/*
 * 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
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE
 * or https://OpenDS.dev.java.net/OpenDS.LICENSE.
 * 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
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE.  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 2009 Sun Microsystems, Inc.
 */

package org.opends.sdk;



import java.util.Arrays;
import java.util.Collections;
import java.util.List;



/**
 * A Search operation alias dereferencing policy as defined in RFC 4511 section
 * 4.5.1.3 is used to indicate whether or not alias entries (as defined in RFC
 * 4512) are to be dereferenced during stages of a Search operation. The act of
 * dereferencing an alias includes recursively dereferencing aliases that refer
 * to aliases.
 *
 * @see <a href="http://tools.ietf.org/html/rfc4511#section-4.5.1.3">RFC 4511 -
 *      Lightweight Directory Access Protocol (LDAP): The Protocol </a>
 * @see <a href="http://tools.ietf.org/html/rfc4512">RFC 4512 - Lightweight
 *      Directory Access Protocol (LDAP): Directory Information Models </a>
 */
public final class DereferenceAliasesPolicy
{
  private static final DereferenceAliasesPolicy[] ELEMENTS = new DereferenceAliasesPolicy[4];

  private static final List<DereferenceAliasesPolicy> IMMUTABLE_ELEMENTS = Collections
      .unmodifiableList(Arrays.asList(ELEMENTS));

  /**
   * Do not dereference aliases in searching or in locating the base object of a
   * Search operation.
   */
  public static final DereferenceAliasesPolicy NEVER = register(0, "never");

  /**
   * While searching subordinates of the base object, dereference any alias
   * within the scope of the Search operation. Dereferenced objects become the
   * vertices of further search scopes where the Search operation is also
   * applied. If the search scope is {@code WHOLE_SUBTREE}, the Search continues
   * in the subtree(s) of any dereferenced object. If the search scope is
   * {@code SINGLE_LEVEL}, the search is applied to any dereferenced objects and
   * is not applied to their subordinates.
   */
  public static final DereferenceAliasesPolicy IN_SEARCHING = register(1,
      "search");

  /**
   * Dereference aliases in locating the base object of a Search operation, but
   * not when searching subordinates of the base object.
   */
  public static final DereferenceAliasesPolicy FINDING_BASE = register(2,
      "find");

  /**
   * Dereference aliases both in searching and in locating the base object of a
   * Search operation.
   */
  public static final DereferenceAliasesPolicy ALWAYS = register(3, "always");



  /**
   * Returns the alias dereferencing policy having the specified integer value
   * as defined in RFC 4511 section 4.5.1.
   *
   * @param intValue
   *          The integer value of the alias dereferencing policy.
   * @return The dereference aliases policy, or {@code null} if there was no
   *         alias dereferencing policy associated with {@code intValue}.
   */
  public static DereferenceAliasesPolicy valueOf(final int intValue)
  {
    if (intValue < 0 || intValue >= ELEMENTS.length)
    {
      return null;
    }
    return ELEMENTS[intValue];
  }



  /**
   * Returns an unmodifiable list containing the set of available alias
   * dereferencing policies indexed on their integer value as defined in RFC
   * 4511 section 4.5.1.
   *
   * @return An unmodifiable list containing the set of available alias
   *         dereferencing policies.
   */
  public static List<DereferenceAliasesPolicy> values()
  {
    return IMMUTABLE_ELEMENTS;
  }



  /**
   * Creates and registers a new alias dereferencing policy with the
   * application.
   *
   * @param intValue
   *          The integer value of the alias dereferencing policy as defined in
   *          RFC 4511 section 4.5.1.
   * @param name
   *          The name of the alias dereferencing policy.
   * @return The new alias dereferencing policy.
   */
  private static DereferenceAliasesPolicy register(final int intValue,
      final String name)
  {
    final DereferenceAliasesPolicy t = new DereferenceAliasesPolicy(intValue,
        name);
    ELEMENTS[intValue] = t;
    return t;
  }



  private final int intValue;

  private final String name;



  // Prevent direct instantiation.
  private DereferenceAliasesPolicy(final int intValue, final String name)
  {
    this.intValue = intValue;
    this.name = name;
  }



  /**
   * {@inheritDoc}
   */
  @Override
  public boolean equals(final Object obj)
  {
    if (this == obj)
    {
      return true;
    }
    else if (obj instanceof DereferenceAliasesPolicy)
    {
      return this.intValue == ((DereferenceAliasesPolicy) obj).intValue;
    }
    else
    {
      return false;
    }
  }



  /**
   * {@inheritDoc}
   */
  @Override
  public int hashCode()
  {
    return intValue;
  }



  /**
   * Returns the integer value of this alias dereferencing policy as defined in
   * RFC 4511 section 4.5.1.
   *
   * @return The integer value of this alias dereferencing policy.
   */
  public int intValue()
  {
    return intValue;
  }



  /**
   * Returns the string representation of this alias dereferencing policy.
   *
   * @return The string representation of this alias dereferencing policy.
   */
  @Override
  public String toString()
  {
    return name;
  }
}