/**
 * 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.account;

import org.waveprotocol.wave.model.util.Preconditions;
import org.waveprotocol.wave.model.wave.ParticipantId;

import java.util.Set;

/**
 * A wrapper for Indexability that provides default values for absent
 * assignments. Setting an indexability to the default value clears the
 * assignment.
 *
 */
public class DefaultingIndexability implements MutableIndexability {
  private final MutableIndexability target;
  private final IndexDecision defaultDecision;

  public DefaultingIndexability(
      final MutableIndexability indexability, IndexDecision defaultDecision) {
    Preconditions.checkNotNull(indexability, "indexability can't be null");
    this.target = indexability;
    this.defaultDecision = defaultDecision;
  }

  @Override
  public Set<ParticipantId> getIndexDecisions() {
    return target.getIndexDecisions();
  }

  @Override
  public IndexDecision getIndexability(ParticipantId participant) {
    IndexDecision result = target.getIndexability(participant);
    if (result == null) {
      return defaultDecision;
    }
    return result;
  }

  @Override
  public void setIndexability(ParticipantId participant, IndexDecision indexability) {
    if (indexability == defaultDecision) {
      target.setIndexability(participant, null);
    } else {
      target.setIndexability(participant, indexability);
    }
  }

}