/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at legal-notices/CDDLv1_0.txt
 * or http://forgerock.org/license/CDDLv1.0.html.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at legal-notices/CDDLv1_0.txt.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information:
 *      Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 *
 *
 *      Copyright 2008-2010 Sun Microsystems, Inc.
 *      Portions Copyright 2015 ForgeRock AS.
 */

package org.opends.guitools.controlpanel.util;

import java.util.HashSet;
import java.util.Set;

import javax.naming.NamingEnumeration;
import javax.naming.directory.SearchControls;
import javax.naming.directory.SearchResult;
import javax.naming.ldap.InitialLdapContext;

import org.opends.guitools.controlpanel.datamodel.CustomSearchResult;
import org.opends.guitools.controlpanel.event.EntryReadErrorEvent;
import org.opends.guitools.controlpanel.event.EntryReadEvent;
import org.opends.guitools.controlpanel.event.EntryReadListener;

/**
 * A class that reads an entry on the background.  This is used in the LDAP
 * entries browser.  When the entry is read it notifies to the EntryReadListener
 * objects that have been registered.
 *
 */
public class LDAPEntryReader extends BackgroundTask<CustomSearchResult>
{
  private final String dn;
  private final InitialLdapContext ctx;
  private final Set<EntryReadListener> listeners = new HashSet<>();
  private boolean isOver;
  private boolean notifyListeners;

  /**
   * Constructor of the entry reader.
   * @param dn the DN of the entry.
   * @param ctx the connection to the server.
   */
  public LDAPEntryReader(String dn, InitialLdapContext ctx)
  {
    this.dn = dn;
    this.ctx = ctx;
    this.notifyListeners = true;
  }

  /** {@inheritDoc} */
  @Override
  public CustomSearchResult processBackgroundTask() throws Throwable
  {
    isOver = false;
    NamingEnumeration<SearchResult> en = null;
    try
    {
      SearchControls controls = new SearchControls();

      String[] attrs = {"*", "+"};
      controls.setReturningAttributes(attrs);
      controls.setSearchScope(SearchControls.OBJECT_SCOPE);
      final String filter = "(|(objectclass=*)(objectclass=ldapsubentry))";

      en = ctx.search(Utilities.getJNDIName(dn), filter, controls);

      SearchResult sr = null;
      while (en.hasMore())
      {
        sr = en.next();
      }

      return new CustomSearchResult(sr, dn);
    }
    finally
    {
      if (isInterrupted())
      {
        isOver = true;
      }
      if (en != null)
      {
        en.close();
      }
    }
  }

  /** {@inheritDoc} */
  @Override
  public void backgroundTaskCompleted(CustomSearchResult sr,
      Throwable throwable)
  {
    if (!isInterrupted() && isNotifyListeners())
    {
      if (throwable == null)
      {
        notifyListeners(sr);
      }
      else
      {
        notifyListeners(throwable);
      }
    }
    isOver = true;
  }

  /**
   * Returns whether this entry reader will notify the listeners once it is
   * over.
   * @return whether this entry reader will notify the listeners once it is
   * over.
   */
  public boolean isNotifyListeners()
  {
    return notifyListeners;
  }

  /**
   * Sets whether this entry reader will notify the listeners once it is
   * over.
   * @param notifyListeners whether this entry reader will notify the listeners
   * once it is over.
   */
  public void setNotifyListeners(boolean notifyListeners)
  {
    this.notifyListeners = notifyListeners;
  }

  /**
   * Returns <CODE>true</CODE> if the read process is over and
   * <CODE>false</CODE> otherwise.
   * @return <CODE>true</CODE> if the read process is over and
   * <CODE>false</CODE> otherwise.
   */
  public boolean isOver()
  {
    return isOver;
  }

  /**
   * Notifies listeners that a new entry was read.
   * @param sr the new entry in form of CustomSearchResult.
   */
  private void notifyListeners(CustomSearchResult sr)
  {
    EntryReadEvent ev = new EntryReadEvent(this, sr);
    for (EntryReadListener listener : listeners)
    {
      listener.entryRead(ev);
    }
  }

  /**
   * Notifies the listeners that an error occurred reading an entry.
   * @param t the error that occurred reading an entry.
   */
  private void notifyListeners(Throwable t)
  {
    EntryReadErrorEvent ev = new EntryReadErrorEvent(this, dn, t);
    for (EntryReadListener listener : listeners)
    {
      listener.entryReadError(ev);
    }
  }

  /**
   * Adds an EntryReadListener.
   * @param listener the listener.
   */
  public void addEntryReadListener(EntryReadListener listener)
  {
    listeners.add(listener);
  }

  /**
   * Removes an EntryReadListener.
   * @param listener the listener.
   */
  public void removeEntryReadListener(EntryReadListener listener)
  {
    listeners.remove(listener);
  }
}