🚀 4단계 - 수강신청(요구사항 변경)

md/step4.md

@@ -0,0 +1,29 @@
+# 🚀 4단계 - 수강신청(요구사항 변경)
+
+## 핵심 학습 목표
+
+- DB 테이블이 변경될 때도 스트랭글러 패턴을 적용해 점진적인 리팩터링을 연습한다.
+    - [스트랭글러(교살자) 패턴 - 마틴 파울러](https://martinfowler.com/bliki/StranglerFigApplication.html)
+    - [스트랭글러 무화과 패턴](https://docs.microsoft.com/ko-kr/azure/architecture/patterns/strangler-fig)
+
+<br>
+
+## 변경된 기능 요구사항
+### **강의 수강신청은 강의 상태가 모집중일 때만 가능하다.**
+- [X] 강의가 진행 중인 상태에서도 수강신청이 가능해야 한다.
+    - 강의 진행 상태(준비중, 진행중, 종료)와 모집 상태(비모집중, 모집중)로 상태 값을 분리해야 한다.
+
+### **강의는 강의 커버 이미지 정보를 가진다.**
+- [X] 강의는 **하나 이상**의 커버 이미지를 가질 수 있다.
+
+### 강사가 승인하지 않아도 수강 신청하는 모든 사람이 수강 가능하다.
+- [ ] 우아한테크코스(무료), 우아한테크캠프 Pro(유료)와 같이 선발된 인원만 수강 가능해야 한다.
+    - [ ] 강사는 수강신청한 사람 중 선발된 인원에 대해서만 수강 승인이 가능해야 한다.
+    - [ ] 강사는 수강신청한 사람 중 선발되지 않은 사람은 수강을 취소할 수 있어야 한다.
+
+<br>
+
+## 프로그래밍 요구사항
+- 리팩터링할 때 컴파일 에러와 기존의 단위 테스트의 실패를 최소화하면서 점진적인 리팩터링이 가능하도록 한다.
+- DB 테이블에 데이터가 존재한다는 가정하에 리팩터링해야 한다.
+    - 즉, 기존에 쌓인 데이터를 제거하지 않은 상태로 리팩터링 해야 한다.

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

@@ -0,0 +1,21 @@
+package nextstep.courses.domain;
+
+import nextstep.courses.exception.EmptyCoverImageException;
+
+import java.util.List;
+
+public class CoverImages {
+
+    private List<CoverImage> images;
+
+    public CoverImages(List<CoverImage> images) {
+        validateIsNull(images);
+        this.images = images;
+    }
+
+    private void validateIsNull(List<CoverImage> images) {
+        if (images == null || images.isEmpty()) {
+            throw new EmptyCoverImageException();
+        }
+    }
+}

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

@@ -25,10 +25,6 @@ private void validatePeriod(LocalDate startDate, LocalDate endDate) {
         }
     }
 
-    public boolean isDateWithinRange(LocalDate date) {
-        return !date.isBefore(startDate) && !date.isAfter(endDate);
-    }
-
     public LocalDate startDate() {
         return startDate;
     }

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

@@ -0,0 +1,27 @@
+package nextstep.courses.domain;
+
+import nextstep.courses.exception.InvalidRecruitmentStatusException;
+
+import java.util.Arrays;
+
+public enum RecruitmentStatus {
+    NOT_RECRUITMENT,
+    RECRUITING;
+
+    private static final RecruitmentStatus[] VALUES = values();
+
+    public static RecruitmentStatus findByName(String name) {
+        return Arrays.stream(VALUES)
+                .filter(status -> status.name().equalsIgnoreCase(name))
+                .findFirst()
+                .orElseThrow(() -> new InvalidRecruitmentStatusException(name));
+    }
+
+    public RecruitmentStatus ofRecruiting() {
+        return RECRUITING;
+    }
+
+    public boolean isRecruiting() {
+        return this == RECRUITING;
+    }
+}

