feat: 스터디 통계 조회 API 추가

src/main/java/com/gdschongik/gdsc/domain/study/api/MentorStudyDetailController.java

@@ -5,6 +5,7 @@
 import com.gdschongik.gdsc.domain.study.dto.response.AssignmentResponse;
 import com.gdschongik.gdsc.domain.study.dto.response.StudyCurriculumResponse;
 import com.gdschongik.gdsc.domain.study.dto.response.StudyMentorAttendanceResponse;
+import com.gdschongik.gdsc.domain.study.dto.response.StudyStatisticsResponse;
 import io.swagger.v3.oas.annotations.Operation;
 import io.swagger.v3.oas.annotations.tags.Tag;
 import jakarta.validation.Valid;
@@ -80,4 +81,11 @@ public ResponseEntity<List<StudyMentorAttendanceResponse>> getAttendanceNumbers(
         List<StudyMentorAttendanceResponse> response = mentorStudyDetailService.getAttendanceNumbers(studyId);
         return ResponseEntity.ok(response);
     }
+
+    @Operation(summary = "스터디 통계 조회", description = "멘토가 자신의 스터디 출석률, 과제 제출률, 수료율에 대한 통계를 조회합니다. 휴강 주차는 계산에서 제외합니다.")
+    @GetMapping("/statistics")
+    public ResponseEntity<StudyStatisticsResponse> getStudyStatistics(@RequestParam(name = "studyId") Long studyId) {
+        StudyStatisticsResponse response = mentorStudyDetailService.getStudyStatistics(studyId);
+        return ResponseEntity.ok(response);
+    }
 }

src/main/java/com/gdschongik/gdsc/domain/study/application/MentorStudyDetailService.java

@@ -1,15 +1,26 @@
 package com.gdschongik.gdsc.domain.study.application;
 
+import static com.gdschongik.gdsc.domain.study.domain.AssignmentSubmissionStatus.SUCCESS;
+import static com.gdschongik.gdsc.domain.study.dto.response.StudyWeekStatisticsResponse.*;
 import static com.gdschongik.gdsc.global.exception.ErrorCode.*;
 
 import com.gdschongik.gdsc.domain.member.domain.Member;
+import com.gdschongik.gdsc.domain.study.dao.AssignmentHistoryRepository;
+import com.gdschongik.gdsc.domain.study.dao.AttendanceRepository;
 import com.gdschongik.gdsc.domain.study.dao.StudyDetailRepository;
+import com.gdschongik.gdsc.domain.study.dao.StudyHistoryRepository;
+import com.gdschongik.gdsc.domain.study.dao.StudyRepository;
+import com.gdschongik.gdsc.domain.study.domain.Study;
 import com.gdschongik.gdsc.domain.study.domain.StudyDetail;
 import com.gdschongik.gdsc.domain.study.domain.StudyDetailValidator;
+import com.gdschongik.gdsc.domain.study.domain.StudyHistory;
+import com.gdschongik.gdsc.domain.study.domain.StudyValidator;
 import com.gdschongik.gdsc.domain.study.dto.request.AssignmentCreateUpdateRequest;
 import com.gdschongik.gdsc.domain.study.dto.response.AssignmentResponse;
 import com.gdschongik.gdsc.domain.study.dto.response.StudyCurriculumResponse;
 import com.gdschongik.gdsc.domain.study.dto.response.StudyMentorAttendanceResponse;
+import com.gdschongik.gdsc.domain.study.dto.response.StudyStatisticsResponse;
+import com.gdschongik.gdsc.domain.study.dto.response.StudyWeekStatisticsResponse;
 import com.gdschongik.gdsc.global.exception.CustomException;
 import com.gdschongik.gdsc.global.util.MemberUtil;
 import java.time.LocalDate;
@@ -27,6 +38,11 @@ public class MentorStudyDetailService {
     private final MemberUtil memberUtil;
     private final StudyDetailRepository studyDetailRepository;
     private final StudyDetailValidator studyDetailValidator;
+    private final StudyHistoryRepository studyHistoryRepository;
+    private final AttendanceRepository attendanceRepository;
+    private final AssignmentHistoryRepository assignmentHistoryRepository;
+    private final StudyValidator studyValidator;
+    private final StudyRepository studyRepository;
 
