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          * Returns the derivatives for the given track.
 349          *
 350          * @param track
 351          *            The track to get the derivatives for
 352          * @return The derivatives for the given track
 353          * @throws DatabaseException
 354          *             if a database error occurs
 355          */
 356         public Collection<TrackDerivative> getTrackDerivativesByTrack(Track track) throws DatabaseException {
 357                 Query query = new Query(Type.SELECT, "TRACK_DERIVATIVES");
 358                 query.addField(new Field("TRACK_DERIVATIVES.*"));
 359                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_DERIVATIVES.TRACK", new StringParameter(track.getId()))));
 360                 return loadTrackDerivativeProperties(database.getMultiple(query, trackDerivativeCreator));
 361         }
 362
 363         /**
 364          * Loads the properties for the given track derivative.
 365          *
 366          * @param trackDerivative
 367          *            The track derivative to load the properties for
 368          * @return The track derivative with its properties loaded
 369          * @throws DatabaseException
 370          *             if a database error occurs
 371          */
 372         public TrackDerivative loadTrackDerivativeProperties(TrackDerivative trackDerivative) throws DatabaseException {
 373                 return loadProperties(trackDerivative, "TRACK_DERIVATIVE_PROPERTIES", "TRACK_DERIVATIVE");
 374         }
 375
 376         /**
 377          * Loads the properties for the given track derivatives.
 378          *
 379          * @param trackDerivatives
 380          *            The track derivatives to load the properties for
 381          * @return The track derivatives with their properties loaded
 382          * @throws DatabaseException
 383          *             if a database error occurs
 384          */
 385         public List<TrackDerivative> loadTrackDerivativeProperties(List<TrackDerivative> trackDerivatives) throws DatabaseException {
 386                 for (TrackDerivative trackDerivative : trackDerivatives) {
 387                         loadTrackDerivativeProperties(trackDerivative);
 388                 }
 389                 return trackDerivatives;
 390         }
 391
 392         /**
 393          * Returns all groups the artist with the given ID belongs to.
 394          *
 395          * @param artistId
 396          *            The ID of the artist
 397          * @return All groups the artist belongs to
 398          * @throws DatabaseException
 399          *             if a database error occurs
 400          */
 401         public Collection<Group> getGroupsByArtist(String artistId) throws DatabaseException {
 402                 Query query = new Query(Type.SELECT, "GROUPS");
 403                 query.addField(new Field("GROUPS.*"));
 404                 query.addJoin(new Join(JoinType.INNER, "GROUP_ARTISTS", new Field("GROUPS.ID"), new Field("GROUP_ARTISTS.GROUP_")));
 405                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUP_ARTISTS.ARTIST", new StringParameter(artistId))));
 406                 return database.getMultiple(query, groupCreator);
 407         }
 408
 409         /**
 410          * Returns all styles for the track with the given ID.
 411          *
 412          * @param trackId
 413          *            The ID of the track
 414          * @return All styles for the given track
 415          * @throws DatabaseException
 416          *             if a database error occurs
 417          */
 418         public Collection<Style> getStylesByTrack(String trackId) throws DatabaseException {
 419                 Query query = new Query(Type.SELECT, "STYLES");
 420                 query.addField(new Field("STYLES.*"));
 421                 query.addJoin(new Join(JoinType.INNER, "TRACK_STYLES", new Field("STYLES.ID"), new Field("TRACK_STYLES.STYLE")));
 422                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_STYLES.TRACK", new StringParameter(trackId))));
 423                 return database.getMultiple(query, styleCreator);
 424         }
 425
 426         /**
 427          * Returns the user with the given name.
 428          *
 429          * @param username
 430          *            The name of the user
 431          * @return The user, or {@code null} if the user does not exist
 432          * @throws DatabaseException
 433          *             if a database error occurs
 434          */
 435         public User getUserByName(String username) throws DatabaseException {
 436                 Query query = new Query(Type.SELECT, "USERS");
 437                 query.addField(new Field("USERS.*"));
 438                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USERS.NAME", new StringParameter(username))));
 439                 return database.getSingle(query, userCreator);
 440         }
 441
 442         /**
 443          * Returns the user connected with the given OpenID.
 444          *
 445          * @param openId
 446          *            The OpenID to find the user for
 447          * @return The user connected with the given OpenID, or {@code null} if
 448          *         there is no such user
 449          * @throws DatabaseException
 450          *             if a database error occurs
 451          */
 452         public User getUserByOpenId(String openId) throws DatabaseException {
 453                 Query query = new Query(Type.SELECT, "USERS");
 454                 query.addField(new Field("USERS.*"));
 455                 query.addJoin(new Join(JoinType.INNER, "USER_OPENIDS", new Field("USER_OPENIDS.USER"), new Field("USERS.ID")));
 456                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USER_OPENIDS.OPENID", new StringParameter(openId))));
 457                 return database.getSingle(query, userCreator);
 458         }
 459
 460         /**
 461          * Returns all OpenIDs connected with the user with the given ID.
