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 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 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 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 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 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          * Returns all remix artists involved in the track with the given ID.
 187          *
 188          * @param trackId
 189          *            The ID of the track
 190          * @return All remix artists involved in the track, in preferred order
 191          * @throws DatabaseException
 192          *             if a database error occurs
 193          */
 194         public List<Artist> getRemixArtistsByTrack(String trackId) throws DatabaseException {
 195                 Query query = new Query(Type.SELECT, "ARTISTS");
 196                 query.addField(new Field("ARTISTS.*"));
 197                 query.addJoin(new Join(JoinType.INNER, "TRACK_REMIX_ARTISTS", new Field("TRACK_REMIX_ARTISTS.ARTIST"), new Field("ARTISTS.ID")));
 198                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_REMIX_ARTISTS.TRACK", new StringParameter(trackId))));
 199                 query.addOrderField(new OrderField(new Field("TRACK_REMIX_ARTISTS.DISPLAY_ORDER")));
 200                 return database.getMultiple(query, artistCreator);
 201         }
 202
 203         /**
 204          * Returns all related tracks for the track with the given ID.
 205          *
 206          * @param trackId
 207          *            The ID of the tracks
 208          * @return A mapping from relationship to all tracks that match the relation
 209          * @throws DatabaseException
 210          *             if a database error occurs
 211          */
 212         public Map<Relationship, Collection<Track>> getRelatedTracksByTrack(String trackId) throws DatabaseException {
 213                 Query query = new Query(Type.SELECT, "TRACKS");
 214                 query.addField(new Field("TRACKS.*"));
 215                 query.addField(new Field("TRACK_RELATIONS.*"));
 216                 query.addJoin(new Join(JoinType.INNER, "TRACK_RELATIONS", new Field("TRACK_RELATIONS.TRACK"), new Field("TRACK_RELATIONS.RELATED_TRACK")));
 217                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_RELATIONS.TRACK", new StringParameter(trackId))));
 218                 final Map<Relationship, Collection<Track>> relatedTracks = new EnumMap<Relationship, Collection<Track>>(Relationship.class);
 219                 database.process(query, new ResultProcessor() {
 220
 221                         @Override
 222                         @SuppressWarnings("synthetic-access")
 223                         public void processResult(ResultSet resultSet) throws SQLException {
 224                                 Track track = trackCreator.createObject(resultSet);
 225                                 Relationship relationship = Relationship.valueOf(resultSet.getString("TRACK_RELATIONS.RELATIONSHIP"));
 226                                 if (!relatedTracks.containsKey(relationship)) {
 227                                         relatedTracks.put(relationship, new HashSet<Track>());
 228                                 }
 229                                 relatedTracks.get(relationship).add(track);
 230                         }
 231                 });
 232                 return relatedTracks;
 233         }
 234
 235         /**
 236          * Returns the track with the given ID.
 237          *
 238          * @param id
 239          *            The ID of the track
 240          * @return The track with the given ID, or {@code null} if there is no such
 241          *         track
 242          * @throws DatabaseException
 243          *             if a database error occurs
 244          */
 245         public Track getTrackById(String id) throws DatabaseException {
 246                 Query query = new Query(Type.SELECT, "TRACKS");
 247                 query.addField(new Field("TRACKS.*"));
 248                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACKS.ID", new StringParameter(id))));
 249                 return database.getSingle(query, trackCreator);
 250         }
 251
 252         /**
 253          * Returns all tracks by the artist with the given ID.
 254          *
 255          * @param artistId
 256          *            The ID of the artist
 257          * @return All tracks by the given artist
 258          * @throws DatabaseException
 259          *             if a database error occurs
 260          */
 261         public Collection<Track> getTracksByArtist(String artistId) throws DatabaseException {
 262                 Query query = new Query(Type.SELECT, "TRACKS");
 263                 query.addField(new Field("TRACKS.*"));
 264                 query.addJoin(new Join(JoinType.INNER, "TRACK_ARTISTS", new Field("TRACKS.ID"), new Field("TRACK_ARTISTS.TRACK")));
 265                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_ARTISTS.ARTIST", new StringParameter(artistId))));
 266                 return database.getMultiple(query, trackCreator);
 267         }
 268
 269         /**
 270          * Returns all groups the artist with the given ID belongs to.
