feat: add endpoint to retrieve paid application count by school

Author: polyglot-k

src/main/java/life/mosu/mosuserver/application/application/ApplicationService.java

@@ -19,6 +19,7 @@
 import life.mosu.mosuserver.presentation.application.dto.ApplicationResponse;
 import life.mosu.mosuserver.presentation.application.dto.CreateApplicationResponse;
 import life.mosu.mosuserver.presentation.application.dto.ExamApplicationRequest;
+import life.mosu.mosuserver.presentation.application.dto.SchoolApplicationCountResponse;
 import life.mosu.mosuserver.presentation.common.FileRequest;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
@@ -103,4 +104,9 @@ private CreateApplicationResponse handleApplication(
     public List<ApplicationResponse> getApplications(Long userId) {
         return getApplicationsStepProcessor.process(userId);
     }
+
+    @Transactional(readOnly = true)
+    public List<SchoolApplicationCountResponse> getPaidApplicationCountBySchool() {
+        return applicationJpaRepository.findPaidApplicationCountBySchool();
+    }
 }

src/main/java/life/mosu/mosuserver/domain/application/repository/ApplicationJpaRepository.java

@@ -3,6 +3,7 @@
 import java.time.LocalDateTime;
 import java.util.List;
 import life.mosu.mosuserver.domain.application.entity.ApplicationJpaEntity;
+import life.mosu.mosuserver.presentation.application.dto.SchoolApplicationCountResponse;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Modifying;
 import org.springframework.data.jpa.repository.Query;
@@ -29,6 +30,21 @@ AND a.status IN ('PENDING', 'ABORT')
             """)
     List<ApplicationJpaEntity> findAllByUserId(@Param("userId") Long userId);
 
+    @Query("""
+            SELECT new life.mosu.mosuserver.presentation.application.dto.SchoolApplicationCountResponse(
+                e.schoolName,
+                COUNT(a.id)
+            )
+            FROM ApplicationJpaEntity a
+            JOIN ExamApplicationJpaEntity ea ON ea.applicationId = a.id
+            JOIN ExamJpaEntity e ON e.id = ea.examId
+            WHERE a.deleted = false
+            AND a.status = 'APPROVED'
+            GROUP BY e.schoolName
+            ORDER BY e.schoolName
+            """)
+    List<SchoolApplicationCountResponse> findPaidApplicationCountBySchool();
+
     @Modifying
     @Query(value = """
             UPDATE application a

src/main/java/life/mosu/mosuserver/presentation/application/dto/SchoolApplicationCountResponse.java

@@ -0,0 +1,13 @@
+package life.mosu.mosuserver.presentation.application.dto;
+
+import io.swagger.v3.oas.annotations.media.Schema;
+
+@Schema(description = "학교별 결제된 신청 수 응답")
+public record SchoolApplicationCountResponse(
+        @Schema(description = "학교명", example = "서울고등학교")
+        String schoolName,
+
+        @Schema(description = "결제된 신청 수", example = "25")
+        Long paidApplicationCount
+) {
+}