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

@@ -1,8 +1,6 @@
 package nextstep.courses.domain;
 
 import nextstep.courses.exception.InvalidSessionException;
-import nextstep.courses.exception.NotOpenSessionException;
-import nextstep.courses.exception.OutOfSessionException;
 import nextstep.payments.domain.Payment;
 
 import java.time.LocalDate;
@@ -13,39 +11,39 @@ public class Session extends BaseEntity {
     private final Long id;
     private final Long courseId;
     private final SessionType type;
-    private final CoverImage coverImage;
+    private final CoverImages coverImages;
     private final Period period;
-    private Status status;
+    private final Status status;
     private final Students students;
     private final PaidCondition paidCondition;
 
-    public static Session ofFree(Long id, Long courseId, CoverImage coverImage, LocalDate startDate, LocalDate endDate) {
-        return new Session(id, courseId, SessionType.FREE, coverImage, new Period(startDate, endDate), Status.NOT_OPEN, 0, 0L, LocalDateTime.now(), null);
+    public static Session ofFree(Long id, Long courseId, CoverImages coverImages, LocalDate startDate, LocalDate endDate) {
+        return new Session(id, courseId, SessionType.FREE, coverImages, new Period(startDate, endDate), new Status(LocalDate.now(), startDate, endDate), 0, 0L, LocalDateTime.now(), null);
     }
 
-    public static Session ofPaid(Long id, Long courseId, CoverImage coverImage, LocalDate startDate, LocalDate endDate, int maxStudents, Long fee) {
-        return new Session(id, courseId, SessionType.PAID, coverImage, new Period(startDate, endDate), Status.NOT_OPEN, maxStudents, fee, LocalDateTime.now(), null);
+    public static Session ofPaid(Long id, Long courseId, CoverImages coverImages, LocalDate startDate, LocalDate endDate, int maxStudents, Long fee) {
+        return new Session(id, courseId, SessionType.PAID, coverImages, new Period(startDate, endDate), new Status(LocalDate.now(), startDate, endDate), maxStudents, fee, LocalDateTime.now(), null);
     }
 
-    public static Session of(Long id, Long courseId, SessionType type, CoverImage coverImage, Status status, LocalDate startDate, LocalDate endDate, int maxStudents, Long fee, LocalDateTime createdAt, LocalDateTime updatedAt) {
-        return new Session(id, courseId, type, coverImage, new Period(startDate, endDate), status, maxStudents, fee, createdAt, updatedAt);
+    public static Session of(Long id, Long courseId, SessionType type, CoverImages coverImages, RecruitmentStatus recruitmentStatus, LocalDate startDate, LocalDate endDate, int maxStudents, Long fee, LocalDateTime createdAt, LocalDateTime updatedAt) {
+        return new Session(id, courseId, type, coverImages, new Period(startDate, endDate), new Status(LocalDate.now(), startDate, endDate, recruitmentStatus), maxStudents, fee, createdAt, updatedAt);
     }
 
-    private Session(Long id, Long courseId, SessionType type, CoverImage coverImage, Period period, Status status, int maxStudents, Long fee, LocalDateTime createdAt, LocalDateTime updatedAt) {
+    private Session(Long id, Long courseId, SessionType type, CoverImages coverImages, Period period, Status status, int maxStudents, Long fee, LocalDateTime createdAt, LocalDateTime updatedAt) {
         super(createdAt, updatedAt);
-        validateNotNull(id, coverImage, period);
+        validateNotNull(id, coverImages, period);
         this.id = id;
         this.courseId = courseId;
         this.type = type;
-        this.coverImage = coverImage;
+        this.coverImages = coverImages;
         this.period = period;
         this.status = status;
         this.students = new Students();
         this.paidCondition = new PaidCondition(maxStudents, fee);
     }
 
