df3e9db9fed06f881b6c1a2dc319c99b7a517afb
[demoscenemusic.git] / src / main / java / net / pterodactylus / demoscenemusic / data / DataManager.java
1 /*
2  * DemosceneMusic - DataManager.java - Copyright © 2012 David Roden
3  *
4  * This program is free software: you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation, either version 3 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
16  */
17
18 package net.pterodactylus.demoscenemusic.data;
19
20 import java.sql.ResultSet;
21 import java.sql.SQLException;
22 import java.util.Collection;
23 import java.util.EnumMap;
24 import java.util.HashSet;
25 import java.util.List;
26 import java.util.Map;
27 import java.util.Map.Entry;
28 import java.util.UUID;
29 import java.util.concurrent.Callable;
30
31 import net.pterodactylus.demoscenemusic.data.Track.Relationship;
32 import net.pterodactylus.util.collection.Memoizer;
33 import net.pterodactylus.util.database.Database;
34 import net.pterodactylus.util.database.DatabaseException;
35 import net.pterodactylus.util.database.Field;
36 import net.pterodactylus.util.database.Join;
37 import net.pterodactylus.util.database.Join.JoinType;
38 import net.pterodactylus.util.database.ObjectCreator;
39 import net.pterodactylus.util.database.ObjectCreator.StringCreator;
40 import net.pterodactylus.util.database.OrderField;
41 import net.pterodactylus.util.database.Parameter.StringParameter;
42 import net.pterodactylus.util.database.Query;
43 import net.pterodactylus.util.database.Query.Type;
44 import net.pterodactylus.util.database.ResultProcessor;
45 import net.pterodactylus.util.database.ValueField;
46 import net.pterodactylus.util.database.ValueFieldWhereClause;
47
48 /**
49  * Interface between the database and the application.
50  *
51  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
52  */
53 public class DataManager {
54
55         /** The artist object creator. */
56         @SuppressWarnings("synthetic-access")
57         private final ObjectCreator<Artist> artistCreator = new ArtistCreator();
58
59         /** The group object creator. */
60         @SuppressWarnings("synthetic-access")
61         private final ObjectCreator<Group> groupCreator = new GroupCreator();
62
63         /** The track object creator. */
64         @SuppressWarnings("synthetic-access")
65         private final ObjectCreator<Track> trackCreator = new TrackCreator();
66
67         /** The track object creator. */
68         @SuppressWarnings("synthetic-access")
69         private final ObjectCreator<TrackDerivative> trackDerivativeCreator = new TrackDerivativeCreator();
70
71         /** The style object creator. */
72         @SuppressWarnings("synthetic-access")
73         private final ObjectCreator<Style> styleCreator = new StyleCreator();
74
75         /** The {@link User} object creator. */
76         @SuppressWarnings("synthetic-access")
77         private final ObjectCreator<User> userCreator = new UserCreator();
78
79         /** The database. */
80         private final Database database;
81
82         /**
83          * Creates a new data manager.
84          *
85          * @param database
86          *            The database to operate on
87          */
88         public DataManager(Database database) {
89                 this.database = database;
90         }
91
92         /**
93          * Returns all artists.
94          *
95          * @return All artists
96          * @throws DatabaseException
97          *             if a database error occurs
98          */
99         public Collection<Artist> getAllArtists() throws DatabaseException {
100                 Query query = new Query(Type.SELECT, "ARTISTS");
101                 query.addField(new Field("ARTISTS.*"));
102                 return loadArtistProperties(database.getMultiple(query, artistCreator));
103         }
104
105         /**
106          * Returns the artist with the given ID.
107          *
108          * @param id
109          *            The ID of the artist
110          * @return The artist with the given ID, or {@code null} if there is no
111          *         artist with the given ID
112          * @throws DatabaseException
113          *             if a database error occurs
114          */
115         public Artist getArtistById(String id) throws DatabaseException {
116                 Query query = new Query(Type.SELECT, "ARTISTS");
117                 query.addField(new Field("ARTISTS.*"));
118                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("ARTISTS.ID", new StringParameter(id))));
119                 return loadArtistProperties(database.getSingle(query, artistCreator));
120         }
121
122         /**
123          * Returns all artists that belong to the group with the given ID.
