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A tool for merging GTFS feeds.
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/**
 * Copyright (C) 2012 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.onebusaway.gtfs_merge;

import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.onebusaway.gtfs.services.GtfsMutableRelationalDao;
import org.onebusaway.gtfs.services.GtfsRelationalDao;
import org.onebusaway.gtfs_merge.strategies.EDuplicateDetectionStrategy;

/**
 * Manages state for the current merge operation, which is specific to
 * particular feed and GTFS entity type.
 * 
 * @author bdferris
 */
public class GtfsMergeContext {

  private final GtfsRelationalDao source;

  private final GtfsMutableRelationalDao target;

  private final String prefix;

  private final Map entityByRawId;

  private final Set entitiesJustAdded = new HashSet();

  private int _sequenceCounter = 1;

  private EDuplicateDetectionStrategy _resolvedDuplicateDetectionStrategy;

  public GtfsMergeContext(GtfsRelationalDao source,
      GtfsMutableRelationalDao target, String prefix,
      Map entityByRawId) {
    this.source = source;
    this.target = target;
    this.prefix = prefix;
    this.entityByRawId = entityByRawId;
  }

  /**
   * @return the source feed GTFS DAO from which entities should be read.
   */
  public GtfsRelationalDao getSource() {
    return source;
  }

  /**
   * @return the target feed GTFS DAO where merged entities should be written.
   */
  public GtfsMutableRelationalDao getTarget() {
    return target;
  }

  /**
   * @return a unique prefix that can be used to make duplicate or overlapping
   *         ids unique during the current merge operation.
   */
  public String getPrefix() {
    return prefix;
  }

  /**
   * Indicate that an entity with the specified raw GTFS id as been added to the
   * merged output GTFS feed. Since typically only a single entity can be added
   * to a feed for a particular id, this method can be used in combination with
   * {@link #getEntityForRawId(String)} to detect id and entity collisions
   * across feeds.
   * 
   * @param rawId
   * @param entity
   */
  public void putEntityWithRawId(String rawId, Object entity) {
    entityByRawId.put(rawId, entity);
    entitiesJustAdded.add(rawId);
  }

  /**
   * Find an entity registered with {@link #putEntityWithRawId(String, Object)}
   * for the current entity type across feeds merged so far, including the
   * current feed. Can be used to detect id and entity collisions across feeds.
   * 
   * @param rawId
   * @return an entity associated with the specified raw GTFS id for the current
   *         entity type, or null if no entity with the specified id exists.
   */
  public Object getEntityForRawId(String rawId) {
    return entityByRawId.get(rawId);
  }

  /**
   * It can be useful to know if an entity returned by
   * {@link #getEntityForRawId(String)} was added from the current source feed
   * or from some previous feed.
   * 
   * @param rawId
   * @return true if an entity with the specified id was added from the feed
   *         currently being processed with a call to
   *         {@link #putEntityWithRawId(String, Object)}.
   */
  public boolean isEntityJustAddedWithRawId(String rawId) {
    return entitiesJustAdded.contains(rawId);
  }

  /**
   * 
   * @return a unique integer for the current merge operation.
   */
  public int getNextSequenceCounter() {
    return _sequenceCounter++;
  }

  /**
   * @return the duplicate detection strategy that has been chosen for the
   *         current entity type.
   */
  public EDuplicateDetectionStrategy getResolvedDuplicateDetectionStrategy() {
    return _resolvedDuplicateDetectionStrategy;
  }

  /**
   * Set the duplicate detection strategy that has been chosen for this entity
   * type. A strategy might have been specified directly by the user or we might
   * have auto-detected the best strategy based on available data.
   * 
   * @param resolvedDuplicateDetectionStrategy
   */
  public void setResolvedDuplicateDetectionStrategy(
      EDuplicateDetectionStrategy resolvedDuplicateDetectionStrategy) {
    _resolvedDuplicateDetectionStrategy = resolvedDuplicateDetectionStrategy;
  }
}