 462          *
 463          * @param userId
 464          *            The ID of the user
 465          * @return All OpenIDs connected with the given user
 466          * @throws DatabaseException
 467          *             if a database error occurs
 468          */
 469         public Collection<String> getOpenIdsByUser(String userId) throws DatabaseException {
 470                 Query query = new Query(Type.SELECT, "USER_OPENIDS");
 471                 query.addField(new Field("USER_OPENIDS.*"));
 472                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USER_OPENIDS.USER", new StringParameter(userId))));
 473                 return database.getMultiple(query, new StringCreator("USER_OPENIDS.OPENID"));
 474         }
 475
 476         //
 477         // PRIVATE METHODS
 478         //
 479
 480         /**
 481          * Loads the properties for the given object.
 482          *
 483          * @param <T>
 484          *            The type of the object
 485          * @param object
 486          *            The object
 487          * @param table
 488          *            The table to load the properties from
 489          * @param type
 490          *            The type of the object (“ARTIST,” “TRACK,” etc.)
 491          * @return The object with its properties loaded
 492          * @throws DatabaseException
 493          *             if a database error occurs
 494          */
 495         private <T extends Base> T loadProperties(final T object, final String table, String type) throws DatabaseException {
 496                 Query query = new Query(Type.SELECT, table);
 497                 query.addField(new Field(table + ".PROPERTY"));
 498                 query.addField(new Field(table + ".VALUE"));
 499                 query.addWhereClause(new ValueFieldWhereClause(new ValueField(type, new StringParameter(object.getId()))));
 500                 database.process(query, new ResultProcessor() {
 501
 502                         @Override
 503                         public void processResult(ResultSet resultSet) throws SQLException {
 504                                 if (resultSet.isFirst()) {
 505                                         object.getProperties().removeAll();
 506                                 }
 507                                 object.getProperties().set(resultSet.getString(table + ".PROPERTY"), resultSet.getString(table + ".VALUE"));
 508                         }
 509
 510                 });
 511                 return object;
 512         }
 513
 514         /**
 515          * {@link Artist} implementation that retrieves some attributes (such as
 516          * {@link #getGroups()}, and {@link #getTracks()}) from the
 517          * {@link DataManager} on demand.
 518          *
 519          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 520          */
 521         private class LazyArtist extends DefaultArtist {
 522
 523                 /** Memoizer for the tracks by this artist. */
 524                 private final Memoizer<Void> tracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
 525                         @Override
 526                         public Void call() throws DatabaseException {
 527                                 if (!hasValue("tracks")) {
 528                                         getValue("tracks", Collection.class).set(getTracksByArtist(getId()));
 529                                 }
 530                                 return null;
 531                         }
 532                 });
 533
 534                 /** Memoizer for the groups of this artist. */
 535                 private final Memoizer<Void> groupsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 536
 537                         @Override
 538                         public Void call() throws Exception {
 539                                 if (!hasValue("groups")) {
 540                                         getValue("groups", Collection.class).set(getGroupsByArtist(getId()));
 541                                 }
 542                                 return null;
 543                         }
 544
 545                 });
 546
 547                 /**
 548                  * Creates a new lazy artist.
 549                  *
 550                  * @param id
 551                  *            The ID of the artist
 552                  */
 553                 public LazyArtist(String id) {
 554                         super(id);
 555                 }
 556
 557                 //
 558                 // DEFAULTARTIST METHODS
 559                 //
 560
 561                 /**
 562                  * {@inheritDoc}
 563                  */
 564                 @Override
 565                 public Collection<Group> getGroups() {
 566                         groupsMemoizer.get();
 567                         return super.getGroups();
 568                 }
 569
 570                 /**
 571                  * {@inheritDoc}
 572                  */
 573                 @Override
 574                 public Collection<Track> getTracks() {
 575                         tracksMemoizer.get();
 576                         return super.getTracks();
 577                 }
 578
 579         }
 580
 581         /**
 582          * {@link ObjectCreator} implementation that can create {@link Artist}
 583          * objects. This specific class actually creates {@link LazyArtist}
 584          * instances.
 585          *
 586          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 587          */
 588         private class ArtistCreator implements ObjectCreator<Artist> {
 589
 590                 /**
 591                  * {@inheritDoc}
 592                  */
 593                 @Override
 594                 public Artist createObject(ResultSet resultSet) throws SQLException {
 595                         return new LazyArtist(resultSet.getString("ARTISTS.ID")).setName(resultSet.getString("ARTISTS.NAME"));
 596                 }
 597
 598         }
 599
 600         /**
 601          * {@link Group} implementation that retrieves some attributes (such as
 602          * {@link #getArtists()}) from the {@link DataManager} on demand.
