/*
 * 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 2006-2009 Sun Microsystems, Inc.
 *      Portions Copyright 2013-2014 ForgeRock AS.
 */
package org.opends.server.replication.protocol;

import java.io.UnsupportedEncodingException;
import java.util.zip.DataFormatException;

import org.opends.server.replication.common.AssuredMode;
import org.opends.server.replication.common.CSN;

/**
 * Abstract class that must be extended to define a message
 * used for sending Updates between servers.
 */
public class UpdateMsg extends ReplicationMsg
                                    implements Comparable<UpdateMsg>
{
  /**
   * Protocol version.
   */
  protected short protocolVersion;

  /**
   * The CSN of this update.
   */
  protected CSN csn;

  /**
   * True when the update must use assured replication.
   */
  protected boolean assuredFlag = false;

  /**
   * When assuredFlag is true, defines the requested assured mode.
   */
  protected AssuredMode assuredMode = AssuredMode.SAFE_DATA_MODE;

  /**
   * When assured mode is safe data, gives the requested level.
   */
  protected byte safeDataLevel = (byte)1;

  /**
   * The payload that must be encoded in this message.
   */
  private byte[] payload;


  /**
   * Creates a new empty UpdateMsg.
   */
  protected UpdateMsg()
  {}

  /**
   * Creates a new UpdateMsg with the given information.
   *
   * @param bytes A Byte Array with the encoded form of the message.
   *
   * @throws DataFormatException If bytes is not valid.
   */
  UpdateMsg(byte[] bytes) throws DataFormatException
  {
    // Decode header
    int pos = decodeHeader(MSG_TYPE_GENERIC_UPDATE, bytes);

    // Read the payload : all the remaining bytes but the terminating 0
    int length = bytes.length - pos;
    payload = new byte[length];
    try
    {
      System.arraycopy(bytes, pos, payload, 0, length);
    } catch (IndexOutOfBoundsException e)
    {
      throw new DataFormatException(e.getMessage());
    } catch (ArrayStoreException e)
    {
      throw new DataFormatException(e.getMessage());
    } catch (NullPointerException e)
    {
      throw new DataFormatException(e.getMessage());
    }
  }

  /**
   * Creates a new UpdateMsg with the given informations.
   * <p>
   * This constructor is only used for testing.
   *
   * @param csn  The CSN associated with the change encoded in this message.
   * @param payload       The payload that must be encoded in this message.
   */
  public UpdateMsg(CSN csn, byte[] payload)
  {
    this.payload = payload;
    this.protocolVersion = ProtocolVersion.getCurrentVersion();
    this.csn = csn;
  }

  /**
   * Get the CSN from the message.
   * @return the CSN
   */
  public CSN getCSN()
  {
    return csn;
  }

  /**
   * Get a boolean indicating if the Update must be processed as an
   * Asynchronous or as an assured replication.
   *
   * @return Returns the assuredFlag.
   */
  public boolean isAssured()
  {
    return assuredFlag;
  }

  /**
   * Set the Update message as an assured message.
   *
   * @param assured If the message is assured or not. Using true implies
   * setAssuredMode method must be called.
   */
  public void setAssured(boolean assured)
  {
    assuredFlag = assured;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public boolean equals(Object obj)
  {
    return obj != null && obj.getClass() == this.getClass() &&
        csn.equals(((UpdateMsg) obj).csn);
  }

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

  /**
   * {@inheritDoc}
   */
  @Override
  public int compareTo(UpdateMsg msg)
  {
    return csn.compareTo(msg.getCSN());
  }

  /**
   * Get the assured mode in this message.
   * @return The assured mode in this message
   */
  public AssuredMode getAssuredMode()
  {
    return assuredMode;
  }

  /**
   * Get the safe data level in this message.
   * @return The safe data level in this message
   */
  public byte getSafeDataLevel()
  {
    return safeDataLevel;
  }

  /**
   * Set the assured mode. Assured boolean must be set to true for this field
   * to mean something.
   * @param assuredMode The chosen assured mode.
   */
  public void setAssuredMode(AssuredMode assuredMode)
  {
    this.assuredMode = assuredMode;
  }

  /**
   * Set the safe data level. Assured mode should be set to safe data for this
   * field to mean something.
   * @param safeDataLevel The chosen safe data level.
   */
  public void setSafeDataLevel(byte safeDataLevel)
  {
    this.safeDataLevel = safeDataLevel;
  }

  /**
   * Get the version included in the update message. Means the replication
   * protocol version with which this update message was instantiated.
   *
   * @return The version with which this update message was instantiated.
   */
  public short getVersion()
  {
    return protocolVersion;
  }

