Move functionality from AnswerController to AnswerFacade

application/module-exercise/src/main/java/org/fuseri/moduleexercise/answer/AnswerController.java

 package org.fuseri.moduleexercise.answer;
 
-import jakarta.persistence.EntityNotFoundException;
 import org.fuseri.model.dto.exercise.AnswerCreateDto;
 import org.fuseri.model.dto.exercise.AnswerDto;
 import org.fuseri.model.dto.exercise.AnswersCreateDto;
-import org.fuseri.moduleexercise.question.Question;
-import org.fuseri.moduleexercise.question.QuestionService;
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.http.HttpStatus;
 import org.springframework.web.bind.annotation.*;
 import org.springframework.web.server.ResponseStatusException;
 
-import java.util.ArrayList;
 import java.util.List;
 
 /**
@@ -22,22 +17,11 @@ import java.util.List;
 @RequestMapping("/answers")
 public class AnswerController {
 
-    private final AnswerService answerService;
-    private final QuestionService questionService;
-    private final AnswerMapper mapper;
+    private final AnswerFacade facade;
 
-    /**
-     * Constructor for AnswerController
-     *
-     * @param answerService   the service responsible for handling answer-related logic
-     * @param questionService the service responsible for handling question-related logic
-     * @param mapper          the mapper responsible for converting between DTOs and entities
-     */
     @Autowired
-    public AnswerController(AnswerService answerService, QuestionService questionService, AnswerMapper mapper) {
-        this.answerService = answerService;
-        this.questionService = questionService;
-        this.mapper = mapper;
+    public AnswerController(AnswerFacade facade) {
+        this.facade = facade;
     }
 
     /**
@@ -48,7 +32,7 @@ public class AnswerController {
      */
     @GetMapping("/{question_id}")
     public List<AnswerDto> findAllByQuestionId(@PathVariable("question_id") String questionId) {
-        return mapper.toDtoList(answerService.findAllByQuestionId(questionId));
+        return facade.findAllByQuestionId(questionId);
     }
 
     /**
@@ -60,24 +44,7 @@ public class AnswerController {
      */
     @PostMapping
     public List<AnswerDto> createMultiple(@RequestBody AnswersCreateDto dto) {
-        List<Answer> createdAnswers = new ArrayList<>();
-        for (var answerDto : dto.getAnswers()) {
-            Question question;
-            try {
-                question = questionService.find(dto.getQuestionId());
-            } catch (EntityNotFoundException e) {
-                throw new ResponseStatusException(HttpStatus.NOT_FOUND,
-                        "Answer not found with id: " + dto.getQuestionId());
-            }
-
-            Answer answer = mapper.fromCreateDto(answerDto);
-            answer.setQuestionId(question.getId());
-            var createdAnswer = answerService.create(answer);
-            question.getAnswers().add(answer);
-            createdAnswers.add(createdAnswer);
-        }
-
-        return mapper.toDtoList(createdAnswers);
+        return facade.createMultiple(dto);
     }
 
     /**
@@ -88,26 +55,8 @@ public class AnswerController {
      * @throws ResponseStatusException if the question id specified in the dto does not exist
      */
     @PutMapping("/{id}")
-    public AnswerDto update(@PathVariable String id, AnswerCreateDto dto) {
-        var updatedAnswer = mapper.fromCreateDto(dto);
-        updatedAnswer.setId(id);
-        answerService.update(updatedAnswer);
-
-        Question question;
-        try {
-            question = questionService.find(dto.getQuestionId());
-        } catch (EntityNotFoundException e) {
-            throw new ResponseStatusException(HttpStatus.NOT_FOUND,
-                    "Question not found with id: " + dto.getQuestionId());
-        }
-
-        var questionAnswers = question.getAnswers();
-        questionAnswers.removeIf(a -> a.getId().equals(id));
-        questionAnswers.add(updatedAnswer);
-        question.setAnswers(questionAnswers);
-        questionService.update(question);
-
-        return mapper.toDto(updatedAnswer);
+    public AnswerDto update(@PathVariable String id, @RequestBody AnswerCreateDto dto) {
+        return facade.update(id, dto);
     }
 
     /**
@@ -118,19 +67,6 @@ public class AnswerController {
      */
     @DeleteMapping("/{id}")
     public void delete(@PathVariable String id) {
-        var answer = answerService.find(id);
-
-        Question question;
-        try {
-            question = questionService.find(answer.getQuestionId());
-        } catch (EntityNotFoundException e) {
-            throw new ResponseStatusException(HttpStatus.NOT_FOUND,
-                    "Question not found with id: " + answer.getQuestionId());
-        }
-        var questionAnswers = question.getAnswers();
-        questionAnswers.removeIf(a -> a.getId().equals(answer.getId()));
-        question.setAnswers(questionAnswers);
-
-        answerService.delete(id);
+        facade.delete(id);
     }
 }

application/module-exercise/src/main/java/org/fuseri/moduleexercise/answer/AnswerFacade.java

