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