124          *
125          * @param groupId
126          *            The ID of the group
127          * @return All artists belonging to the given group
128          * @throws DatabaseException
129          *             if a database error occurs
130          */
131         public Collection<Artist> getArtistsByGroup(String groupId) throws DatabaseException {
132                 Query query = new Query(Type.SELECT, "ARTISTS");
133                 query.addField(new Field("ARTISTS.*"));
134                 query.addJoin(new Join(JoinType.INNER, "GROUP_ARTISTS", new Field("ARTISTS.ID"), new Field("GROUP_ARTISTS.ARTIST")));
135                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUP_ARTISTS.GROUP_", new StringParameter(groupId))));
136                 return loadArtistProperties(database.getMultiple(query, artistCreator));
137         }
138
139         /**
140          * Returns all artists involved in the track with the given ID.
141          *
142          * @param trackId
143          *            The ID of the track
144          * @return All artists involved in the track, in preferred order
145          * @throws DatabaseException
146          *             if a database error occurs
147          */
148         public List<Artist> getArtistsByTrack(String trackId) throws DatabaseException {
149                 Query query = new Query(Type.SELECT, "ARTISTS");
150                 query.addField(new Field("ARTISTS.*"));
151                 query.addJoin(new Join(JoinType.INNER, "TRACK_ARTISTS", new Field("TRACK_ARTISTS.ARTIST"), new Field("ARTISTS.ID")));
152                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_ARTISTS.TRACK", new StringParameter(trackId))));
153                 query.addOrderField(new OrderField(new Field("TRACK_ARTISTS.DISPLAY_ORDER")));
154                 return loadArtistProperties(database.getMultiple(query, artistCreator));
155         }
156
157         /**
158          * Creates a new artist with the given name.
159          *
160          * @param name
161          *            The name of the artist
162          * @return The created artist
163          * @throws DatabaseException
164          *             if a database error occurs
165          */
166         public Artist createArtist(String name) throws DatabaseException {
167                 Query query = new Query(Type.INSERT, "ARTISTS");
168                 String id = UUID.randomUUID().toString();
169                 query.addValueField(new ValueField("ID", new StringParameter(id)));
170                 query.addValueField(new ValueField("NAME", new StringParameter(name)));
171                 database.insert(query);
172                 return loadArtistProperties(getArtistById(id));
173         }
174
175         /**
176          * Saves the given artist.
177          *
178          * @param artist
179          *            The artist to save
180          * @throws DatabaseException
181          *             if a database error occurs
182          */
183         public void saveArtist(Artist artist) throws DatabaseException {
184                 Query query = new Query(Type.UPDATE, "ARTISTS");
185                 query.addValueField(new ValueField("NAME", new StringParameter(artist.getName())));
186                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("ID", new StringParameter(artist.getId()))));
187                 database.update(query);
188                 saveArtistProperties(artist);
189         }
190
191         /**
192          * Saves the properties of the given artist.
193          *
194          * @param artist
195          *            The artist whose properties to save
196          * @throws DatabaseException
197          *             if a database error occurs
198          */
199         public void saveArtistProperties(Artist artist) throws DatabaseException {
200                 saveProperties(artist.getProperties(), "ARTIST_PROPERTIES", "ARTIST", artist.getId());
201         }
202
203         /**
204          * Saves the given properties to the given table for the given principal.
205          *
206          * @param properties
207          *            The properties to save
208          * @param table
209          *            The table in which to save the properties
210          * @param type
211          *            The type of the principal (e. g. “ARTIST” or “TRACK”)
212          * @param id
213          *            The ID of the principial
214          * @throws DatabaseException
215          *             if a database error occurs
216          */
217         public void saveProperties(Properties properties, String table, String type, String id) throws DatabaseException {
218                 if (!properties.isDirty()) {
219                         return;
220                 }
221                 Query query = new Query(Type.DELETE, table);
222                 query.addWhereClause(new ValueFieldWhereClause(new ValueField(type, new StringParameter(id))));
223                 database.update(query);
224                 for (Entry<String, String> property : properties) {
225                         Query insertQuery = new Query(Type.INSERT, table);
226                         insertQuery.addValueField(new ValueField(type, new StringParameter(id)));
227                         insertQuery.addValueField(new ValueField("PROPERTY", new StringParameter(property.getKey())));
228                         insertQuery.addValueField(new ValueField("VALUE", new StringParameter(property.getValue())));
229                         database.insert(insertQuery);
230                 }
231                 properties.resetDirty();
232         }
233
234         /**
235          * Loads the properties for an artist.