 603          *
 604          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 605          */
 606         private class LazyGroup extends DefaultGroup {
 607
 608                 /** Memoizer for the artist. */
 609                 private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 610
 611                         @Override
 612                         public Void call() throws Exception {
 613                                 if (!hasValue("artists")) {
 614                                         getValue("artists", Collection.class).set(getArtistsByGroup(getId()));
 615                                 }
 616                                 return null;
 617                         }
 618
 619                 });
 620
 621                 /**
 622                  * Creates a new lazy group.
 623                  *
 624                  * @param id
 625                  *            The ID of the group
 626                  */
 627                 public LazyGroup(String id) {
 628                         super(id);
 629                 }
 630
 631                 //
 632                 // DEFAULTGROUP METHODS
 633                 //
 634
 635                 /**
 636                  * {@inheritDoc}
 637                  */
 638                 @Override
 639                 public Collection<Artist> getArtists() {
 640                         artistsMemoizer.get();
 641                         return super.getArtists();
 642                 }
 643
 644         }
 645
 646         /**
 647          * {@link ObjectCreator} implementation that can create {@link Group}
 648          * objects. This specific implementation creates {@link LazyGroup}
 649          * instances.
 650          *
 651          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 652          */
 653         private class GroupCreator implements ObjectCreator<Group> {
 654
 655                 /**
 656                  * {@inheritDoc}
 657                  */
 658                 @Override
 659                 public Group createObject(ResultSet resultSet) throws SQLException {
 660                         return new LazyGroup(resultSet.getString("GROUPS.ID")).setName(resultSet.getString("GROUPS.NAME")).setUrl(resultSet.getString("GROUPS.URL"));
 661                 }
 662
 663         }
 664
 665         /**
 666          * {@link Track} implementation that retrieves some attributes (such as
 667          * {@link #getArtists()}, and {@link #getStyles()}) from the
 668          * {@link DataManager} on demand.
 669          *
 670          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 671          */
 672         private class LazyTrack extends DefaultTrack {
 673
 674                 /** Memoizer for the artists. */
 675                 private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 676
 677                         @Override
 678                         public Void call() throws Exception {
 679                                 if (!hasValue("artists")) {
 680                                         getValue("artists", List.class).set(getArtistsByTrack(getId()));
 681                                 }
 682                                 return null;
 683                         }
 684
 685                 });
 686
 687                 /** Memoizer for the styles. */
 688                 private final Memoizer<Void> stylesMemoizer = new Memoizer<Void>(new Callable<Void>() {
 689
 690                         @Override
 691                         public Void call() throws Exception {
 692                                 if (!hasValue("styles")) {
 693                                         getValue("styles", Collection.class).set(getStylesByTrack(getId()));
 694                                 }
 695                                 return null;
 696                         }
 697
 698                 });
 699
 700                 /** Memoizer for the remix artists. */
 701                 private final Memoizer<Void> remixArtistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 702
 703                         @Override
 704                         public Void call() throws Exception {
 705                                 if (!hasValue("remixArtists")) {
 706                                         getValue("remixArtists", List.class).set(getRemixArtistsByTrack(getId()));
 707                                 }
 708                                 return null;
 709                         }
 710
 711                 });
 712
 713                 /** Memoizer for the track derivatives. */
 714                 private final Memoizer<Void> derivativesMemoizer = new Memoizer<Void>(new Callable<Void>() {
 715
 716                         @Override
 717                         public Void call() throws Exception {
 718                                 if (!hasValue("derivatives")) {
 719                                         getValue("derivatives", Collection.class).set(getTrackDerivativesByTrack(LazyTrack.this));
 720                                 }
 721                                 return null;
 722                         }
 723
 724                 });
 725
 726                 /** Memoizer for the related tracks. */
 727                 private final Memoizer<Void> relatedTracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
 728
 729                         @Override
 730                         public Void call() throws Exception {
 731                                 if (!hasValue("relatedTracks")) {
 732                                         getValue("relatedTracks", Map.class).set(getRelatedTracksByTrack(getId()));
 733                                 }
 734                                 return null;
 735                         }
 736                 });
 737
 738                 /**
 739                  * Creates a new track.
