content: /*
   * Copyright 2014-2025 Real Logic Limited.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   * https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package io.aeron.command;
  
  import org.agrona.BitUtil;
  import org.agrona.MutableDirectBuffer;
  
  import static org.agrona.BitUtil.SIZE_OF_INT;
  import static org.agrona.BitUtil.SIZE_OF_LONG;
  
  /**
   * Message to denote that new buffers for a publication image are ready for a subscription.
   * <p>
   * <b>Note:</b> Layout should be SBE 2.0 compliant so that the source identity length is aligned.
   *
   * @see ControlProtocolEvents
   * <pre>
   *   0                   1                   2                   3
   *   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   *  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   *  |                       Correlation ID                          |
   *  |                                                               |
   *  +---------------------------------------------------------------+
   *  |                         Session ID                            |
   *  +---------------------------------------------------------------+
   *  |                          Stream ID                            |
   *  +---------------------------------------------------------------+
   *  |                 Subscription Registration Id                  |
   *  |                                                               |
   *  +---------------------------------------------------------------+
   *  |                    Subscriber Position Id                     |
   *  +---------------------------------------------------------------+
   *  |                       Log File Length                         |
   *  +---------------------------------------------------------------+
   *  |                     Log File Name (ASCII)                    ...
   * ...                                                              |
   *  +---------------------------------------------------------------+
   *  |                    Source identity Length                     |
   *  +---------------------------------------------------------------+
   *  |                    Source identity (ASCII)                   ...
   * ...                                                              |
   *  +---------------------------------------------------------------+
   * </pre>
   */
  public class ImageBuffersReadyFlyweight
  {
      private static final int CORRELATION_ID_OFFSET = 0;
      private static final int SESSION_ID_OFFSET = CORRELATION_ID_OFFSET + SIZE_OF_LONG;
      private static final int STREAM_ID_FIELD_OFFSET = SESSION_ID_OFFSET + SIZE_OF_INT;
      private static final int SUBSCRIPTION_REGISTRATION_ID_OFFSET = STREAM_ID_FIELD_OFFSET + SIZE_OF_INT;
      private static final int SUBSCRIBER_POSITION_ID_OFFSET = SUBSCRIPTION_REGISTRATION_ID_OFFSET + SIZE_OF_LONG;
      private static final int LOG_FILE_NAME_OFFSET = SUBSCRIBER_POSITION_ID_OFFSET + SIZE_OF_INT;
  
      private MutableDirectBuffer buffer;
      private int offset;
  
      /**
       * Wrap the buffer at a given offset for updates.
       *
       * @param buffer to wrap.
       * @param offset at which the message begins.
       * @return this for a fluent API.
       */
      public final ImageBuffersReadyFlyweight wrap(final MutableDirectBuffer buffer, final int offset)
      {
          this.buffer = buffer;
          this.offset = offset;
  
          return this;
      }
  
      /**
       * The correlation id field.
       *
       * @return correlation id field.
       */
      public long correlationId()
      {
          return buffer.getLong(offset + CORRELATION_ID_OFFSET);
      }
  
      /**
       * Set correlation id field.
       *
       * @param correlationId field value.
       * @return this for a fluent API.
       */
      public ImageBuffersReadyFlyweight correlationId(final long correlationId)
      {
          buffer.putLong(offset + CORRELATION_ID_OFFSET, correlationId);
  
          return this;
      }
  
      /**
       * Get the session id field.
       *
       * @return session id field.
       */
      public int sessionId()
      {
          return buffer.getInt(offset + SESSION_ID_OFFSET);
      }
  
      /**
       * Set session id field.
       *
       * @param sessionId field value.
       * @return this for a fluent API.
       */
      public ImageBuffersReadyFlyweight sessionId(final int sessionId)
      {
          buffer.putInt(offset + SESSION_ID_OFFSET, sessionId);
  
          return this;
      }
  
      /**
       * The stream id field.
       *
       * @return stream id field.
       */
      public int streamId()
      {
          return buffer.getInt(offset + STREAM_ID_FIELD_OFFSET);
      }
  