236          *
237          * @param artist
238          *            The artist to load the properties for
239          * @return The artist
240          * @throws DatabaseException
241          *             if a database error occurs
242          */
243         public Artist loadArtistProperties(final Artist artist) throws DatabaseException {
244                 return loadProperties(artist, "ARTIST_PROPERTIES", "ARTIST");
245         }
246
247         /**
248          * Loads the properties of all given artists.
249          *
250          * @param artists
251          *            The artists to load the properties for
252          * @return The list of artists
253          * @throws DatabaseException
254          *             if a database error occurs
255          */
256         public List<Artist> loadArtistProperties(List<Artist> artists) throws DatabaseException {
257                 for (Artist artist : artists) {
258                         loadArtistProperties(artist);
259                 }
260                 return artists;
261         }
262
263         /**
264          * Returns all remix artists involved in the track with the given ID.
265          *
266          * @param trackId
267          *            The ID of the track
268          * @return All remix artists involved in the track, in preferred order
269          * @throws DatabaseException
270          *             if a database error occurs
271          */
272         public List<Artist> getRemixArtistsByTrack(String trackId) throws DatabaseException {
273                 Query query = new Query(Type.SELECT, "ARTISTS");
274                 query.addField(new Field("ARTISTS.*"));
275                 query.addJoin(new Join(JoinType.INNER, "TRACK_REMIX_ARTISTS", new Field("TRACK_REMIX_ARTISTS.ARTIST"), new Field("ARTISTS.ID")));
276                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_REMIX_ARTISTS.TRACK", new StringParameter(trackId))));
277                 query.addOrderField(new OrderField(new Field("TRACK_REMIX_ARTISTS.DISPLAY_ORDER")));
278                 return database.getMultiple(query, artistCreator);
279         }
280
281         /**
282          * Returns all related tracks for the track with the given ID.
283          *
284          * @param trackId
285          *            The ID of the tracks
286          * @return A mapping from relationship to all tracks that match the relation
287          * @throws DatabaseException
288          *             if a database error occurs
289          */
290         public Map<Relationship, Collection<Track>> getRelatedTracksByTrack(String trackId) throws DatabaseException {
291                 Query query = new Query(Type.SELECT, "TRACKS");
292                 query.addField(new Field("TRACKS.*"));
293                 query.addField(new Field("TRACK_RELATIONS.*"));
294                 query.addJoin(new Join(JoinType.INNER, "TRACK_RELATIONS", new Field("TRACK_RELATIONS.TRACK"), new Field("TRACK_RELATIONS.RELATED_TRACK")));
295                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_RELATIONS.TRACK", new StringParameter(trackId))));
296                 final Map<Relationship, Collection<Track>> relatedTracks = new EnumMap<Relationship, Collection<Track>>(Relationship.class);
297                 database.process(query, new ResultProcessor() {
298
299                         @Override
300                         @SuppressWarnings("synthetic-access")
301                         public void processResult(ResultSet resultSet) throws SQLException {
302                                 Track track = trackCreator.createObject(resultSet);
303                                 Relationship relationship = Relationship.valueOf(resultSet.getString("TRACK_RELATIONS.RELATIONSHIP"));
304                                 if (!relatedTracks.containsKey(relationship)) {
305                                         relatedTracks.put(relationship, new HashSet<Track>());
306                                 }
307                                 relatedTracks.get(relationship).add(track);
308                         }
309                 });
310                 return relatedTracks;
311         }
312
313         /**
314          * Returns the track with the given ID.
