/*
 * Copyright 2000-2006 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package jetbrains.communicator.core.impl;

import jetbrains.communicator.core.EventBroadcaster;
import jetbrains.communicator.core.IDEtalkEvent;
import jetbrains.communicator.core.IDEtalkListener;
import org.apache.log4j.Logger;

import java.util.ArrayList;
import java.util.List;

/**
 * @author Kir Maximov
 */
public class EventBroadcasterImpl implements EventBroadcaster {
  private static final Logger LOG = Logger.getLogger(EventBroadcasterImpl.class);
  public static final Runnable NO_ACTION = new Runnable() { public void run() { } };

  private final List<IDEtalkListener> myListeners = new ArrayList<IDEtalkListener>();

  public synchronized void addListener(IDEtalkListener listener) {
    assert !myListeners.contains(listener);
    myListeners.add(listener);
  }

  public synchronized void removeListener(IDEtalkListener listener) {
    myListeners.remove(listener);
  }

  public void doChange(IDEtalkEvent event, Runnable action) {
    try {
      fireBeforeChange(event);
      action.run();
    } finally {
      fireAfterChange(event);
    }
  }

  public void fireEvent(IDEtalkEvent event) {
    doChange(event, NO_ACTION);
  }

  private void fireBeforeChange(IDEtalkEvent event) {
    for (IDEtalkListener listener : getListeners()) {
      listener.beforeChange(event);
    }
  }

  private void fireAfterChange(IDEtalkEvent event) {
    if (LOG.isDebugEnabled()) {
      LOG.debug("afterChange: " + event);
    }
    for (IDEtalkListener listener : getListeners()) {
      listener.afterChange(event);
    }
  }

  /** public for tests */
  public synchronized IDEtalkListener[] getListeners() {
    return myListeners.toArray(new IDEtalkListener[myListeners.size()]);
  }

  /** for tests */
  public synchronized void clearListeners() {
    myListeners.clear();
  }

}