/**
 * Copyright 2010 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.model.wave.data.impl;

import org.waveprotocol.wave.model.id.WaveId;
import org.waveprotocol.wave.model.id.WaveletId;
import org.waveprotocol.wave.model.version.HashedVersion;
import org.waveprotocol.wave.model.wave.ParticipantId;
import org.waveprotocol.wave.model.wave.data.ReadableBlipData;
import org.waveprotocol.wave.model.wave.data.ReadableWaveletData;

import java.util.Collections;
import java.util.Set;

/**
 * A basic implementation for an empty ReadableWaveletData.
 */
public class EmptyWaveletSnapshot implements ReadableWaveletData {

  private final WaveId waveId;
  private final WaveletId waveletId;
  private final ParticipantId creator;
  private final long creationTime;
  private final HashedVersion hashedVersion;

  /**
   * Creates an empty snapshot.
   */
  public EmptyWaveletSnapshot(WaveId waveId, WaveletId waveletId, ParticipantId creator,
      HashedVersion version, long creationTime) {
    this.waveId = waveId;
    this.waveletId = waveletId;
    this.creator = creator;
    this.hashedVersion = version;
    this.creationTime = creationTime;
  }

  @Override
  public long getCreationTime() {
    return creationTime;
  }

  @Override
  public ParticipantId getCreator() {
    return creator;
  }

  @Override
  public HashedVersion getHashedVersion() {
    return hashedVersion;
  }

  @Override
  public ReadableBlipData getDocument(String documentName) {
    return null;
  }

  @Override
  public Set<String> getDocumentIds() {
    return Collections.emptySet();
  }

  @Override
  public long getLastModifiedTime() {
    return getCreationTime();
  }

  @Override
  public Set<ParticipantId> getParticipants() {
    return Collections.emptySet();
  }

  @Override
  public long getVersion() {
    return getHashedVersion().getVersion();
  }

  @Override
  public WaveId getWaveId() {
    return waveId;
  }

  @Override
  public WaveletId getWaveletId() {
    return waveletId;
  }

}