[feat] 유저 닉네임을 통해 랭킹 조회

backend/src/main/java/io/f1/backend/domain/stat/api/StatController.java

@@ -11,6 +11,7 @@
 import org.springframework.data.web.PageableDefault;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
@@ -29,4 +30,13 @@ public ResponseEntity<StatPageResponse> getRankings(
 
         return ResponseEntity.ok().body(response);
     }
+
+    @LimitPageSize
+    @GetMapping("/rankings/{nickname}")
+    public ResponseEntity<StatPageResponse> getRankingsByNickname(
+            @PathVariable String nickname, @PageableDefault Pageable pageable) {
+        StatPageResponse response =
+                statService.getRanksByNickname(nickname, pageable.getPageSize());
+        return ResponseEntity.ok().body(response);
+    }
 }

backend/src/main/java/io/f1/backend/domain/stat/app/StatService.java

@@ -5,21 +5,49 @@
 import io.f1.backend.domain.stat.dao.StatRepository;
 import io.f1.backend.domain.stat.dto.StatPageResponse;
 import io.f1.backend.domain.stat.dto.StatWithNickname;
+import io.f1.backend.global.exception.CustomException;
+import io.f1.backend.global.exception.errorcode.RoomErrorCode;
 
 import lombok.RequiredArgsConstructor;
 
 import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Sort;
+import org.springframework.data.domain.Sort.Direction;
 import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
 
 @Service
 @RequiredArgsConstructor
 public class StatService {
 
     private final StatRepository statRepository;
 
+    @Transactional(readOnly = true)
     public StatPageResponse getRanks(Pageable pageable) {
-        Page<StatWithNickname> stats = statRepository.findWithUser(pageable);
+        Page<StatWithNickname> stats = statRepository.findAllStatsWithUser(pageable);
         return toStatListPageResponse(stats);
     }
+
+    @Transactional(readOnly = true)
+    public StatPageResponse getRanksByNickname(String nickname, int pageSize) {
+
+        Page<StatWithNickname> stats =
+                statRepository.findAllStatsWithUser(getPageableFromNickname(nickname, pageSize));
+
+        return toStatListPageResponse(stats);
+    }
+
+    private Pageable getPageableFromNickname(String nickname, int pageSize) {
+        long score =
+                statRepository
+                        .findScoreByNickname(nickname)
+                        .orElseThrow(() -> new CustomException(RoomErrorCode.PLAYER_NOT_FOUND));
+
+        long rowNum = statRepository.countByScoreGreaterThan(score);
+
+        int pageNumber = rowNum > 0 ? (int) (rowNum / pageSize) : 0;
+        return PageRequest.of(pageNumber, pageSize, Sort.by(Direction.DESC, "score"));
+    }
 }

backend/src/main/java/io/f1/backend/domain/stat/dao/StatRepository.java

@@ -8,6 +8,8 @@
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
 
+import java.util.Optional;
+
 public interface StatRepository extends JpaRepository<Stat, Long> {
 
     @Query(
@@ -18,5 +20,10 @@ public interface StatRepository extends JpaRepository<Stat, Long> {
             FROM
             		Stat s JOIN s.user u
             """)
-    Page<StatWithNickname> findWithUser(Pageable pageable);
+    Page<StatWithNickname> findAllStatsWithUser(Pageable pageable);
+
+    @Query("SELECT s.score FROM Stat s WHERE s.user.nickname = :nickname")
+    Optional<Long> findScoreByNickname(String nickname);
+
+    long countByScoreGreaterThan(Long score);
 }

backend/src/test/java/io/f1/backend/domain/stat/StatBrowserTest.java

@@ -1,6 +1,7 @@
 package io.f1.backend.domain.stat;
 
 import static io.f1.backend.global.exception.errorcode.CommonErrorCode.INVALID_PAGINATION;
+import static io.f1.backend.global.exception.errorcode.RoomErrorCode.PLAYER_NOT_FOUND;
 
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
@@ -35,7 +36,7 @@ void totalRankingForSingleUser() throws Exception {
 
     @Test
     @DisplayName("100을 넘는 페이지 크기 요청이 오면 예외를 발생시킨다")
-    void totalRankingForSingleUserWithInvalidPageSize() throws Exception {
+    void totalRankingWithInvalidPageSize() throws Exception {
         // when
         ResultActions result = mockMvc.perform(get("/stats/rankings").param("size", "101"));
 
@@ -86,4 +87,61 @@ void totalRankingForThreeUserWithPageSize2() throws Exception {
                 jsonPath("$.totalElements").value(1),
                 jsonPath("$.ranks.length()").value(1));
     }
+
+    @Test
+    @DataSet("datasets/stat/three-user-stat.yml")
+    @DisplayName("랭킹 페이지에서 존재하지 않는 닉네임을 검색하면 예외를 발생시킨다.")
+    void totalRankingWithUnregisteredNickname() throws Exception {
+        // given
+        String nickname = "UNREGISTERED";
+
+        // when
+        ResultActions result = mockMvc.perform(get("/stats/rankings/" + nickname));
+
+        // then
+        result.andExpectAll(
+                status().isNotFound(), jsonPath("$.code").value(PLAYER_NOT_FOUND.getCode()));
+    }
+
+    @Test
+    @DataSet("datasets/stat/three-user-stat.yml")
+    @DisplayName("총 유저 수가 3명이고 페이지 크기가 2일 때 1위 유저의 닉네임을 검색하면 첫 번째 페이지에 2개의 결과를 반환한다")
+    void totalRankingForThreeUserWithFirstRankedNickname() throws Exception {
+        // given
+        String nickname = "USER3";
+
+        // when
+        ResultActions result =
+                mockMvc.perform(get("/stats/rankings/" + nickname).param("size", "2"));
+
+        // then
+        result.andExpectAll(
+                status().isOk(),
+                jsonPath("$.totalPages").value(2),
+                jsonPath("$.currentPage").value(1),
+                jsonPath("$.totalElements").value(2),
+                jsonPath("$.ranks.length()").value(2),
+                jsonPath("$.ranks[0].nickname").value(nickname));
+    }
+
+    @Test
+    @DataSet("datasets/stat/three-user-stat.yml")
+    @DisplayName("총 유저 수가 3명이고 페이지 크기가 2일 때 3위 유저의 닉네임을 검색하면 두 번째 페이지에 1개의 결과를 반환한다")
+    void totalRankingForThreeUserWithLastRankedNickname() throws Exception {
+        // given
+        String nickname = "USER1";
+
+        // when
+        ResultActions result =
+                mockMvc.perform(get("/stats/rankings/" + nickname).param("size", "2"));
+
+        // then
+        result.andExpectAll(
+                status().isOk(),
+                jsonPath("$.totalPages").value(2),
+                jsonPath("$.currentPage").value(2),
+                jsonPath("$.totalElements").value(1),
+                jsonPath("$.ranks.length()").value(1),
+                jsonPath("$.ranks[0].nickname").value(nickname));
+    }
 }