "\r\n" + "Showing threads stack trace:\r\n" + "There should be ", String.valueOf(count), " Threads\r\n");
			
			for (Thread t : threads)
			{
				if (t == null)
					continue;
				
				StringUtil.append(sb, t.getName(), "\r\n");
				
				for (StackTraceElement ste : t.getStackTrace())
				{
					StringUtil.append(sb, ste.toString(), "\r\n");
				}
			}
		}
		
		sb.append("Packet Tp stack traces printed.\r\n");
		
		return sb.toString();
	}
	
	protected class PurgeTask implements Runnable
	{
		@Override
		public void run()
		{
			_effectsScheduledThreadPool.purge();
			_generalScheduledThreadPool.purge();
			_aiScheduledThreadPool.purge();
		}
	}
	
	private static class SingletonHolder
	{
		protected static final ThreadPoolManager _instance = new ThreadPoolManager();
	}
}