👔 회원 가입 비즈니스 로직 추가(#3)

api/src/main/java/hexagonal/api/member/application/service/RegisterMemberService.java

@@ -1,13 +1,42 @@
 package hexagonal.api.member.application.service;
 
+import hexagonal.api.member.application.port.in.RegisterMemberCommand;
 import hexagonal.api.member.application.port.in.RegisterMemberUseCase;
+import hexagonal.api.member.application.port.out.FindMemberPort;
+import hexagonal.api.member.application.port.out.SaveMemberPort;
+import hexagonal.core.domain.jpa.MemberJpaEntity;
 import lombok.RequiredArgsConstructor;
 
+import javax.persistence.EntityNotFoundException;
+
 @RequiredArgsConstructor
 public class RegisterMemberService implements RegisterMemberUseCase {
 
+    private final FindMemberPort findMemberPort;
+    private final SaveMemberPort saveMemberPort;
+
     @Override
-    public boolean registerMember() {
+    public Long registerMember(RegisterMemberCommand command) {
+        // 중복 이메일 검사
+        if (!checkMemberEmailExists(command.getEmail())) {
+            // ToDo Global Exception
+            return -1L;
+        }
+        MemberJpaEntity memberJpaEntity = command.toJpaEntity();
+        // 모델 상태 조작
+        Long memberId = saveMemberPort.saveMember(memberJpaEntity);
+        // 출력 값 반환
+        return memberId;
+    }
+
+    private boolean checkMemberEmailExists(String email) {
+        try {
+            findMemberPort.findMember(email);
+        } catch (EntityNotFoundException e) {
+            return true;
+        }
+
         return false;
     }
+
 }