[BE] refactor: 꿀조합 랭킹 알고리즘 개선

backend/src/main/java/com/funeat/recipe/application/RecipeService.java

@@ -1,10 +1,5 @@
 package com.funeat.recipe.application;
 
-import static com.funeat.member.exception.MemberErrorCode.MEMBER_DUPLICATE_FAVORITE;
-import static com.funeat.member.exception.MemberErrorCode.MEMBER_NOT_FOUND;
-import static com.funeat.product.exception.ProductErrorCode.PRODUCT_NOT_FOUND;
-import static com.funeat.recipe.exception.RecipeErrorCode.RECIPE_NOT_FOUND;
-
 import com.funeat.common.ImageUploader;
 import com.funeat.common.dto.PageDto;
 import com.funeat.member.domain.Member;
@@ -36,23 +31,29 @@
 import com.funeat.recipe.exception.RecipeException.RecipeNotFoundException;
 import com.funeat.recipe.persistence.RecipeImageRepository;
 import com.funeat.recipe.persistence.RecipeRepository;
-import java.util.List;
-import java.util.Objects;
-import java.util.stream.Collectors;
 import org.springframework.dao.DataIntegrityViolationException;
 import org.springframework.data.domain.Page;
-import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Pageable;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.web.multipart.MultipartFile;
 
+import java.util.Comparator;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+import static com.funeat.member.exception.MemberErrorCode.MEMBER_DUPLICATE_FAVORITE;
+import static com.funeat.member.exception.MemberErrorCode.MEMBER_NOT_FOUND;
+import static com.funeat.product.exception.ProductErrorCode.PRODUCT_NOT_FOUND;
+import static com.funeat.recipe.exception.RecipeErrorCode.RECIPE_NOT_FOUND;
+
 @Service
 @Transactional(readOnly = true)
 public class RecipeService {
 
-    private static final int THREE = 3;
-    private static final int TOP = 0;
+    private static final long RANKING_MINIMUM_FAVORITE_COUNT = 1L;
+    private static final int RANKING_SIZE = 3;
 
     private final MemberRepository memberRepository;
     private final ProductRepository productRepository;
@@ -190,9 +191,11 @@ public SearchRecipeResultsResponse getSearchResults(final String query, final Pa
     }
 
     public RankingRecipesResponse getTop3Recipes() {
-        final List<Recipe> recipes = recipeRepository.findRecipesByOrderByFavoriteCountDesc(PageRequest.of(TOP, THREE));
+        final List<Recipe> recipes = recipeRepository.findRecipesByFavoriteCountGreaterThanEqual(RANKING_MINIMUM_FAVORITE_COUNT);
 
         final List<RankingRecipeDto> dtos = recipes.stream()
+                .sorted(Comparator.comparing(Recipe::calculateRankingScore).reversed())
+                .limit(RANKING_SIZE)
                 .map(recipe -> {
                     final List<RecipeImage> findRecipeImages = recipeImageRepository.findByRecipe(recipe);
                     final RecipeAuthorDto author = RecipeAuthorDto.toDto(recipe.getMember());

backend/src/main/java/com/funeat/recipe/domain/Recipe.java

@@ -1,7 +1,7 @@
 package com.funeat.recipe.domain;
 
 import com.funeat.member.domain.Member;
-import java.time.LocalDateTime;
+
 import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.FetchType;
@@ -10,10 +10,14 @@
 import javax.persistence.Id;
 import javax.persistence.JoinColumn;
 import javax.persistence.ManyToOne;
+import java.time.LocalDateTime;
+import java.time.temporal.ChronoUnit;
 
 @Entity
 public class Recipe {
 
+    private static final double RANKING_GRAVITY = 0.1;
+
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
@@ -48,6 +52,21 @@ public Recipe(final String title, final String content, final Member member,
         this.favoriteCount = favoriteCount;
     }
 
+    public Recipe(final String title, final String content, final Member member, final Long favoriteCount,
+                  final LocalDateTime createdAt) {
+        this.title = title;
+        this.content = content;
+        this.member = member;
+        this.favoriteCount = favoriteCount;
+        this.createdAt = createdAt;
+    }
+
+    public Double calculateRankingScore() {
+        final long age = ChronoUnit.DAYS.between(createdAt, LocalDateTime.now());
+        final double denominator = Math.pow(age + 1.0, RANKING_GRAVITY);
+        return favoriteCount / denominator;
+    }
+
     public void addFavoriteCount() {
         this.favoriteCount++;
     }

backend/src/main/java/com/funeat/recipe/persistence/RecipeRepository.java

@@ -1,19 +1,20 @@
 package com.funeat.recipe.persistence;
 
