[BE] feat: 매칭 기능 구현(#6)

backend/build.gradle

@@ -29,6 +29,7 @@ dependencies {
 
     // Etc
     implementation 'org.projectlombok:lombok'
+    annotationProcessor 'org.projectlombok:lombok'
 
     // Database
     runtimeOnly 'com.h2database:h2'

backend/src/main/java/corea/member/domain/Matching.java

@@ -0,0 +1,33 @@
+package corea.member.domain;
+
+import corea.domain.Member;
+import lombok.NoArgsConstructor;
+import org.springframework.stereotype.Component;
+
+import java.util.*;
+import java.util.stream.IntStream;
+
+import static lombok.AccessLevel.PROTECTED;
+
+@NoArgsConstructor(access = PROTECTED)
+@Component
+public class Matching {
+
+    public Map<Long, List<Long>> matchGroup(final List<Member> members, final int matchingSize) {
+        final Map<Long, List<Long>> matchedGroup = new HashMap<>();
+
+        final List<Long> memberIds = new ArrayList<>(members.stream().map(Member::getId).toList());
+        Collections.shuffle(memberIds);
+
+        final List<List<Long>> groupedMemberIds = IntStream.range(0, (members.size() + matchingSize - 1) / matchingSize)
+                .mapToObj(i -> memberIds.subList(i * matchingSize, Math.min(i * matchingSize + matchingSize, memberIds.size())))
+                .toList();
+
+        long groupId = 1L;
+        for (List<Long> l : groupedMemberIds) {
+            matchedGroup.put(groupId++, l);
+        }
+
+        return matchedGroup;
+    }
+}

backend/src/main/java/corea/member/entity/MatchedGroup.java

@@ -0,0 +1,28 @@
+package corea.member.entity;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import lombok.AllArgsConstructor;
+import lombok.NoArgsConstructor;
+
+import static jakarta.persistence.GenerationType.IDENTITY;
+import static lombok.AccessLevel.PROTECTED;
+
+@Entity
+@NoArgsConstructor(access = PROTECTED)
+@AllArgsConstructor
+public class MatchedGroup {
+
+    @Id
+    @GeneratedValue(strategy = IDENTITY)
+    private Long id;
+
+    private Long groupId;
+
+    private Long memberId;
+
+    public MatchedGroup(final Long groupId, final Long memberId) {
+        this(null, groupId, memberId);
+    }
+}

backend/src/main/java/corea/member/repository/MatchedGroupRepository.java

@@ -0,0 +1,13 @@
+package corea.member.repository;
+
+import corea.member.entity.MatchedGroup;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.List;
+
+public interface MatchedGroupRepository extends JpaRepository<MatchedGroup, Long> {
+
+    Long findGroupIdByMemberId(final Long memberId);
+
+    List<Long> findMemberIdsByGroupId(final Long groupId);
+}

backend/src/main/java/corea/member/repository/MemberRepository.java

@@ -0,0 +1,7 @@
+package corea.member.repository;
+
+import corea.domain.Member;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface MemberRepository extends JpaRepository<Member, Long> {
+}

backend/src/main/java/corea/member/service/MatchingService.java

@@ -0,0 +1,27 @@
+package corea.member.service;
+
+import corea.member.domain.Matching;
+import corea.member.entity.MatchedGroup;
+import corea.domain.Member;
+import corea.member.repository.MatchedGroupRepository;
+import lombok.AllArgsConstructor;
+import org.springframework.stereotype.Service;
+
+import java.util.List;
+import java.util.Map;
+
+@Service
+@AllArgsConstructor
+public class MatchingService {
+
+    private final MatchedGroupRepository matchedGroupRepository;
+    private final Matching matching;
+
+    public void matchMaking(final List<Member> members, final int matchingSize) {
+        final Map<Long, List<Long>> results = matching.matchGroup(members, matchingSize);
+        results.entrySet().stream()
+                .flatMap(entry -> entry.getValue().stream()
+                        .map(memberId -> new MatchedGroup(entry.getKey(), memberId)))
+                .forEach(matchedGroupRepository::save);
+    }
+}

backend/src/test/java/corea/member/domain/MatchingTest.java

@@ -0,0 +1,33 @@
+package corea.member.domain;
+
+import corea.domain.Member;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import java.util.List;
+import java.util.Map;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class MatchingTest {
+
+    private final Matching matching = new Matching();
+
+    @Test
+    @DisplayName("멤버 리스트를 받아서 매칭 결과를 반환한다.")
+    void matchGroup(){
+        List<Member> members = List.of(
+                new Member(1L, "[email protected]"),
+                new Member(2L, "[email protected]"),
+                new Member(3L, "[email protected]"),
+                new Member(4L, "[email protected]")
+                );
+        int matchingSize = 2;
+
+        Map<Long, List<Long>> results = matching.matchGroup(members, matchingSize);
+
+        assertThat(results).hasSize(2);
+        assertThat(results.get(1L)).hasSize(2);
+        assertThat(results.get(2L)).hasSize(2);
+    }
+}

backend/src/test/java/corea/member/service/MatchingServiceTest.java

@@ -0,0 +1,42 @@
+package corea.member.service;
+
+import corea.domain.Member;
+import corea.member.repository.MatchedGroupRepository;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@SpringBootTest
+class MatchingServiceTest {
+
+    private final MatchingService matchingService;
+    private final MatchedGroupRepository matchedGroupRepository;
+
+    @Autowired
+    public MatchingServiceTest(MatchingService matchingService, MatchedGroupRepository matchedGroupRepository) {
+        this.matchingService = matchingService;
+        this.matchedGroupRepository = matchedGroupRepository;
+    }
+
+    @Test
+    @DisplayName("멤버 리스트를 받아 매칭 결과를 반환한다.")
+    void matchMaking() {
+        List<Member> members = List.of(
+                new Member(1L, "[email protected]"),
+                new Member(2L, "[email protected]"),
+                new Member(3L, "[email protected]"),
+                new Member(4L, "[email protected]")
+        );
+        int matchingSize = 2;
+
+        matchingService.matchMaking(members, matchingSize);
+
+        assertThat(matchedGroupRepository.findAll()).hasSize(4);
+    }
+
+}