[BE] feat: 친구 관련 API

src/backend/user-server/build.gradle

@@ -46,6 +46,13 @@ dependencies {
 	testImplementation 'org.springframework.boot:spring-boot-starter-test'
 	testRuntimeOnly 'org.junit.platform:junit-platform-launcher'
 
+	// queryDSL
+	annotationProcessor "jakarta.annotation:jakarta.annotation-api"
+	annotationProcessor "jakarta.persistence:jakarta.persistence-api"
+
+	implementation 'com.querydsl:querydsl-jpa:5.0.0:jakarta'
+	annotationProcessor "com.querydsl:querydsl-apt:5.0.0:jakarta"
+
 	// Security
 	implementation 'org.springframework.boot:spring-boot-starter-security'
 	implementation 'org.springframework.security:spring-security-oauth2-client'

src/backend/user-server/src/main/java/com/asyncgate/user_server/config/QuerydslConfig.java

@@ -0,0 +1,19 @@
+package com.asyncgate.user_server.config;
+
+import com.querydsl.jpa.impl.JPAQueryFactory;
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.PersistenceContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class QuerydslConfig {
+
+    @PersistenceContext
+    private EntityManager entityManager;
+
+    @Bean
+    public JPAQueryFactory jpaQueryFactory() {
+        return new JPAQueryFactory(entityManager);
+    }
+}

src/backend/user-server/src/main/java/com/asyncgate/user_server/controller/FriendController.java

@@ -0,0 +1,133 @@
+package com.asyncgate.user_server.controller;
+
+import com.asyncgate.user_server.controller.docs.FriendControllerDocs;
+import com.asyncgate.user_server.domain.Friend;
+import com.asyncgate.user_server.domain.Member;
+import com.asyncgate.user_server.dto.response.FriendResponse;
+import com.asyncgate.user_server.dto.response.FriendsResponse;
+import com.asyncgate.user_server.dto.response.MemberResponse;
+import com.asyncgate.user_server.security.annotation.MemberID;
+import com.asyncgate.user_server.support.response.SuccessResponse;
+import com.asyncgate.user_server.usecase.FriendUseCase;
+import lombok.RequiredArgsConstructor;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.List;
+
+@RestController
+@RequiredArgsConstructor
+@RequestMapping("/friends")
+public class FriendController implements FriendControllerDocs {
+
+    private final FriendUseCase friendUseCase;
+
+    /**
+     * 회원 검색 (이메일 기준)
+     */
+    @Override
+    @GetMapping
+    public SuccessResponse<MemberResponse> searchTarget(final @RequestParam String email) {
+        Member findMember = friendUseCase.getByEmail(email);
+        return SuccessResponse.ok(
+                MemberResponse.from(findMember)
+        );
+    }
+
+    /**
+     * 친구 요청: 현재 사용자(userId)가 toUserId에게 친구 요청
+     * URL 예시: POST /friends/request/{toUserId}
+     */
+    @Override
+    @PostMapping("/request/{toUserId}")
+    public SuccessResponse<FriendResponse> requestFriend(
+            final @MemberID String userId,
+            final @PathVariable String toUserId
+    ) {
+        Friend friend = friendUseCase.registerFriend(userId, toUserId);
+        return SuccessResponse.created(
+                FriendResponse.from(friend)
+        );
+    }
+
+    /**
+     * 친구 수락: 현재 사용자(userId)가 friendId에 해당하는 친구 요청을 수락
+     * URL 예시: POST /friends/accept/{friendId}
+     */
+    @Override
+    @PostMapping("/accept/{friendId}")
+    public SuccessResponse<FriendResponse> acceptFriend(
+            final @MemberID String userId,
+            final @PathVariable String friendId
+    ) {
+        Friend friend = friendUseCase.acceptFriend(userId, friendId);
+        return SuccessResponse.ok(
+                FriendResponse.from(friend)
+        );
+    }
+
+    /**
+     * 친구 거절: 현재 사용자(userId)가 friendId에 해당하는 친구 요청을 거절
+     * URL 예시: POST /friends/reject/{friendId}
+     */
+    @Override
+    @PostMapping("/reject/{friendId}")
+    public SuccessResponse<FriendResponse> rejectFriend(
+            final @MemberID String userId,
+            @PathVariable String friendId) {
+        Friend friend = friendUseCase.rejectFriend(userId, friendId);
+        return SuccessResponse.ok(FriendResponse.from(friend));
+    }
+
+    /**
+     * 친구 삭제(soft delete): 현재 사용자(userId)가 friendId에 해당하는 친구 관계를 soft delete 처리
+     * URL 예시: DELETE /friends/{friendId}
+     */
+    @Override
+    @DeleteMapping("/{friendId}")
+    public SuccessResponse<String> deleteFriend(
+            final @MemberID String userId,
+            final @PathVariable String friendId
+    ) {
+        friendUseCase.deleteFriend(userId, friendId);
+        return SuccessResponse.ok(String.format("UserId[&s]인 친구를 삭제했습니다.", friendId));
+    }
+
+    /**
+     * 본인이 보낸 친구 요청 목록 조회 (상태: PENDING)
+     * URL 예시: GET /friends/sent
+     */
+    @Override
+    @GetMapping("/sent")
+    public SuccessResponse<FriendsResponse> getSentFriendRequests(final @MemberID String userId) {
+        List<Friend> sent = friendUseCase.getSentFriendRequests(userId);
+        return SuccessResponse.ok(
+                FriendsResponse.from(sent)
+        );
+    }
+
+    /**
+     * 본인이 받은 친구 요청 목록 조회 (상태: PENDING)
+     * URL 예시: GET /friends/received
+     */
+    @Override
+    @GetMapping("/received")
+    public SuccessResponse<FriendsResponse> getReceivedFriendRequests(final @MemberID String userId) {
+        List<Friend> received = friendUseCase.getReceivedFriendRequests(userId);
+        return SuccessResponse.ok(
+                FriendsResponse.from(received)
+        );
+    }
+
+    /**
+     * 본인의 실제 친구 목록 조회 (상태: ACCEPTED)
+     * URL 예시: GET /friends/list
+     */
+    @Override
+    @GetMapping("/list")
+    public SuccessResponse<FriendsResponse> getFriends(final @MemberID String userId) {
+        List<Friend> friends = friendUseCase.getFriends(userId);
+        return SuccessResponse.ok(
+                FriendsResponse.from(friends)
+        );
+    }
+}

