[CHORE] 그룹 생성 정책 수정

src/main/java/com/atmd/backend/domain/group/dto/request/GroupCreateRequestDTO.java

@@ -1,6 +1,9 @@
 package com.atmd.backend.domain.group.dto.request;
 
+import jakarta.validation.constraints.Max;
+import jakarta.validation.constraints.Min;
 import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
 import jakarta.validation.constraints.Size;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
@@ -18,8 +21,11 @@ public class GroupCreateRequestDTO {
     private String penalty;
 
     /**
-     * 첫 그룹이 아닌 경우(SUBSCRIBED)에만 사용. 2~5 사이 값.
-     * 첫 그룹은 서버에서 2로 고정하므로 null 허용.
+     * 그룹 가용 최대 인원 (방장 포함, 2~5).
+     * 2인은 무료(GENERAL), 3~5인은 유료(SUBSCRIBED, (maxMemberCount - 2) × 500원).
      */
+    @NotNull
+    @Min(2)
+    @Max(5)
     private Integer maxMemberCount;
 }

src/main/java/com/atmd/backend/domain/group/entity/Group.java

@@ -24,9 +24,9 @@
 public class Group extends BaseEntity {
 
     public static final int MAX_GROUPS_PER_USER = 5;
-    public static final int GENERAL_MAX_MEMBER_COUNT = 2;
-    public static final int SUBSCRIBED_MIN_MEMBER_COUNT = 2;
-    public static final int SUBSCRIBED_MAX_MEMBER_COUNT = 5;
+    public static final int MIN_MEMBER_COUNT = 2;
+    public static final int MAX_MEMBER_COUNT = 5;
+    public static final int FREE_MEMBER_THRESHOLD = 2;
     public static final int PRICE_PER_MEMBER = 500;
 
     @Id
@@ -75,44 +75,34 @@ private Group(
         this.price = price;
     }
 
-    public static Group createFirst(
-            User owner,
-            String name,
-            String inviteCode,
-            String penalty
-    ) {
-        return Group.builder()
-                .owner(owner)
-                .name(name)
-                .membership(GroupMembership.GENERAL)
-                .inviteCode(inviteCode)
-                .penalty(penalty)
-                .maxMemberCount(GENERAL_MAX_MEMBER_COUNT)
-                .price(0)
-                .build();
-    }
-
-    public static Group createSubscribed(
+    public static Group create(
             User owner,
             String name,
             String inviteCode,
             String penalty,
             int maxMemberCount
     ) {
+        GroupMembership membership = maxMemberCount <= FREE_MEMBER_THRESHOLD
+                ? GroupMembership.GENERAL
+                : GroupMembership.SUBSCRIBED;
+        int price = calculatePrice(maxMemberCount);
         return Group.builder()
                 .owner(owner)
                 .name(name)
-                .membership(GroupMembership.SUBSCRIBED)
+                .membership(membership)
                 .inviteCode(inviteCode)
                 .penalty(penalty)
                 .maxMemberCount(maxMemberCount)
-                .price(maxMemberCount * PRICE_PER_MEMBER)
+                .price(price)
                 .build();
     }
 
-    public static boolean isValidSubscribedCapacity(int memberCount) {
-        return memberCount >= SUBSCRIBED_MIN_MEMBER_COUNT
-                && memberCount <= SUBSCRIBED_MAX_MEMBER_COUNT;
+    public static int calculatePrice(int maxMemberCount) {
+        return Math.max(0, maxMemberCount - FREE_MEMBER_THRESHOLD) * PRICE_PER_MEMBER;
+    }
+
+    public static boolean isValidMemberCount(int memberCount) {
+        return memberCount >= MIN_MEMBER_COUNT && memberCount <= MAX_MEMBER_COUNT;
     }
 
     public boolean isOwner(Long userId) {

src/main/java/com/atmd/backend/domain/group/service/GroupService.java

@@ -48,20 +48,17 @@ public GroupResponseDTO create(Long userId, GroupCreateRequestDTO request) {
             throw new GeneralException(GroupErrorCode.MAX_GROUPS_EXCEEDED);
         }
 
