🚀 1단계 - 구간 추가 기능 변경

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

@@ -3,17 +3,13 @@
 import nextstep.subway.applicaion.dto.LineRequest;
 import nextstep.subway.applicaion.dto.LineResponse;
 import nextstep.subway.applicaion.dto.SectionRequest;
-import nextstep.subway.applicaion.dto.StationResponse;
 import nextstep.subway.domain.Line;
 import nextstep.subway.domain.LineRepository;
-import nextstep.subway.domain.Section;
 import nextstep.subway.domain.Station;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
-import java.util.Collections;
 import java.util.List;
-import java.util.stream.Collectors;
 
 @Service
 @Transactional
@@ -27,29 +23,33 @@ public LineService(LineRepository lineRepository, StationService stationService)
     }
 
     public LineResponse saveLine(LineRequest request) {
-        Line line = lineRepository.save(new Line(request.getName(), request.getColor()));
+        Line saveLine = lineRepository.save(new Line(request.getName(), request.getColor()));
+        addSectionInLine(request, saveLine);
+
+        return LineResponse.from(saveLine);
+    }
+
+    private void addSectionInLine(LineRequest request, Line line) {
         if (request.getUpStationId() != null && request.getDownStationId() != null && request.getDistance() != 0) {
             Station upStation = stationService.findById(request.getUpStationId());
             Station downStation = stationService.findById(request.getDownStationId());
-            line.getSections().add(new Section(line, upStation, downStation, request.getDistance()));
+            line.addSection(upStation, downStation, request.getDistance());
         }
-        return createLineResponse(line);
     }
 
     @Transactional(readOnly = true)
     public List<LineResponse> showLines() {
-        return lineRepository.findAll().stream()
-                .map(this::createLineResponse)
-                .collect(Collectors.toList());
+        return LineResponse.from(lineRepository.findAll());
     }
 
     @Transactional(readOnly = true)
     public LineResponse findById(Long id) {
-        return createLineResponse(lineRepository.findById(id).orElseThrow(IllegalArgumentException::new));
+        Line findLine = findLine(id);
+        return LineResponse.from(findLine);
     }
 
     public void updateLine(Long id, LineRequest lineRequest) {
-        Line line = lineRepository.findById(id).orElseThrow(IllegalArgumentException::new);
+        Line line = findLine(id);
 
         if (lineRequest.getName() != null) {
             line.setName(lineRequest.getName());
@@ -66,46 +66,26 @@ public void deleteLine(Long id) {
     public void addSection(Long lineId, SectionRequest sectionRequest) {
         Station upStation = stationService.findById(sectionRequest.getUpStationId());
         Station downStation = stationService.findById(sectionRequest.getDownStationId());
-        Line line = lineRepository.findById(lineId).orElseThrow(IllegalArgumentException::new);
+        Line findLine = findLine(lineId);
 
-        line.getSections().add(new Section(line, upStation, downStation, sectionRequest.getDistance()));
-    }
-
-    private LineResponse createLineResponse(Line line) {
-        return new LineResponse(
-                line.getId(),
-                line.getName(),
-                line.getColor(),
-                createStationResponses(line),
-                line.getCreatedDate(),
-                line.getModifiedDate()
-        );
-    }
-
-    private List<StationResponse> createStationResponses(Line line) {
-        if (line.getSections().isEmpty()) {
-            return Collections.emptyList();
-        }
-
-        List<Station> stations = line.getSections().stream()
-                .map(Section::getDownStation)
-                .collect(Collectors.toList());
-
-        stations.add(0, line.getSections().get(0).getUpStation());
-
-        return stations.stream()
-                .map(it -> stationService.createStationResponse(it))
-                .collect(Collectors.toList());
+        findLine.addSection(upStation, downStation, sectionRequest.getDistance());
     }
 
     public void deleteSection(Long lineId, Long stationId) {
-        Line line = lineRepository.findById(lineId).orElseThrow(IllegalArgumentException::new);
-        Station station = stationService.findById(stationId);
+        Line line = findLine(lineId);
+        Station deleteStation = stationService.findById(stationId);
+        Station findLastDownStation = line.getLastDownStation();
 