-import static javax.persistence.LockModeType.PESSIMISTIC_WRITE;
-
 import com.funeat.member.domain.Member;
 import com.funeat.product.domain.Product;
 import com.funeat.recipe.domain.Recipe;
-import java.util.List;
-import java.util.Optional;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Lock;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;
 
+import java.util.List;
+import java.util.Optional;
+
+import static javax.persistence.LockModeType.PESSIMISTIC_WRITE;
+
 public interface RecipeRepository extends JpaRepository<Recipe, Long> {
 
     @Query("SELECT r FROM Recipe r "
@@ -37,4 +38,6 @@ public interface RecipeRepository extends JpaRepository<Recipe, Long> {
     @Lock(PESSIMISTIC_WRITE)
     @Query("SELECT r FROM Recipe r WHERE r.id=:id")
     Optional<Recipe> findByIdForUpdate(final Long id);
+
+    List<Recipe> findRecipesByFavoriteCountGreaterThanEqual(final Long favoriteCount);
 }

backend/src/test/java/com/funeat/fixture/RecipeFixture.java

@@ -6,6 +6,8 @@
 import com.funeat.recipe.domain.RecipeImage;
 import com.funeat.recipe.dto.RecipeCreateRequest;
 import com.funeat.recipe.dto.RecipeFavoriteRequest;
+
+import java.time.LocalDateTime;
 import java.util.List;
 
 @SuppressWarnings("NonAsciiCharacters")
@@ -33,6 +35,11 @@ public class RecipeFixture {
         return new Recipe("The most delicious recipes", "More rice, more rice, more rice.. Done!!", member, favoriteCount);
     }
 
+    public static Recipe 레시피_생성(final Member member, final Long favoriteCount, final LocalDateTime createdAt) {
+        return new Recipe("The most delicious recipes", "More rice, more rice, more rice.. Done!!",
+                member, favoriteCount, createdAt);
+    }
+
     public static RecipeFavorite 레시피_좋아요_생성(final Member member, final Recipe recipe, final Boolean favorite) {
         return new RecipeFavorite(member, recipe, favorite);
     }

backend/src/test/java/com/funeat/recipe/application/RecipeServiceTest.java

@@ -1,5 +1,32 @@
 package com.funeat.recipe.application;
 
+import com.funeat.common.ServiceTest;
+import com.funeat.common.dto.PageDto;
+import com.funeat.member.domain.Member;
+import com.funeat.member.dto.MemberRecipeDto;
+import com.funeat.member.dto.MemberRecipeProductDto;
+import com.funeat.member.dto.MemberRecipesResponse;
+import com.funeat.member.exception.MemberException.MemberNotFoundException;
+import com.funeat.product.domain.Category;
+import com.funeat.product.domain.CategoryType;
+import com.funeat.product.domain.Product;
+import com.funeat.product.exception.ProductException.ProductNotFoundException;
+import com.funeat.recipe.dto.RankingRecipeDto;
+import com.funeat.recipe.dto.RankingRecipesResponse;
+import com.funeat.recipe.dto.RecipeAuthorDto;
+import com.funeat.recipe.dto.RecipeCreateRequest;
+import com.funeat.recipe.dto.RecipeDetailResponse;
+import com.funeat.recipe.dto.RecipeDto;
+import com.funeat.recipe.exception.RecipeException.RecipeNotFoundException;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import java.time.LocalDateTime;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
 import static com.funeat.fixture.CategoryFixture.카테고리_간편식사_생성;
 import static com.funeat.fixture.CategoryFixture.카테고리_즉석조리_생성;
 import static com.funeat.fixture.ImageFixture.여러_이미지_생성;
@@ -24,29 +51,6 @@
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.assertj.core.api.SoftAssertions.assertSoftly;
 
