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          * Returns all remix artists involved in the track with the given ID.
 172          *
 173          * @param trackId
 174          *            The ID of the track
 175          * @return All remix artists involved in the track, in preferred order
 176          * @throws DatabaseException
 177          *             if a database error occurs
 178          */
 179         public List<Artist> getRemixArtistsByTrack(String trackId) throws DatabaseException {
 180                 Query query = new Query(Type.SELECT, "ARTISTS");
 181                 query.addField(new Field("ARTISTS.*"));
 182                 query.addJoin(new Join(JoinType.INNER, "TRACK_REMIX_ARTISTS", new Field("TRACK_REMIX_ARTISTS.ARTIST"), new Field("ARTISTS.ID")));
 183                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_REMIX_ARTISTS.TRACK", new StringParameter(trackId))));
 184                 query.addOrderField(new OrderField(new Field("TRACK_REMIX_ARTISTS.DISPLAY_ORDER")));
 185                 return database.getMultiple(query, artistCreator);
 186         }
 187
 188         /**
 189          * Returns all related tracks for the track with the given ID.
 190          *
 191          * @param trackId
 192          *            The ID of the tracks
 193          * @return A mapping from relationship to all tracks that match the relation
 194          * @throws DatabaseException
 195          *             if a database error occurs
 196          */
 197         public Map<Relationship, Collection<Track>> getRelatedTracksByTrack(String trackId) throws DatabaseException {
 198                 Query query = new Query(Type.SELECT, "TRACKS");
 199                 query.addField(new Field("TRACKS.*"));
 200                 query.addField(new Field("TRACK_RELATIONS.*"));
 201                 query.addJoin(new Join(JoinType.INNER, "TRACK_RELATIONS", new Field("TRACK_RELATIONS.TRACK"), new Field("TRACK_RELATIONS.RELATED_TRACK")));
 202                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_RELATIONS.TRACK", new StringParameter(trackId))));
 203                 final Map<Relationship, Collection<Track>> relatedTracks = new EnumMap<Relationship, Collection<Track>>(Relationship.class);
 204                 database.process(query, new ResultProcessor() {
 205
 206                         @Override
 207                         @SuppressWarnings("synthetic-access")
 208                         public void processResult(ResultSet resultSet) throws SQLException {
 209                                 Track track = trackCreator.createObject(resultSet);
 210                                 Relationship relationship = Relationship.valueOf(resultSet.getString("TRACK_RELATIONS.RELATIONSHIP"));
 211                                 if (!relatedTracks.containsKey(relationship)) {
 212                                         relatedTracks.put(relationship, new HashSet<Track>());
 213                                 }
 214                                 relatedTracks.get(relationship).add(track);
 215                         }
 216                 });
 217                 return relatedTracks;
 218         }
 219
 220         /**
 221          * Returns the track with the given ID.
 222          *
 223          * @param id
 224          *            The ID of the track
 225          * @return The track with the given ID, or {@code null} if there is no such
 226          *         track
 227          * @throws DatabaseException
 228          *             if a database error occurs
 229          */
 230         public Track getTrackById(String id) throws DatabaseException {
 231                 Query query = new Query(Type.SELECT, "TRACKS");
 232                 query.addField(new Field("TRACKS.*"));
 233                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACKS.ID", new StringParameter(id))));
 234                 return database.getSingle(query, trackCreator);
 235         }
 236
 237         /**
 238          * Returns all tracks by the artist with the given ID.
 239          *
 240          * @param artistId
 241          *            The ID of the artist
 242          * @return All tracks by the given artist
 243          * @throws DatabaseException
 244          *             if a database error occurs
 245          */
 246         public Collection<Track> getTracksByArtist(String artistId) throws DatabaseException {
 247                 Query query = new Query(Type.SELECT, "TRACKS");
 248                 query.addField(new Field("TRACKS.*"));
 249                 query.addJoin(new Join(JoinType.INNER, "TRACK_ARTISTS", new Field("TRACKS.ID"), new Field("TRACK_ARTISTS.TRACK")));
 250                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_ARTISTS.ARTIST", new StringParameter(artistId))));
 251                 return database.getMultiple(query, trackCreator);
 252         }
 253
 254         /**
 255          * Returns all groups the artist with the given ID belongs to.
 256          *
 257          * @param artistId
 258          *            The ID of the artist
 259          * @return All groups the artist belongs to
 260          * @throws DatabaseException
 261          *             if a database error occurs
 262          */
 263         public Collection<Group> getGroupsByArtist(String artistId) throws DatabaseException {
 264                 Query query = new Query(Type.SELECT, "GROUPS");
 265                 query.addField(new Field("GROUPS.*"));
 266                 query.addJoin(new Join(JoinType.INNER, "GROUP_ARTISTS", new Field("GROUPS.ID"), new Field("GROUP_ARTISTS.GROUP_")));
 267                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("GROUP_ARTISTS.ARTIST", new StringParameter(artistId))));
 268                 return database.getMultiple(query, groupCreator);
 269         }
 270
 271         /**
 272          * Returns all styles for the track with the given ID.
