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.UUID;
  28 import java.util.concurrent.Callable;
  29
  30 import net.pterodactylus.demoscenemusic.data.Track.Relationship;
  31 import net.pterodactylus.util.collection.Memoizer;
  32 import net.pterodactylus.util.database.Database;
  33 import net.pterodactylus.util.database.DatabaseException;
  34 import net.pterodactylus.util.database.Field;
  35 import net.pterodactylus.util.database.Join;
  36 import net.pterodactylus.util.database.Join.JoinType;
  37 import net.pterodactylus.util.database.ObjectCreator;
  38 import net.pterodactylus.util.database.ObjectCreator.StringCreator;
  39 import net.pterodactylus.util.database.OrderField;
  40 import net.pterodactylus.util.database.Parameter.StringParameter;
  41 import net.pterodactylus.util.database.Query;
  42 import net.pterodactylus.util.database.Query.Type;
  43 import net.pterodactylus.util.database.ResultProcessor;
  44 import net.pterodactylus.util.database.ValueField;
  45 import net.pterodactylus.util.database.ValueFieldWhereClause;
  46
  47 /**
  48  * Interface between the database and the application.
  49  *
  50  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  51  */
  52 public class DataManager {
  53
  54         /** The artist object creator. */
  55         @SuppressWarnings("synthetic-access")
  56         private final ObjectCreator<Artist> artistCreator = new ArtistCreator();
  57
  58         /** The group object creator. */
  59         @SuppressWarnings("synthetic-access")
  60         private final ObjectCreator<Group> groupCreator = new GroupCreator();
  61
  62         /** The track object creator. */
  63         @SuppressWarnings("synthetic-access")
  64         private final ObjectCreator<Track> trackCreator = new TrackCreator();
  65
  66         /** The style object creator. */
  67         @SuppressWarnings("synthetic-access")
  68         private final ObjectCreator<Style> styleCreator = new StyleCreator();
  69
  70         /** The {@link User} object creator. */
  71         @SuppressWarnings("synthetic-access")
  72         private final ObjectCreator<User> userCreator = new UserCreator();
  73
  74         /** The database. */
  75         private final Database database;
  76
  77         /**
  78          * Creates a new data manager.
  79          *
  80          * @param database
  81          *            The database to operate on
  82          */
  83         public DataManager(Database database) {
  84                 this.database = database;
  85         }
  86
  87         /**
  88          * Returns all artists.
  89          *
  90          * @return All artists
  91          * @throws DatabaseException
  92          *             if a database error occurs
  93          */
  94         public Collection<Artist> getAllArtists() throws DatabaseException {
  95                 Query query = new Query(Type.SELECT, "ARTISTS");
  96                 query.addField(new Field("ARTISTS.*"));
  97                 return loadProperties(database.getMultiple(query, artistCreator));
  98         }
  99
 100         /**
 101          * Returns the artist with the given ID.
 102          *
 103          * @param id
 104          *            The ID of the artist
 105          * @return The artist with the given ID, or {@code null} if there is no
 106          *         artist with the given ID
 107          * @throws DatabaseException
 108          *             if a database error occurs
 109          */
 110         public Artist getArtistById(String id) throws DatabaseException {
 111                 Query query = new Query(Type.SELECT, "ARTISTS");
 112                 query.addField(new Field("ARTISTS.*"));
 113                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("ARTISTS.ID", new StringParameter(id))));
 114                 return loadProperties(database.getSingle(query, artistCreator));
 115         }
 116
 117         /**
 118          * Returns all artists that belong to the group with the given ID.
 119          *
 120          * @param groupId
 121          *            The ID of the group
 122          * @return All artists belonging to the given group
 123          * @throws DatabaseException
 124          *             if a database error occurs
 125          */
 126         public Collection<Artist> getArtistsByGroup(String groupId) throws DatabaseException {
 127                 Query query = new Query(Type.SELECT, "ARTISTS");
 128                 query.addField(new Field("ARTISTS.*"));
 129                 query.addJoin(new Join(JoinType.INNER, "GROUP_ARTISTS", new Field("ARTISTS.ID"), new Field("GROUP_ARTISTS.ARTIST")));
 130                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUP_ARTISTS.GROUP_", new StringParameter(groupId))));
 131                 return loadProperties(database.getMultiple(query, artistCreator));
 132         }
 133
 134         /**
 135          * Returns all artists involved in the track with the given ID.
