🚀 1단계 - 레거시 코드 리팩터링 (#792)

* 질문 삭제하기 : 도메인 모델화

* 질문 삭제하기 : 규칙7 - 3개이상의 인스턴스 변수를 가진 클래스를 쓰지 않는다

Author: Eundms

Step.md

@@ -0,0 +1,11 @@
+# 질문 삭제하기 
+- 로그인 사용자 = 질문한 사용자 -> 삭제 가능
+- 답변 없음 -> 삭제 가능
+- 질문 삭제 -> 답변 삭제 : 모두 soft delete
+  - 질문자와 답변 글의 모든 답변자가 같으면 삭제 가능
+- 질문자 != 답변자 -> 답변 삭제 불가능
+  - 질문과 답변 삭제 이력에 대한 정보를 DeleteHistory를 활용해 남기기 
+
+## deleQuestion() 메서드
+- 단위 테스트 가능한 코드를 도메인 모델 객체에 구현하기 
+- 도메인 모델로 이동하는 리팩터링을 진행할 때 TDD로 구현하기 

src/main/java/nextstep/qna/domain/Answer.java

@@ -4,76 +4,62 @@
 import nextstep.qna.UnAuthorizedException;
 import nextstep.users.domain.NsUser;
 
-import java.time.LocalDateTime;
-
-public class Answer {
-    private Long id;
-
-    private NsUser writer;
-
+public class Answer extends BaseEntity {
+    private AnswerPost post;
     private Question question;
+    private boolean deleted;
 
-    private String contents;
-
-    private boolean deleted = false;
-
-    private LocalDateTime createdDate = LocalDateTime.now();
-
-    private LocalDateTime updatedDate;
-
-    public Answer() {
+    public Answer(Long id, AnswerPost post, Question question, boolean deleted) {
+        super(id);
+        validateQuestion(question);
+        this.post = post;
+        this.question = question;
+        this.deleted = deleted;
     }
 
     public Answer(NsUser writer, Question question, String contents) {
         this(null, writer, question, contents);
     }
 
     public Answer(Long id, NsUser writer, Question question, String contents) {
-        this.id = id;
-        if(writer == null) {
+        this(id, new AnswerPost(writer, contents), question, false);
+        validateWriter(writer);
+    }
+
+    private static void validateWriter(NsUser writer) {
+        if (writer == null) {
             throw new UnAuthorizedException();
         }
+    }
 
-        if(question == null) {
+    private static void validateQuestion(Question question) {
+        if (question == null) {
             throw new NotFoundException();
         }
-
-        this.writer = writer;
-        this.question = question;
-        this.contents = contents;
-    }
-
-    public Long getId() {
-        return id;
-    }
-
-    public Answer setDeleted(boolean deleted) {
-        this.deleted = deleted;
-        return this;
     }
 
     public boolean isDeleted() {
         return deleted;
     }
 
-    public boolean isOwner(NsUser writer) {
-        return this.writer.equals(writer);
+    public boolean isOwner(NsUser user) {
+        return post.isOwner(user);
     }
 
     public NsUser getWriter() {
-        return writer;
+        return post.getWriter();
     }
 
-    public String getContents() {
-        return contents;
+    public void delete() {
+        this.deleted = true;
     }
 
-    public void toQuestion(Question question) {
-        this.question = question;
+    public DeleteHistory createDeleteHistory() {
+        return new DeleteHistory(ContentType.ANSWER, getId(), getWriter());
     }
 
     @Override
     public String toString() {
-        return "Answer [id=" + getId() + ", writer=" + writer + ", contents=" + contents + "]";
+        return "Answer [id=" + getId() + ", writer=" + getWriter() + ", contents=" + post.getContents() + "]";
     }
 }

src/main/java/nextstep/qna/domain/AnswerPost.java

@@ -0,0 +1,25 @@
+package nextstep.qna.domain;
+
+import nextstep.users.domain.NsUser;
+
+public class AnswerPost {
+    private final NsUser writer;
+    private final String contents;
+
+    public AnswerPost(NsUser writer, String contents) {
+        this.writer = writer;
+        this.contents = contents;
+    }
+
+    public boolean isOwner(NsUser user) {
+        return writer.equals(user);
+    }
+
+    public NsUser getWriter() {
+        return writer;
+    }
+
+    public String getContents() {
+        return contents;
+    }
+}