src/backend/user-server/src/main/java/com/asyncgate/user_server/controller/docs/FriendControllerDocs.java

@@ -0,0 +1,103 @@
+package com.asyncgate.user_server.controller.docs;
+
+import com.asyncgate.user_server.dto.response.FriendResponse;
+import com.asyncgate.user_server.dto.response.FriendsResponse;
+import com.asyncgate.user_server.dto.response.MemberResponse;
+import com.asyncgate.user_server.security.annotation.MemberID;
+import com.asyncgate.user_server.support.response.SuccessResponse;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.Parameter;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.responses.ApiResponses;
+import org.springframework.web.bind.annotation.*;
+
+public interface FriendControllerDocs {
+
+    @Operation(summary = "회원 검색", description = "이메일을 기반으로 회원 정보를 조회합니다.")
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "200", description = "정상적으로 조회되었습니다.")
+    })
+    @GetMapping
+    SuccessResponse<MemberResponse> searchTarget(
+            @Parameter(description = "검색할 회원의 이메일", required = true)
+            @RequestParam String email
+    );
+
+
+    @Operation(summary = "친구 요청", description = "현재 사용자(@MemberID)가 지정된 toUserId에게 친구 요청을 보냅니다.")
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "201", description = "친구 요청이 생성되었습니다.")
+    })
+    @PostMapping("/request/{toUserId}")
+    SuccessResponse<FriendResponse> requestFriend(
+            @Parameter(hidden = true) @MemberID String userId,
+            @Parameter(description = "친구 요청 대상의 사용자 ID", required = true)
+            @PathVariable String toUserId
+    );
+
+
+    @Operation(summary = "친구 요청 수락", description = "현재 사용자(@MemberID)가 friendId에 해당하는 친구 요청을 수락합니다.")
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "200", description = "친구 요청이 수락되었습니다.")
+    })
+    @PostMapping("/accept/{friendId}")
+    SuccessResponse<FriendResponse> acceptFriend(
+            @Parameter(hidden = true) @MemberID String userId,
+            @Parameter(description = "수락할 친구 요청의 ID", required = true)
+            @PathVariable String friendId
+    );
+
+
+    @Operation(summary = "친구 요청 거절", description = "현재 사용자(@MemberID)가 friendId에 해당하는 친구 요청을 거절합니다.")
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "200", description = "친구 요청이 거절되었습니다.")
+    })
+    @PostMapping("/reject/{friendId}")
+    SuccessResponse<FriendResponse> rejectFriend(
+            @Parameter(hidden = true) @MemberID String userId,
+            @Parameter(description = "거절할 친구 요청의 ID", required = true)
+            @PathVariable String friendId
+    );
+
+
+    @Operation(summary = "친구 삭제", description = "현재 사용자(@MemberID)가 friendId에 해당하는 친구 관계를 삭제(soft delete)합니다.")
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "200", description = "친구 관계가 삭제되었습니다.")
+    })
+    @DeleteMapping("/{friendId}")
+    SuccessResponse<String> deleteFriend(
+            @Parameter(hidden = true) @MemberID String userId,
+            @Parameter(description = "삭제할 친구 관계의 ID", required = true)
+            @PathVariable String friendId
+    );
+
+
+    @Operation(summary = "보낸 친구 요청 목록 조회", description = "현재 사용자(@MemberID)가 보낸 친구 요청 목록(PENDING)을 조회합니다.")
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "200", description = "보낸 친구 요청 목록이 조회되었습니다.")
+    })
+    @GetMapping("/sent")
+    SuccessResponse<FriendsResponse> getSentFriendRequests(
+            @Parameter(hidden = true) @MemberID String userId
+    );
+
+
+    @Operation(summary = "받은 친구 요청 목록 조회", description = "현재 사용자(@MemberID)가 받은 친구 요청 목록(PENDING)을 조회합니다.")
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "200", description = "받은 친구 요청 목록이 조회되었습니다.")
+    })
+    @GetMapping("/received")
+    SuccessResponse<FriendsResponse> getReceivedFriendRequests(
+            @Parameter(hidden = true) @MemberID String userId
+    );
+
+
+    @Operation(summary = "친구 목록 조회", description = "현재 사용자(@MemberID)의 실제 친구 목록(ACCEPTED)을 조회합니다.")
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "200", description = "친구 목록이 조회되었습니다.")
+    })
+    @GetMapping("/list")
+    SuccessResponse<FriendsResponse> getFriends(
+            @Parameter(hidden = true) @MemberID String userId
+    );
+}

