/*
 * 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 2010 Sun Microsystems, Inc.
 */
package org.opends.sdk.controls;



import static com.sun.opends.sdk.messages.Messages.ERR_VLVRES_CONTROL_BAD_OID;
import static com.sun.opends.sdk.messages.Messages.INFO_VLVRES_CONTROL_CANNOT_DECODE_VALUE;
import static com.sun.opends.sdk.messages.Messages.INFO_VLVRES_CONTROL_NO_VALUE;
import static com.sun.opends.sdk.util.StaticUtils.getExceptionMessage;

import java.io.IOException;

import org.opends.sdk.*;
import org.opends.sdk.asn1.ASN1;
import org.opends.sdk.asn1.ASN1Reader;
import org.opends.sdk.asn1.ASN1Writer;

import com.sun.opends.sdk.util.Validator;



/**
 * The virtual list view response control as defined in
 * draft-ietf-ldapext-ldapv3-vlv. This control is included with a search result
 * in response to a virtual list view request included with a search request.
 * <p>
 * If the result code included with this control indicates that the virtual list
 * view request succeeded then the content count and target position give
 * sufficient information for the client to update a list box slider position to
 * match the newly retrieved entries and identify the target entry.
 * <p>
 * The content count and context ID should be used in a subsequent virtual list
 * view requests.
 *
 * @see VirtualListViewRequestControl
 * @see <a href="http://tools.ietf.org/html/draft-ietf-ldapext-ldapv3-vlv">
 *         draft-ietf-ldapext-ldapv3-vlv - LDAP Extensions for Scrolling View
 *         Browsing of Search Results </a>
 */
public final class VirtualListViewResponseControl implements Control
{
  /**
   * The OID for the virtual list view request control.
   */
  public static final String OID = "2.16.840.1.113730.3.4.10";

  /**
   * A decoder which can be used for decoding the virtual list view response
   * control.
   */
  public static final ControlDecoder<VirtualListViewResponseControl> DECODER =
    new ControlDecoder<VirtualListViewResponseControl>()
  {

    public VirtualListViewResponseControl decodeControl(final Control control,
        final DecodeOptions options) throws DecodeException
    {
      Validator.ensureNotNull(control);

      if (control instanceof VirtualListViewResponseControl)
      {
        return (VirtualListViewResponseControl) control;
      }

      if (!control.getOID().equals(OID))
      {
        final LocalizableMessage message = ERR_VLVRES_CONTROL_BAD_OID.get(
            control.getOID(), OID);
        throw DecodeException.error(message);
      }

      if (!control.hasValue())
      {
        // The response control must always have a value.
        final LocalizableMessage message = INFO_VLVRES_CONTROL_NO_VALUE.get();
        throw DecodeException.error(message);
      }

      final ASN1Reader reader = ASN1.getReader(control.getValue());
      try
      {
        reader.readStartSequence();

        final int targetPosition = (int) reader.readInteger();
        final int contentCount = (int) reader.readInteger();
        final ResultCode result = ResultCode.valueOf(reader.readEnumerated());
        ByteString contextID = null;
        if (reader.hasNextElement())
        {
          contextID = reader.readOctetString();
        }

        return new VirtualListViewResponseControl(control.isCritical(),
            targetPosition, contentCount, result, contextID);
      }
      catch (final IOException e)
      {
        final LocalizableMessage message = INFO_VLVRES_CONTROL_CANNOT_DECODE_VALUE
            .get(getExceptionMessage(e));
        throw DecodeException.error(message, e);
      }
    }



    public String getOID()
    {
      return OID;
    }
  };