 136          *
 137          * @param trackId
 138          *            The ID of the track
 139          * @return All artists involved in the track, in preferred order
 140          * @throws DatabaseException
 141          *             if a database error occurs
 142          */
 143         public List<Artist> getArtistsByTrack(String trackId) throws DatabaseException {
 144                 Query query = new Query(Type.SELECT, "ARTISTS");
 145                 query.addField(new Field("ARTISTS.*"));
 146                 query.addJoin(new Join(JoinType.INNER, "TRACK_ARTISTS", new Field("TRACK_ARTISTS.ARTIST"), new Field("ARTISTS.ID")));
 147                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_ARTISTS.TRACK", new StringParameter(trackId))));
 148                 query.addOrderField(new OrderField(new Field("TRACK_ARTISTS.DISPLAY_ORDER")));
 149                 return loadProperties(database.getMultiple(query, artistCreator));
 150         }
 151
 152         /**
 153          * Creates a new artist with the given name.
 154          *
 155          * @param name
 156          *            The name of the artist
 157          * @return The created artist
 158          * @throws DatabaseException
 159          *             if a database error occurs
 160          */
 161         public Artist createArtist(String name) throws DatabaseException {
 162                 Query query = new Query(Type.INSERT, "ARTISTS");
 163                 String id = UUID.randomUUID().toString();
 164                 query.addValueField(new ValueField("ID", new StringParameter(id)));
 165                 query.addValueField(new ValueField("NAME", new StringParameter(name)));
 166                 database.insert(query);
 167                 return loadProperties(getArtistById(id));
 168         }
 169
 170         /**
 171          * Saves the given artist.
 172          *
 173          * @param artist
 174          *            The artist to save
 175          * @throws DatabaseException
 176          *             if a database error occurs
 177          */
 178         public void saveArtist(Artist artist) throws DatabaseException {
 179                 Query query = new Query(Type.UPDATE, "ARTISTS");
 180                 query.addValueField(new ValueField("NAME", new StringParameter(artist.getName())));
 181                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("ID", new StringParameter(artist.getId()))));
 182                 database.update(query);
 183         }
 184
 185         /**
 186          * Loads the properties for an artist.
 187          *
 188          * @param artist
 189          *            The artist to load the properties for
 190          * @return The artist
 191          * @throws DatabaseException
 192          *             if a database error occurs
 193          */
 194         public Artist loadProperties(final Artist artist) throws DatabaseException {
 195                 Query query = new Query(Type.SELECT, "ARTIST_PROPERTIES");
 196                 query.addField(new Field("ARTIST_PROPERTIES.PROPERTY"));
 197                 query.addField(new Field("ARTIST_PROPERTIES.VALUE"));
 198                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("ARTIST", new StringParameter(artist.getId()))));
 199                 database.process(query, new ResultProcessor() {
 200
 201                         @Override
 202                         public void processResult(ResultSet resultSet) throws SQLException {
 203                                 if (resultSet.isFirst()) {
 204                                         artist.getProperties().removeAll();
 205                                 }
 206                                 artist.getProperties().set(resultSet.getString("ARTIST_PROPERTIES.PROPERTY"), resultSet.getString("ARTIST_PROPERTIES.VALUE"));
 207                         }
 208
 209                 });
 210                 return artist;
 211         }
 212
 213         /**
 214          * Loads the properties of all given artists.
 215          *
 216          * @param artists
 217          *            The artists to load the properties for
 218          * @return The list of artists
 219          * @throws DatabaseException
 220          *             if a database error occurs
 221          */
 222         public List<Artist> loadProperties(List<Artist> artists) throws DatabaseException {
 223                 for (Artist artist : artists) {
 224                         loadProperties(artist);
 225                 }
 226                 return artists;
 227         }
 228
 229         /**
 230          * Returns all remix artists involved in the track with the given ID.
 231          *
 232          * @param trackId
 233          *            The ID of the track
 234          * @return All remix artists involved in the track, in preferred order
 235          * @throws DatabaseException
 236          *             if a database error occurs
 237          */
 238         public List<Artist> getRemixArtistsByTrack(String trackId) throws DatabaseException {
 239                 Query query = new Query(Type.SELECT, "ARTISTS");
 240                 query.addField(new Field("ARTISTS.*"));
 241                 query.addJoin(new Join(JoinType.INNER, "TRACK_REMIX_ARTISTS", new Field("TRACK_REMIX_ARTISTS.ARTIST"), new Field("ARTISTS.ID")));
 242                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_REMIX_ARTISTS.TRACK", new StringParameter(trackId))));
 243                 query.addOrderField(new OrderField(new Field("TRACK_REMIX_ARTISTS.DISPLAY_ORDER")));
 244                 return database.getMultiple(query, artistCreator);
 245         }
 246
 247         /**
 248          * Returns all related tracks for the track with the given ID.
