/**
 * Copyright 2009 Google Inc.
 *
 * 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
 *
 *      http://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 org.waveprotocol.wave.concurrencycontrol.channel;

import org.waveprotocol.wave.concurrencycontrol.common.ChannelException;
import org.waveprotocol.wave.model.operation.wave.TransformedWaveletDelta;
import org.waveprotocol.wave.model.operation.wave.WaveletDelta;
import org.waveprotocol.wave.model.version.HashedVersion;
import org.waveprotocol.wave.model.wave.data.ObservableWaveletData;

import java.util.List;

/**
 * A raw channel for messages on a single wavelet.
 *
 * @author anorth@google.com (Alex North)
 */
public interface WaveletChannel {

  /**
   * Receiver for wavelet updates.
   */
  interface Listener {
    /**
     * Called when a stream update is received. At least one of {@code deltas} and
     * {@code lastCommittedVersion} will be non-null or non-empty. {@code
     * currentSignedVersion} is non-null only in the first message when a stream
     * is reconnecting.
     *
     * @param deltas optional update message
     * @param lastCommittedVersion optional committed version (may be null)
     * @param currentSignedVersion optional current/latest version on the server
     * @throw ChannelException if the channel fails in processing the update
     */
    public void onWaveletUpdate(List<TransformedWaveletDelta> deltas,
        HashedVersion lastCommittedVersion, HashedVersion currentSignedVersion)
        throws ChannelException;

    /**
     * Called when a stream update is received. At least one of {@code snapshot} and
     * {@code lastCommittedVersion} will be non-null. {@code
     * currentSignedVersion} is non-null only in the first message when a stream
     * is reconnecting.
     *
     * @param snapshot optional wavelet metadata (may be null)
     * @param lastCommittedVersion optional committed version (may be null)
     * @param currentSignedVersion optional current/latest version on the server
     * @throw ChannelException if the channel fails in processing the update
     */
    public void onWaveletSnapshot(ObservableWaveletData snapshot,
        HashedVersion lastCommittedVersion,
        HashedVersion currentSignedVersion)
        throws ChannelException;
  }

  /**
   * Submits a delta on this channel.
   *
   * @param delta delta to submit
   * @param callback invoked with the submission response
   */
  public void submit(WaveletDelta delta, SubmitCallback callback);

  /**
   * @return Debug string that details profile information regarding data being sent.
   */
  public String debugGetProfilingInfo();
}