[feat/#104] 문항 썸네일 조회 api

src/main/java/com/moplus/moplus_server/client/problem/controller/ProblemGetController.java

@@ -3,6 +3,7 @@
 import com.moplus.moplus_server.client.problem.dto.response.AllProblemGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ChildProblemClientGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ProblemClientGetResponse;
+import com.moplus.moplus_server.client.problem.dto.response.ProblemThumbnailResponse;
 import com.moplus.moplus_server.client.problem.dto.response.PublishClientGetResponse;
 import com.moplus.moplus_server.client.problem.service.ProblemsGetService;
 import com.moplus.moplus_server.global.annotation.AuthUser;
@@ -65,4 +66,13 @@ public ResponseEntity<ChildProblemClientGetResponse> getChildProblem(
         return ResponseEntity.ok(
                 problemsGetService.getChildProblem(member.getId(), publishId, problemId, childProblemId));
     }
+
+    @GetMapping("problem/thumbnail/{publishId}/{number}")
+    @Operation(summary = "문항 썸네일 조회", description = "바로 풀어보기/단계별로 풀어보기 화면에서 필요한 문항을 조회합니다.")
+    public ResponseEntity<ProblemThumbnailResponse> getProblemThumbnail(
+            @PathVariable Long publishId,
+            @PathVariable int number
+    ) {
+        return ResponseEntity.ok(problemsGetService.getProblemThumbnail(publishId, number));
+    }
 }

src/main/java/com/moplus/moplus_server/client/problem/dto/response/ProblemThumbnailResponse.java

@@ -0,0 +1,21 @@
+package com.moplus.moplus_server.client.problem.dto.response;
+
+import com.moplus.moplus_server.domain.problem.domain.problem.Problem;
+import lombok.Builder;
+
+@Builder
+public record ProblemThumbnailResponse(
+        int number,
+        String imageUrl,
+        Integer recommendedMinute,
+        Integer recommendedSecond
+) {
+    public static ProblemThumbnailResponse of(int number, Problem problem) {
+        return ProblemThumbnailResponse.builder()
+                .number(number)
+                .imageUrl(problem.getMainProblemImageUrl())
+                .recommendedMinute(problem.getRecommendedTime().getMinute())
+                .recommendedSecond(problem.getRecommendedTime().getSecond())
+                .build();
+    }
+}

src/main/java/com/moplus/moplus_server/client/problem/service/ProblemsGetService.java

@@ -6,6 +6,7 @@
 import com.moplus.moplus_server.client.problem.dto.response.ChildProblemClientGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ProblemClientGetResponse;
 import com.moplus.moplus_server.client.problem.dto.response.ProblemFeedProgressesGetResponse;
+import com.moplus.moplus_server.client.problem.dto.response.ProblemThumbnailResponse;
 import com.moplus.moplus_server.client.problem.dto.response.PublishClientGetResponse;
 import com.moplus.moplus_server.client.submit.domain.ChildProblemSubmit;
 import com.moplus.moplus_server.client.submit.domain.ChildProblemSubmitStatus;
@@ -214,4 +215,25 @@ private ProblemFeedProgressesGetResponse getProblemStatus(Long memberId, Long pu
 
         return ProblemFeedProgressesGetResponse.of(problemStatus, childProblemStatuses, number);
     }
+
+    @Transactional(readOnly = true)
+    public ProblemThumbnailResponse getProblemThumbnail(Long publishId, int number) {
+        // 발행 조회
+        Publish publish = publishRepository.findByIdElseThrow(publishId);
+        denyAccessToFuturePublish(publish);
+
+        // 문항 세트 조회
+        ProblemSet problemSet = problemSetRepository.findByIdElseThrow(publish.getProblemSetId());
+        List<Long> problemIds = problemSet.getProblemIds();
+
+        int index = number - 1;
+        if (index < 0 || index >= problemIds.size()) {
+            throw new NotFoundException(ErrorCode.PROBLEM_NUMBER_NOT_FOUND);
+        }
+
+        //문항 조회
+        Long problemId = problemIds.get(index);
+        Problem problem = problemRepository.findByIdElseThrow(problemId);
+        return ProblemThumbnailResponse.of(number, problem);
+    }
 }

src/main/java/com/moplus/moplus_server/global/error/exception/ErrorCode.java

@@ -35,6 +35,7 @@ public enum ErrorCode {
     INVALID_CONFIRM_PROBLEM(HttpStatus.BAD_REQUEST, "유효하지 않은 문항들 : "),
     INVALID_DIFFICULTY(HttpStatus.BAD_REQUEST, "난이도는 1~10 사이의 숫자여야 합니다"),
     PROBLEM_NOT_FOUND_IN_PROBLEM_SET(HttpStatus.NOT_FOUND, "해당 날짜에 발행된 문항세트에 존재하는 문항이 아닙니다."),
+    PROBLEM_NUMBER_NOT_FOUND(HttpStatus.NOT_FOUND, "번호에 해당하는 문항을 찾을 수 없습니다."),
 
     //새끼 문항
     CHILD_PROBLEM_NOT_FOUND(HttpStatus.NOT_FOUND, "해당 새끼 문제를 찾을 수 없습니다"),