Step3

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

@@ -0,0 +1,23 @@
+package nextstep.common.domain;
+
+import java.time.LocalDateTime;
+
+public class BaseEntity {
+    protected Long id;
+    protected LocalDateTime createdAt;
+    protected LocalDateTime updatedAt;
+
+    public BaseEntity(final Long id, final LocalDateTime createdAt, final LocalDateTime updatedAt) {
+        this.id = id;
+        this.createdAt = createdAt;
+        this.updatedAt = updatedAt;
+    }
+
+    public Long getId() {
+        return this.id;
+    }
+
+    public LocalDateTime getCreatedAt() {
+        return this.createdAt;
+    }
+}

src/main/java/nextstep/common/utils/DateTimeUtils.java

@@ -0,0 +1,20 @@
+package nextstep.common.utils;
+
+import java.sql.Timestamp;
+import java.time.LocalDateTime;
+
+public class DateTimeUtils {
+    public static Timestamp toTimeStamp(LocalDateTime localDateTime) {
+        if (localDateTime == null) {
+            return null;
+        }
+        return Timestamp.valueOf(localDateTime);
+    }
+
+    public static LocalDateTime toLocalDateTime(Timestamp timestamp) {
+        if (timestamp == null) {
+            return null;
+        }
+        return timestamp.toLocalDateTime();
+    }
+}

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

@@ -1,25 +1,19 @@
 package nextstep.courses.domain;
 
+import nextstep.common.domain.BaseEntity;
 import nextstep.courses.domain.session.Session;
 
 import java.time.LocalDateTime;
 import java.util.List;
 
-public class Course {
+public class Course extends BaseEntity {
     private Long id;
 
     private String title;
 
     private Long creatorId;
-
-    private LocalDateTime createdAt;
-
-    private LocalDateTime updatedAt;
     private List<Session> sessions;
 
-    public Course() {
-    }
-
     public Course(String title, Long creatorId) {
         this(0L, title, creatorId, LocalDateTime.now(), null, null);
     }
@@ -28,11 +22,9 @@ public Course(Long id, String title, Long creatorId, LocalDateTime createdAt, Lo
         this(0L, title, creatorId, createdAt, updatedAt, null);
     }
     public Course(Long id, String title, Long creatorId, LocalDateTime createdAt, LocalDateTime updatedAt, List<Session> sessions) {
-        this.id = id;
+        super(id, createdAt, updatedAt);
         this.title = title;
         this.creatorId = creatorId;
-        this.createdAt = createdAt;
-        this.updatedAt = updatedAt;
         this.sessions = sessions;
     }
 
@@ -44,10 +36,6 @@ public Long getCreatorId() {
         return creatorId;
     }
 
-    public LocalDateTime getCreatedAt() {
-        return createdAt;
-    }
-
     @Override
     public String toString() {
         return "Course{" +

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

@@ -1,7 +1,9 @@
 package nextstep.courses.domain;
 
+import java.util.Optional;
+
 public interface CourseRepository {
-    int save(Course course);
+    long save(Course course);
 
-    Course findById(Long id);
+    Optional<Course> findById(Long id);
 }

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

@@ -1,12 +1,29 @@
 package nextstep.courses.domain;
 
-public class Enrollment{
-        private Long id;
-        private Long nsUserId;
-        private Long sessionId;
-
-        public Enrollment(final Long nsUserId, final Long sessionId) {
-            this.nsUserId = nsUserId;
-            this.sessionId = sessionId;
-        }
+import nextstep.common.domain.BaseEntity;
+
+import java.time.LocalDateTime;
+
+public class Enrollment extends BaseEntity {
+    private Long nsUserId;
+    private Long sessionId;
+
+
+    public Enrollment(final Long nsUserId, final Long sessionId) {
+        this(null, nsUserId, sessionId, LocalDateTime.now(), null);
+    }
+
+    public Enrollment(final Long id, final Long nsUserId, final Long sessionId, LocalDateTime createAt, LocalDateTime updatedAt) {
+        super(id, createAt, updatedAt);
+        this.nsUserId = nsUserId;
+        this.sessionId = sessionId;
+    }
+
+    public Long nsUserId() {
+        return nsUserId;
+    }
+
+    public Long sessionId() {
+        return sessionId;
+    }
 }

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

@@ -0,0 +1,9 @@
+package nextstep.courses.domain;
+
+import java.util.Optional;
+
+public interface EnrollmentRepository {
+    long save(Enrollment enrollment);
+
+    Optional<Enrollment> findById(Long id);
+}

src/main/java/nextstep/courses/domain/image/CoverImage.java

@@ -8,17 +8,26 @@ public class CoverImage {
     private static final int MIN_WIDTH = 300;
     private static final int MIN_HEIGHT = 200;
     private static final Long MAX_SIZE = 1024L * 1024L;
+    private static final int WIDTH_RATIO = 3;
+    private static final int HEIGHT_RATIO = 2;
+    private final Long id;
 
     private final int width;
     private final int height;
     private final long size;
     private final ImageType imageType;
 
-    public CoverImage(final long size, final int width, final int height, final ImageType imageType) {
+
+    public CoverImage(int width, int height, long size, ImageType imageType) {
+        this(null, width, height, size, imageType);
+    }
+
+    public CoverImage(Long id, int width, int height, long size, ImageType imageType) {
         validateImage(size, width, height);
-        this.size = size;
+        this.id = id;
         this.width = width;
         this.height = height;
+        this.size = size;
         this.imageType = imageType;
     }
 
@@ -35,7 +44,7 @@ private void validateSize(final long size) {
     }
 
     private void validateRatio(final int width, final int height) {
-        if (width * 2 != height * 3) {
+        if (width * HEIGHT_RATIO != height * WIDTH_RATIO) {
             throw new IllegalArgumentException(INVALID_IMAGE_RATIO_MESSAGE);
         }
     }
@@ -45,4 +54,24 @@ private void validatePixel(final int width, final int height) {
             throw new IllegalArgumentException(INVALID_IMAGE_PIXEL_MESSAGE);
         }
     }
+
+    public int getWidth() {
+        return width;
+    }
+
+    public int getHeight() {
+        return height;
+    }
+
+    public long getSize() {
+        return size;
+    }
+
+    public ImageType getImageType() {
+        return imageType;
+    }
+
+    public Long getId() {
+        return id;
+    }
 }

src/main/java/nextstep/courses/domain/image/ImageRepository.java

@@ -0,0 +1,9 @@
+package nextstep.courses.domain.image;
+
+import java.util.Optional;
+
+public interface ImageRepository {
+    long save(CoverImage coverImage);
+
+    Optional<CoverImage> findById(Long id);
+}

src/main/java/nextstep/courses/domain/session/EnrollmentCount.java

@@ -2,18 +2,20 @@
 
 public class EnrollmentCount {
     private int availableCount;
-    private int remainCount;
 
     public EnrollmentCount(final int availableCount) {
         this.availableCount = availableCount;
-        this.remainCount = availableCount;
     }
 
     public boolean isNoRemaining() {
-        return remainCount <= 0;
+        return availableCount < 1;
     }
 
     public void decrease() {
-        this.remainCount--;
+        this.availableCount--;
+    }
+
+    public int getAvailableCount() {
+        return availableCount;
     }
 }