package org.musicontroller.repair;
   
   
   import java.util.ArrayList;
   import java.util.HashMap;
   import java.util.List;
   import java.util.Map;
   import java.util.Map.Entry;
   
  import org.apache.log4j.Logger;
  import org.musicontroller.core.AIBag;
  import org.musicontroller.core.AIRelation;
  import org.musicontroller.core.Artist;
  import org.musicontroller.dao.Dao;
  
  /**
   * Merges all Artists in the database that are equal into one.
   * @author drexler
   * @version $Id: MergeArtistCopies.java,v 1.1 2010/03/16 18:55:42 varienaja Exp $
   */
  public class MergeArtistCopies {
  	private static final Logger log = Logger.getLogger(MergeArtistCopies.class);
  
  	@SuppressWarnings("unchecked")
  	public static void execute(Dao dao) {
  		if(dao==null) {
  			log.error("MergeArtistCopies.execute() invoked with a null DAO. The merge could not take place.");
  			return;
  		}
  		log.info("Merge artist copy job started.");
  		List<Long> allArtists = dao.search("select a.id from Artist a", null, 0);
  		// The artist map will contain an entry for each distinct artist. The
  		// entries value is a list of all copies of that artist.
  		Map<Artist, List<Long>> artistMap = new HashMap<Artist,List<Long>>();
  		for (long anArtistId : allArtists) {
  			Artist artist = dao.getArtistById(anArtistId);
  			List<Long> entry = artistMap.get(artist);
  			if(entry==null) {
  				// A new artist : create an empty entry
  				entry = new ArrayList<Long>();
  				artistMap.put(artist, entry);
  			} else {
  				// We have found a duplicate. Add it to the list.
  				entry.add(anArtistId);
  			}
  		}
  		// Now we have to merge the duplicates.
  		for(Entry<Artist,List<Long>> entry : artistMap.entrySet()) {
  			List<Long> duplicates = artistMap.get(entry.getValue());
  			for(long duplicateId : duplicates) {
  				mergeArtists(entry.getKey(),duplicateId,dao);
  			}
  		}
  		log.info("Merge artist copy job finished.");
  	}
  
  	/**
  	 * Merge the artist duplicateId into the artist keep.
  	 * @param keep The artist to keep.
  	 * @param duplicateId The artist to merge.
  	 */
  	@SuppressWarnings("unchecked")
  	private static void mergeArtists(Artist keep, long duplicateId,Dao dao) {
  		String hql = "select distinct bag.id from AIBag bag left join bag.relations rel" +
  				" where rel.artist_id=:artistid";
  		Map<String,Object> params = new HashMap<String,Object>();
  		params.put("artistid", duplicateId);
  		List<Long> bagIdList = dao.search(hql, params, 0);
  		for(long bag_id: bagIdList) {
  			AIBag bag = dao.getAIBagById(bag_id);
  			for(AIRelation rel: bag.getRelations()) {
  				if(rel.getArtist_id()==duplicateId) {
  					rel.setArtist_id(keep.getId());
  					log.info("Changing reference to artist "+duplicateId+" into a reference to artist "+keep.getId()+".");
  				}
  			}
  			dao.save(bag);
  		}
  		// Delete the duplicate artist.
  		Artist duplicate = dao.getArtistById(duplicateId);
  		dao.deleteArtist(duplicate);
  		log.info("Artist id: "+duplicateId+" has been removed.");
  	}
  }