-import com.funeat.common.ServiceTest;
-import com.funeat.common.dto.PageDto;
-import com.funeat.member.domain.Member;
-import com.funeat.member.dto.MemberRecipeDto;
-import com.funeat.member.dto.MemberRecipeProductDto;
-import com.funeat.member.dto.MemberRecipesResponse;
-import com.funeat.member.exception.MemberException.MemberNotFoundException;
-import com.funeat.product.domain.Category;
-import com.funeat.product.domain.CategoryType;
-import com.funeat.product.domain.Product;
-import com.funeat.product.exception.ProductException.ProductNotFoundException;
-import com.funeat.recipe.dto.RecipeCreateRequest;
-import com.funeat.recipe.dto.RecipeDetailResponse;
-import com.funeat.recipe.dto.RecipeDto;
-import com.funeat.recipe.exception.RecipeException.RecipeNotFoundException;
-import org.junit.jupiter.api.Nested;
-import org.junit.jupiter.api.Test;
-
-import java.util.Collections;
-import java.util.List;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
 @SuppressWarnings("NonAsciiCharacters")
 class RecipeServiceTest extends ServiceTest {
 
@@ -545,6 +549,135 @@ class likeRecipe_실패_테스트 {
         }
     }
 
+    @Nested
+    class getTop3Recipes_성공_테스트 {
+
+        @Nested
+        class 꿀조합_개수에_대한_테스트 {
+
+            @Test
+            void 전체_꿀조합이_하나도_없어도_반환값은_있어야한다() {
+                // given
+                final var expected = RankingRecipesResponse.toResponse(Collections.emptyList());
+
+                // when
+                final var actual = recipeService.getTop3Recipes();
+
+                // then
+                assertThat(actual).usingRecursiveComparison()
+                        .isEqualTo(expected);
+            }
+
+            @Test
+            void 전체_꿀조합이_1개_이상_3개_미만이라도_꿀조합이_나와야한다() {
+                // given
+                final var member = 멤버_멤버1_생성();
+                단일_멤버_저장(member);
+
+                final var now = LocalDateTime.now();
+                final var recipe1 = 레시피_생성(member, 2L, now.minusDays(1L));
+                final var recipe2 = 레시피_생성(member, 2L, now);
+                복수_꿀조합_저장(recipe1, recipe2);
+
+                final var author = RecipeAuthorDto.toDto(member);
+                final var rankingRecipeDto1 = RankingRecipeDto.toDto(recipe1, Collections.emptyList(), author);
+                final var rankingRecipeDto2 = RankingRecipeDto.toDto(recipe2, Collections.emptyList(), author);
+                final var rankingRecipesDtos = List.of(rankingRecipeDto2, rankingRecipeDto1);
+                final var expected = RankingRecipesResponse.toResponse(rankingRecipesDtos);
+
+                // when
+                final var actual = recipeService.getTop3Recipes();
+
+                // then
+                assertThat(actual).usingRecursiveComparison()
+                        .isEqualTo(expected);
+            }
+
+            @Test
+            void 전체_꿀조합_중_랭킹이_높은_상위_3개_꿀조합을_구할_수_있다() {
+                // given
+                final var member = 멤버_멤버1_생성();
+                단일_멤버_저장(member);
+
+                final var now = LocalDateTime.now();
+                final var recipe1 = 레시피_생성(member, 4L, now.minusDays(10L));
+                final var recipe2 = 레시피_생성(member, 6L, now.minusDays(10L));
+                final var recipe3 = 레시피_생성(member, 5L, now);
+                final var recipe4 = 레시피_생성(member, 6L, now);
+                복수_꿀조합_저장(recipe1, recipe2, recipe3, recipe4);
+
+                final var author = RecipeAuthorDto.toDto(member);
+                final var rankingRecipeDto1 = RankingRecipeDto.toDto(recipe1, Collections.emptyList(), author);
+                final var rankingRecipeDto2 = RankingRecipeDto.toDto(recipe2, Collections.emptyList(), author);
+                final var rankingRecipeDto3 = RankingRecipeDto.toDto(recipe3, Collections.emptyList(), author);
+                final var rankingRecipeDto4 = RankingRecipeDto.toDto(recipe4, Collections.emptyList(), author);
+                final var rankingRecipesDtos = List.of(rankingRecipeDto4, rankingRecipeDto3, rankingRecipeDto2);
+                final var expected = RankingRecipesResponse.toResponse(rankingRecipesDtos);
+
+                // when
+                final var actual = recipeService.getTop3Recipes();
+
+                // then
+                assertThat(actual).usingRecursiveComparison()
+                        .isEqualTo(expected);
+            }
+        }
+
+        @Nested
+        class 꿀조합_랭킹_점수에_대한_테스트 {
+
+            @Test
+            void 꿀조합_좋아요_수가_같으면_최근_생성된_꿀조합의_랭킹을_더_높게_반환한다() {
+                // given
+                final var member = 멤버_멤버1_생성();
+                단일_멤버_저장(member);
+
+                final var now = LocalDateTime.now();
+                final var recipe1 = 레시피_생성(member, 10L, now.minusDays(9L));
+                final var recipe2 = 레시피_생성(member, 10L, now.minusDays(4L));
+                복수_꿀조합_저장(recipe1, recipe2);
+
+                final var author = RecipeAuthorDto.toDto(member);
+                final var rankingRecipeDto1 = RankingRecipeDto.toDto(recipe1, Collections.emptyList(), author);
+                final var rankingRecipeDto2 = RankingRecipeDto.toDto(recipe2, Collections.emptyList(), author);
+                final var rankingRecipesDtos = List.of(rankingRecipeDto2, rankingRecipeDto1);
+                final var expected = RankingRecipesResponse.toResponse(rankingRecipesDtos);
+
+                // when
+                final var actual = recipeService.getTop3Recipes();
+
+                // then
+                assertThat(actual).usingRecursiveComparison()
+                        .isEqualTo(expected);
+            }
+
+            @Test
+            void 꿀조합_생성_일자가_같으면_좋아요_수가_많은_꿀조합의_랭킹을_더_높게_반환한다() {
+                // given
+                final var member = 멤버_멤버1_생성();
+                단일_멤버_저장(member);
+
+                final var now = LocalDateTime.now();
+                final var recipe1 = 레시피_생성(member, 2L, now.minusDays(1L));
+                final var recipe2 = 레시피_생성(member, 4L, now.minusDays(1L));
+                복수_꿀조합_저장(recipe1, recipe2);
+
+                final var author = RecipeAuthorDto.toDto(member);
+                final var rankingRecipeDto1 = RankingRecipeDto.toDto(recipe1, Collections.emptyList(), author);
+                final var rankingRecipeDto2 = RankingRecipeDto.toDto(recipe2, Collections.emptyList(), author);
+                final var rankingRecipesDtos = List.of(rankingRecipeDto2, rankingRecipeDto1);
+                final var expected = RankingRecipesResponse.toResponse(rankingRecipesDtos);
+
+                // when
+                final var actual = recipeService.getTop3Recipes();
+
+                // then
+                assertThat(actual).usingRecursiveComparison()
+                        .isEqualTo(expected);
+            }
+        }
+    }
+
     private <T> void 해당멤버의_꿀조합과_페이징_결과를_검증한다(final MemberRecipesResponse actual, final List<T> expectedRecipesDtos,
                                              final PageDto expectedPage) {
         assertSoftly(soft -> {

