refactor : category 리팩토링

src/main/java/org/ezcode/codetest/application/problem/dto/request/ProblemCreateRequest.java

@@ -1,5 +1,7 @@
 package org.ezcode.codetest.application.problem.dto.request;
 
+import java.util.List;
+
 import org.ezcode.codetest.domain.problem.model.entity.Problem;
 import org.ezcode.codetest.domain.problem.model.enums.Category;
 import org.ezcode.codetest.domain.problem.model.enums.Difficulty;
@@ -14,7 +16,7 @@ public record ProblemCreateRequest(
 
 	@NotNull(message = "카테고리를 설정해야 합니다.")
 	@Schema(description = "카테고리", example = "FOR_BEGINNER")
-	Category category,
+	List<Category> categories,
 
 	@NotBlank(message = "문제 제목을 입력하세요.")
 	@Schema(description = "제목", example = "A+B")
@@ -47,7 +49,7 @@ public static Problem toEntity(ProblemCreateRequest request, User user) {
 
 		return Problem.builder()
 			.creator(user)
-			.category(request.category)
+			.categories(request.categories)
 			.title(request.title)
 			.description(request.description)
 			.difficulty(request.difficulty.getDifficulty())

src/main/java/org/ezcode/codetest/application/problem/dto/request/ProblemUpdateRequest.java

@@ -1,5 +1,7 @@
 package org.ezcode.codetest.application.problem.dto.request;
 
+import java.util.List;
+
 import org.ezcode.codetest.domain.problem.model.entity.Problem;
 import org.ezcode.codetest.domain.problem.model.enums.Category;
 import org.ezcode.codetest.domain.problem.model.enums.Difficulty;
@@ -11,7 +13,7 @@
 public record ProblemUpdateRequest(
 
 	@Schema(description = "카테고리", example = "FOR_BEGINNER")
-	Category category,
+	List<Category> categories,
 
 	@Schema(description = "제목", example = "A+B")
 	String title,
@@ -37,7 +39,7 @@ public static Problem from(ProblemUpdateRequest request, User user) {
 
 		return Problem.builder()
 			.creator(user)
-			.category(request.category)
+			.categories(request.categories)
 			.title(request.title)
 			.description(request.description)
 			.difficulty(request.difficulty.getDifficulty())

src/main/java/org/ezcode/codetest/application/problem/dto/response/ProblemDetailResponse.java

@@ -1,6 +1,7 @@
 package org.ezcode.codetest.application.problem.dto.response;
 
 import java.time.LocalDateTime;
+import java.util.List;
 
 import org.ezcode.codetest.domain.problem.model.entity.Problem;
 import org.ezcode.codetest.domain.problem.model.enums.Category;
@@ -19,7 +20,7 @@ public record ProblemDetailResponse(
 	String creator,
 
 	@Schema(description = "카테고리", example = "FOR_BEGINNER")
-	Category category,
+	List<Category> categories,
 
 	@Schema(description = "제목", example = "A+B")
 	String title,
@@ -55,7 +56,7 @@ public static ProblemDetailResponse from(Problem problem) {
 		return ProblemDetailResponse.builder()
 			.id(problem.getId())
 			.creator(problem.getCreator().getNickname())
-			.category(problem.getCategory())
+			.categories(problem.getCategories())
 			.title(problem.getTitle())
 			.description(problem.getDescription())
 			.score(problem.getScore())

src/main/java/org/ezcode/codetest/application/problem/dto/response/ProblemResponse.java

@@ -1,5 +1,7 @@
 package org.ezcode.codetest.application.problem.dto.response;
 
+import java.util.List;
+
 import org.ezcode.codetest.domain.problem.model.entity.Problem;
 import org.ezcode.codetest.domain.problem.model.enums.Category;
 import org.ezcode.codetest.domain.problem.model.enums.Reference;
@@ -17,7 +19,7 @@ public record ProblemResponse(
 	String creator,
 
 	@Schema(description = "카테고리", example = "FOR_BEGINNER")
-	Category category,
+	List<Category> categories,
 