  /**
   * Return the number of bytes used by this message.
   *
   * @return The number of bytes used by this message.
   */
  public int size()
  {
    return 10 + payload.length;
  }

  /**
   * Encode the common header for all the UpdateMsg. This uses the current
   * protocol version.
   *
   * @param type the type of UpdateMsg to encode.
   * @param additionalLength additional length needed to encode the remaining
   *                         part of the UpdateMsg.
   * @param version The ProtocolVersion to use when encoding.
   * @return a byte array containing the common header and enough space to
   *         encode the remaining bytes of the UpdateMsg as was specified
   *         by the additionalLength.
   *         (byte array length = common header length + additionalLength)
   * @throws UnsupportedEncodingException if UTF-8 is not supported.
   */
  protected byte[] encodeHeader(byte type, int additionalLength, short version)
    throws UnsupportedEncodingException
  {
    byte[] csnByte = getCSN().toString().getBytes("UTF-8");

    /* The message header is stored in the form :
     * <operation type><protocol version><CSN><assured>
     * <assured mode> <safe data level>
     * the length of result byte array is therefore :
     *   1 + 1 + CSN length + 1 + 1
     *   + 1 + 1 + additional_length
     */
    int length = 6 + csnByte.length + additionalLength;

    byte[] encodedMsg = new byte[length];

    // put the type of the operation
    encodedMsg[0] = type;

    // put the protocol version
    encodedMsg[1] = (byte)ProtocolVersion.getCurrentVersion();
    int pos = 2;

    // Put the CSN
    pos = addByteArray(csnByte, encodedMsg, pos);

    // Put the assured flag
    encodedMsg[pos++] = (assuredFlag ? (byte) 1 : 0);

    // Put the assured mode
    encodedMsg[pos++] = assuredMode.getValue();

    // Put the safe data level
    encodedMsg[pos++] = safeDataLevel;

    return encodedMsg;
  }

  /**
   * Decode the Header part of this Update LocalizableMessage, and check its type.
   *
   * @param type The allowed type of this Update LocalizableMessage.
   * @param encodedMsg the encoded form of the UpdateMsg.
   * @return the position at which the remaining part of the message starts.
   * @throws DataFormatException if the encodedMsg does not contain a valid
   *         common header.
   */
  protected int decodeHeader(byte type, byte[] encodedMsg)
                          throws DataFormatException
  {
    /* The message header is stored in the form :
     * <operation type><protocol version><CSN><assured>
     * <assured mode> <safe data level>
     */
    if (!(type == encodedMsg[0]))
      throw new DataFormatException("byte[] is not a valid update msg: "
        + encodedMsg[0]);

    // read the protocol version
    protocolVersion = encodedMsg[1];

    try
    {
      // Read the CSN
      int pos = 2;
      int length = getNextLength(encodedMsg, pos);
      String csnStr = new String(encodedMsg, pos, length, "UTF-8");
      pos += length + 1;
      csn = new CSN(csnStr);

      // Read the assured information
      assuredFlag = encodedMsg[pos++] == 1;

      // Read the assured mode
      assuredMode = AssuredMode.valueOf(encodedMsg[pos++]);

      // Read the safe data level
      safeDataLevel = encodedMsg[pos++];

      return pos;
    } catch (UnsupportedEncodingException e)
    {
      throw new DataFormatException("UTF-8 is not supported by this jvm.");
    } catch (IllegalArgumentException e)
    {
      throw new DataFormatException(e.getMessage());
    }
  }

  /**
   * Returns the encoded representation of this update message using the current
   * protocol version.
   *
   * @return The encoded representation of this update message.
   * @throws UnsupportedEncodingException
   *           If the message could not be encoded.
   */
  public byte[] getBytes() throws UnsupportedEncodingException
  {
    return getBytes(ProtocolVersion.getCurrentVersion());
  }

  /**
   * This implementation is only called during unit testing, so we are free to
   * force the protocol version. Underlying implementations override this method
   * in order to provide version specific encodings.
   *
   * {@inheritDoc}
   */
  @Override
  public byte[] getBytes(short protocolVersion)
      throws UnsupportedEncodingException
  {
    // Encode the header in a byte[] large enough to also contain the payload
    byte[] resultByteArray = encodeHeader(MSG_TYPE_GENERIC_UPDATE,
        payload.length, ProtocolVersion.getCurrentVersion());

    int pos = resultByteArray.length - payload.length;

    // Add the payload
    for (int i = 0; i < payload.length; i++, pos++)
    {
      resultByteArray[pos] = payload[i];
    }
    return resultByteArray;
  }

  /**
   * Get the payload of the UpdateMsg.
   *
   * @return The payload of the UpdateMsg.
   */
  public byte[] getPayload()
  {
    return payload;
  }
}