backend/src/main/java/nju/seec/helper/aspect/message/MessageAspect.java

package nju.seec.helper.aspect.message;

import com.google.common.collect.ImmutableMap;
import nju.seec.helper.dao.*;
import nju.seec.helper.dto.reply.ReplyDTO;
import nju.seec.helper.entity.Comment;
import nju.seec.helper.entity.Course;
import nju.seec.helper.entity.Quiz;
import nju.seec.helper.entity.Slide;
import nju.seec.helper.enums.MessageType;
import nju.seec.helper.enums.QuizState;
import nju.seec.helper.enums.SlideState;
import nju.seec.helper.service.MessageService;
import nju.seec.helper.vo.CommentVO;
import nju.seec.helper.vo.NoticeVO;
import nju.seec.helper.vo.quiz.QuizVO;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;
import org.springframework.transaction.annotation.Transactional;

import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Stream;

/**
 * @author cst
 */
@Component
@Aspect
public class MessageAspect {
    private final Map<MessageType, MessageCreator> messageCreatorMap;

    public MessageAspect(CourseDAO courseDAO, SlideDAO slideDAO, QuizDAO quizDAO, CommentDAO commentDAO, ChooseDAO chooseDAO, MessageService messageService) {
        messageCreatorMap = ImmutableMap.<MessageType, MessageCreator>builder()
                .put(MessageType.SLIDE_IN_CLASS, ((joinPoint, object) ->
                        Stream.of(joinPoint.getArgs())
                                .filter(o -> o instanceof Long)
                                .map(o -> (Long) o)
                                .findFirst()
                                .ifPresent(slideId -> {
                                    Slide slide = slideDAO.findSlideById(slideId);
                                    if (slide.getState() == SlideState.IN_CLASS) {
                                        Set<Long> studentIds = chooseDAO.findStudentIdsByCourseId(slide.getCourse().getId());
                                        messageService.createMessage(studentIds, MessageType.SLIDE_IN_CLASS, String.format("[%s] - [%s] 已开课", slide.getCourse().getName(), slide.getName()), slide.getId());
                                    }
                                }))
                )
                .put(MessageType.COMMENT_NEW, (joinPoint, object) -> {
                    if (object instanceof CommentVO) {
                        CommentVO commentVO = (CommentVO) object;
                        if (commentVO.getShow()) {
                            Slide slide = slideDAO.findSlideById(commentVO.getSlideId());
                            messageService.createMessage(Collections.singleton(slide.getTeacher().getId()), MessageType.COMMENT_NEW, String.format("[%s] - [%s] 在第%d页有新评论", slide.getCourse().getName(), slide.getName(), commentVO.getPageNumber()), slide.getId());
                        }
                    }
                })
                .put(MessageType.COMMENT_REPLY, (joinPoint, object) ->
                        Stream.of(joinPoint.getArgs())
                                .filter(o -> o instanceof ReplyDTO)
                                .map(o -> (ReplyDTO) o)
                                .findFirst()
                                .ifPresent(replyDTO -> {
                                    Comment comment = commentDAO.findCommentById(replyDTO.getCommentId());
                                    Slide slide = slideDAO.findSlideById(comment.getSlideId());
                                    messageService.createMessage(Collections.singleton(comment.getUser().getId()), MessageType.COMMENT_REPLY, String.format("您在 [%s] - [%s] 第%d页发表的讨论帖已收到回复", slide.getCourse().getName(), slide.getName(), comment.getPageNumber()), slide.getId());
                                })
                )
                .put(MessageType.NOTICE_NEW, (joinPoint, object) -> {
                    if (object instanceof NoticeVO) {
                        NoticeVO noticeVO = (NoticeVO) object;
                        Set<Long> studentIds = chooseDAO.findStudentIdsByCourseId(noticeVO.getCourseId());
                        Course course = courseDAO.findCourseById(noticeVO.getCourseId());
                        messageService.createMessage(studentIds, MessageType.NOTICE_NEW, String.format("[%s] 发布了新公告", course.getName()), course.getId());
                    }
                })
                .put(MessageType.QUIZ_NEW, new MessageCreator() {
                    @Override
                    public void createMessage(JoinPoint joinPoint, Object object) {
                        if (object instanceof QuizVO) {
                            sendMessages(quizDAO.findQuizById(((QuizVO) object).getId()));
                        } else {
                            Stream.of(joinPoint.getArgs())
                                    .filter(o -> o instanceof Slide)
                                    .map(o -> (Slide) o)
                                    .findFirst()
                                    .ifPresent(slide -> {
                                        List<Quiz> quizzes = quizDAO.findBySlide(slide);
                                        quizzes.forEach(this::sendMessages);
                                    })
                            ;
                        }
                    }

                    private void sendMessages(Quiz quiz) {
                        if (quiz.getState() == QuizState.ONGOING) {
                            Slide slide = quiz.getSlide();
                            Course course = slide.getCourse();
                            Set<Long> chooseStudentIds = chooseDAO.findStudentIdsByCourseId(course.getId());
                            messageService.createMessage(chooseStudentIds, MessageType.QUIZ_NEW, String.format("[%s] - [%s] 的测试 [%s] 已开放", course.getName(), slide.getName(), quiz.getName()), quiz.getId());
                        }
                    }
                })
                .build();
    }

    @Transactional(rollbackFor = Exception.class)
    @AfterReturning(value = "@annotation(message)", returning = "object")
    public void createMessage(JoinPoint joinPoint, Message message, Object object) {
        messageCreatorMap.getOrDefault(message.value(), doNothing).createMessage(joinPoint, object);
    }

    @FunctionalInterface
    interface MessageCreator {
        /**
         * 创建消息
         *
         * @param joinPoint
         * @param object
         */
        void createMessage(JoinPoint joinPoint, Object object);
    }

    private final MessageCreator doNothing = ((joinPoint, object) -> {
    });
}