feat: 목표 탐색 상세 API 추가

src/main/java/com/groom/orbit/goal/app/MemberGoalService.java

@@ -286,4 +286,8 @@ public GetMemberGoalResponseDto createOtherGoal(Long memberId, Long memberGoalId
         copyMemberGoal.getCompletedDate().toLocalDate(),
         questDtos);
   }
+
+  public List<MemberGoal> findAllMemberGoal(Long goalId) {
+    return memberGoalRepository.findAllWithQuestsByGoalId(goalId);
+  }
 }

src/main/java/com/groom/orbit/goal/app/dto/response/GoalSearchDetailResponseDto.java

@@ -0,0 +1,5 @@
+package com.groom.orbit.goal.app.dto.response;
+
+import java.util.List;
+
+public record GoalSearchDetailResponseDto(String category, String goalName, List<String> quests) {}

src/main/java/com/groom/orbit/goal/app/query/GoalSearchService.java

@@ -0,0 +1,51 @@
+package com.groom.orbit.goal.app.query;
+
+import java.util.Collection;
+import java.util.Comparator;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+import com.groom.orbit.common.exception.CommonException;
+import com.groom.orbit.common.exception.ErrorCode;
+import com.groom.orbit.goal.app.MemberGoalService;
+import com.groom.orbit.goal.app.dto.response.GoalSearchDetailResponseDto;
+import com.groom.orbit.goal.dao.entity.Goal;
+import com.groom.orbit.goal.dao.entity.MemberGoal;
+import com.groom.orbit.goal.dao.entity.Quest;
+
+import lombok.RequiredArgsConstructor;
+
+@Service
+@Transactional(readOnly = true)
+@RequiredArgsConstructor
+public class GoalSearchService {
+
+  private final MemberGoalService memberGoalService;
+
+  public GoalSearchDetailResponseDto findGoal(Long goalId) {
+    List<MemberGoal> memberGoals = memberGoalService.findAllMemberGoal(goalId);
+    Goal goal = findGoal(memberGoals);
+    List<String> questTitles =
+        memberGoals.stream()
+            .map(MemberGoal::getQuests)
+            .flatMap(Collection::stream)
+            .collect(Collectors.toSet())
+            .stream()
+            .sorted(Comparator.comparing(Quest::getCreatedAt).reversed())
+            .map(Quest::getTitle)
+            .toList();
+
+    return new GoalSearchDetailResponseDto(
+        goal.getCategory().getCategory(), goal.getTitle(), questTitles);
+  }
+
+  private static Goal findGoal(List<MemberGoal> memberGoals) {
+    if (memberGoals.isEmpty()) {
+      throw new CommonException(ErrorCode.NOT_FOUND_GOAL);
+    }
+    return memberGoals.getFirst().getGoal();
+  }
+}

src/main/java/com/groom/orbit/goal/controller/query/GoalSearchController.java

@@ -0,0 +1,26 @@
+package com.groom.orbit.goal.controller.query;
+
+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;
+
+import com.groom.orbit.common.dto.ResponseDto;
+import com.groom.orbit.goal.app.dto.response.GoalSearchDetailResponseDto;
+import com.groom.orbit.goal.app.query.GoalSearchService;
+
+import lombok.RequiredArgsConstructor;
+
+@RestController
+@RequiredArgsConstructor
+@RequestMapping("/api/goal/search")
+public class GoalSearchController {
+
+  private final GoalSearchService goalSearchService;
+
+  @GetMapping("/{goal_id}")
+  public ResponseDto<GoalSearchDetailResponseDto> getSearchDetail(
+      @PathVariable("goal_id") Long goalId) {
+    return ResponseDto.ok(goalSearchService.findGoal(goalId));
+  }
+}

src/main/java/com/groom/orbit/goal/dao/MemberGoalRepository.java

@@ -44,4 +44,11 @@ List<MemberGoal> findByMemberIdAndIsComplete(
 
   List<MemberGoal> findAllByMemberIdAndIsCompleteFalseAndSequenceGreaterThan(
       Long memberId, Long sequence);
+
+  @Query(
+      "select mg from MemberGoal mg"
+          + " join fetch mg.goal g"
+          + " join fetch mg.quests q"
+          + " where g.goalId=:goal_id")
+  List<MemberGoal> findAllWithQuestsByGoalId(@Param("goal_id") Long goalId);
 }