Add recommendations

src/main/java/ru/yandex/practicum/filmorate/dal/FilmStorage.java

@@ -51,4 +51,5 @@ public interface FilmStorage {
 	/// Удаление фильма по id
 	void removeFilm(long filmId);
 
+	Collection<Film> getFilmsByIds(Collection<Long> ids);
 }

src/main/java/ru/yandex/practicum/filmorate/dal/database/FilmDbStorage.java

@@ -39,7 +39,7 @@ public Film createFilm(Film film) {
 		film.setId(id);
 		insertGenreIds(film);
 		insertDirectorIds(film);
-		return film;
+		return findById(id).get();
 	}
 
 	@Override
@@ -56,7 +56,7 @@ public Film updateFilm(Film film) {
 		);
 		insertGenreIds(film);
 		insertDirectorIds(film);
-		return film;
+		return findById(film.getId()).get();
 	}
 
 	@Override
@@ -157,29 +157,19 @@ public void removeFilm(long filmId) {
 	}
 
 	private void insertGenreIds(Film film) {
-		Set<Integer> genreIds = film.getGenreIds();
-		if (genreIds.isEmpty()) {
-			jdbc.update("DELETE FROM genres_of_films WHERE film_id = ?", film.getId());
-			return;
-		}
 		jdbc.update("DELETE FROM genres_of_films WHERE film_id = ?", film.getId());
-		String placeholders = String.join(
-				",", Collections.nCopies(genreIds.size(), " (" + film.getId() + ", ?)")
-		);
+		Set<Integer> genreIds = film.getGenreIds();
+		if (genreIds == null || genreIds.isEmpty()) return;
+		String placeholders = String.join(",", Collections.nCopies(genreIds.size(), " (" + film.getId() + ", ?)"));
 		String sql = SQL_FILMS_INSERT_GENREIDS + placeholders;
 		updateWithControl(sql, genreIds.toArray());
 	}
 
 	private void insertDirectorIds(Film film) {
-		Set<Integer> directorIds = film.getDirectorIds();
-		if (directorIds.isEmpty()) {
-			jdbc.update("DELETE FROM directors_of_films WHERE film_id = ?", film.getId());
-			return;
-		}
 		jdbc.update("DELETE FROM directors_of_films WHERE film_id = ?", film.getId());
-		String placeholders = String.join(
-				",", Collections.nCopies(directorIds.size(), " (" + film.getId() + ", ?)")
-		);
+		Set<Integer> directorIds = film.getDirectorIds();
+		if (directorIds == null || directorIds.isEmpty()) return;
+		String placeholders = String.join(",", Collections.nCopies(directorIds.size(), " (" + film.getId() + ", ?)"));
 		String sql = SQL_FILMS_INSERT_DIRECTORIDS + placeholders;
 		updateWithControl(sql, directorIds.toArray());
 	}
@@ -198,17 +188,11 @@ private Collection<Film> findManyFilms(String query, Object... params) {
 					}
 				});
 				long userId = rs.getLong("user_id");
-				if (!rs.wasNull() && film != null) {
-					film.addLike(userId);
-				}
+				if (!rs.wasNull() && film != null) film.addLike(userId);
 				int genreId = rs.getInt("genre_id");
-				if (!rs.wasNull() && film != null) {
-					film.addGenreId(genreId);
-				}
+				if (!rs.wasNull() && film != null) film.addGenreId(genreId);
 				int directorId = rs.getInt("director_id");
-				if (!rs.wasNull() && film != null) {
-					film.addDirectorId(directorId);
-				}
+				if (!rs.wasNull() && film != null) film.addDirectorId(directorId);
 			}
 			return new ArrayList<>(films.values());
 		}, params);
@@ -221,4 +205,25 @@ private Set<Integer> getGenreIdsByFilmId(long filmId) {
 	private Set<Integer> getDirectorIdsByFilmId(long filmId) {
 		return findColumnByQuery(SQL_FILMS_FIND_DIRECTORIDS_BY_FILM_ID, Integer.class, filmId);
 	}
+
+	@Override
+	public Collection<Film> getFilmsByIds(Collection<Long> ids) {
+		if (ids == null || ids.isEmpty()) {
+			return Collections.emptyList();
+		}
+
+		String inSql = String.join(",", Collections.nCopies(ids.size(), "?"));
+
+		String sql = String.format("""
+                SELECT f.id, f.film_name, f.description, f.release_date, f.duration, f.mpa_id,
+                       l.user_id, gof.genre_id, dof.director_id
+                FROM films f
+                LEFT JOIN likes l ON f.id = l.film_id
+                LEFT JOIN genres_of_films gof ON f.id = gof.film_id
+                LEFT JOIN directors_of_films dof ON f.id = dof.film_id
+                WHERE f.id IN (%s)
+                """, inSql);
+
+		return findManyFilms(sql, ids.toArray());
+	}
 }

src/main/java/ru/yandex/practicum/filmorate/dal/inmemory/InMemoryFilmStorage.java