315          *
316          * @param id
317          *            The ID of the track
318          * @return The track with the given ID, or {@code null} if there is no such
319          *         track
320          * @throws DatabaseException
321          *             if a database error occurs
322          */
323         public Track getTrackById(String id) throws DatabaseException {
324                 Query query = new Query(Type.SELECT, "TRACKS");
325                 query.addField(new Field("TRACKS.*"));
326                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACKS.ID", new StringParameter(id))));
327                 return database.getSingle(query, trackCreator);
328         }
329
330         /**
331          * Returns all tracks by the artist with the given ID.
332          *
333          * @param artistId
334          *            The ID of the artist
335          * @return All tracks by the given artist
336          * @throws DatabaseException
337          *             if a database error occurs
338          */
339         public Collection<Track> getTracksByArtist(String artistId) throws DatabaseException {
340                 Query query = new Query(Type.SELECT, "TRACKS");
341                 query.addField(new Field("TRACKS.*"));
342                 query.addJoin(new Join(JoinType.INNER, "TRACK_ARTISTS", new Field("TRACKS.ID"), new Field("TRACK_ARTISTS.TRACK")));
343                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_ARTISTS.ARTIST", new StringParameter(artistId))));
344                 return database.getMultiple(query, trackCreator);
345         }
346
347         /**
348          * Creates a new track with the given name.
349          *
350          * @param name
351          *            The name of the track
352          * @return The created track
353          * @throws DatabaseException
354          *             if a database error occurs
355          */
356         public Track createTrack(String name) throws DatabaseException {
357                 Query query = new Query(Type.INSERT, "TRACKS");
358                 String id = UUID.randomUUID().toString();
359                 query.addValueField(new ValueField("ID", new StringParameter(id)));
360                 query.addValueField(new ValueField("NAME", new StringParameter(name)));
361                 database.insert(query);
362                 return getTrackById(id);
363         }
364
365         /**
366          * Returns the derivative with the given ID.
367          *
368          * @param id
369          *            The ID of the derivatives to load
370          * @return The derivative with the given ID
371          * @throws DatabaseException
372          *             if a database error occurs
373          */
374         public TrackDerivative getTrackDerivativeById(String id) throws DatabaseException {
375                 Query query = new Query(Type.SELECT, "TRACK_DERIVATIVES");
376                 query.addField(new Field("TRACK_DERIVATIVES.*"));
377                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_DERIVATIVES.ID", new StringParameter(id))));
378                 return loadTrackDerivativeProperties(database.getSingle(query, trackDerivativeCreator));
379         }
380
381         /**
382          * Returns the derivatives for the given track.
383          *
384          * @param track
385          *            The track to get the derivatives for
386          * @return The derivatives for the given track
387          * @throws DatabaseException
388          *             if a database error occurs
389          */
390         public Collection<TrackDerivative> getTrackDerivativesByTrack(Track track) throws DatabaseException {
391                 Query query = new Query(Type.SELECT, "TRACK_DERIVATIVES");
392                 query.addField(new Field("TRACK_DERIVATIVES.*"));
393                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_DERIVATIVES.TRACK", new StringParameter(track.getId()))));
394                 return loadTrackDerivativeProperties(database.getMultiple(query, trackDerivativeCreator));
395         }
396
397         /**
398          * Creates a new derivative for the given track.
399          *
400          * @param track
401          *            The track to create the derivative for
402          * @return The created derivative
403          * @throws DatabaseException
404          *             if a database error occurs
405          */
406         public TrackDerivative createTrackDerivative(Track track) throws DatabaseException {
407                 Query query = new Query(Type.INSERT, "TRACK_DERIVATIVES");
408                 String id = UUID.randomUUID().toString();
409                 query.addValueField(new ValueField("TRACK_DERIVATIVES.ID", new StringParameter(id)));
410                 query.addValueField(new ValueField("TRACK_DERIVATIVES.TRACK", new StringParameter(track.getId())));
411                 database.insert(query);
412                 return getTrackDerivativeById(id);
413         }
414
415         /**
416          * Loads the properties for the given track derivative.
417          *
418          * @param trackDerivative
419          *            The track derivative to load the properties for
420          * @return The track derivative with its properties loaded
421          * @throws DatabaseException
422          *             if a database error occurs
423          */
424         public TrackDerivative loadTrackDerivativeProperties(TrackDerivative trackDerivative) throws DatabaseException {
425                 return loadProperties(trackDerivative, "TRACK_DERIVATIVE_PROPERTIES", "TRACK_DERIVATIVE");
426         }
427
428         /**
429          * Loads the properties for the given track derivatives.