 740                  *
 741                  * @param id
 742                  *            The ID of the track
 743                  */
 744                 public LazyTrack(String id) {
 745                         super(id);
 746                 }
 747
 748                 //
 749                 // DEFAULTTRACK METHODS
 750                 //
 751
 752                 /**
 753                  * {@inheritDoc}
 754                  */
 755                 @Override
 756                 public List<Artist> getArtists() {
 757                         artistsMemoizer.get();
 758                         return super.getArtists();
 759                 }
 760
 761                 /**
 762                  * {@inheritDoc}
 763                  */
 764                 @Override
 765                 public Collection<Style> getStyles() {
 766                         stylesMemoizer.get();
 767                         return super.getStyles();
 768                 }
 769
 770                 /**
 771                  * {@inheritDoc}
 772                  */
 773                 @Override
 774                 public List<Artist> getRemixArtists() {
 775                         remixArtistsMemoizer.get();
 776                         return super.getRemixArtists();
 777                 }
 778
 779                 /**
 780                  * {@inheritDoc}
 781                  */
 782                 @Override
 783                 public Collection<TrackDerivative> getDerivatives() {
 784                         derivativesMemoizer.get();
 785                         return super.getDerivatives();
 786                 }
 787
 788                 /**
 789                  * {@inheritDoc}
 790                  */
 791                 @Override
 792                 public Map<Relationship, Collection<Track>> getRelatedTracks() {
 793                         relatedTracksMemoizer.get();
 794                         return super.getRelatedTracks();
 795                 }
 796
 797         }
 798
 799         /**
 800          * {@link ObjectCreator} implementation that can create {@link Track}
 801          * objects. This specific implementation creates {@link LazyTrack}
 802          * instances.
 803          *
 804          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 805          */
 806         private class TrackCreator implements ObjectCreator<Track> {
 807
 808                 /**
 809                  * {@inheritDoc}
 810                  */
 811                 @Override
 812                 public Track createObject(ResultSet resultSet) throws SQLException {
 813                         return new LazyTrack(resultSet.getString("TRACKS.ID")).setName(resultSet.getString("TRACKS.NAME")).setRemix(resultSet.getString("TRACKS.REMIX"));
 814                 }
 815
 816         }
 817
 818         /**
 819          * {@link ObjectCreator} implementation that can create
 820          * {@link TrackDerivative} objects.
 821          *
 822          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 823          */
 824         private class TrackDerivativeCreator implements ObjectCreator<TrackDerivative> {
 825
 826                 /**
 827                  * {@inheritDoc}
 828                  */
 829                 @Override
 830                 public TrackDerivative createObject(ResultSet resultSet) throws SQLException {
 831                         return new DefaultTrackDerivative(resultSet.getString("TRACK_DERIVATIVES.ID"));
 832                 }
 833
 834         }
 835
 836         /**
 837          * {@link ObjectCreator} implementation that can create {@link Style}
 838          * objects.
 839          *
 840          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 841          */
 842         private class StyleCreator implements ObjectCreator<Style> {
 843
 844                 /**
 845                  * {@inheritDoc}
 846                  */
 847                 @Override
 848                 public Style createObject(ResultSet resultSet) throws SQLException {
 849                         return new DefaultStyle(resultSet.getString("STYLES.ID")).setName(resultSet.getString("STYLES.NAME"));
 850                 }
 851
 852         }
 853
 854         /**
 855          * {@link User} implementation that retrieves some attributes (such as
 856          * {@link #getOpenIds()}) from the {@link DataManager} on demand.
 857          *
 858          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 859          */
 860         private class LazyUser extends DefaultUser {
 861
 862                 /** Memoizer for a user’s OpenIDs. */
 863                 private final Memoizer<Void> openIdMemoizer = new Memoizer<Void>(new Callable<Void>() {
 864
 865                         @Override
 866                         public Void call() throws Exception {
 867                                 if (!hasValue("openIds")) {
 868                                         getValue("openIds", Collection.class).set(getOpenIdsByUser(getId()));
 869                                 }
 870                                 return null;
 871                         }
 872                 });
 873
 874                 /**
 875                  * Creates a new user.
 876                  *
 877                  * @param id
 878                  *            The ID of the user
 879                  */
 880                 public LazyUser(String id) {
 881                         super(id);
 882                 }
 883
 884                 /**
 885                  * {@inheritDoc}
 886                  */
 887                 @Override
 888                 public Collection<String> getOpenIds() {
 889                         openIdMemoizer.get();
 890                         return super.getOpenIds();
 891                 }
 892
 893         }
 894
 895         /**
 896          * {@link ObjectCreator} implementation that can create {@link User}
 897          * objects. This specific implementation creates {@link LazyUser} instances.
 898          *
 899          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 900          */
 901         private class UserCreator implements ObjectCreator<User> {
 902
 903                 /**
 904                  * {@inheritDoc}
 905                  */
 906                 @Override
 907                 public User createObject(ResultSet resultSet) throws SQLException {
 908                         return new LazyUser(resultSet.getString("USERS.ID")).setName(resultSet.getString("USERS.NAME")).setPasswordHash(resultSet.getString("USERS.PASSWORD")).setLevel(resultSet.getInt("USERS.LEVEL"));
 909                 }
 910
 911         }
 912
 913 }