+package org.fuseri.moduleexercise.answer;
+
+import jakarta.persistence.EntityNotFoundException;
+import org.fuseri.model.dto.exercise.AnswerCreateDto;
+import org.fuseri.model.dto.exercise.AnswerDto;
+import org.fuseri.model.dto.exercise.AnswersCreateDto;
+import org.fuseri.moduleexercise.question.Question;
+import org.fuseri.moduleexercise.question.QuestionService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
+import org.springframework.stereotype.Service;
+import org.springframework.web.bind.annotation.*;
+import org.springframework.web.server.ResponseStatusException;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Represent facade for managing answers
+ * Provide simplified interface for manipulating with answers
+ */
+@Service
+public class AnswerFacade {
+    private final AnswerService answerService;
+    private final QuestionService questionService;
+    private final AnswerMapper mapper;
+
+
+    /**
+     * Constructor for AnswerFacade
+     *
+     * @param answerService   the service responsible for handling answer-related logic
+     * @param questionService the service responsible for handling question-related logic
+     * @param mapper          the mapper responsible for converting between DTOs and entities
+     */
+    @Autowired
+    public AnswerFacade(AnswerService answerService, QuestionService questionService, AnswerMapper mapper) {
+        this.answerService = answerService;
+        this.questionService = questionService;
+        this.mapper = mapper;
+    }
+
+    /**
+     * Retrieve a list of AnswerDto objects which belong to question with questionId
+     *
+     * @param questionId the ID of the question for which to retrieve answers
+     * @return a List of AnswerDto objects
+     */
+    public List<AnswerDto> findAllByQuestionId(String questionId) {
+        return mapper.toDtoList(answerService.findAllByQuestionId(questionId));
+    }
+
+    /**
+     * Create a new answer for the given question ID
+     *
+     * @param dto the AnswerCreateDto object containing information about the answer to create
+     * @return an AnswerDto object representing the newly created answer
+     * @throws ResponseStatusException if the question ID specified in the dto does not exist
+     */
+    public List<AnswerDto> createMultiple(@RequestBody AnswersCreateDto dto) {
+        List<Answer> createdAnswers = new ArrayList<>();
+        for (var answerDto : dto.getAnswers()) {
+            Question question;
+            try {
+                question = questionService.find(dto.getQuestionId());
+            } catch (EntityNotFoundException e) {
+                throw new ResponseStatusException(HttpStatus.NOT_FOUND,
+                        "Answer not found with id: " + dto.getQuestionId());
+            }
+
+            Answer answer = mapper.fromCreateDto(answerDto);
+            answer.setQuestionId(question.getId());
+            var createdAnswer = answerService.create(answer);
+            question.getAnswers().add(answer);
+            createdAnswers.add(createdAnswer);
+        }
+
+        return mapper.toDtoList(createdAnswers);
+    }
+
+    /**
+     * Update an answer
+     *
+     * @param id  of answer to update
+     * @param dto dto with updated answer information
+     * @throws ResponseStatusException if the question id specified in the dto does not exist
+     */
+    public AnswerDto update(String id, AnswerCreateDto dto) {
+        var updatedAnswer = mapper.fromCreateDto(dto);
+        updatedAnswer.setId(id);
+        answerService.update(updatedAnswer);
+
+        Question question;
+        try {
+            question = questionService.find(dto.getQuestionId());
+        } catch (EntityNotFoundException e) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND,
+                    "Question not found with id: " + dto.getQuestionId());
+        }
+
+        var questionAnswers = question.getAnswers();
+        questionAnswers.removeIf(a -> a.getId().equals(id));
+        questionAnswers.add(updatedAnswer);
+        question.setAnswers(questionAnswers);
+        questionService.update(question);
+
+        return mapper.toDto(updatedAnswer);
+    }
+
+    /**
+     * Delete answer with the given id
+     *
+     * @param id of answer to delete
+     * @throws ResponseStatusException if the question id specified in the dto does not exist
+     */
+    public void delete(String id) {
+        var answer = answerService.find(id);
+
+        Question question;
+        try {
+            question = questionService.find(answer.getQuestionId());
+        } catch (EntityNotFoundException e) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND,
+                    "Question not found with id: " + answer.getQuestionId());
+        }
+        var questionAnswers = question.getAnswers();
+        questionAnswers.removeIf(a -> a.getId().equals(answer.getId()));
+        question.setAnswers(questionAnswers);
+
+        answerService.delete(id);
+    }
+}