     @Transactional(readOnly = true)
     public List<AssignmentResponse> getWeeklyAssignments(Long studyId) {
@@ -108,4 +124,89 @@ public List<StudyMentorAttendanceResponse> getAttendanceNumbers(Long studyId) {
                 .limit(2)
                 .toList();
     }
+
+    @Transactional(readOnly = true)
+    public StudyStatisticsResponse getStudyStatistics(Long studyId) {
+        Member currentMember = memberUtil.getCurrentMember();
+        Study study = studyRepository.findById(studyId).orElseThrow(() -> new CustomException(STUDY_NOT_FOUND));
+        studyValidator.validateStudyMentor(currentMember, study);
+
+        List<StudyHistory> studyHistories = studyHistoryRepository.findAllByStudyId(studyId);
+        long totalStudentCount = studyHistories.size();
+        long studyCompleteStudentCount =
+                studyHistories.stream().filter(StudyHistory::isComplete).count();
+
+        List<StudyDetail> studyDetails = studyDetailRepository.findAllByStudyIdOrderByWeekAsc(studyId);
+        long openedWeekCount = studyDetails.stream()
+                .filter(studyDetail -> studyDetail.getCurriculum().isOpen())
+                .count();
+
+        List<StudyWeekStatisticsResponse> studyWeekStatisticsResponses =
+                calculateStudyWeekStatistics(studyDetails, totalStudentCount);
+
+        long averageAttendanceRate = calculateAverageWeekAttendanceRate(studyWeekStatisticsResponses, openedWeekCount);
+        long averageAssignmentSubmitRate =
+                calculateAverageWeekAssignmentSubmitRate(studyWeekStatisticsResponses, openedWeekCount);
+
+        return StudyStatisticsResponse.of(
+                totalStudentCount,
+                studyCompleteStudentCount,
+                averageAttendanceRate,
+                averageAssignmentSubmitRate,
+                studyWeekStatisticsResponses);
+    }
+
+    private List<StudyWeekStatisticsResponse> calculateStudyWeekStatistics(
+            List<StudyDetail> studyDetails, Long totalStudentCount) {
+
+        return studyDetails.stream()
+                .map((studyDetail -> {
+                    if (!studyDetail.getCurriculum().isOpen()) {
+                        return canceledWeekStatisticsFrom(studyDetail.getWeek());
+                    }
+
+                    if (totalStudentCount == 0) {
+                        return openedWeekStatisticsOf(studyDetail.getWeek(), 0L, 0L);
+                    }
+
+                    long attendanceCount = attendanceRepository.countByStudyDetailId(studyDetail.getId());
+                    long assignmentCount = assignmentHistoryRepository.countByStudyDetailIdAndSubmissionStatusEquals(
+                            studyDetail.getId(), SUCCESS);
+
+                    return openedWeekStatisticsOf(
+                            studyDetail.getWeek(),
+                            Math.round(attendanceCount / (double) totalStudentCount * 100),
+                            Math.round(assignmentCount / (double) totalStudentCount * 100));
+                }))
+                .toList();
+    }
+
+    private long calculateAverageWeekAttendanceRate(
+            List<StudyWeekStatisticsResponse> studyWeekStatisticsResponses, long openedWeekCount) {
+
+        if (openedWeekCount == 0) {
+            return 0;
+        }
+
+        long attendanceRateSum = studyWeekStatisticsResponses.stream()
+                .mapToLong(weekStatistics -> weekStatistics.isCanceledWeek() ? 0 : weekStatistics.attendanceRate())
+                .sum();
+
+        return Math.round(attendanceRateSum / (double) openedWeekCount);
+    }
+
+    private long calculateAverageWeekAssignmentSubmitRate(
+            List<StudyWeekStatisticsResponse> studyWeekStatisticsResponses, long openedWeekCount) {
+
+        if (openedWeekCount == 0) {
+            return 0;
+        }
+
+        long assignmentSubmitRateSum = studyWeekStatisticsResponses.stream()
+                .mapToLong(
+                        weekStatistics -> weekStatistics.isCanceledWeek() ? 0 : weekStatistics.assignmentSubmitRate())
+                .sum();
+
+        return Math.round(assignmentSubmitRateSum / (double) openedWeekCount);
+    }
 }

src/main/java/com/gdschongik/gdsc/domain/study/dao/AssignmentHistoryRepository.java