backend/src/test/java/com/funeat/recipe/domain/RecipeTest.java

@@ -0,0 +1,37 @@
+package com.funeat.recipe.domain;
+
+import org.junit.jupiter.api.DisplayNameGeneration;
+import org.junit.jupiter.api.DisplayNameGenerator;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import java.time.LocalDateTime;
+
+import static com.funeat.fixture.MemberFixture.멤버_멤버1_생성;
+import static com.funeat.fixture.RecipeFixture.레시피_생성;
+import static org.assertj.core.api.Assertions.assertThat;
+
+@SuppressWarnings("NonAsciiCharacters")
+@DisplayNameGeneration(DisplayNameGenerator.ReplaceUnderscores.class)
+class RecipeTest {
+
+    @Nested
+    class calculateRankingScore_성공_테스트 {
+
+        @Test
+        void 꿀조합_좋아요_수와_꿀조합_생성_시간으로_해당_꿀조합의_랭킹_점수를_구할_수_있다() {
+            // given
+            final var member = 멤버_멤버1_생성();
+            final var favoriteCount = 4L;
+            final var recipe = 레시피_생성(member, favoriteCount, LocalDateTime.now().minusDays(1L));
+
+            final var expected = favoriteCount / Math.pow(2.0, 0.1);
+
+            // when
+            final var actual = recipe.calculateRankingScore();
+
+            // then
+            assertThat(actual).isEqualTo(expected);
+        }
+    }
+}