 271          *
 272          * @param artistId
 273          *            The ID of the artist
 274          * @return All groups the artist belongs to
 275          * @throws DatabaseException
 276          *             if a database error occurs
 277          */
 278         public Collection<Group> getGroupsByArtist(String artistId) throws DatabaseException {
 279                 Query query = new Query(Type.SELECT, "GROUPS");
 280                 query.addField(new Field("GROUPS.*"));
 281                 query.addJoin(new Join(JoinType.INNER, "GROUP_ARTISTS", new Field("GROUPS.ID"), new Field("GROUP_ARTISTS.GROUP_")));
 282                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUP_ARTISTS.ARTIST", new StringParameter(artistId))));
 283                 return database.getMultiple(query, groupCreator);
 284         }
 285
 286         /**
 287          * Returns all styles for the track with the given ID.
 288          *
 289          * @param trackId
 290          *            The ID of the track
 291          * @return All styles for the given track
 292          * @throws DatabaseException
 293          *             if a database error occurs
 294          */
 295         public Collection<Style> getStylesByTrack(String trackId) throws DatabaseException {
 296                 Query query = new Query(Type.SELECT, "STYLES");
 297                 query.addField(new Field("STYLES.*"));
 298                 query.addJoin(new Join(JoinType.INNER, "TRACK_STYLES", new Field("STYLES.ID"), new Field("TRACK_STYLES.STYLE")));
 299                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_STYLES.TRACK", new StringParameter(trackId))));
 300                 return database.getMultiple(query, styleCreator);
 301         }
 302
 303         /**
 304          * Returns the user with the given name.
 305          *
 306          * @param username
 307          *            The name of the user
 308          * @return The user, or {@code null} if the user does not exist
 309          * @throws DatabaseException
 310          *             if a database error occurs
 311          */
 312         public User getUserByName(String username) throws DatabaseException {
 313                 Query query = new Query(Type.SELECT, "USERS");
 314                 query.addField(new Field("USERS.*"));
 315                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USERS.NAME", new StringParameter(username))));
 316                 return database.getSingle(query, userCreator);
 317         }
 318
 319         /**
 320          * Returns the user connected with the given OpenID.
 321          *
 322          * @param openId
 323          *            The OpenID to find the user for
 324          * @return The user connected with the given OpenID, or {@code null} if
 325          *         there is no such user
 326          * @throws DatabaseException
 327          *             if a database error occurs
 328          */
 329         public User getUserByOpenId(String openId) throws DatabaseException {
 330                 Query query = new Query(Type.SELECT, "USERS");
 331                 query.addField(new Field("USERS.*"));
 332                 query.addJoin(new Join(JoinType.INNER, "USER_OPENIDS", new Field("USER_OPENIDS.USER"), new Field("USERS.ID")));
 333                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USER_OPENIDS.OPENID", new StringParameter(openId))));
 334                 return database.getSingle(query, userCreator);
 335         }
 336
 337         /**
 338          * Returns all OpenIDs connected with the user with the given ID.
 339          *
 340          * @param userId
 341          *            The ID of the user
 342          * @return All OpenIDs connected with the given user
 343          * @throws DatabaseException
 344          *             if a database error occurs
 345          */
 346         public Collection<String> getOpenIdsByUser(String userId) throws DatabaseException {
 347                 Query query = new Query(Type.SELECT, "USER_OPENIDS");
 348                 query.addField(new Field("USER_OPENIDS.*"));
 349                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USER_OPENIDS.USER", new StringParameter(userId))));
 350                 return database.getMultiple(query, new StringCreator("USER_OPENIDS.OPENID"));
 351         }
 352
 353         /**
 354          * {@link Artist} implementation that retrieves some attributes (such as
 355          * {@link #getGroups()}, and {@link #getTracks()}) from the
 356          * {@link DataManager} on demand.
 357          *
 358          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 359          */
 360         private class LazyArtist extends DefaultArtist {
 361
 362                 /** Memoizer for the tracks by this artist. */
 363                 private final Memoizer<Void> tracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
 364                         @Override
 365                         public Void call() throws DatabaseException {
 366                                 if (!hasValue("tracks")) {
 367                                         getValue("tracks", Collection.class).set(getTracksByArtist(getId()));
 368                                 }
 369                                 return null;
 370                         }
 371                 });
 372
 373                 /** Memoizer for the groups of this artist. */
 374                 private final Memoizer<Void> groupsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 375
 376                         @Override
 377                         public Void call() throws Exception {
 378                                 if (!hasValue("groups")) {
 379                                         getValue("groups", Collection.class).set(getGroupsByArtist(getId()));
 380                                 }
 381                                 return null;
 382                         }
 383
 384                 });
 385
 386                 /**
 387                  * Creates a new lazy artist.