 273          *
 274          * @param trackId
 275          *            The ID of the track
 276          * @return All styles for the given track
 277          * @throws DatabaseException
 278          *             if a database error occurs
 279          */
 280         public Collection<Style> getStylesByTrack(String trackId) throws DatabaseException {
 281                 Query query = new Query(Type.SELECT, "STYLES");
 282                 query.addField(new Field("STYLES.*"));
 283                 query.addJoin(new Join(JoinType.INNER, "TRACK_STYLES", new Field("STYLES.ID"), new Field("TRACK_STYLES.STYLE")));
 284                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("TRACK_STYLES.TRACK", new StringParameter(trackId))));
 285                 return database.getMultiple(query, styleCreator);
 286         }
 287
 288         /**
 289          * Returns the user with the given name.
 290          *
 291          * @param username
 292          *            The name of the user
 293          * @return The user, or {@code null} if the user does not exist
 294          * @throws DatabaseException
 295          *             if a database error occurs
 296          */
 297         public User getUserByName(String username) throws DatabaseException {
 298                 Query query = new Query(Type.SELECT, "USERS");
 299                 query.addField(new Field("USERS.*"));
 300                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USERS.NAME", new StringParameter(username))));
 301                 return database.getSingle(query, userCreator);
 302         }
 303
 304         /**
 305          * Returns the user connected with the given OpenID.
 306          *
 307          * @param openId
 308          *            The OpenID to find the user for
 309          * @return The user connected with the given OpenID, or {@code null} if
 310          *         there is no such user
 311          * @throws DatabaseException
 312          *             if a database error occurs
 313          */
 314         public User getUserByOpenId(String openId) throws DatabaseException {
 315                 Query query = new Query(Type.SELECT, "USERS");
 316                 query.addField(new Field("USERS.*"));
 317                 query.addJoin(new Join(JoinType.INNER, "USER_OPENIDS", new Field("USER_OPENIDS.USER"), new Field("USERS.ID")));
 318                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USER_OPENIDS.OPENID", new StringParameter(openId))));
 319                 return database.getSingle(query, userCreator);
 320         }
 321
 322         /**
 323          * Returns all OpenIDs connected with the user with the given ID.
 324          *
 325          * @param userId
 326          *            The ID of the user
 327          * @return All OpenIDs connected with the given user
 328          * @throws DatabaseException
 329          *             if a database error occurs
 330          */
 331         public Collection<String> getOpenIdsByUser(String userId) throws DatabaseException {
 332                 Query query = new Query(Type.SELECT, "USER_OPENIDS");
 333                 query.addField(new Field("USER_OPENIDS.*"));
 334                 query.addWhereClause(new ValueFieldWhereClause(new ValueField("USER_OPENIDS.USER", new StringParameter(userId))));
 335                 return database.getMultiple(query, new StringCreator("USER_OPENIDS.OPENID"));
 336         }
 337
 338         /**
 339          * {@link Artist} implementation that retrieves some attributes (such as
 340          * {@link #getGroups()}, and {@link #getTracks()}) from the
 341          * {@link DataManager} on demand.
 342          *
 343          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 344          */
 345         private class LazyArtist extends DefaultArtist {
 346
 347                 /** Memoizer for the tracks by this artist. */
 348                 private final Memoizer<Void> tracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
 349                         @Override
 350                         public Void call() throws DatabaseException {
 351                                 if (!hasValue("tracks")) {
 352                                         getValue("tracks", Collection.class).set(getTracksByArtist(getId()));
 353                                 }
 354                                 return null;
 355                         }
 356                 });
 357
 358                 /** Memoizer for the groups of this artist. */
 359                 private final Memoizer<Void> groupsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 360
 361                         @Override
 362                         public Void call() throws Exception {
 363                                 if (!hasValue("groups")) {
 364                                         getValue("groups", Collection.class).set(getGroupsByArtist(getId()));
 365                                 }
 366                                 return null;
 367                         }
 368
 369                 });
 370
 371                 /**
 372                  * Creates a new lazy artist.