430          *
431          * @param trackDerivatives
432          *            The track derivatives to load the properties for
433          * @return The track derivatives with their properties loaded
434          * @throws DatabaseException
435          *             if a database error occurs
436          */
437         public List<TrackDerivative> loadTrackDerivativeProperties(List<TrackDerivative> trackDerivatives) throws DatabaseException {
438                 for (TrackDerivative trackDerivative : trackDerivatives) {
439                         loadTrackDerivativeProperties(trackDerivative);
440                 }
441                 return trackDerivatives;
442         }
443
444         /**
445          * Returns all groups the artist with the given ID belongs to.
446          *
447          * @param artistId
448          *            The ID of the artist
449          * @return All groups the artist belongs to
450          * @throws DatabaseException
451          *             if a database error occurs
452          */
453         public Collection<Group> getGroupsByArtist(String artistId) throws DatabaseException {
454                 Query query = new Query(Type.SELECT, "GROUPS");
455                 query.addField(new Field("GROUPS.*"));
456                 query.addJoin(new Join(JoinType.INNER, "GROUP_ARTISTS", new Field("GROUPS.ID"), new Field("GROUP_ARTISTS.GROUP_")));
457                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUP_ARTISTS.ARTIST", new StringParameter(artistId))));
458                 return database.getMultiple(query, groupCreator);
459         }
460
461         /**
462          * Returns all styles for the track with the given ID.
463          *
464          * @param trackId
465          *            The ID of the track
466          * @return All styles for the given track
467          * @throws DatabaseException
468          *             if a database error occurs
469          */
470         public Collection<Style> getStylesByTrack(String trackId) throws DatabaseException {
471                 Query query = new Query(Type.SELECT, "STYLES");
472                 query.addField(new Field("STYLES.*"));
473                 query.addJoin(new Join(JoinType.INNER, "TRACK_STYLES", new Field("STYLES.ID"), new Field("TRACK_STYLES.STYLE")));
474                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_STYLES.TRACK", new StringParameter(trackId))));
475                 return database.getMultiple(query, styleCreator);
476         }
477
478         /**
479          * Returns the user with the given name.
480          *
481          * @param username
482          *            The name of the user
483          * @return The user, or {@code null} if the user does not exist
484          * @throws DatabaseException
485          *             if a database error occurs
486          */
487         public User getUserByName(String username) throws DatabaseException {
488                 Query query = new Query(Type.SELECT, "USERS");
489                 query.addField(new Field("USERS.*"));
490                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USERS.NAME", new StringParameter(username))));
491                 return database.getSingle(query, userCreator);
492         }
493
494         /**
495          * Returns the user connected with the given OpenID.
496          *
497          * @param openId
498          *            The OpenID to find the user for
499          * @return The user connected with the given OpenID, or {@code null} if
500          *         there is no such user
501          * @throws DatabaseException
502          *             if a database error occurs
503          */
504         public User getUserByOpenId(String openId) throws DatabaseException {
505                 Query query = new Query(Type.SELECT, "USERS");
506                 query.addField(new Field("USERS.*"));
507                 query.addJoin(new Join(JoinType.INNER, "USER_OPENIDS", new Field("USER_OPENIDS.USER"), new Field("USERS.ID")));
508                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USER_OPENIDS.OPENID", new StringParameter(openId))));
509                 return database.getSingle(query, userCreator);
510         }
511
512         /**
513          * Returns all OpenIDs connected with the user with the given ID.
514          *
515          * @param userId
516          *            The ID of the user
517          * @return All OpenIDs connected with the given user
518          * @throws DatabaseException
519          *             if a database error occurs
520          */
521         public Collection<String> getOpenIdsByUser(String userId) throws DatabaseException {
522                 Query query = new Query(Type.SELECT, "USER_OPENIDS");
523                 query.addField(new Field("USER_OPENIDS.*"));
524                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USER_OPENIDS.USER", new StringParameter(userId))));
525                 return database.getMultiple(query, new StringCreator("USER_OPENIDS.OPENID"));
526         }
527
528         //
529         // PRIVATE METHODS
530         //
531
532         /**
533          * Loads the properties for the given object.