 	@Schema(description = "제목", example = "A+B")
 	String title,
@@ -42,7 +44,7 @@ public static ProblemResponse from(Problem problem) {
 		return ProblemResponse.builder()
 			.id(problem.getId())
 			.creator(problem.getCreator() != null ? problem.getCreator().getNickname() : "존재하지 않는 이름.")
-			.category(problem.getCategory())
+			.categories(problem.getCategories())
 			.title(problem.getTitle())
 			.score(problem.getScore())
 			.difficulty(problem.getDifficulty())

src/main/java/org/ezcode/codetest/application/problem/dto/response/ProblemSearchResponse.java

@@ -27,7 +27,7 @@ public static ProblemSearchResponse from(ProblemSearchDocument document) {
 		return ProblemSearchResponse.builder()
 			.id(document.getId())
 			.title(document.getTitle())
-			.category(document.getCategory().toString())
+			.category(document.getCategories().toString())
 			.difficulty(document.getDifficulty())
 			.reference(document.getReference().toString())
 			.description(document.getDescription())

src/main/java/org/ezcode/codetest/application/problem/service/ProblemSearchService.java

@@ -1,5 +1,6 @@
 package org.ezcode.codetest.application.problem.service;
 
+import java.util.Collection;
 import java.util.List;
 import java.util.Optional;
 import java.util.Set;
@@ -21,20 +22,39 @@ public class ProblemSearchService {
 
 	public Set<String> getProblemSuggestions(String keyword) {
 
-		Set<ProblemSearchDocument> result = searchDomainService.getSuggestionsByKeyword(keyword);
-
-		return result.stream()
-			.flatMap(doc -> Stream.of(
-				Optional.ofNullable(doc.getTitle()),
-				Optional.ofNullable(doc.getReference()).map(Enum::toString),
-				Optional.ofNullable(doc.getDifficulty()),
-				Optional.ofNullable(doc.getCategory()).map(Enum::toString),
-				Optional.ofNullable(doc.getDescription()),
-				Optional.ofNullable(doc.getCategoryKor()),
-				Optional.ofNullable(doc.getDifficultyEn()).map(Enum::toString),
+		return searchDomainService
+			.getSuggestionsByKeyword(keyword)
+			.stream()
+			.flatMap(doc -> {
+				Stream.Builder<String> searchedKeyword = Stream.builder();
+
+				Optional.ofNullable(doc.getTitle()).ifPresent(searchedKeyword::add);
+				Optional.ofNullable(doc.getReference())
+					.map(Enum::toString)
+					.ifPresent(searchedKeyword::add);
+				Optional.ofNullable(doc.getDifficulty())
+					.ifPresent(searchedKeyword::add);
+				Optional.ofNullable(doc.getDescription())
+					.ifPresent(searchedKeyword::add);
+				Optional.ofNullable(doc.getDifficultyEn())
+					.map(Enum::toString)
+					.ifPresent(searchedKeyword::add);
 				Optional.ofNullable(doc.getReferenceKor())
-			))
-			.flatMap(Optional::stream)
+					.ifPresent(searchedKeyword::add);
+
+				Optional.ofNullable(doc.getCategories())
+					.stream()
+					.flatMap(Collection::stream)
+					.map(Enum::toString)
+					.forEach(searchedKeyword::add);
+
+				Optional.ofNullable(doc.getCategoriesKor())
+					.stream()
+					.flatMap(Collection::stream)
+					.forEach(searchedKeyword::add);
+
+				return searchedKeyword.build();
+			})
 			.map(String::toUpperCase)
 			.collect(Collectors.toSet());
 	}

src/main/java/org/ezcode/codetest/application/problem/service/ProblemService.java

@@ -75,7 +75,7 @@ public ProblemDetailResponse modifyProblem(Long problemId, ProblemUpdateRequest
 
 		findProblem.update(
 			findProblem.getCreator(),
-			request.category(),
+			request.categories(),
 			request.title(),
 			request.description(),
 			request.difficulty(),

src/main/java/org/ezcode/codetest/domain/game/service/CharacterStatusDomainService.java

