/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.box.server.waveserver;

import org.waveprotocol.box.common.Receiver;
import org.waveprotocol.wave.federation.Proto.ProtocolAppliedWaveletDelta;
import org.waveprotocol.wave.model.id.WaveletName;
import org.waveprotocol.wave.model.operation.wave.TransformedWaveletDelta;
import org.waveprotocol.wave.model.version.HashedVersion;

import java.io.IOException;

/**
 * Reads wavelet deltas for a wavelet.
 *
 * @author soren@google.com (Soren Lassen)
 */
public interface WaveletDeltaRecordReader {

  /** @return the name of the wavelet whose deltas this reader reads */
  WaveletName getWaveletName();

  /** @return true if the collection contains no deltas */
  boolean isEmpty();

  /** @return the resulting version of the last delta */
  HashedVersion getEndVersion();

  /** @return the delta applied at this version, if any, otherwise null */
  WaveletDeltaRecord getDelta(long version) throws IOException;

  /** @return the delta leading to this version, if any, otherwise null */
  WaveletDeltaRecord getDeltaByEndVersion(long version) throws IOException;

  /**
   * Convenience method, approximately equivalent to
   * {@code AppliedDeltaUtil.getHashedVersionAppliedAt(getAppliedDelta(version))}
   *
   * @return the hashed version for the specified version number, if any delta
   *         was applied at this version, otherwise null
   */
  HashedVersion getAppliedAtVersion(long version) throws IOException;

  /**
   * Convenience method, approximately equivalent to
   * {@code getTransformedDelta(version).getResultingVersion()}
   *
   * @return the resulting hashed version of the delta applied at the given
   *         version, if any, otherwise null
   */
  HashedVersion getResultingVersion(long version) throws IOException;

  /**
   * Convenience method, approximately equivalent to
   * {@code getDelta(version).applied)}
   *
   * @return the applied delta applied at this version, if any, otherwise null
   */
  ByteStringMessage<ProtocolAppliedWaveletDelta> getAppliedDelta(long version) throws IOException;

  /**
   * Convenience method, approximately equivalent to
   * {@code getDelta(version).transformed)}
   *
   * @return the transformed delta applied at this version, if any, otherwise
   *         null
   */
  TransformedWaveletDelta getTransformedDelta(long version) throws IOException;

  /**
   * Returns all the persisted deltas. Convenience method to build snapshots
   * with only one call to the persistency component.
   * 
   * @return
   * @throws IOException
   */
  long getAllDeltas(Receiver<WaveletDeltaRecord> receiver) throws IOException;


  /**
   * Returns a range of deltas having their result version greater than startVersion
   * and less or equals than endVersion
   * 
   * @param startVersion 
   * @param endVersion
   * @param receiver
   */
  long getDeltasInRange(long startVersion, long endVersion, Receiver<WaveletDeltaRecord> receiver)
      throws IOException;

  /**
   * Returns the last delta of the wavelet.
   * 
   * @return the last delta
   * @throws IOException 
   */
  WaveletDeltaRecord getLastDelta() throws IOException;

}