[refactor] 비지니스 로직과 엔티티를 리팩토링 하라

강의 상태 변경 같은 간단한 경우에는 엔티티에서 해결하고
수강신청, 승인 및 취소는 별도 클래스에서 비지니스 로직을 수행합니다.

getter와 setter를 제거하고 모든 변수에 final을 추가합니다.

src/main/java/nextstep/courses/domain/BaseEntity.java

@@ -3,31 +3,27 @@
 import java.time.LocalDateTime;
 
 public class BaseEntity {
-    private Long creatorId;
+    private final Long creatorId;
 
-    private LocalDateTime createdAt;
+    private final LocalDateTime createdAt;
 
-    private LocalDateTime updatedAt;
+    private final LocalDateTime updatedAt;
 
     public BaseEntity(Long creatorId, LocalDateTime createdAt, LocalDateTime updatedAt) {
         this.creatorId = creatorId;
         this.createdAt = createdAt;
         this.updatedAt = updatedAt;
     }
 
-    public Long getCreatorId() {
+    public Long creatorId() {
         return creatorId;
     }
 
-    public LocalDateTime getCreatedAt() {
+    public LocalDateTime createdAt() {
         return createdAt;
     }
 
-    public LocalDateTime getUpdatedAt() {
+    public LocalDateTime updatedAt() {
         return updatedAt;
     }
-
-    public void setUpdatedAt(LocalDateTime updatedAt) {
-        this.updatedAt = updatedAt;
-    }
 }

src/main/java/nextstep/courses/domain/course/Course.java

@@ -7,13 +7,13 @@
 import java.time.LocalDateTime;
 
 public class Course extends BaseEntity {
-    private Long id;
+    private final Long id;
 
-    private String title;
+    private final String title;
 
-    private int ordering;
+    private final int ordering;
 
-    private Sessions sessions;
+    private final Sessions sessions;
 
     public Course(String title, int ordering, Long creatorId, LocalDateTime date) {
         this(0L, title, ordering, new Sessions(), creatorId, date, null);
@@ -28,28 +28,24 @@ public Course(Long id, String title, int ordering, Sessions sessions,
         this.sessions = sessions;
     }
 
-    public int sessionSize() {
-        return this.sessions.size();
-    }
-
     public void addSession(Session session) {
         this.sessions.add(session);
     }
 
-    public Long getId() {
+    public Long id() {
         return id;
     }
 
-    public String getTitle() {
+    public String title() {
         return title;
     }
 
-    public int getOrdering() {
+    public int ordering() {
         return this.ordering;
     }
 
-    public Long getCreatorId() {
-        return super.getCreatorId();
+    public Sessions sessions() {
+        return this.sessions;
     }
 
     @Override

src/main/java/nextstep/courses/domain/course/CourseRepository.java

@@ -1,7 +1,7 @@
 package nextstep.courses.domain.course;
 
 public interface CourseRepository {
-    int save(Course course);
+    Course save(Course course);
 
     Course findById(Long id);
 }

src/main/java/nextstep/courses/domain/course/session/Enrollment.java

@@ -2,28 +2,22 @@
 
 import nextstep.courses.domain.course.session.apply.Applies;
 import nextstep.courses.domain.course.session.apply.Apply;
+import nextstep.courses.domain.course.session.apply.ApprovalStatus;
 import nextstep.payments.domain.Payment;
 
 import java.time.LocalDateTime;
 
 public class Enrollment {
-    private Long sessionId;
+    private final Long sessionId;
 
-    private Applies applies;
+    private final Applies applies;
 
-    private SessionState sessionState;
+    private final SessionDetail sessionDetail;
 
-    private SessionProgressStatus sessionProgressStatus;
-
-    private SessionRecruitStatus sessionRecruitStatus;
-
-    public Enrollment(Long sessionId, Applies applies, SessionState sessionState,
-                      SessionProgressStatus sessionProgressStatus, SessionRecruitStatus sessionRecruitStatus) {
+    public Enrollment(Long sessionId, Applies applies, SessionDetail sessionDetail) {
         this.sessionId = sessionId;
         this.applies = applies;
-        this.sessionState = sessionState;
-        this.sessionProgressStatus = sessionProgressStatus;
-        this.sessionRecruitStatus = sessionRecruitStatus;
+        this.sessionDetail = sessionDetail;
     }
 
     public Apply apply(Long nsUserId, Payment payment, LocalDateTime date) {
@@ -33,77 +27,48 @@ public Apply apply(Long nsUserId, Payment payment, LocalDateTime date) {
         checkChargedAndApplySizeIsValid();
         checkApplicantAlreadyExisted(nsUserId);
 
-        return new Apply(sessionId, nsUserId, false, date);
+        return new Apply(sessionId, nsUserId, ApprovalStatus.WAIT, date);
     }
 
     private void checkPaymentIsPaid(Long nsUserId, Payment payment) {
-        if (this.charged()) {
+        if (this.sessionDetail.charged()) {
             checkPaymentIsValid(nsUserId, payment);
         }
     }
 
-    public boolean charged() {
-        return this.sessionState.getSessionType().charged();
-    }
-
     private void checkPaymentIsValid(Long nsUserId, Payment payment) {
         if (payment == null ||
                 !payment.isPaid(
                         nsUserId,
                         sessionId,
-                        sessionState.getAmount()
+                        this.sessionDetail.getAmount()
                 )
         ) {
             throw new IllegalArgumentException("결제를 다시 확인하세요.");
         }
     }
 
     private void checkStatusOnRecruit() {
-        if (this.notRecruiting()) {
+        if (this.sessionDetail.notRecruiting()) {
             throw new IllegalArgumentException("강의 신청은 모집 중일 때만 가능 합니다.");
         }
     }
 
     private void checkStatusOnReadyOrOnGoing() {
-        if (this.notReadyOrOnGoing()) {
+        if (this.sessionDetail.notReadyOrOnGoing()) {
             throw new IllegalArgumentException("강의 신청은 준비, 진행중일 때만 가능 합니다.");
         }
     }
 
     private void checkChargedAndApplySizeIsValid() {
-        if(chargedAndFull()) {
+        if(this.sessionDetail.chargedAndFull(applies.size())) {
             throw new IllegalArgumentException("수강 신청 인원이 초과 되었습니다.");
         }
     }
 
-    private boolean chargedAndFull() {
-        return this.charged() && applySizeFull();
-    }
-
-    private boolean applySizeFull() {
-        return this.sessionState.getQuota() == applies.size();
-    }
-
     private void checkApplicantAlreadyExisted(Long nsUserId) {
-        if (this.containsUserId(nsUserId)) {
+        if (this.applies.containsUserId(nsUserId)) {
             throw new IllegalArgumentException("이미 수강 신청 이력이 있습니다.");
         }
     }
-
-    public boolean containsUserId(Long nsUserId) {
-        return this.applies.getApplies().stream()
-                .anyMatch(apply -> apply.isSameWithUserId(nsUserId));
-    }
-
-    public int size() {
-        return this.applies.size();
-    }
-
-    public boolean notRecruiting() {
-        return this.sessionRecruitStatus.notRecruiting();
-    }
-
-    public boolean notReadyOrOnGoing() {
-        return this.sessionProgressStatus.notReadyOrOnGoing();
-    }
 }