Step3리뷰 요청드립니다.

build.gradle

@@ -19,6 +19,7 @@ dependencies {
 
     // https://mvnrepository.com/artifact/org.projectlombok/lombok
     compileOnly 'org.projectlombok:lombok:1.18.24'
+    annotationProcessor 'org.projectlombok:lombok:1.18.24'
     implementation 'org.apache.commons:commons-text:1.9'
 
     // log

src/main/java/nextstep/subway/applicaion/common/DuplicatedDownStationException.java

@@ -0,0 +1,12 @@
+package nextstep.subway.applicaion.common;
+
+import com.sun.jdi.request.DuplicateRequestException;
+
+import java.util.NoSuchElementException;
+
+public class DuplicatedDownStationException extends DuplicateRequestException {
+
+    public DuplicatedDownStationException() {
+        super("하행역이 이미 존재하는 역입니다.");
+    }
+}

src/main/java/nextstep/subway/applicaion/common/ErrorController.java

@@ -1,5 +1,6 @@
 package nextstep.subway.applicaion.common;
 
+import com.sun.jdi.request.DuplicateRequestException;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.ExceptionHandler;
@@ -11,8 +12,13 @@
 @RestControllerAdvice
 public class ErrorController {
 
-	@ExceptionHandler(value = NoSuchElementException.class)
-	public ResponseEntity<ErrorResponse> noElementAdviser(NoSuchElementException e) {
-		return new ResponseEntity<>(new ErrorResponse(e.getMessage(), HttpStatus.NOT_FOUND), HttpStatus.NOT_FOUND);
-	}
+    @ExceptionHandler(value = NoSuchElementException.class)
+    public ResponseEntity<ErrorResponse> noElementAdviser(NoSuchElementException e) {
+        return new ResponseEntity<>(new ErrorResponse(e.getMessage(), HttpStatus.NOT_FOUND), HttpStatus.NOT_FOUND);
+    }
+
+    @ExceptionHandler(value = {IllegalArgumentException.class, DuplicateRequestException.class})
+    public ResponseEntity<ErrorResponse> noElementAdviser(RuntimeException e) {
+        return new ResponseEntity<>(new ErrorResponse(e.getMessage(), HttpStatus.BAD_REQUEST), HttpStatus.BAD_REQUEST);
+    }
 }

src/main/java/nextstep/subway/applicaion/common/MinimumSectionException.java

@@ -0,0 +1,7 @@
+package nextstep.subway.applicaion.common;
+
+public class MinimumSectionException extends IllegalArgumentException {
+    public MinimumSectionException() {
+        super("해당 라인의 구간 갯수가 최소 갯수이므로 삭제가 불가능합니다.");
+    }
+}

src/main/java/nextstep/subway/applicaion/common/SectionNotFoundException.java

@@ -0,0 +1,10 @@
+package nextstep.subway.applicaion.common;
+
+import java.util.NoSuchElementException;
+
+public class SectionNotFoundException extends NoSuchElementException {
+
+    public SectionNotFoundException() {
+        super("해당 구간이 존재하지 않습니다.");
+    }
+}

src/main/java/nextstep/subway/applicaion/common/UnappropriateStationException.java

@@ -0,0 +1,8 @@
+package nextstep.subway.applicaion.common;
+
+public class UnappropriateStationException extends IllegalArgumentException {
+
+    public UnappropriateStationException() {
+        super("역이 해당 라인의 하행종점역이 아닙니다.");
+    }
+}

src/main/java/nextstep/subway/applicaion/line/LineService.java

@@ -6,36 +6,35 @@
 import nextstep.subway.applicaion.line.dto.LineRequest;
 import nextstep.subway.applicaion.line.dto.LineResponse;
 import nextstep.subway.applicaion.line.dto.LineUpdateRequest;
+import nextstep.subway.applicaion.section.SectionService;
 import nextstep.subway.applicaion.station.StationService;
 import nextstep.subway.applicaion.station.domain.Station;
-import nextstep.subway.applicaion.station.dto.StationResponse;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
 import java.util.List;
-import java.util.NoSuchElementException;
 import java.util.stream.Collectors;
 
 @Service
 @Transactional(readOnly = true)
 public class LineService {
-
-    private LineRepository lineRepository;
-    private StationService stationService;
-
-    public LineService(LineRepository lineRepository, StationService stationService) {
+    private final LineRepository lineRepository;
+    private final StationService stationService;
+    private final SectionService sectionService;
+    public LineService(LineRepository lineRepository, StationService stationService, SectionService sectionService) {
         this.lineRepository = lineRepository;
         this.stationService = stationService;
+        this.sectionService = sectionService;
     }
-
     @Transactional
     public LineResponse saveLine(LineRequest lineRequest) {
-        Station upStation = stationService.getStationById(lineRequest.getUpStationId());
-        Station downStation = stationService.getStationById(lineRequest.getDownStationId());
+        Station upStation = stationService.getStationThrowExceptionIfNotExists(lineRequest.getUpStationId());
+        Station downStation = stationService.getStationThrowExceptionIfNotExists(lineRequest.getDownStationId());
 