 373                  *
 374                  * @param id
 375                  *            The ID of the artist
 376                  */
 377                 public LazyArtist(String id) {
 378                         super(id);
 379                 }
 380
 381                 //
 382                 // DEFAULTARTIST METHODS
 383                 //
 384
 385                 /**
 386                  * {@inheritDoc}
 387                  */
 388                 @Override
 389                 public Collection<Group> getGroups() {
 390                         groupsMemoizer.get();
 391                         return super.getGroups();
 392                 }
 393
 394                 /**
 395                  * {@inheritDoc}
 396                  */
 397                 @Override
 398                 public Collection<Track> getTracks() {
 399                         tracksMemoizer.get();
 400                         return super.getTracks();
 401                 }
 402
 403         }
 404
 405         /**
 406          * {@link ObjectCreator} implementation that can create {@link Artist}
 407          * objects. This specific class actually creates {@link LazyArtist}
 408          * instances.
 409          *
 410          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 411          */
 412         private class ArtistCreator implements ObjectCreator<Artist> {
 413
 414                 /**
 415                  * {@inheritDoc}
 416                  */
 417                 @Override
 418                 public Artist createObject(ResultSet resultSet) throws SQLException {
 419                         return new LazyArtist(resultSet.getString("ARTISTS.ID")).setName(resultSet.getString("ARTISTS.NAME"));
 420                 }
 421
 422         }
 423
 424         /**
 425          * {@link Group} implementation that retrieves some attributes (such as
 426          * {@link #getArtists()}) from the {@link DataManager} on demand.
 427          *
 428          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 429          */
 430         private class LazyGroup extends DefaultGroup {
 431
 432                 /** Memoizer for the artist. */
 433                 private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 434
 435                         @Override
 436                         public Void call() throws Exception {
 437                                 if (!hasValue("artists")) {
 438                                         getValue("artists", Collection.class).set(getArtistsByGroup(getId()));
 439                                 }
 440                                 return null;
 441                         }
 442
 443                 });
 444
 445                 /**
 446                  * Creates a new lazy group.
 447                  *
 448                  * @param id
 449                  *            The ID of the group
 450                  */
 451                 public LazyGroup(String id) {
 452                         super(id);
 453                 }
 454
 455                 //
 456                 // DEFAULTGROUP METHODS
 457                 //
 458
 459                 /**
 460                  * {@inheritDoc}
 461                  */
 462                 @Override
 463                 public Collection<Artist> getArtists() {
 464                         artistsMemoizer.get();
 465                         return super.getArtists();
 466                 }
 467
 468         }
 469
 470         /**
 471          * {@link ObjectCreator} implementation that can create {@link Group}
 472          * objects. This specific implementation creates {@link LazyGroup}
 473          * instances.
 474          *
 475          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 476          */
 477         private class GroupCreator implements ObjectCreator<Group> {
 478
 479                 /**
 480                  * {@inheritDoc}
 481                  */
 482                 @Override
 483                 public Group createObject(ResultSet resultSet) throws SQLException {
 484                         return new LazyGroup(resultSet.getString("GROUPS.ID")).setName(resultSet.getString("GROUPS.NAME")).setUrl(resultSet.getString("GROUPS.URL"));
 485                 }
 486
 487         }
 488
 489         /**
 490          * {@link Track} implementation that retrieves some attributes (such as
 491          * {@link #getArtists()}, and {@link #getStyles()}) from the
 492          * {@link DataManager} on demand.
 493          *
 494          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 495          */
 496         private class LazyTrack extends DefaultTrack {
 497
 498                 /** Memoizer for the artists. */
 499                 private final Memoizer<Void> artistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 500
 501                         @Override
 502                         public Void call() throws Exception {
 503                                 if (!hasValue("artists")) {
 504                                         getValue("artists", List.class).set(getArtistsByTrack(getId()));
 505                                 }
 506                                 return null;
 507                         }
 508
 509                 });
 510
 511                 /** Memoizer for the styles. */
 512                 private final Memoizer<Void> stylesMemoizer = new Memoizer<Void>(new Callable<Void>() {
 513
 514                         @Override
 515                         public Void call() throws Exception {
 516                                 if (!hasValue("styles")) {
 517                                         getValue("styles", Collection.class).set(getStylesByTrack(getId()));
 518                                 }
 519                                 return null;
 520                         }
 521
 522                 });
 523
 524                 /** Memoizer for the remix artists. */
 525                 private final Memoizer<Void> remixArtistsMemoizer = new Memoizer<Void>(new Callable<Void>() {
 526
 527                         @Override
 528                         public Void call() throws Exception {
 529                                 if (!hasValue("remixArtists")) {
 530                                         getValue("remixArtists", List.class).set(getRemixArtistsByTrack(getId()));
 531                                 }
 532                                 return null;
 533                         }
 534
 535                 });
 536
 537                 /** Memoizer for the related tracks. */
 538                 private final Memoizer<Void> relatedTracksMemoizer = new Memoizer<Void>(new Callable<Void>() {
 539
 540                         @Override
 541                         public Void call() throws Exception {
 542                                 if (!hasValue("relatedTracks")) {
 543                                         getValue("relatedTracks", Map.class).set(getRelatedTracksByTrack(getId()));
 544                                 }
 545                                 return null;
 546                         }
 547                 });
 548
 549                 /**
 550                  * Creates a new track.