 249          *
 250          * @param trackId
 251          *            The ID of the tracks
 252          * @return A mapping from relationship to all tracks that match the relation
 253          * @throws DatabaseException
 254          *             if a database error occurs
 255          */
 256         public Map<Relationship, Collection<Track>> getRelatedTracksByTrack(String trackId) throws DatabaseException {
 257                 Query query = new Query(Type.SELECT, "TRACKS");
 258                 query.addField(new Field("TRACKS.*"));
 259                 query.addField(new Field("TRACK_RELATIONS.*"));
 260                 query.addJoin(new Join(JoinType.INNER, "TRACK_RELATIONS", new Field("TRACK_RELATIONS.TRACK"), new Field("TRACK_RELATIONS.RELATED_TRACK")));
 261                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_RELATIONS.TRACK", new StringParameter(trackId))));
 262                 final Map<Relationship, Collection<Track>> relatedTracks = new EnumMap<Relationship, Collection<Track>>(Relationship.class);
 263                 database.process(query, new ResultProcessor() {
 264
 265                         @Override
 266                         @SuppressWarnings("synthetic-access")
 267                         public void processResult(ResultSet resultSet) throws SQLException {
 268                                 Track track = trackCreator.createObject(resultSet);
 269                                 Relationship relationship = Relationship.valueOf(resultSet.getString("TRACK_RELATIONS.RELATIONSHIP"));
 270                                 if (!relatedTracks.containsKey(relationship)) {
 271                                         relatedTracks.put(relationship, new HashSet<Track>());
 272                                 }
 273                                 relatedTracks.get(relationship).add(track);
 274                         }
 275                 });
 276                 return relatedTracks;
 277         }
 278
 279         /**
 280          * Returns the track with the given ID.
 281          *
 282          * @param id
 283          *            The ID of the track
 284          * @return The track with the given ID, or {@code null} if there is no such
 285          *         track
 286          * @throws DatabaseException
 287          *             if a database error occurs
 288          */
 289         public Track getTrackById(String id) throws DatabaseException {
 290                 Query query = new Query(Type.SELECT, "TRACKS");
 291                 query.addField(new Field("TRACKS.*"));
 292                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACKS.ID", new StringParameter(id))));
 293                 return database.getSingle(query, trackCreator);
 294         }
 295
 296         /**
 297          * Returns all tracks by the artist with the given ID.
 298          *
 299          * @param artistId
 300          *            The ID of the artist
 301          * @return All tracks by the given artist
 302          * @throws DatabaseException
 303          *             if a database error occurs
 304          */
 305         public Collection<Track> getTracksByArtist(String artistId) throws DatabaseException {
 306                 Query query = new Query(Type.SELECT, "TRACKS");
 307                 query.addField(new Field("TRACKS.*"));
 308                 query.addJoin(new Join(JoinType.INNER, "TRACK_ARTISTS", new Field("TRACKS.ID"), new Field("TRACK_ARTISTS.TRACK")));
 309                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_ARTISTS.ARTIST", new StringParameter(artistId))));
 310                 return database.getMultiple(query, trackCreator);
 311         }
 312
 313         /**
 314          * Returns all groups the artist with the given ID belongs to.
 315          *
 316          * @param artistId
 317          *            The ID of the artist
 318          * @return All groups the artist belongs to
 319          * @throws DatabaseException
 320          *             if a database error occurs
 321          */
 322         public Collection<Group> getGroupsByArtist(String artistId) throws DatabaseException {
 323                 Query query = new Query(Type.SELECT, "GROUPS");
 324                 query.addField(new Field("GROUPS.*"));
 325                 query.addJoin(new Join(JoinType.INNER, "GROUP_ARTISTS", new Field("GROUPS.ID"), new Field("GROUP_ARTISTS.GROUP_")));
 326                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUP_ARTISTS.ARTIST", new StringParameter(artistId))));
 327                 return database.getMultiple(query, groupCreator);
 328         }
 329
 330         /**
 331          * Returns all styles for the track with the given ID.