         Line line = lineRepository.save(lineRequest.toLine());
+        line.getSections().add(line, upStation, downStation, lineRequest.getDistance());
 
-        return new LineResponse(line.getId(), line.getName(), line.getColor(), List.of(new StationResponse(upStation.getId(), upStation.getName()), new StationResponse(downStation.getId(), downStation.getName())));
+        return createLineResponse(line);
     }
 
     public List<LineResponse> findAllLines() {
@@ -53,7 +52,7 @@ public LineResponse findLineById(Long id) {
     @Transactional
     public void updateLineById(Long id, LineUpdateRequest lineRequest) {
         Line line = lineRepository.findById(id).orElseThrow(LineNotFoundException::new);
-        line.updateLine(lineRequest.getName(), lineRequest.getColor());
+        line.updateLineInfo(lineRequest.getName(), lineRequest.getColor());
     }
 
     @Transactional
@@ -62,14 +61,10 @@ public void deleteLineById(Long id) {
     }
 
     private LineResponse createLineResponse(Line line) {
-        Station upStation = stationService.getStationById(line.getUpStationId());
-        Station downStation = stationService.getStationById(line.getDownStationId());
-
         return new LineResponse(
                 line.getId(),
                 line.getName(),
                 line.getColor(),
-                List.of(new StationResponse(upStation.getId(), upStation.getName()), new StationResponse(downStation.getId(), downStation.getName()))
-        );
+                line.getSections().stations().stream().map(stationService::createStationResponse).collect(Collectors.toList()));
     }
 }

src/main/java/nextstep/subway/applicaion/line/domain/Line.java

@@ -1,52 +1,30 @@
 package nextstep.subway.applicaion.line.domain;
 
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+
 import javax.persistence.*;
 
+@Getter
 @Entity
+@NoArgsConstructor
 public class Line {
-	@Id
-	@GeneratedValue(strategy = GenerationType.IDENTITY)
-	private Long id;
-	@Column(unique = true)
-	private String name;
-	private String color;
-	private Long upStationId;
-	private Long downStationId;
-	private Integer distance;
-
-	public Line() {
-	}
-
-	public Long getId() {
-		return id;
-	}
-
-	public String getName() {
-		return name;
-	}
-
-	public String getColor() {
-		return color;
-	}
-
-	public Long getUpStationId() {
-		return upStationId;
-	}
-
-	public Long getDownStationId() {
-		return downStationId;
-	}
-
-	public Line(String name, String color, Long upStationId, Long downStationId, Integer distance) {
-		this.name = name;
-		this.color = color;
-		this.upStationId = upStationId;
-		this.downStationId = downStationId;
-		this.distance = distance;
-	}
-
-	public void updateLine(String name, String color) {
-		this.name = name;
-		this.color = color;
-	}
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+    @Column(unique = true)
+    private String name;
+    private String color;
+    @Embedded
+    private Sections sections = new Sections();
+
+    public Line(String name, String color) {
+        this.name = name;
+        this.color = color;
+    }
+
+    public void updateLineInfo(String name, String color) {
+        this.name = name;
+        this.color = color;
+    }
 }