src/backend/user-server/src/main/java/com/asyncgate/user_server/domain/Friend.java

@@ -0,0 +1,44 @@
+package com.asyncgate.user_server.domain;
+
+import lombok.Getter;
+
+import java.util.UUID;
+
+@Getter
+public class Friend {
+    private final String id;
+    private final String userId1;
+    private final String userId2;
+    private final String requestedBy;
+    private FriendStatus status;
+
+    private Friend(String id, String userId1, String userId2, String requestedBy, FriendStatus status) {
+        this.id = id;
+        this.userId1 = userId1;
+        this.userId2 = userId2;
+        this.requestedBy = requestedBy;
+        this.status = status;
+    }
+
+    public static Friend create(String requestUserId, String toUserId) {
+        // 두 사용자 ID를 사전 순으로 정렬하여 저장
+        if (requestUserId.compareTo(toUserId) < 0) {
+            return new Friend(UUID.randomUUID().toString(), requestUserId, toUserId, requestUserId, FriendStatus.PENDING);
+        } else {
+            return new Friend(UUID.randomUUID().toString(), toUserId, requestUserId, requestUserId, FriendStatus.PENDING);
+        }
+    }
+
+    public static Friend of(String id, String userId1, String userId2, String requestedBy, FriendStatus status) {
+        return new Friend(id, userId1, userId2, requestedBy, status);
+    }
+
+    public void accept() {
+        this.status = FriendStatus.ACCEPTED;
+    }
+
+    public void reject() {
+        this.status = FriendStatus.REJECTED;
+    }
+
+}

src/backend/user-server/src/main/java/com/asyncgate/user_server/domain/FriendStatus.java

@@ -0,0 +1,7 @@
+package com.asyncgate.user_server.domain;
+
+public enum FriendStatus {
+    PENDING,
+    ACCEPTED,
+    REJECTED
+}

src/backend/user-server/src/main/java/com/asyncgate/user_server/dto/response/FriendResponse.java

@@ -0,0 +1,16 @@
+package com.asyncgate.user_server.dto.response;
+
+import com.asyncgate.user_server.domain.Friend;
+import com.asyncgate.user_server.domain.FriendStatus;
+
+public record FriendResponse(String id, String userId1, String userId2, String requestedBy, FriendStatus status) {
+    public static FriendResponse from(final Friend friend) {
+        return new FriendResponse(
+                friend.getId(),
+                friend.getUserId1(),
+                friend.getUserId2(),
+                friend.getRequestedBy(),
+                friend.getStatus()
+        );
+    }
+}

src/backend/user-server/src/main/java/com/asyncgate/user_server/dto/response/FriendsResponse.java

@@ -0,0 +1,14 @@
+package com.asyncgate.user_server.dto.response;
+
+import com.asyncgate.user_server.domain.Friend;
+
+import java.util.List;
+
+public record FriendsResponse(List<FriendResponse> friends) {
+    public static FriendsResponse from(final List<Friend> friendList) {
+        List<FriendResponse> responses = friendList.stream()
+                .map(FriendResponse::from)
+                .toList();
+        return new FriendsResponse(responses);
+    }
+}

src/backend/user-server/src/main/java/com/asyncgate/user_server/dto/response/MemberResponse.java

@@ -0,0 +1,13 @@
+package com.asyncgate.user_server.dto.response;
+
+import com.asyncgate.user_server.domain.Member;
+
+import java.time.LocalDate;
+
+public record MemberResponse(String email, String name, String nickname, String profileImgUrl, LocalDate birth) {
+
+    public static MemberResponse from(Member member) {
+        return new MemberResponse(member.getEmail(), member.getName(), member.getNickname(), member.getProfileImgUrl(), member.getBirth());
+    }
+
+}