-        boolean isFirstGroup = !owner.isFirstGroupCreated();
-        String inviteCode = generateUniqueInviteCode();
+        Integer maxMemberCount = request.getMaxMemberCount();
+        if (maxMemberCount == null || !Group.isValidMemberCount(maxMemberCount)) {
+            throw new GeneralException(GroupErrorCode.INVALID_MEMBER_COUNT);
+        }
 
-        Group group = isFirstGroup
-                ? Group.createFirst(owner, request.getName(), inviteCode, request.getPenalty())
-                : createSubscribedGroup(owner, request, inviteCode);
+        String inviteCode = generateUniqueInviteCode();
+        Group group = Group.create(owner, request.getName(), inviteCode, request.getPenalty(), maxMemberCount);
 
         groupRepository.save(group);
         groupUserRepository.save(GroupUser.of(group, owner));
 
-        if (isFirstGroup) {
-            owner.markFirstGroupCreated();
-        }
-
         return GroupResponseDTO.of(group, 1L, userId);
     }
 
@@ -166,14 +163,6 @@ private GroupJoinResponseDTO joinInternal(String inviteCode, User user) {
         return GroupJoinResponseDTO.of(group.getId(), group.getName(), currentCount + 1);
     }
 
-    private Group createSubscribedGroup(User owner, GroupCreateRequestDTO request, String inviteCode) {
-        Integer requested = request.getMaxMemberCount();
-        if (requested == null || !Group.isValidSubscribedCapacity(requested)) {
-            throw new GeneralException(GroupErrorCode.INVALID_MEMBER_COUNT);
-        }
-        return Group.createSubscribed(owner, request.getName(), inviteCode, request.getPenalty(), requested);
-    }
-
     private String generateUniqueInviteCode() {
         for (int i = 0; i < MAX_GENERATION_ATTEMPTS; i++) {
             String code = randomCode();

src/main/java/com/atmd/backend/domain/user/entity/User.java

@@ -63,9 +63,6 @@ public class User extends BaseEntity {
     @JoinColumn(name = "address_id")
     private Address address;
 
-    @Column(name = "first_group_created", nullable = false)
-    private boolean firstGroupCreated = false;
-
     @Builder
     private User(String email, String nickname, Provider provider, String providerId, Role role,
                  Integer age, Gender gender, Double height, Double weight, Address address) {
@@ -113,8 +110,4 @@ private Double calculateBmi(Double height, Double weight) {
     public void updateAddress(Address address) {
         this.address = address;
     }
-
-    public void markFirstGroupCreated() {
-        this.firstGroupCreated = true;
-    }
 }

src/main/resources/db/migration/V7__add_users_first_group_created.sql

@@ -0,0 +1,6 @@
+-- users 테이블에 그룹 도메인용 first_group_created 컬럼 추가
+-- 프로덕션 DB에는 이미 수동으로 추가되어 있을 수 있으므로 IF NOT EXISTS 사용 (idempotent)
+-- 새 환경 배포 및 DR 상황에서도 안전하게 실행됨
+
+ALTER TABLE users
+    ADD COLUMN IF NOT EXISTS first_group_created BOOLEAN NOT NULL DEFAULT FALSE;

src/main/resources/db/migration/V8__drop_users_first_group_created.sql

@@ -0,0 +1,5 @@
+-- 그룹 생성 정책 변경(2인 무료/3~5인 유료)으로 first_group_created 플래그 미사용 처리
+-- 프로덕션 DB에 컬럼이 없는 환경에서도 안전하게 실행되도록 IF EXISTS 사용 (idempotent)
+
+ALTER TABLE users
+    DROP COLUMN IF EXISTS first_group_created;