@@ -5,6 +5,7 @@
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.ThreadLocalRandom;
 import java.util.stream.Stream;
 
 import org.ezcode.codetest.domain.game.exception.GameException;
@@ -56,12 +57,14 @@ public GameCharacter getGameCharacter(Long userId) {
 			.orElseThrow(() -> new GameException(GameExceptionCode.CHARACTER_NOT_FOUND));
 	}
 
-	public void gameCharacterLevelUp(Long userId, boolean isProblemSolved, String problemCategory) {
+	public void gameCharacterLevelUp(Long userId, boolean isProblemSolved, List<String> problemCategory) {
 
 		if (!isProblemSolved)
 			return;
 
-		Map<Stat, Double> increaseStatRate = statUpdateUtil.getStatIncreasePerProblem(problemCategory);
+		int randomIndex = ThreadLocalRandom.current().nextInt(problemCategory.size());
+
+		Map<Stat, Double> increaseStatRate = statUpdateUtil.getStatIncreasePerProblem(problemCategory.get(randomIndex));
 
 		GameCharacter character = characterRepository.findByUserId(userId)
 			.orElseThrow(() -> new GameException(GameExceptionCode.CHARACTER_NOT_FOUND));

src/main/java/org/ezcode/codetest/domain/problem/model/entity/Problem.java

@@ -10,6 +10,7 @@
 import org.ezcode.codetest.domain.user.model.entity.User;
 
 import jakarta.persistence.CascadeType;
+import jakarta.persistence.CollectionTable;
 import jakarta.persistence.Column;
 import jakarta.persistence.ElementCollection;
 import jakarta.persistence.Entity;
@@ -40,10 +41,6 @@ public class Problem extends BaseEntity {
 	@JoinColumn(name = "creator_id", nullable = false)
 	private User creator;
 
-	@Enumerated(EnumType.STRING)
-	@Column(nullable = false)
-	private Category category;
-
 	@Column(nullable = false)
 	private String title;
 
@@ -81,11 +78,21 @@ public class Problem extends BaseEntity {
 	@ElementCollection(fetch = FetchType.LAZY)
 	private List<String> imageUrl = new ArrayList<>();
 
+	@ElementCollection(fetch = FetchType.LAZY)
+	@CollectionTable(
+		name = "problem_categories",
+		joinColumns = @JoinColumn(name = "problem_id")
+	)
+	@Column(name = "category")
+	@Enumerated(EnumType.STRING)
+	private List<Category> categories = new ArrayList<>();
+
 	@Builder
-	public Problem(User creator, Category category, String title, String description, int score, String difficulty,
+	public Problem(User creator, List<Category> categories, String title, String description, int score,
+		String difficulty,
 		Long memoryLimit, Long timeLimit, Reference reference) {
 		this.creator = creator;
-		this.category = category;
+		this.categories = categories;
 		this.title = title;
 		this.description = description;
 		this.score = score;
@@ -99,12 +106,13 @@ public Problem(User creator, Category category, String title, String description
 	}
 
 	// 여러개를 하나의 객체로 만드는 것
-	public static Problem of(User creator, Category category, String title, String description, int score, String difficulty,
+	public static Problem of(User creator, List<Category> categories, String title, String description, int score,
+		String difficulty,
 		Long memoryLimit, Long timeLimit, Reference reference) {
 
 		return Problem.builder()
 			.creator(creator)
-			.category(category)
+			.categories(categories)
 			.title(title)
 			.description(description)
 			.score(score)
@@ -116,20 +124,27 @@ public static Problem of(User creator, Category category, String title, String d
 	}
 
 	// 문제 수정 로직
-	public void update(User creator, Category category, String title, String description, Difficulty difficulty,
+	public void update(User creator, List<Category> categories, String title, String description, Difficulty difficulty,
 		Long memoryLimit, Long timeLimit, Reference reference) {
 