@@ -2,11 +2,14 @@
 
 import com.gdschongik.gdsc.domain.member.domain.Member;
 import com.gdschongik.gdsc.domain.study.domain.AssignmentHistory;
+import com.gdschongik.gdsc.domain.study.domain.AssignmentSubmissionStatus;
 import com.gdschongik.gdsc.domain.study.domain.StudyDetail;
 import java.util.Optional;
 import org.springframework.data.jpa.repository.JpaRepository;
 
 public interface AssignmentHistoryRepository
         extends JpaRepository<AssignmentHistory, Long>, AssignmentHistoryCustomRepository {
     Optional<AssignmentHistory> findByMemberAndStudyDetail(Member member, StudyDetail studyDetail);
+
+    long countByStudyDetailIdAndSubmissionStatusEquals(Long studyDetailId, AssignmentSubmissionStatus status);
 }

src/main/java/com/gdschongik/gdsc/domain/study/dao/AttendanceRepository.java

@@ -5,4 +5,6 @@
 
 public interface AttendanceRepository extends JpaRepository<Attendance, Long>, AttendanceCustomRepository {
     boolean existsByStudentIdAndStudyDetailId(Long studentId, Long studyDetailId);
+
+    long countByStudyDetailId(Long studyDetailId);
 }

src/main/java/com/gdschongik/gdsc/domain/study/domain/StudyHistory.java

@@ -82,4 +82,8 @@ public void complete() {
     public boolean isWithinApplicationAndCourse() {
         return study.isWithinApplicationAndCourse();
     }
+
+    public boolean isComplete() {
+        return studyHistoryStatus == COMPLETED;
+    }
 }

src/main/java/com/gdschongik/gdsc/domain/study/dto/response/StudyStatisticsResponse.java

@@ -0,0 +1,28 @@
+package com.gdschongik.gdsc.domain.study.dto.response;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+import java.util.List;
+
+public record StudyStatisticsResponse(
+        @Schema(description = "스터디 전체 수강생 수") Long totalStudentCount,
+        @Schema(description = "스터디 수료 수강생 수") Long completeStudentCount,
+        @Schema(description = "평균 출석률") Long averageAttendanceRate,
+        @Schema(description = "평균 과제 제출률") Long averageAssignmentSubmitRate,
+        @Schema(description = "스터디 수료율") Long studyCompleteRate,
+        @Schema(description = "주차별 출석률 및 과제 제출률") List<StudyWeekStatisticsResponse> studyWeekStatisticsResponses) {
+
+    public static StudyStatisticsResponse of(
+            Long totalStudentCount,
+            Long completeStudentCount,
+            Long averageAttendanceRate,
+            Long averageAssignmentSubmitRate,
+            List<StudyWeekStatisticsResponse> studyWeekStatisticsResponses) {
+        return new StudyStatisticsResponse(
+                totalStudentCount,
+                completeStudentCount,
+                averageAttendanceRate,
+                averageAssignmentSubmitRate,
+                Math.round(completeStudentCount / (double) totalStudentCount * 100),
+                studyWeekStatisticsResponses);
+    }
+}

src/main/java/com/gdschongik/gdsc/domain/study/dto/response/StudyWeekStatisticsResponse.java

@@ -0,0 +1,19 @@
+package com.gdschongik.gdsc.domain.study.dto.response;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+public record StudyWeekStatisticsResponse(
+        @Schema(description = "스터디 주차") Long week,
+        @Schema(description = "출석률") Long attendanceRate,
+        @Schema(description = "과제 제출률") Long assignmentSubmitRate,
+        @Schema(description = "휴강 여부") boolean isCanceledWeek) {
+
+    public static StudyWeekStatisticsResponse openedWeekStatisticsOf(
+            Long studyWeek, Long attendanceRate, Long assignmentSubmitRate) {
+        return new StudyWeekStatisticsResponse(studyWeek, attendanceRate, assignmentSubmitRate, false);
+    }
+
+    public static StudyWeekStatisticsResponse canceledWeekStatisticsFrom(Long studyWeek) {
+        return new StudyWeekStatisticsResponse(studyWeek, 0L, 0L, true);
+    }
+}