 332          *
 333          * @param trackId
 334          *            The ID of the track
 335          * @return All styles for the given track
 336          * @throws DatabaseException
 337          *             if a database error occurs
 338          */
 339         public Collection<Style> getStylesByTrack(String trackId) throws DatabaseException {
 340                 Query query = new Query(Type.SELECT, "STYLES");
 341                 query.addField(new Field("STYLES.*"));
 342                 query.addJoin(new Join(JoinType.INNER, "TRACK_STYLES", new Field("STYLES.ID"), new Field("TRACK_STYLES.STYLE")));
 343                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_STYLES.TRACK", new StringParameter(trackId))));
 344                 return database.getMultiple(query, styleCreator);
 345         }
 346
 347         /**
 348          * Returns the user with the given name.
 349          *
 350          * @param username
 351          *            The name of the user
 352          * @return The user, or {@code null} if the user does not exist
 353          * @throws DatabaseException
 354          *             if a database error occurs
 355          */
 356         public User getUserByName(String username) throws DatabaseException {
 357                 Query query = new Query(Type.SELECT, "USERS");
 358                 query.addField(new Field("USERS.*"));
 359                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USERS.NAME", new StringParameter(username))));
 360                 return database.getSingle(query, userCreator);
 361         }
 362
 363         /**
 364          * Returns the user connected with the given OpenID.
 365          *
 366          * @param openId
 367          *            The OpenID to find the user for
 368          * @return The user connected with the given OpenID, or {@code null} if
 369          *         there is no such user
 370          * @throws DatabaseException
 371          *             if a database error occurs
 372          */
 373         public User getUserByOpenId(String openId) throws DatabaseException {
 374                 Query query = new Query(Type.SELECT, "USERS");
 375                 query.addField(new Field("USERS.*"));
 376                 query.addJoin(new Join(JoinType.INNER, "USER_OPENIDS", new Field("USER_OPENIDS.USER"), new Field("USERS.ID")));
 377                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USER_OPENIDS.OPENID", new StringParameter(openId))));
 378                 return database.getSingle(query, userCreator);
 379         }
 380
 381         /**
 382          * Returns all OpenIDs connected with the user with the given ID.
 383          *
 384          * @param userId
 385          *            The ID of the user
 386          * @return All OpenIDs connected with the given user
 387          * @throws DatabaseException
 388          *             if a database error occurs
 389          */
 390         public Collection<String> getOpenIdsByUser(String userId) throws DatabaseException {
 391                 Query query = new Query(Type.SELECT, "USER_OPENIDS");
 392                 query.addField(new Field("USER_OPENIDS.*"));
 393                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USER_OPENIDS.USER", new StringParameter(userId))));
 394                 return database.getMultiple(query, new StringCreator("USER_OPENIDS.OPENID"));
 395         }
 396
 397         /**
 398          * {@link Artist} implementation that retrieves some attributes (such as
 399          * {@link #getGroups()}, and {@link #getTracks()}) from the
 400          * {@link DataManager} on demand.
 401          *
 402          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 403          */
 404         private class LazyArtist extends DefaultArtist {
 405
 406                 /** Memoizer for the tracks by this artist. */
 407                 private final Memoizer<Void> tracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
 408                         @Override
 409                         public Void call() throws DatabaseException {
 410                                 if (!hasValue("tracks")) {
 411                                         getValue("tracks", Collection.class).set(getTracksByArtist(getId()));
 412                                 }
 413                                 return null;
 414                         }
 415                 });
 416
 417                 /** Memoizer for the groups of this artist. */
 418                 private final Memoizer<Void> groupsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 419
 420                         @Override
 421                         public Void call() throws Exception {
 422                                 if (!hasValue("groups")) {
 423                                         getValue("groups", Collection.class).set(getGroupsByArtist(getId()));
 424                                 }
 425                                 return null;
 426                         }
 427
 428                 });
 429
 430                 /**
 431                  * Creates a new lazy artist.
 432                  *
 433                  * @param id
 434                  *            The ID of the artist
 435                  */
 436                 public LazyArtist(String id) {
 437                         super(id);
 438                 }
 439
 440                 //
 441                 // DEFAULTARTIST METHODS
 442                 //
 443
 444                 /**
 445                  * {@inheritDoc}
 446                  */
 447                 @Override
 448                 public Collection<Group> getGroups() {
 449                         groupsMemoizer.get();
 450                         return super.getGroups();
 451                 }
 452
 453                 /**
 454                  * {@inheritDoc}
 455                  */
 456                 @Override
 457                 public Collection<Track> getTracks() {
 458                         tracksMemoizer.get();
 459                         return super.getTracks();
 460                 }
 461
 462         }
 463
 464         /**
 465          * {@link ObjectCreator} implementation that can create {@link Artist}
 466          * objects. This specific class actually creates {@link LazyArtist}
 467          * instances.