-		if (creator != null) this.creator = creator;
-		if (category != null) this.category = category;
-		if (title != null) this.title = title;
-		if (description != null) this.description = description;
+		if (creator != null)
+			this.creator = creator;
+		if (categories != null)
+			this.categories = categories;
+		if (title != null)
+			this.title = title;
+		if (description != null)
+			this.description = description;
 		if (difficulty != null) {
 			this.difficulty = difficulty.getDifficulty();
 			this.score = difficulty.getScore();
 		}
-		if (memoryLimit != null)this.memoryLimit = memoryLimit;
-		if (timeLimit != null) this.timeLimit = timeLimit;
-		if (reference != null) this.reference = reference;
+		if (memoryLimit != null)
+			this.memoryLimit = memoryLimit;
+		if (timeLimit != null)
+			this.timeLimit = timeLimit;
+		if (reference != null)
+			this.reference = reference;
 	}
 
 	public void softDelete() {
@@ -145,7 +160,6 @@ public void addImage(String image) {
 		if (imageUrl.contains(image)) {
 			return; // 중복된 URL 무시
 		}
-
 		imageUrl.add(image);
 	}
 

src/main/java/org/ezcode/codetest/domain/problem/model/entity/ProblemSearchDocument.java

@@ -1,5 +1,7 @@
 package org.ezcode.codetest.domain.problem.model.entity;
 
+import java.util.*;
+
 import org.ezcode.codetest.domain.problem.model.enums.Category;
 import org.ezcode.codetest.domain.problem.model.enums.Difficulty;
 import org.ezcode.codetest.domain.problem.model.enums.Reference;
@@ -56,7 +58,7 @@ public class ProblemSearchDocument {
 			)
 		}
 	)
-	private Category category;
+	private List<Category> categories;
 
 	@MultiField(
 		mainField = @Field(
@@ -71,7 +73,7 @@ public class ProblemSearchDocument {
 			)
 		}
 	)
-	private String categoryKor;
+	private List<String> categoriesKor;
 
 	@MultiField(
 		mainField = @Field(
@@ -153,23 +155,23 @@ public class ProblemSearchDocument {
 	public ProblemSearchDocument(
 		Long id,
 		String title,
-		Category category,
+		List<Category> categories,
 		String difficulty,
 		Reference reference,
 		String description,
-		String categoryKor,
+		List<String> categoriesKor,
 		Difficulty difficultyEn,
 		String referenceKor,
 		int score,
 		Boolean isDeleted
 	) {
 		this.id = id;
 		this.title = title;
-		this.category = category;
+		this.categories = categories;
 		this.difficulty = difficulty;
 		this.reference = reference;
 		this.description = description;
-		this.categoryKor = categoryKor;
+		this.categoriesKor = categoriesKor;
 		this.difficultyEn = difficultyEn;
 		this.referenceKor = referenceKor;
 		this.score = score;
@@ -180,12 +182,12 @@ public static ProblemSearchDocument from(Problem problem) {
 		return ProblemSearchDocument.builder()
 			.id(problem.getId())
 			.title(problem.getTitle())
-			.category(problem.getCategory())
+			.categories(problem.getCategories())
 			.difficulty(problem.getDifficulty())
 			.reference(problem.getReference())
 			.description(problem.getDescription())
 			.score(problem.getScore())
-			.categoryKor(problem.getCategory().getDescription())
+			.categoriesKor(problem.getCategories().stream().map(Category::getDescription).toList())
 			.difficultyEn(Difficulty.getDifficultyFromKor(problem.getDifficulty()))
 			.referenceKor(problem.getReference().getDescription())
 			.isDeleted(problem.getIsDeleted())
@@ -199,7 +201,7 @@ public void softDelete() {
 	public void update(Problem problem) {
 		if (problem.getId().equals(this.id)) {
 			this.title = problem.getTitle();
-			this.category = problem.getCategory();
+			this.categories = problem.getCategories();
 			this.difficulty = problem.getDifficulty();
 			this.reference = problem.getReference();
 			this.description = problem.getDescription();