-        if (!line.getSections().get(line.getSections().size() - 1).getDownStation().equals(station)) {
+        if (!findLastDownStation.equals(deleteStation)) {
             throw new IllegalArgumentException();
         }
 
-        line.getSections().remove(line.getSections().size() - 1);
+        int lastIndexOfSection = line.sizeOfSection() - 1;
+        line.removeSection(lastIndexOfSection);
+    }
+
+    private Line findLine(Long id) {
+        return lineRepository.findById(id)
+                .orElseThrow(IllegalArgumentException::new);
     }
 }

src/main/java/nextstep/subway/applicaion/StationService.java

@@ -21,32 +21,24 @@ public StationService(StationRepository stationRepository) {
 
     public StationResponse saveStation(StationRequest stationRequest) {
         Station station = stationRepository.save(new Station(stationRequest.getName()));
-        return createStationResponse(station);
+        return StationResponse.from(station);
     }
 
     @Transactional(readOnly = true)
     public List<StationResponse> findAllStations() {
         List<Station> stations = stationRepository.findAll();
 
         return stations.stream()
-                .map(this::createStationResponse)
-                .collect(Collectors.toList());
+                       .map(StationResponse::from)
+                       .collect(Collectors.toList());
     }
 
     public void deleteStationById(Long id) {
         stationRepository.deleteById(id);
     }
 
-    public StationResponse createStationResponse(Station station) {
-        return new StationResponse(
-                station.getId(),
-                station.getName(),
-                station.getCreatedDate(),
-                station.getModifiedDate()
-        );
-    }
-
     public Station findById(Long id) {
-        return stationRepository.findById(id).orElseThrow(IllegalArgumentException::new);
+        return stationRepository.findById(id)
+                                .orElseThrow(IllegalArgumentException::new);
     }
 }

src/main/java/nextstep/subway/applicaion/dto/ErrorResponse.java

@@ -0,0 +1,32 @@
+package nextstep.subway.applicaion.dto;
+
+import org.springframework.http.HttpStatus;
+
+import java.time.LocalDateTime;
+
+public class ErrorResponse {
+
+    private HttpStatus status;
+
+    private String reason;
+
+    private LocalDateTime date;
+
+    public ErrorResponse(HttpStatus status, String reason, LocalDateTime date) {
+        this.status = status;
+        this.reason = reason;
+        this.date = LocalDateTime.now();
+    }
+
+    public HttpStatus getStatus() {
+        return status;
+    }
+
+    public String getReason() {
+        return reason;
+    }
+
+    public LocalDateTime getDate() {
+        return date;
+    }
+}

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

@@ -7,6 +7,22 @@ public class LineRequest {
     private Long downStationId;
     private int distance;
 
+    public LineRequest() {
+    }
+
+    public LineRequest(String name, String color) {
+        this.name = name;
+        this.color = color;
+    }
+
+    public LineRequest(String name, String color, Long upStationId, Long downStationId, int distance) {
+        this.name = name;
+        this.color = color;
+        this.upStationId = upStationId;
+        this.downStationId = downStationId;
+        this.distance = distance;
+    }
+
     public String getName() {
         return name;
     }

src/main/java/nextstep/subway/applicaion/dto/LineResponse.java

@@ -1,7 +1,10 @@
 package nextstep.subway.applicaion.dto;
 
+import nextstep.subway.domain.Line;
+
 import java.time.LocalDateTime;
 import java.util.List;
+import java.util.stream.Collectors;
 
 public class LineResponse {
     private Long id;
@@ -43,5 +46,21 @@ public LocalDateTime getCreatedDate() {
     public LocalDateTime getModifiedDate() {
         return modifiedDate;
     }
-}
 
+    public static List<LineResponse> from(List<Line> lines) {
+        return lines.stream()
+                    .map(LineResponse::from)
+                    .collect(Collectors.toList());
+    }
+
+    public static LineResponse from(Line line) {
+        return new LineResponse(
+                line.getId(),
+                line.getName(),
+                line.getColor(),
+                StationResponse.from(line),
+                line.getCreatedDate(),
+                line.getModifiedDate()
+        );
+    }
+}