feature: 회원가입 api 구현 (#31)

* feature: 회원가입 api 구현

* docs: 로그 추가

src/main/java/com/goldbalance/dive/domain/member/api/MemberController.java

@@ -1,3 +1,26 @@
 package com.goldbalance.dive.domain.member.api;
 
-public class MemberController {}
+import com.goldbalance.dive.domain.member.dto.request.MemberSignin;
+import com.goldbalance.dive.domain.member.service.MemberService;
+import jakarta.validation.Valid;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatusCode;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PostMapping;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+@RequestMapping("/members")
+@RequiredArgsConstructor
+public class MemberController {
+
+    private final MemberService memberService;
+
+    @PostMapping
+    public ResponseEntity<Void> signin(@Valid @RequestBody MemberSignin request) {
+        memberService.signin(request);
+        return ResponseEntity.status(HttpStatusCode.valueOf(201)).build();
+    }
+}

src/main/java/com/goldbalance/dive/domain/member/dto/request/MemberSignin.java

@@ -0,0 +1,3 @@
+package com.goldbalance.dive.domain.member.dto.request;
+
+public record MemberSignin(String nickname) {}

src/main/java/com/goldbalance/dive/domain/member/repository/MemberRepository.java

@@ -3,4 +3,6 @@
 import com.goldbalance.dive.domain.member.domain.Member;
 import org.springframework.data.jpa.repository.JpaRepository;
 
-public interface MemberRepository extends JpaRepository<Member, Long> {}
+public interface MemberRepository extends JpaRepository<Member, Long> {
+    boolean existsByNickname(String nickname);
+}

src/main/java/com/goldbalance/dive/domain/member/service/MemberService.java

@@ -1,3 +1,31 @@
 package com.goldbalance.dive.domain.member.service;
 
-public class MemberService {}
+import com.goldbalance.dive.domain.member.domain.Member;
+import com.goldbalance.dive.domain.member.dto.request.MemberSignin;
+import com.goldbalance.dive.domain.member.repository.MemberRepository;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Slf4j
+@Service
+@Transactional(readOnly = true)
+@RequiredArgsConstructor
+public class MemberService {
+
+    private final MemberRepository memberRepository;
+
+    @Transactional
+    public void signin(MemberSignin request) {
+        boolean isDuplicate = memberRepository.existsByNickname(request.nickname());
+        if (isDuplicate) {
+            throw new IllegalArgumentException();
+        }
+
+        Member member = Member.create(request.nickname());
+        memberRepository.save(member);
+
+        log.info("[MemberService] 멤버 회원가입 memberId = {}", member.getId());
+    }
+}