534          *
535          * @param <T>
536          *            The type of the object
537          * @param object
538          *            The object
539          * @param table
540          *            The table to load the properties from
541          * @param type
542          *            The type of the object (“ARTIST,” “TRACK,” etc.)
543          * @return The object with its properties loaded
544          * @throws DatabaseException
545          *             if a database error occurs
546          */
547         private <T extends Base> T loadProperties(final T object, final String table, String type) throws DatabaseException {
548                 Query query = new Query(Type.SELECT, table);
549                 query.addField(new Field(table + ".PROPERTY"));
550                 query.addField(new Field(table + ".VALUE"));
551                 query.addWhereClause(new ValueFieldWhereClause(new ValueField(type, new StringParameter(object.getId()))));
552                 database.process(query, new ResultProcessor() {
553
554                         @Override
555                         public void processResult(ResultSet resultSet) throws SQLException {
556                                 if (resultSet.isFirst()) {
557                                         object.getProperties().removeAll();
558                                 }
559                                 object.getProperties().set(resultSet.getString(table + ".PROPERTY"), resultSet.getString(table + ".VALUE"));
560                         }
561
562                 });
563                 return object;
564         }
565
566         /**
567          * {@link Artist} implementation that retrieves some attributes (such as
568          * {@link #getGroups()}, and {@link #getTracks()}) from the
569          * {@link DataManager} on demand.
570          *
571          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
572          */
573         private class LazyArtist extends DefaultArtist {
574
575                 /** Memoizer for the tracks by this artist. */
576                 private final Memoizer<Void> tracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
577                         @Override
578                         public Void call() throws DatabaseException {
579                                 if (!hasValue("tracks")) {
580                                         getValue("tracks", Collection.class).set(getTracksByArtist(getId()));
581                                 }
582                                 return null;
583                         }
584                 });
585
586                 /** Memoizer for the groups of this artist. */
587                 private final Memoizer<Void> groupsMemoizer = new Memoizer<Void>(new Callable<Void>() {
588
589                         @Override
590                         public Void call() throws Exception {
591                                 if (!hasValue("groups")) {
592                                         getValue("groups", Collection.class).set(getGroupsByArtist(getId()));
593                                 }
594                                 return null;
595                         }
596
597                 });
598
599                 /**
600                  * Creates a new lazy artist.
601                  *
602                  * @param id
603                  *            The ID of the artist
604                  */
605                 public LazyArtist(String id) {
606                         super(id);
607                 }
608
609                 //
610                 // DEFAULTARTIST METHODS
611                 //
612
613                 /**
614                  * {@inheritDoc}
615                  */
616                 @Override
617                 public Collection<Group> getGroups() {
618                         groupsMemoizer.get();
619                         return super.getGroups();
620                 }
621
622                 /**
623                  * {@inheritDoc}
624                  */
625                 @Override
626                 public Collection<Track> getTracks() {
627                         tracksMemoizer.get();
628                         return super.getTracks();
629                 }
630
631         }
632
633         /**
634          * {@link ObjectCreator} implementation that can create {@link Artist}
635          * objects. This specific class actually creates {@link LazyArtist}
636          * instances.
637          *
638          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
639          */
640         private class ArtistCreator implements ObjectCreator<Artist> {
641
642                 /**
643                  * {@inheritDoc}
644                  */
645                 @Override
646                 public Artist createObject(ResultSet resultSet) throws SQLException {
647                         return new LazyArtist(resultSet.getString("ARTISTS.ID")).setName(resultSet.getString("ARTISTS.NAME"));
648                 }
649
650         }
651
652         /**
653          * {@link Group} implementation that retrieves some attributes (such as
654          * {@link #getArtists()}) from the {@link DataManager} on demand.
655          *
656          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
657          */
658         private class LazyGroup extends DefaultGroup {
659
660                 /** Memoizer for the artist. */
661                 private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
662
663                         @Override
664                         public Void call() throws Exception {
665                                 if (!hasValue("artists")) {
666                                         getValue("artists", Collection.class).set(getArtistsByGroup(getId()));
667                                 }
668                                 return null;
669                         }
670
671                 });
672
673                 /**
674                  * Creates a new lazy group.