 388                  *
 389                  * @param id
 390                  *            The ID of the artist
 391                  */
 392                 public LazyArtist(String id) {
 393                         super(id);
 394                 }
 395
 396                 //
 397                 // DEFAULTARTIST METHODS
 398                 //
 399
 400                 /**
 401                  * {@inheritDoc}
 402                  */
 403                 @Override
 404                 public Collection<Group> getGroups() {
 405                         groupsMemoizer.get();
 406                         return super.getGroups();
 407                 }
 408
 409                 /**
 410                  * {@inheritDoc}
 411                  */
 412                 @Override
 413                 public Collection<Track> getTracks() {
 414                         tracksMemoizer.get();
 415                         return super.getTracks();
 416                 }
 417
 418         }
 419
 420         /**
 421          * {@link ObjectCreator} implementation that can create {@link Artist}
 422          * objects. This specific class actually creates {@link LazyArtist}
 423          * instances.
 424          *
 425          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 426          */
 427         private class ArtistCreator implements ObjectCreator<Artist> {
 428
 429                 /**
 430                  * {@inheritDoc}
 431                  */
 432                 @Override
 433                 public Artist createObject(ResultSet resultSet) throws SQLException {
 434                         return new LazyArtist(resultSet.getString("ARTISTS.ID")).setName(resultSet.getString("ARTISTS.NAME"));
 435                 }
 436
 437         }
 438
 439         /**
 440          * {@link Group} implementation that retrieves some attributes (such as
 441          * {@link #getArtists()}) from the {@link DataManager} on demand.
 442          *
 443          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 444          */
 445         private class LazyGroup extends DefaultGroup {
 446
 447                 /** Memoizer for the artist. */
 448                 private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 449
 450                         @Override
 451                         public Void call() throws Exception {
 452                                 if (!hasValue("artists")) {
 453                                         getValue("artists", Collection.class).set(getArtistsByGroup(getId()));
 454                                 }
 455                                 return null;
 456                         }
 457
 458                 });
 459
 460                 /**
 461                  * Creates a new lazy group.
 462                  *
 463                  * @param id
 464                  *            The ID of the group
 465                  */
 466                 public LazyGroup(String id) {
 467                         super(id);
 468                 }
 469
 470                 //
 471                 // DEFAULTGROUP METHODS
 472                 //
 473
 474                 /**
 475                  * {@inheritDoc}
 476                  */
 477                 @Override
 478                 public Collection<Artist> getArtists() {
 479                         artistsMemoizer.get();
 480                         return super.getArtists();
 481                 }
 482
 483         }
 484
 485         /**
 486          * {@link ObjectCreator} implementation that can create {@link Group}
 487          * objects. This specific implementation creates {@link LazyGroup}
 488          * instances.
 489          *
 490          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 491          */
 492         private class GroupCreator implements ObjectCreator<Group> {
 493
 494                 /**
 495                  * {@inheritDoc}
 496                  */
 497                 @Override
 498                 public Group createObject(ResultSet resultSet) throws SQLException {
 499                         return new LazyGroup(resultSet.getString("GROUPS.ID")).setName(resultSet.getString("GROUPS.NAME")).setUrl(resultSet.getString("GROUPS.URL"));
 500                 }
 501
 502         }
 503
 504         /**
 505          * {@link Track} implementation that retrieves some attributes (such as
 506          * {@link #getArtists()}, and {@link #getStyles()}) from the
 507          * {@link DataManager} on demand.
 508          *
 509          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 510          */
 511         private class LazyTrack extends DefaultTrack {
 512
 513                 /** Memoizer for the artists. */
 514                 private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 515
 516                         @Override
 517                         public Void call() throws Exception {
 518                                 if (!hasValue("artists")) {
 519                                         getValue("artists", List.class).set(getArtistsByTrack(getId()));
 520                                 }
 521                                 return null;
 522                         }
 523
 524                 });
 525
 526                 /** Memoizer for the styles. */
 527                 private final Memoizer<Void> stylesMemoizer = new Memoizer<Void>(new Callable<Void>() {
 528
 529                         @Override
 530                         public Void call() throws Exception {
 531                                 if (!hasValue("styles")) {
 532                                         getValue("styles", Collection.class).set(getStylesByTrack(getId()));
 533                                 }
 534                                 return null;
 535                         }
 536
 537                 });
 538
 539                 /** Memoizer for the remix artists. */
 540                 private final Memoizer<Void> remixArtistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 541
 542                         @Override
 543                         public Void call() throws Exception {
 544                                 if (!hasValue("remixArtists")) {
 545                                         getValue("remixArtists", List.class).set(getRemixArtistsByTrack(getId()));
 546                                 }
 547                                 return null;
 548                         }
 549
 550                 });
 551
 552                 /** Memoizer for the related tracks. */
 553                 private final Memoizer<Void> relatedTracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
 554
 555                         @Override
 556                         public Void call() throws Exception {
 557                                 if (!hasValue("relatedTracks")) {
 558                                         getValue("relatedTracks", Map.class).set(getRelatedTracksByTrack(getId()));
 559                                 }
 560                                 return null;
 561                         }
 562                 });
 563
 564                 /**
 565                  * Creates a new track.