@@ -82,4 +82,9 @@ public Collection<Film> search(String query, String by) {
 	public void removeFilm(long filmId) {
 		throw new MethodNotImplementedException();
 	}
+
+	@Override
+	public Collection<Film> getFilmsByIds(Collection<Long> ids) {
+		throw new MethodNotImplementedException();
+	}
 }

src/main/java/ru/yandex/practicum/filmorate/service/FilmService.java

@@ -354,4 +354,18 @@ public Collection<FilmDto> search(String query, String by) {
 				))
 				.toList();
 	}
+
+	public Collection<FilmDto> getFilmsByIds(Collection<Long> ids) {
+		if (ids == null || ids.isEmpty()) {
+			return Collections.emptyList();
+		}
+		return filmStorage.getFilmsByIds(ids).stream()
+				.map(film -> FilmMapper.mapToFilmDto(
+						film,
+						mpas.get(film.getMpaId()),
+						getGenresByIds(film.getGenreIds()),
+						getDirectorsByIds(film.getDirectorIds())
+				))
+				.toList();
+	}
 }

src/main/java/ru/yandex/practicum/filmorate/service/ReviewService.java

@@ -18,7 +18,6 @@
 
 import java.util.Collection;
 import java.util.Optional;
-import java.util.stream.Stream;
 
 @Service
 @Slf4j

src/main/java/ru/yandex/practicum/filmorate/service/UserService.java

@@ -206,7 +206,6 @@ private void logUserUpdate(UserUpdateRequest request, User user) {
 		log.info("Данные для обновления: [{}]", updatedData);
 	}
 
-	// Рекомендации
 	public Collection<FilmDto> getRecommendations(long userId) {
 		log.info("Получение рекомендаций для пользователя id={}.", userId);
 		easyCheckUser(userId);
@@ -218,8 +217,7 @@ public Collection<FilmDto> getRecommendations(long userId) {
 			return Collections.emptyList();
 		}
 
-		long similarUserId = -1;
-		int maxOverlap = 0;
+		Map<Long, Integer> similarityMap = new HashMap<>();
 
 		for (Map.Entry<Long, Set<Long>> entry : allLikes.entrySet()) {
 			long otherUserId = entry.getKey();
@@ -230,20 +228,33 @@ public Collection<FilmDto> getRecommendations(long userId) {
 					.filter(otherUserLikes::contains)
 					.count();
 
-			if (overlap > maxOverlap) {
-				maxOverlap = overlap;
-				similarUserId = otherUserId;
+			if (overlap > 0) {
+				similarityMap.put(otherUserId, overlap);
 			}
 		}
 
-		if (similarUserId == -1) {
+		if (similarityMap.isEmpty()) {
 			return Collections.emptyList();
 		}
 
-		Set<Long> similarUserLikes = allLikes.get(similarUserId);
-		return similarUserLikes.stream()
-				.filter(filmId -> !targetUserLikes.contains(filmId))
-				.map(filmService::findById)
+		List<Long> similarUserIds = similarityMap.entrySet().stream()
+				.sorted(Map.Entry.<Long, Integer>comparingByValue().reversed())
+				.limit(15)
+				.map(Map.Entry::getKey)
 				.collect(Collectors.toList());
+
+		Set<Long> recommendedFilmIds = new HashSet<>();
+		for (Long simId : similarUserIds) {
+			Set<Long> likedBySimilarUser = allLikes.get(simId);
+			likedBySimilarUser.stream()
+					.filter(filmId -> !targetUserLikes.contains(filmId))
+					.forEach(recommendedFilmIds::add);
+		}
+
+		if (recommendedFilmIds.isEmpty()) {
+			return Collections.emptyList();
+		}
+
+		return filmService.getFilmsByIds(recommendedFilmIds);
 	}
 }