675                  *
676                  * @param id
677                  *            The ID of the group
678                  */
679                 public LazyGroup(String id) {
680                         super(id);
681                 }
682
683                 //
684                 // DEFAULTGROUP METHODS
685                 //
686
687                 /**
688                  * {@inheritDoc}
689                  */
690                 @Override
691                 public Collection<Artist> getArtists() {
692                         artistsMemoizer.get();
693                         return super.getArtists();
694                 }
695
696         }
697
698         /**
699          * {@link ObjectCreator} implementation that can create {@link Group}
700          * objects. This specific implementation creates {@link LazyGroup}
701          * instances.
702          *
703          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
704          */
705         private class GroupCreator implements ObjectCreator<Group> {
706
707                 /**
708                  * {@inheritDoc}
709                  */
710                 @Override
711                 public Group createObject(ResultSet resultSet) throws SQLException {
712                         return new LazyGroup(resultSet.getString("GROUPS.ID")).setName(resultSet.getString("GROUPS.NAME")).setUrl(resultSet.getString("GROUPS.URL"));
713                 }
714
715         }
716
717         /**
718          * {@link Track} implementation that retrieves some attributes (such as
719          * {@link #getArtists()}, and {@link #getStyles()}) from the
720          * {@link DataManager} on demand.
721          *
722          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
723          */
724         private class LazyTrack extends DefaultTrack {
725
726                 /** Memoizer for the artists. */
727                 private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
728
729                         @Override
730                         public Void call() throws Exception {
731                                 if (!hasValue("artists")) {
732                                         getValue("artists", List.class).set(getArtistsByTrack(getId()));
733                                 }
734                                 return null;
735                         }
736
737                 });
738
739                 /** Memoizer for the styles. */
740                 private final Memoizer<Void> stylesMemoizer = new Memoizer<Void>(new Callable<Void>() {
741
742                         @Override
743                         public Void call() throws Exception {
744                                 if (!hasValue("styles")) {
745                                         getValue("styles", Collection.class).set(getStylesByTrack(getId()));
746                                 }
747                                 return null;
748                         }
749
750                 });
751
752                 /** Memoizer for the remix artists. */
753                 private final Memoizer<Void> remixArtistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
754
755                         @Override
756                         public Void call() throws Exception {
757                                 if (!hasValue("remixArtists")) {
758                                         getValue("remixArtists", List.class).set(getRemixArtistsByTrack(getId()));
759                                 }
760                                 return null;
761                         }
762
763                 });
764
765                 /** Memoizer for the track derivatives. */
766                 private final Memoizer<Void> derivativesMemoizer = new Memoizer<Void>(new Callable<Void>() {
767
768                         @Override
769                         public Void call() throws Exception {
770                                 if (!hasValue("derivatives")) {
771                                         getValue("derivatives", Collection.class).set(getTrackDerivativesByTrack(LazyTrack.this));
772                                 }
773                                 return null;
774                         }
775
776                 });
777
778                 /** Memoizer for the related tracks. */
779                 private final Memoizer<Void> relatedTracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
780
781                         @Override
782                         public Void call() throws Exception {
783                                 if (!hasValue("relatedTracks")) {
784                                         getValue("relatedTracks", Map.class).set(getRelatedTracksByTrack(getId()));
785                                 }
786                                 return null;
787                         }
788                 });
789
790                 /**
791                  * Creates a new track.