src/main/java/nextstep/subway/applicaion/line/domain/Sections.java

@@ -0,0 +1,65 @@
+package nextstep.subway.applicaion.line.domain;
+
+import nextstep.subway.applicaion.common.DuplicatedDownStationException;
+import nextstep.subway.applicaion.common.MinimumSectionException;
+import nextstep.subway.applicaion.common.UnappropriateStationException;
+import nextstep.subway.applicaion.section.domain.Section;
+import nextstep.subway.applicaion.station.domain.Station;
+
+import javax.persistence.*;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+@Embeddable
+public class Sections {
+    private final Integer MINIMUM_SECTION_SIZE = 1;
+    @OneToMany(fetch = FetchType.LAZY, cascade = {CascadeType.MERGE, CascadeType.PERSIST}, orphanRemoval = true)
+    @JoinColumn(name = "line_id")
+    private List<Section> sections = new ArrayList<>();
+
+    public void add(Line line, Station upStation, Station downStation, Integer distance) {
+        Section section = new Section(upStation, downStation, distance, line);
+        sections.add(section);
+    }
+
+    public List<Station> stations() {
+        List<Station> stations = sections.stream().map(Section::getUpStation).collect(Collectors.toList());
+        stations.add(getLastStation());
+        return stations;
+    }
+
+    public void removeStation(Long stationId) {
+        if (sections.size() <= MINIMUM_SECTION_SIZE) {
+            throw new MinimumSectionException();
+        }
+
+        if (!Objects.equals(getLastStation().getId(), stationId)) {
+            throw new UnappropriateStationException();
+        }
+        sections.remove(getLastSection());
+    }
+
+    public void checkIsLastStation(Station station) {
+        if (!Objects.equals(getLastStation().getId(), station.getId())) {
+            throw new UnappropriateStationException();
+        }
+    }
+
+    public void checkIsNewStation(Station station) {
+        stations().forEach(it -> {
+            if (Objects.equals(it.getId(), station.getId())) {
+                throw new DuplicatedDownStationException();
+            }
+        });
+    }
+
+    private Section getLastSection() {
+        return sections.get(sections.size() - 1);
+    }
+
+    private Station getLastStation() {
+        return getLastSection().getDownStation();
+    }
+}

src/main/java/nextstep/subway/applicaion/line/dto/LineRequest.java

@@ -38,6 +38,6 @@ public LineRequest(String name, String color, Long upStationId, Long downStation
 	}
 
 	public Line toLine() {
-		return new Line(name, color, upStationId, downStationId, distance);
+		return new Line(name, color);
 	}
 }

src/main/java/nextstep/subway/applicaion/section/SectionService.java

@@ -0,0 +1,41 @@
+package nextstep.subway.applicaion.section;
+
+import nextstep.subway.applicaion.common.LineNotFoundException;
+import nextstep.subway.applicaion.line.domain.Line;
+import nextstep.subway.applicaion.line.domain.LineRepository;
+import nextstep.subway.applicaion.section.dto.SectionRequest;
+import nextstep.subway.applicaion.station.StationService;
+import nextstep.subway.applicaion.station.domain.Station;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@Transactional
+public class SectionService {
+    private final StationService stationService;
+    private final LineRepository lineRepository;
+
+    public SectionService(StationService stationService, LineRepository lineRepository) {
+        this.stationService = stationService;
+        this.lineRepository = lineRepository;
+    }
+
+    public void saveSection(Long lineId, SectionRequest sectionRequest) {
+        Line line = lineRepository.findById(lineId).orElseThrow(LineNotFoundException::new);
+
+        Station upStation = stationService.getStationThrowExceptionIfNotExists(sectionRequest.getUpStationId());
+        Station downStation = stationService.getStationThrowExceptionIfNotExists(sectionRequest.getDownStationId());
+
+        line.getSections().checkIsLastStation(upStation);
+        line.getSections().checkIsNewStation(downStation);
+
+        line.getSections().add(line, upStation, downStation, sectionRequest.getDistance());
+    }
+
+    public void deleteSection(Long lineId, Long stationId) {
+        Line line = lineRepository.findById(lineId).orElseThrow(LineNotFoundException::new);
+
+        line.getSections().removeStation(stationId);
+
+    }
+}

src/main/java/nextstep/subway/applicaion/section/domain/Section.java

@@ -0,0 +1,35 @@
+package nextstep.subway.applicaion.section.domain;
+
+import lombok.Getter;
+import lombok.NoArgsConstructor;
+import nextstep.subway.applicaion.line.domain.Line;
+import nextstep.subway.applicaion.station.domain.Station;
+
+import javax.persistence.*;
+
+@Getter
+@Entity
+@NoArgsConstructor
+public class Section {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+    @ManyToOne(cascade = CascadeType.PERSIST)
+    @JoinColumn(name = "up_station_id")
+    private Station upStation;
+    @ManyToOne(cascade = CascadeType.PERSIST)
+    @JoinColumn(name = "down_station_id")
+    private Station downStation;
+    private Integer distance;
+    @ManyToOne(cascade = CascadeType.PERSIST)
+    @JoinColumn(name = "line_id")
+    private Line line;
+
+    public Section(Station upStation, Station downStation, Integer distance, Line line) {
+        this.upStation = upStation;
+        this.downStation = downStation;
+        this.distance = distance;
+        this.line = line;
+    }
+}

src/main/java/nextstep/subway/applicaion/section/domain/SectionRepository.java

@@ -0,0 +1,10 @@
+package nextstep.subway.applicaion.section.domain;
+
+import nextstep.subway.applicaion.line.domain.Line;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+import java.util.List;
+
+public interface SectionRepository extends JpaRepository<Section, Long> {
+    List<Section> findAllByLineId(Long lineId);
+}