/*
 *                    BioJava development code
 *
 * This code may be freely distributed and modified under the
 * terms of the GNU Lesser General Public Licence.  This should
 * be distributed with the code.  If you do not have a copy,
 * see:
 *
 *      http://www.gnu.org/copyleft/lesser.html
 *
 * Copyright for this code is held jointly by the individual
 * authors.  These should be listed in @author doc comments.
 *
 * For more information on the BioJava project and its aims,
 * or to join the biojava-l mailing list, visit the home page
 * at:
 *
 *      http://www.biojava.org/
 *
 */
package org.biojava.bio.program.das;

import java.net.URL;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

import org.biojava.bio.BioException;
import org.biojava.bio.seq.db.SequenceDB;
import org.biojava.bio.seq.distributed.DistDataSource;
import org.biojava.utils.ChangeEvent;
import org.biojava.utils.ChangeListener;
import org.biojava.utils.ChangeSupport;
import org.biojava.utils.ChangeType;
import org.biojava.utils.ChangeVetoException;
import org.biojava.utils.Changeable;

/**
 * Reflects a reference server on the DAS network.
 *
 * @author Matthew Pocock
 * @author Thomas Down
 */
 
public class ReferenceServer
  extends
    DataSource
  implements
    Changeable
{
  public static final ChangeType ANNOTATOR = new ChangeType(
    "Annotator added", ReferenceServer.class, "ANNOTATOR"
  );
  
  private Set annotators;
  private Set publicAnnotators;
  private transient ChangeSupport changeSupport = null;

  protected boolean hasListeners() {
    return changeSupport != null;
  }

  protected ChangeSupport getChangeSupport(ChangeType ct) {
    if(changeSupport != null) {
      return changeSupport;
    }
    
    synchronized(this) {
      if(changeSupport == null) {
        changeSupport = new ChangeSupport();
      }
    }
    
    return changeSupport;
  }

  public final void addChangeListener(ChangeListener cl) {
    addChangeListener(cl, ChangeType.UNKNOWN);
  }

  public final void addChangeListener(ChangeListener cl, ChangeType ct) {
    ChangeSupport cs = getChangeSupport(ct);
    cs.addChangeListener(cl, ct);
  }

  public final void removeChangeListener(ChangeListener cl) {
    removeChangeListener(cl, ChangeType.UNKNOWN);
  }

  public final void removeChangeListener(ChangeListener cl, ChangeType ct) {
    if(hasListeners()) {
      ChangeSupport cs = getChangeSupport(ct);
      cs.removeChangeListener(cl, ct);
    }
  }
  
  public final boolean isUnchanging(ChangeType ct) {
    ChangeSupport cs = getChangeSupport(ct);
    return cs.isUnchanging(ct);
  }
  
  {
    annotators = new HashSet();
    publicAnnotators = Collections.unmodifiableSet(annotators);
  }

  ReferenceServer(URL dasURL, String name, String description) {
    super(dasURL, dasURL, name, description);
  }
  
  void addAnnotator(DataSource ann) throws ChangeVetoException {
    if(hasListeners()) {
      ChangeSupport cs = getChangeSupport(ANNOTATOR);
      synchronized(cs) {
        ChangeEvent ce = new ChangeEvent(this, ANNOTATOR);
        cs.firePreChangeEvent(ce);
        annotators.add(ann);
        cs.firePostChangeEvent(ce);
      }
    } else {
      annotators.add(ann);
    }
  }
  
  public Set getAnnotaters() {
    return publicAnnotators;
  }
  
  public SequenceDB getDB() throws BioException {
    return new DASSequenceDB(getURL());
  }

    public DistDataSource getDistDataSource() 
        throws BioException
    {
	return new DASDistDataSource(getURL());
    }
}