content: /**
   * This file is part of Aion-Lightning <aion-lightning.org>.
   *
   *  Aion-Lightning 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.
   *
   *  Aion-Lightning 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 Aion-Lightning.
   *  If not, see <http://www.gnu.org/licenses/>.
   */
  
  package com.aionemu.commons.callbacks.util;
  
  import java.util.concurrent.CopyOnWriteArrayList;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import com.aionemu.commons.callbacks.Callback;
  import com.aionemu.commons.callbacks.CallbackResult;
  import com.aionemu.commons.utils.ClassUtils;
  
  /**
   * This class is used to manage global callbacks.<br>
   * Callbacks are stored according to their priority.
   *
   * @author SoulKeeper
   */
  @SuppressWarnings("rawtypes")
  public class GlobalCallbackHelper {
  
  	private static final Logger log = LoggerFactory.getLogger(GlobalCallbackHelper.class);
  
  	private static final CopyOnWriteArrayList<Callback> globalCallbacks = new CopyOnWriteArrayList<Callback>();
  
  	/**
  	 * Private constructor to prevent initialization
  	 */
  	private GlobalCallbackHelper() {
  
  	}
  
  	/**
  	 * Registers global callback.<br>
  	 * Please note that invoking this method from scripts can cause memory leak,
  	 * callbacks are not weak references. You should unregister callback
  	 * manually in case of global adding global callback.
  	 *
  	 * @param callback
  	 *            callback to add
  	 */
  	public static void addCallback(Callback<?> callback) {
  		synchronized (GlobalCallbackHelper.class) {
  			CallbacksUtil.insertCallbackToList(callback, globalCallbacks);
  		}
  	}
  
  	/**
  	 * Removes global callback from the list.<br>
  	 *
  	 * @param callback
  	 *            callback to remove
  	 */
  	public static void removeCallback(Callback<?> callback) {
  		synchronized (GlobalCallbackHelper.class) {
  			globalCallbacks.remove(callback);
  		}
  	}
  
  	/**
  	 * <b><font color="red">THIS METHOD SHOULD NOT BE CALLED MANUALLY</font></b>
  	 *
  	 * @param obj
  	 *            method on whom was invoked
  	 * @param callbackClass
  	 *            what method was actually invoked
  	 * @param args
  	 *            method arguments
  	 * @return result of invocation callbacks
  	 */
  	@SuppressWarnings({ "unchecked" })
  	public static CallbackResult<?> beforeCall(Object obj, Class callbackClass, Object... args) {
  
  		CallbackResult<?> cr = null;
  		for (Callback cb : globalCallbacks) {
  			if (!ClassUtils.isSubclass(cb.getBaseClass(), callbackClass)) {
  				continue;
  			}
  
  			try {
  				cr = cb.beforeCall(obj, args);
  				if (cr.isBlockingCallbacks()) {
  					break;
  				}
  			} catch (Exception e) {
  				log.error("Exception in global callback", e);
  			}
  		}
  
  		return cr == null ? CallbackResult.newContinue() : cr;
  	}
  
  	/**
  	 * <b></><font color="red">THIS METHOD SHOULD NOT BE CALLED
  	 * MANUALLY</font></b>
  	 *
  	 * @param obj
  	 *            method on whom was invoked
  	 * @param callbackClass
  	 *            what method was actually invoked
  	 * @param args
  	 *            method arguments
  	 * @param result
  	 *            original method result
  	 * @return global result, callback or method, doesn't matter
  	 */
  	@SuppressWarnings({ "unchecked" })
  	public static CallbackResult<?> afterCall(Object obj, Class callbackClass, Object[] args, Object result) {
  
  		CallbackResult<?> cr = null;
  		for (Callback cb : globalCallbacks) {
  			if (!ClassUtils.isSubclass(cb.getBaseClass(), callbackClass)) {
  				continue;
  			}
  
  			try {
  				cr = cb.afterCall(obj, args, result);
  				if (cr.isBlockingCallbacks()) {
  					break;
  				}
  			} catch (Exception e) {
  				log.error("Exception in global callback", e);
  			}
  		}
  
  		return cr == null ? CallbackResult.newContinue() : cr;
  	}
  }
  