 551                  *
 552                  * @param id
 553                  *            The ID of the track
 554                  */
 555                 public LazyTrack(String id) {
 556                         super(id);
 557                 }
 558
 559                 //
 560                 // DEFAULTTRACK METHODS
 561                 //
 562
 563                 /**
 564                  * {@inheritDoc}
 565                  */
 566                 @Override
 567                 public List<Artist> getArtists() {
 568                         artistsMemoizer.get();
 569                         return super.getArtists();
 570                 }
 571
 572                 /**
 573                  * {@inheritDoc}
 574                  */
 575                 @Override
 576                 public Collection<Style> getStyles() {
 577                         stylesMemoizer.get();
 578                         return super.getStyles();
 579                 }
 580
 581                 /**
 582                  * {@inheritDoc}
 583                  */
 584                 @Override
 585                 public List<Artist> getRemixArtists() {
 586                         remixArtistsMemoizer.get();
 587                         return super.getRemixArtists();
 588                 }
 589
 590                 /**
 591                  * {@inheritDoc}
 592                  */
 593                 @Override
 594                 public Map<Relationship, Collection<Track>> getRelatedTracks() {
 595                         relatedTracksMemoizer.get();
 596                         return super.getRelatedTracks();
 597                 }
 598
 599         }
 600
 601         /**
 602          * {@link ObjectCreator} implementation that can create {@link Track}
 603          * objects. This specific implementation creates {@link LazyTrack}
 604          * instances.
 605          *
 606          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 607          */
 608         private class TrackCreator implements ObjectCreator<Track> {
 609
 610                 /**
 611                  * {@inheritDoc}
 612                  */
 613                 @Override
 614                 public Track createObject(ResultSet resultSet) throws SQLException {
 615                         return new LazyTrack(resultSet.getString("TRACKS.ID")).setName(resultSet.getString("TRACKS.NAME")).setRemix(resultSet.getString("TRACKS.REMIX"));
 616                 }
 617
 618         }
 619
 620         /**
 621          * {@link ObjectCreator} implementation that can create {@link Style}
 622          * objects.
 623          *
 624          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 625          */
 626         private class StyleCreator implements ObjectCreator<Style> {
 627
 628                 /**
 629                  * {@inheritDoc}
 630                  */
 631                 @Override
 632                 public Style createObject(ResultSet resultSet) throws SQLException {
 633                         return new DefaultStyle(resultSet.getString("STYLES.ID")).setName(resultSet.getString("STYLES.NAME"));
 634                 }
 635
 636         }
 637
 638         /**
 639          * {@link User} implementation that retrieves some attributes (such as
 640          * {@link #getOpenIds()}) from the {@link DataManager} on demand.
 641          *
 642          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 643          */
 644         private class LazyUser extends DefaultUser {
 645
 646                 /** Memoizer for a user’s OpenIDs. */
 647                 private final Memoizer<Void> openIdMemoizer = new Memoizer<Void>(new Callable<Void>() {
 648
 649                         @Override
 650                         public Void call() throws Exception {
 651                                 if (!hasValue("openIds")) {
 652                                         getValue("openIds", Collection.class).set(getOpenIdsByUser(getId()));
 653                                 }
 654                                 return null;
 655                         }
 656                 });
 657
 658                 /**
 659                  * Creates a new user.
 660                  *
 661                  * @param id
 662                  *            The ID of the user
 663                  */
 664                 public LazyUser(String id) {
 665                         super(id);
 666                 }
 667
 668                 /**
 669                  * {@inheritDoc}
 670                  */
 671                 @Override
 672                 public Collection<String> getOpenIds() {
 673                         openIdMemoizer.get();
 674                         return super.getOpenIds();
 675                 }
 676
 677         }
 678
 679         /**
 680          * {@link ObjectCreator} implementation that can create {@link User}
 681          * objects. This specific implementation creates {@link LazyUser} instances.
 682          *
 683          * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
 684          */
 685         private class UserCreator implements ObjectCreator<User> {
 686
 687                 /**
 688                  * {@inheritDoc}
 689                  */
 690                 @Override
 691                 public User createObject(ResultSet resultSet) throws SQLException {
 692                         return new LazyUser(resultSet.getString("USERS.ID")).setName(resultSet.getString("USERS.NAME")).setPasswordHash(resultSet.getString("USERS.PASSWORD")).setLevel(resultSet.getInt("USERS.LEVEL"));
 693                 }
 694
 695         }
 696
 697 }