  /**
   * Creates a new virtual list view response control.
   *
   * @param targetPosition
   *          The position of the target entry in the result set.
   * @param contentCount
   *          An estimate of the total number of entries in the result set.
   * @param result
   *          The result code indicating the outcome of the virtual list view
   *          request.
   * @param contextID
   *          A server-defined octet string. If present, the contextID should be
   *          sent back to the server by the client in a subsequent virtual list
   *          request.
   * @return The new control.
   * @throws IllegalArgumentException
   *           If {@code targetPosition} or {@code contentCount} were less than
   *           {@code 0}.
   * @throws NullPointerException
   *           If {@code result} was {@code null}.
   */
  public static VirtualListViewResponseControl newControl(
      final int targetPosition, final int contentCount,
      final ResultCode result, final ByteString contextID)
      throws IllegalArgumentException, NullPointerException
  {
    Validator.ensureNotNull(result);
    Validator.ensureTrue(targetPosition >= 0, "targetPosition is less than 0");
    Validator.ensureTrue(contentCount >= 0, "contentCount is less than 0");

    return new VirtualListViewResponseControl(false, targetPosition,
        contentCount, result, contextID);
  }



  private final int targetPosition;

  private final int contentCount;

  private final ResultCode result;

  private final ByteString contextID;

  private final boolean isCritical;



  private VirtualListViewResponseControl(final boolean isCritical,
      final int targetPosition, final int contentCount,
      final ResultCode result, final ByteString contextID)
  {
    this.isCritical = isCritical;
    this.targetPosition = targetPosition;
    this.contentCount = contentCount;
    this.result = result;
    this.contextID = contextID;
  }



  /**
   * Returns the estimated total number of entries in the result set.
   *
   * @return The estimated total number of entries in the result set.
   */
  public int getContentCount()
  {
    return contentCount;
  }



  /**
   * Returns a server-defined octet string which, if present, should be sent
   * back to the server by the client in a subsequent virtual list request.
   *
   * @return A server-defined octet string which, if present, should be sent
   *         back to the server by the client in a subsequent virtual list
   *         request, or {@code null} if there is no context ID.
   */
  public ByteString getContextID()
  {
    return contextID;
  }



  /**
   * {@inheritDoc}
   */
  public String getOID()
  {
    return OID;
  }



  /**
   * Returns result code indicating the outcome of the virtual list view
   * request.
   *
   * @return The result code indicating the outcome of the virtual list view
   *         request.
   */
  public ResultCode getResult()
  {
    return result;
  }



  /**
   * Returns the position of the target entry in the result set.
   *
   * @return The position of the target entry in the result set.
   */
  public int getTargetPosition()
  {
    return targetPosition;
  }



  /**
   * {@inheritDoc}
   */
  public ByteString getValue()
  {
    final ByteStringBuilder buffer = new ByteStringBuilder();
    final ASN1Writer writer = ASN1.getWriter(buffer);
    try
    {
      writer.writeStartSequence();
      writer.writeInteger(targetPosition);
      writer.writeInteger(contentCount);
      writer.writeEnumerated(result.intValue());
      if (contextID != null)
      {
        writer.writeOctetString(contextID);
      }
      writer.writeEndSequence();
      return buffer.toByteString();
    }
    catch (final IOException ioe)
    {
      // This should never happen unless there is a bug somewhere.
      throw new RuntimeException(ioe);
    }
  }



  /**
   * {@inheritDoc}
   */
  public boolean hasValue()
  {
    return true;
  }



  /**
   * {@inheritDoc}
   */
  public boolean isCritical()
  {
    return isCritical;
  }



  /**
   * {@inheritDoc}
   */
  @Override
  public String toString()
  {
    final StringBuilder builder = new StringBuilder();
    builder.append("VirtualListViewResponseControl(oid=");
    builder.append(getOID());
    builder.append(", criticality=");
    builder.append(isCritical());
    builder.append(", targetPosition=");
    builder.append(targetPosition);
    builder.append(", contentCount=");
    builder.append(contentCount);
    builder.append(", result=");
    builder.append(result);
    if (contextID != null)
    {
      builder.append(", contextID=");
      builder.append(contextID);
    }
    builder.append(")");
    return builder.toString();
  }

}