-    private void validateNotNull(Long id, CoverImage coverImage, Period period) {
-        if (id == null || coverImage == null || period == null) {
+    private void validateNotNull(Long id, CoverImages coverImages, Period period) {
+        if (id == null || coverImages == null || period == null) {
             throw new InvalidSessionException();
         }
     }
@@ -59,20 +57,11 @@ public void register(Payment payment) {
     }
 
     protected void validateStatus() {
-        if (!status.isOpen()) {
-            throw new NotOpenSessionException();
-        }
-    }
-
-    public void openSession() {
-        if (!period.isDateWithinRange(LocalDate.now())) {
-            throw new OutOfSessionException();
-        }
-        changeStatusOpen();
+        this.status.validate();
     }
 
-    private void changeStatusOpen() {
-        this.status = status.ofOpen();
+    public void startRecruiting() {
+        this.status.startRecruiting();
     }
 
     public Long id() {
@@ -83,16 +72,16 @@ public Long courseId() {
         return courseId;
     }
 
-    public Long imageId() {
-        return coverImage.getId();
-    }
-
     public String type() {
         return type.name();
     }
 
-    public String status() {
-        return status.name();
+    public String sessionStatus() {
+        return status.sessionStatus();
+    }
+
+    public String recruitmentStatus() {
+        return status.recruitmentStatus();
     }
 
     public LocalDate startDate() {
@@ -115,8 +104,9 @@ public Long fee() {
     public String toString() {
         return "Session{" +
                 "id=" + id +
+                ", courseId=" + courseId +
                 ", type=" + type +
-                ", coverImage=" + coverImage +
+                ", coverImages=" + coverImages +
                 ", period=" + period +
                 ", status=" + status +
                 ", students=" + students +

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

@@ -0,0 +1,25 @@
+package nextstep.courses.domain;
+
+import java.time.LocalDate;
+
+public enum SessionStatus {
+    PREPARING,
+    IN_PROGRESS,
+    COMPLETED;
+
+    public static SessionStatus of(LocalDate now, LocalDate startDate, LocalDate endDate) {
+        if (now.isBefore(startDate)) {
+            return PREPARING;
+        }
+
+        if (now.isAfter(startDate) && now.isBefore(endDate)) {
+            return IN_PROGRESS;
+        }
+
+        return COMPLETED;
+    }
+
+    public boolean isInProgress() {
+        return this == IN_PROGRESS;
+    }
+}

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

@@ -1,27 +1,42 @@
 package nextstep.courses.domain;
 
-import nextstep.courses.exception.InvalidSessionStatusException;
+import nextstep.courses.exception.NotOpenSessionException;
 
-import java.util.Arrays;
+import java.time.LocalDate;
 
-public enum Status {
-    NOT_OPEN,
-    OPEN,
-    CLOSED;
+public class Status {
 
+    private SessionStatus sessionStatus;
+    private RecruitmentStatus recruitmentStatus;
 
-    public Status ofOpen() {
-        return OPEN;
+    public Status(LocalDate now, LocalDate startDate, LocalDate endDate) {
+        this(SessionStatus.of(now, startDate, endDate), RecruitmentStatus.NOT_RECRUITMENT);
     }
 
-    public boolean isOpen() {
-        return this == OPEN;
+    public Status(LocalDate now, LocalDate startDate, LocalDate endDate, RecruitmentStatus recruitmentStatus) {
+        this(SessionStatus.of(now, startDate, endDate), recruitmentStatus);
     }
 
-    public static Status findByName(String name) {
-        return Arrays.stream(values())
-                .filter(status -> status.name().equalsIgnoreCase(name))
-                .findFirst()
-                .orElseThrow(() -> new InvalidSessionStatusException(name));
+    public Status(SessionStatus sessionStatus, RecruitmentStatus recruitmentStatus) {
+        this.sessionStatus = sessionStatus;
+        this.recruitmentStatus = recruitmentStatus;
+    }
+
+    public void validate() {
+        if (!sessionStatus.isInProgress() && !recruitmentStatus.isRecruiting()) {
+            throw new NotOpenSessionException();
+        }
+    }
+
+    public void startRecruiting() {
+        this.recruitmentStatus = recruitmentStatus.ofRecruiting();
+    }
+
+    public String sessionStatus() {
+        return this.sessionStatus.name();
+    }
+
+    public String recruitmentStatus() {
+        return this.recruitmentStatus.name();
     }
 }