 468          *
 469          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 470          */
 471         private class ArtistCreator implements ObjectCreator<Artist> {
 472
 473                 /**
 474                  * {@inheritDoc}
 475                  */
 476                 @Override
 477                 public Artist createObject(ResultSet resultSet) throws SQLException {
 478                         return new LazyArtist(resultSet.getString("ARTISTS.ID")).setName(resultSet.getString("ARTISTS.NAME"));
 479                 }
 480
 481         }
 482
 483         /**
 484          * {@link Group} implementation that retrieves some attributes (such as
 485          * {@link #getArtists()}) from the {@link DataManager} on demand.
 486          *
 487          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 488          */
 489         private class LazyGroup extends DefaultGroup {
 490
 491                 /** Memoizer for the artist. */
 492                 private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 493
 494                         @Override
 495                         public Void call() throws Exception {
 496                                 if (!hasValue("artists")) {
 497                                         getValue("artists", Collection.class).set(getArtistsByGroup(getId()));
 498                                 }
 499                                 return null;
 500                         }
 501
 502                 });
 503
 504                 /**
 505                  * Creates a new lazy group.
 506                  *
 507                  * @param id
 508                  *            The ID of the group
 509                  */
 510                 public LazyGroup(String id) {
 511                         super(id);
 512                 }
 513
 514                 //
 515                 // DEFAULTGROUP METHODS
 516                 //
 517
 518                 /**
 519                  * {@inheritDoc}
 520                  */
 521                 @Override
 522                 public Collection<Artist> getArtists() {
 523                         artistsMemoizer.get();
 524                         return super.getArtists();
 525                 }
 526
 527         }
 528
 529         /**
 530          * {@link ObjectCreator} implementation that can create {@link Group}
 531          * objects. This specific implementation creates {@link LazyGroup}
 532          * instances.
 533          *
 534          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 535          */
 536         private class GroupCreator implements ObjectCreator<Group> {
 537
 538                 /**
 539                  * {@inheritDoc}
 540                  */
 541                 @Override
 542                 public Group createObject(ResultSet resultSet) throws SQLException {
 543                         return new LazyGroup(resultSet.getString("GROUPS.ID")).setName(resultSet.getString("GROUPS.NAME")).setUrl(resultSet.getString("GROUPS.URL"));
 544                 }
 545
 546         }
 547
 548         /**
 549          * {@link Track} implementation that retrieves some attributes (such as
 550          * {@link #getArtists()}, and {@link #getStyles()}) from the
 551          * {@link DataManager} on demand.
 552          *
 553          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 554          */
 555         private class LazyTrack extends DefaultTrack {
 556
 557                 /** Memoizer for the artists. */
 558                 private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 559
 560                         @Override
 561                         public Void call() throws Exception {
 562                                 if (!hasValue("artists")) {
 563                                         getValue("artists", List.class).set(getArtistsByTrack(getId()));
 564                                 }
 565                                 return null;
 566                         }
 567
 568                 });
 569
 570                 /** Memoizer for the styles. */
 571                 private final Memoizer<Void> stylesMemoizer = new Memoizer<Void>(new Callable<Void>() {
 572
 573                         @Override
 574                         public Void call() throws Exception {
 575                                 if (!hasValue("styles")) {
 576                                         getValue("styles", Collection.class).set(getStylesByTrack(getId()));
 577                                 }
 578                                 return null;
 579                         }
 580
 581                 });
 582
 583                 /** Memoizer for the remix artists. */
 584                 private final Memoizer<Void> remixArtistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 585
 586                         @Override
 587                         public Void call() throws Exception {
 588                                 if (!hasValue("remixArtists")) {
 589                                         getValue("remixArtists", List.class).set(getRemixArtistsByTrack(getId()));
 590                                 }
 591                                 return null;
 592                         }
 593
 594                 });
 595
 596                 /** Memoizer for the related tracks. */
 597                 private final Memoizer<Void> relatedTracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
 598
 599                         @Override
 600                         public Void call() throws Exception {
 601                                 if (!hasValue("relatedTracks")) {
 602                                         getValue("relatedTracks", Map.class).set(getRelatedTracksByTrack(getId()));
 603                                 }
 604                                 return null;
 605                         }
 606                 });
 607
 608                 /**
 609                  * Creates a new track.