      /**
       * Set stream id field.
       *
       * @param streamId field value.
       * @return this for a fluent API.
       */
      public ImageBuffersReadyFlyweight streamId(final int streamId)
      {
          buffer.putInt(offset + STREAM_ID_FIELD_OFFSET, streamId);
  
          return this;
      }
  
      /**
       * Set the position counter Id for the subscriber.
       *
       * @param id for the subscriber position counter.
       * @return this for a fluent API.
       */
      public ImageBuffersReadyFlyweight subscriberPositionId(final int id)
      {
          buffer.putInt(offset + SUBSCRIBER_POSITION_ID_OFFSET, id);
  
          return this;
      }
  
      /**
       * The position counter Id for the subscriber.
       *
       * @return position counter Id for the subscriber.
       */
      public int subscriberPositionId()
      {
          return buffer.getInt(offset + SUBSCRIBER_POSITION_ID_OFFSET);
      }
  
      /**
       * Set the registration Id for the Subscription.
       *
       * @param id for the Subscription.
       * @return this for a fluent API.
       */
      public ImageBuffersReadyFlyweight subscriptionRegistrationId(final long id)
      {
          buffer.putLong(offset + SUBSCRIPTION_REGISTRATION_ID_OFFSET, id);
  
          return this;
      }
  
      /**
       * Return the registration Id for the Subscription.
       *
       * @return registration Id for the Subscription.
       */
      public long subscriptionRegistrationId()
      {
          return buffer.getLong(offset + SUBSCRIPTION_REGISTRATION_ID_OFFSET);
      }
  
      /**
       * The Log Filename in ASCII.
       *
       * @return log filename.
       */
      public String logFileName()
      {
          return buffer.getStringAscii(offset + LOG_FILE_NAME_OFFSET);
      }
  
      /**
       * Append the log file name to an {@link Appendable}.
       *
       * @param appendable to append log file name to.
       */
      public void appendLogFileName(final Appendable appendable)
      {
          buffer.getStringAscii(offset + LOG_FILE_NAME_OFFSET, appendable);
      }
  
      /**
       * Set the log filename in ASCII.
       *
       * @param logFileName for the image.
       * @return this for a fluent API.
       */
      public ImageBuffersReadyFlyweight logFileName(final String logFileName)
      {
          buffer.putStringAscii(offset + LOG_FILE_NAME_OFFSET, logFileName);
          return this;
      }
  
      /**
       * The source identity string in ASCII.
       *
       * @return source identity string.
       */
      public String sourceIdentity()
      {
          return buffer.getStringAscii(offset + sourceIdentityOffset());
      }
  
      /**
       * Append the source identity to an {@link Appendable}.
       *
       * @param appendable to append source identity to.
       */
      public void appendSourceIdentity(final Appendable appendable)
      {
          buffer.getStringAscii(offset + sourceIdentityOffset(), appendable);
      }
  
      /**
       * Set the source identity string in ASCII.
       * <p>Note: Can be called only after log file name was set!</p>
       *
       * @param value for the source identity.
       * @return this for a fluent API.
       * @see #logFileName(String)
       */
      public ImageBuffersReadyFlyweight sourceIdentity(final String value)
      {
          buffer.putStringAscii(offset + sourceIdentityOffset(), value);
          return this;
      }
  
      /**
       * Get the length of the current message.
       * <p>
       * NB: must be called after the data is written in order to be accurate.
       *
       * @return the length of the current message.
       */
      public int length()
      {
          final int sourceIdentityOffset = sourceIdentityOffset();
          return sourceIdentityOffset + buffer.getInt(offset + sourceIdentityOffset) + SIZE_OF_INT;
      }
  
      private int sourceIdentityOffset()
      {
          final int alignedLength = BitUtil.align(buffer.getInt(offset + LOG_FILE_NAME_OFFSET), SIZE_OF_INT);
  
          return LOG_FILE_NAME_OFFSET + SIZE_OF_INT + alignedLength;
      }
  }
  