 566                  *
 567                  * @param id
 568                  *            The ID of the track
 569                  */
 570                 public LazyTrack(String id) {
 571                         super(id);
 572                 }
 573
 574                 //
 575                 // DEFAULTTRACK METHODS
 576                 //
 577
 578                 /**
 579                  * {@inheritDoc}
 580                  */
 581                 @Override
 582                 public List<Artist> getArtists() {
 583                         artistsMemoizer.get();
 584                         return super.getArtists();
 585                 }
 586
 587                 /**
 588                  * {@inheritDoc}
 589                  */
 590                 @Override
 591                 public Collection<Style> getStyles() {
 592                         stylesMemoizer.get();
 593                         return super.getStyles();
 594                 }
 595
 596                 /**
 597                  * {@inheritDoc}
 598                  */
 599                 @Override
 600                 public List<Artist> getRemixArtists() {
 601                         remixArtistsMemoizer.get();
 602                         return super.getRemixArtists();
 603                 }
 604
 605                 /**
 606                  * {@inheritDoc}
 607                  */
 608                 @Override
 609                 public Map<Relationship, Collection<Track>> getRelatedTracks() {
 610                         relatedTracksMemoizer.get();
 611                         return super.getRelatedTracks();
 612                 }
 613
 614         }
 615
 616         /**
 617          * {@link ObjectCreator} implementation that can create {@link Track}
 618          * objects. This specific implementation creates {@link LazyTrack}
 619          * instances.
 620          *
 621          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 622          */
 623         private class TrackCreator implements ObjectCreator<Track> {
 624
 625                 /**
 626                  * {@inheritDoc}
 627                  */
 628                 @Override
 629                 public Track createObject(ResultSet resultSet) throws SQLException {
 630                         return new LazyTrack(resultSet.getString("TRACKS.ID")).setName(resultSet.getString("TRACKS.NAME")).setRemix(resultSet.getString("TRACKS.REMIX"));
 631                 }
 632
 633         }
 634
 635         /**
 636          * {@link ObjectCreator} implementation that can create {@link Style}
 637          * objects.
 638          *
 639          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 640          */
 641         private class StyleCreator implements ObjectCreator<Style> {
 642
 643                 /**
 644                  * {@inheritDoc}
 645                  */
 646                 @Override
 647                 public Style createObject(ResultSet resultSet) throws SQLException {
 648                         return new DefaultStyle(resultSet.getString("STYLES.ID")).setName(resultSet.getString("STYLES.NAME"));
 649                 }
 650
 651         }
 652
 653         /**
 654          * {@link User} implementation that retrieves some attributes (such as
 655          * {@link #getOpenIds()}) from the {@link DataManager} on demand.
 656          *
 657          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 658          */
 659         private class LazyUser extends DefaultUser {
 660
 661                 /** Memoizer for a user’s OpenIDs. */
 662                 private final Memoizer<Void> openIdMemoizer = new Memoizer<Void>(new Callable<Void>() {
 663
 664                         @Override
 665                         public Void call() throws Exception {
 666                                 if (!hasValue("openIds")) {
 667                                         getValue("openIds", Collection.class).set(getOpenIdsByUser(getId()));
 668                                 }
 669                                 return null;
 670                         }
 671                 });
 672
 673                 /**
 674                  * Creates a new user.
 675                  *
 676                  * @param id
 677                  *            The ID of the user
 678                  */
 679                 public LazyUser(String id) {
 680                         super(id);
 681                 }
 682
 683                 /**
 684                  * {@inheritDoc}
 685                  */
 686                 @Override
 687                 public Collection<String> getOpenIds() {
 688                         openIdMemoizer.get();
 689                         return super.getOpenIds();
 690                 }
 691
 692         }
 693
 694         /**
 695          * {@link ObjectCreator} implementation that can create {@link User}
 696          * objects. This specific implementation creates {@link LazyUser} instances.
 697          *
 698          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 699          */
 700         private class UserCreator implements ObjectCreator<User> {
 701
 702                 /**
 703                  * {@inheritDoc}
 704                  */
 705                 @Override
 706                 public User createObject(ResultSet resultSet) throws SQLException {
 707                         return new LazyUser(resultSet.getString("USERS.ID")).setName(resultSet.getString("USERS.NAME")).setPasswordHash(resultSet.getString("USERS.PASSWORD")).setLevel(resultSet.getInt("USERS.LEVEL"));
 708                 }
 709
 710         }
 711
 712 }