792                  *
793                  * @param id
794                  *            The ID of the track
795                  */
796                 public LazyTrack(String id) {
797                         super(id);
798                 }
799
800                 //
801                 // DEFAULTTRACK METHODS
802                 //
803
804                 /**
805                  * {@inheritDoc}
806                  */
807                 @Override
808                 public List<Artist> getArtists() {
809                         artistsMemoizer.get();
810                         return super.getArtists();
811                 }
812
813                 /**
814                  * {@inheritDoc}
815                  */
816                 @Override
817                 public Collection<Style> getStyles() {
818                         stylesMemoizer.get();
819                         return super.getStyles();
820                 }
821
822                 /**
823                  * {@inheritDoc}
824                  */
825                 @Override
826                 public List<Artist> getRemixArtists() {
827                         remixArtistsMemoizer.get();
828                         return super.getRemixArtists();
829                 }
830
831                 /**
832                  * {@inheritDoc}
833                  */
834                 @Override
835                 public Collection<TrackDerivative> getDerivatives() {
836                         derivativesMemoizer.get();
837                         return super.getDerivatives();
838                 }
839
840                 /**
841                  * {@inheritDoc}
842                  */
843                 @Override
844                 public Map<Relationship, Collection<Track>> getRelatedTracks() {
845                         relatedTracksMemoizer.get();
846                         return super.getRelatedTracks();
847                 }
848
849         }
850
851         /**
852          * {@link ObjectCreator} implementation that can create {@link Track}
853          * objects. This specific implementation creates {@link LazyTrack}
854          * instances.
855          *
856          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
857          */
858         private class TrackCreator implements ObjectCreator<Track> {
859
860                 /**
861                  * {@inheritDoc}
862                  */
863                 @Override
864                 public Track createObject(ResultSet resultSet) throws SQLException {
865                         return new LazyTrack(resultSet.getString("TRACKS.ID")).setName(resultSet.getString("TRACKS.NAME")).setRemix(resultSet.getString("TRACKS.REMIX"));
866                 }
867
868         }
869
870         /**
871          * {@link ObjectCreator} implementation that can create
872          * {@link TrackDerivative} objects.
873          *
874          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
875          */
876         private class TrackDerivativeCreator implements ObjectCreator<TrackDerivative> {
877
878                 /**
879                  * {@inheritDoc}
880                  */
881                 @Override
882                 public TrackDerivative createObject(ResultSet resultSet) throws SQLException {
883                         return new DefaultTrackDerivative(resultSet.getString("TRACK_DERIVATIVES.ID"));
884                 }
885
886         }
887
888         /**
889          * {@link ObjectCreator} implementation that can create {@link Style}
890          * objects.
891          *
892          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
893          */
894         private class StyleCreator implements ObjectCreator<Style> {
895
896                 /**
897                  * {@inheritDoc}
898                  */
899                 @Override
900                 public Style createObject(ResultSet resultSet) throws SQLException {
901                         return new DefaultStyle(resultSet.getString("STYLES.ID")).setName(resultSet.getString("STYLES.NAME"));
902                 }
903
904         }
905
906         /**
907          * {@link User} implementation that retrieves some attributes (such as
908          * {@link #getOpenIds()}) from the {@link DataManager} on demand.
909          *
910          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
911          */
912         private class LazyUser extends DefaultUser {
913
914                 /** Memoizer for a user’s OpenIDs. */
915                 private final Memoizer<Void> openIdMemoizer = new Memoizer<Void>(new Callable<Void>() {
916
917                         @Override
918                         public Void call() throws Exception {
919                                 if (!hasValue("openIds")) {
920                                         getValue("openIds", Collection.class).set(getOpenIdsByUser(getId()));
921                                 }
922                                 return null;
923                         }
924                 });
925
926                 /**
927                  * Creates a new user.
928                  *
929                  * @param id
930                  *            The ID of the user
931                  */
932                 public LazyUser(String id) {
933                         super(id);
934                 }
935
936                 /**
937                  * {@inheritDoc}
938                  */
939                 @Override
940                 public Collection<String> getOpenIds() {
941                         openIdMemoizer.get();
942                         return super.getOpenIds();
943                 }
944
945         }
946
947         /**
948          * {@link ObjectCreator} implementation that can create {@link User}
949          * objects. This specific implementation creates {@link LazyUser} instances.
950          *
951          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
952          */
953         private class UserCreator implements ObjectCreator<User> {
954
955                 /**
956                  * {@inheritDoc}
957                  */
958                 @Override
959                 public User createObject(ResultSet resultSet) throws SQLException {
960                         return new LazyUser(resultSet.getString("USERS.ID")).setName(resultSet.getString("USERS.NAME")).setPasswordHash(resultSet.getString("USERS.PASSWORD")).setLevel(resultSet.getInt("USERS.LEVEL"));
961                 }
962
963         }
964
965 }