src/main/java/nextstep/courses/exception/EmptyCoverImageException.java

@@ -0,0 +1,8 @@
+package nextstep.courses.exception;
+
+public class EmptyCoverImageException extends RuntimeException {
+
+    public EmptyCoverImageException() {
+        super("강의는 하나 이상의 커버 이미지를 가져야 합니다.");
+    }
+}

src/main/java/nextstep/courses/exception/InvalidRecruitmentStatusException.java

@@ -0,0 +1,8 @@
+package nextstep.courses.exception;
+
+public class InvalidRecruitmentStatusException extends RuntimeException {
+
+    public InvalidRecruitmentStatusException(String code) {
+        super("존재하지 않는 강의 모집 상태입니다." + code);
+    }
+}

src/main/java/nextstep/courses/exception/NotOpenSessionException.java

@@ -2,6 +2,6 @@
 
 public class NotOpenSessionException extends RuntimeException {
     public NotOpenSessionException() {
-        super("모집 중인 강의가 아닙니다.");
+        super("진행 중이거나 모집 중인 강의가 아닙니다.");
     }
 }

src/main/java/nextstep/courses/infrastructure/JdbcCoverImageRepository.java

@@ -8,6 +8,7 @@
 
 import java.sql.Timestamp;
 import java.time.LocalDateTime;
+import java.util.List;
 
 @Repository("coverImageRepository")
 public class JdbcCoverImageRepository implements CoverImageRepository {
@@ -19,23 +20,33 @@ public JdbcCoverImageRepository(JdbcOperations jdbcTemplate) {
     }
 
     @Override
-    public int save(CoverImage image) {
-        String sql = "insert into cover_image (id, size, extension, width, height, created_at) values(?, ?, ?, ?, ?, ?)";
-        return jdbcTemplate.update(sql, image.getId(), image.getSize(), image.getExtension(), image.getWidth(), image.getHeight(), image.getCreatedAt());
+    public int save(CoverImage image, Long sessionId) {
+        String sql = "insert into cover_image (id, session_id, size, extension, width, height, created_at) values(?, ?, ?, ?, ?, ?, ?)";
+        return jdbcTemplate.update(sql, image.getId(), sessionId, image.getSize(), image.getExtension(), image.getWidth(), image.getHeight(), image.getCreatedAt());
     }
 
     @Override
     public CoverImage findById(Long id) {
-        String sql = "select id, size, extension, width, height, created_at, updated_at from cover_image where id = ?";
+        String sql = "select id, session_id, size, extension, width, height, created_at, updated_at from cover_image where id = ?";
+        return jdbcTemplate.queryForObject(sql, rowMapper(), id);
+    }
+
+    @Override
+    public List<CoverImage> findAllBySessionId(Long id) {
+        String sql = "select id, session_id, size, extension, width, height, created_at, updated_at from cover_image where session_id = ?";
+        return jdbcTemplate.query(sql, rowMapper(), id);
+    }
+
+    private RowMapper<CoverImage> rowMapper() {
         RowMapper<CoverImage> rowMapper = (rs, rowNum) -> new CoverImage(
                 rs.getLong(1),
-                rs.getLong(2),
-                rs.getString(3),
-                rs.getInt(4),
+                rs.getLong(3),
+                rs.getString(4),
                 rs.getInt(5),
-                toLocalDateTime(rs.getTimestamp(6)),
-                toLocalDateTime(rs.getTimestamp(7)));
-        return jdbcTemplate.queryForObject(sql, rowMapper, id);
+                rs.getInt(6),
+                toLocalDateTime(rs.getTimestamp(7)),
+                toLocalDateTime(rs.getTimestamp(8)));
+        return rowMapper;
     }
 
     private LocalDateTime toLocalDateTime(Timestamp timestamp) {