 610                  *
 611                  * @param id
 612                  *            The ID of the track
 613                  */
 614                 public LazyTrack(String id) {
 615                         super(id);
 616                 }
 617
 618                 //
 619                 // DEFAULTTRACK METHODS
 620                 //
 621
 622                 /**
 623                  * {@inheritDoc}
 624                  */
 625                 @Override
 626                 public List<Artist> getArtists() {
 627                         artistsMemoizer.get();
 628                         return super.getArtists();
 629                 }
 630
 631                 /**
 632                  * {@inheritDoc}
 633                  */
 634                 @Override
 635                 public Collection<Style> getStyles() {
 636                         stylesMemoizer.get();
 637                         return super.getStyles();
 638                 }
 639
 640                 /**
 641                  * {@inheritDoc}
 642                  */
 643                 @Override
 644                 public List<Artist> getRemixArtists() {
 645                         remixArtistsMemoizer.get();
 646                         return super.getRemixArtists();
 647                 }
 648
 649                 /**
 650                  * {@inheritDoc}
 651                  */
 652                 @Override
 653                 public Map<Relationship, Collection<Track>> getRelatedTracks() {
 654                         relatedTracksMemoizer.get();
 655                         return super.getRelatedTracks();
 656                 }
 657
 658         }
 659
 660         /**
 661          * {@link ObjectCreator} implementation that can create {@link Track}
 662          * objects. This specific implementation creates {@link LazyTrack}
 663          * instances.
 664          *
 665          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 666          */
 667         private class TrackCreator implements ObjectCreator<Track> {
 668
 669                 /**
 670                  * {@inheritDoc}
 671                  */
 672                 @Override
 673                 public Track createObject(ResultSet resultSet) throws SQLException {
 674                         return new LazyTrack(resultSet.getString("TRACKS.ID")).setName(resultSet.getString("TRACKS.NAME")).setRemix(resultSet.getString("TRACKS.REMIX"));
 675                 }
 676
 677         }
 678
 679         /**
 680          * {@link ObjectCreator} implementation that can create {@link Style}
 681          * objects.
 682          *
 683          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 684          */
 685         private class StyleCreator implements ObjectCreator<Style> {
 686
 687                 /**
 688                  * {@inheritDoc}
 689                  */
 690                 @Override
 691                 public Style createObject(ResultSet resultSet) throws SQLException {
 692                         return new DefaultStyle(resultSet.getString("STYLES.ID")).setName(resultSet.getString("STYLES.NAME"));
 693                 }
 694
 695         }
 696
 697         /**
 698          * {@link User} implementation that retrieves some attributes (such as
 699          * {@link #getOpenIds()}) from the {@link DataManager} on demand.
 700          *
 701          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 702          */
 703         private class LazyUser extends DefaultUser {
 704
 705                 /** Memoizer for a user’s OpenIDs. */
 706                 private final Memoizer<Void> openIdMemoizer = new Memoizer<Void>(new Callable<Void>() {
 707
 708                         @Override
 709                         public Void call() throws Exception {
 710                                 if (!hasValue("openIds")) {
 711                                         getValue("openIds", Collection.class).set(getOpenIdsByUser(getId()));
 712                                 }
 713                                 return null;
 714                         }
 715                 });
 716
 717                 /**
 718                  * Creates a new user.
 719                  *
 720                  * @param id
 721                  *            The ID of the user
 722                  */
 723                 public LazyUser(String id) {
 724                         super(id);
 725                 }
 726
 727                 /**
 728                  * {@inheritDoc}
 729                  */
 730                 @Override
 731                 public Collection<String> getOpenIds() {
 732                         openIdMemoizer.get();
 733                         return super.getOpenIds();
 734                 }
 735
 736         }
 737
 738         /**
 739          * {@link ObjectCreator} implementation that can create {@link User}
 740          * objects. This specific implementation creates {@link LazyUser} instances.
 741          *
 742          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 743          */
 744         private class UserCreator implements ObjectCreator<User> {
 745
 746                 /**
 747                  * {@inheritDoc}
 748                  */
 749                 @Override
 750                 public User createObject(ResultSet resultSet) throws SQLException {
 751                         return new LazyUser(resultSet.getString("USERS.ID")).setName(resultSet.getString("USERS.NAME")).setPasswordHash(resultSet.getString("USERS.PASSWORD")).setLevel(resultSet.getInt("USERS.LEVEL"));
 752                 }
 753
 754         }
 755
 756 }