src/main/java/nextstep/qna/domain/Answers.java

@@ -0,0 +1,57 @@
+package nextstep.qna.domain;
+
+import java.util.ArrayList;
+import java.util.List;
+import nextstep.qna.CannotDeleteException;
+import nextstep.users.domain.NsUser;
+
+public class Answers {
+
+  private List<Answer> answers;
+
+  public Answers() {
+    this(new ArrayList<>());
+  }
+
+  public Answers(List<Answer> answers) {
+    this.answers = new ArrayList<>(answers);
+  }
+
+  public void create(Answer answer) {
+    answers.add(answer);
+  }
+
+  public void deleteBy(NsUser nsUser) throws CannotDeleteException {
+    validateDeleteBy(nsUser);
+    for (Answer answer : answers) {
+      answer.delete();
+    }
+  }
+
+  private void validateDeleteBy(NsUser writer) throws CannotDeleteException {
+    for (Answer answer : answers) {
+      if (!answer.isOwner(writer)) {
+        throw new CannotDeleteException("다른 사람이 쓴 답변이 있어 삭제할 수 없습니다.");
+      }
+    }
+  }
+
+  public boolean allDeleted() {
+    return answers.stream().allMatch(Answer::isDeleted);
+  }
+
+  public boolean contains(Answer answer) {
+    return answers.contains(answer);
+  }
+
+  public List<DeleteHistory> createDeleteHistories() {
+    List<DeleteHistory> deleteHistories = new ArrayList<>();
+    for (Answer answer : answers) {
+      if (answer.isDeleted()) {
+        deleteHistories.add(answer.createDeleteHistory());
+      }
+    }
+    return deleteHistories;
+  }
+
+}

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

@@ -0,0 +1,23 @@
+package nextstep.qna.domain;
+
+import java.time.LocalDateTime;
+
+public abstract class BaseEntity {
+    private Long id;
+    private LocalDateTime createdDate = LocalDateTime.now();
+
+    protected BaseEntity() {
+    }
+
+    protected BaseEntity(Long id) {
+        this.id = id;
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public LocalDateTime getCreatedDate() {
+        return createdDate;
+    }
+}

src/main/java/nextstep/qna/domain/DeleteHistory.java

@@ -2,49 +2,42 @@
 
 import nextstep.users.domain.NsUser;
 
-import java.time.LocalDateTime;
 import java.util.Objects;
 
-public class DeleteHistory {
-    private Long id;
-
+public class DeleteHistory extends BaseEntity {
     private ContentType contentType;
-
     private Long contentId;
-
     private NsUser deletedBy;
 
-    private LocalDateTime createdDate = LocalDateTime.now();
-
-    public DeleteHistory() {
-    }
-
-    public DeleteHistory(ContentType contentType, Long contentId, NsUser deletedBy, LocalDateTime createdDate) {
+    public DeleteHistory(Long id, ContentType contentType, Long contentId, NsUser deletedBy) {
+        super(id);
         this.contentType = contentType;
         this.contentId = contentId;
         this.deletedBy = deletedBy;
-        this.createdDate = createdDate;
+    }
+    public DeleteHistory(ContentType contentType, Long contentId, NsUser deletedBy) {
+        this(null, contentType, contentId, deletedBy);
     }
 
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         DeleteHistory that = (DeleteHistory) o;
-        return Objects.equals(id, that.id) &&
+        return Objects.equals(getId(), that.getId()) &&
                 contentType == that.contentType &&
                 Objects.equals(contentId, that.contentId) &&
                 Objects.equals(deletedBy, that.deletedBy);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(id, contentType, contentId, deletedBy);
+        return Objects.hash(getId(), contentType, contentId, deletedBy);
     }
 
     @Override
     public String toString() {
-        return "DeleteHistory [id=" + id + ", contentType=" + contentType + ", contentId=" + contentId + ", deletedBy="
-                + deletedBy + ", createdDate=" + createdDate + "]";
+        return "DeleteHistory [id=" + getId() + ", contentType=" + contentType + ", contentId=" + contentId
+                + ", deletedBy=" + deletedBy + ", createdDate=" + getCreatedDate() + "]";
     }
 }