package nju.seec.helper.service.impl;

import nju.seec.helper.aspect.auth.LoginUser;
import nju.seec.helper.aspect.message.Message;
import nju.seec.helper.dao.CommentDAO;
import nju.seec.helper.dao.SlideDAO;
import nju.seec.helper.dao.UserDAO;
import nju.seec.helper.dto.comment.CommentDTO;
import nju.seec.helper.entity.Comment;
import nju.seec.helper.entity.Slide;
import nju.seec.helper.enums.ExceptionType;
import nju.seec.helper.enums.MessageType;
import nju.seec.helper.exception.HelperException;
import nju.seec.helper.service.CommentService;
import nju.seec.helper.service.MessageService;
import nju.seec.helper.vo.CommentVO;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.stream.Collectors;

/**
 * @author cst
 */
@Service
public class CommentServiceImpl implements CommentService {
    private final CommentDAO commentDAO;
    private final SlideDAO slideDAO;
    private final UserDAO userDAO;

    private final MessageService messageService;

    public CommentServiceImpl(CommentDAO commentDAO, SlideDAO slideDAO, UserDAO userDAO, MessageService messageService) {
        this.commentDAO = commentDAO;
        this.slideDAO = slideDAO;
        this.userDAO = userDAO;
        this.messageService = messageService;
    }

    @Message(MessageType.COMMENT_NEW)
    @Transactional(rollbackFor = Exception.class)
    @Override
    public CommentVO createComment(LoginUser user, CommentDTO commentDTO) {
        Slide slide = slideDAO.findSlideById(commentDTO.getSlideId());

        Comment comment = commentDAO.save(
                new Comment()
                        .setSlideId(slide.getId())
                        .setPageNumber(commentDTO.getPageNumber())
                        .setUser(userDAO.findUserById(user.getId()))
                        .setTitle(commentDTO.getTitle())
                        .setContent(commentDTO.getContent())
                        .setShow(commentDTO.getShow())
        );

        return new CommentVO(comment);
    }

    @Transactional(rollbackFor = Exception.class)
    @Override
    public void deleteComment(LoginUser user, Long commentId) {
        Comment comment = commentDAO.findCommentById(commentId);

        if (!existsDelAuth(user, comment)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权删除该评论");
        }

        unTopComment(comment);
        commentDAO.delete(comment);
    }

    @Transactional(rollbackFor = Exception.class)
    @Override
    public void topComment(LoginUser user, Long commentId) {
        Comment comment = commentDAO.findCommentById(commentId);

        if (!comment.getShow()) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "私密评论，无法置顶");
        }

        if (!existsUpdateAuth(user, comment)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权在该评论区置顶评论");
        }

        unTopComment(comment);
        comment.setTopNumber((int) countTopComments(comment.getSlideId(), comment.getPageNumber()) + 1);
        commentDAO.save(comment);
    }

    private long countTopComments(Long slideId, Integer pageNumber) {
        return commentDAO.countBySlideIdAndPageNumberAndTopNumberNot(slideId, pageNumber, 0);
    }

    @Transactional(rollbackFor = Exception.class)
    @Override
    public void unTopComment(LoginUser user, Long commentId) {
        Comment comment = commentDAO.findCommentById(commentId);

        if (!existsUpdateAuth(user, comment)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权在该评论区取消置顶评论");
        }

        unTopComment(comment);
        commentDAO.save(comment);
    }

    @Transactional(readOnly = true)
    @Override
    public Page<CommentVO> getCommentsBySlideAndPageNumber(Long slideId, Integer pageNumber, Pageable pageable) {
        return commentDAO.findBySlideIdAndPageNumberAndShow(slideId, pageNumber, true, pageable).map(CommentVO::new);
    }

    @Transactional(readOnly = true)
    @Override
    public CommentVO getOneComment(LoginUser user, Long commentId) {
        Comment comment = commentDAO.findCommentById(commentId);

        if (!existsGetAuth(user, comment)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权获取该评论");
        }

        return new CommentVO(comment);
    }

    @Transactional(readOnly = true)
    @Override
    public Page<CommentVO> getSelfCommentsBySlideAndPageNumber(LoginUser user, Long slideId, Integer pageNumber, Boolean show, Pageable pageable) {
        return commentDAO.findBySlideIdAndPageNumberAndUserAndShow(slideId, pageNumber, userDAO.findUserById(user.getId()), show, pageable).map(CommentVO::new);
    }

    @Transactional(rollbackFor = Exception.class)
    @Override
    public void modifyCommentShow(LoginUser user, Long commentId, Boolean show) {
        Comment comment = commentDAO.findCommentById(commentId);

        if (comment.getShow().equals(show)) {
            return;
        }

        if (!existsUpdateAuth(user, comment)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权修改该评论的展示状态");
        }

        unTopComment(comment);
        commentDAO.save(comment.setShow(show));
    }

    @Transactional(readOnly = true)
    @Override
    public Page<CommentVO> getSelfComments(LoginUser user, String key, Pageable pageable) {
        return commentDAO.findByUserIdAndKey(user.getId(), key, pageable).map(CommentVO::new);
    }

    private void unTopComment(Comment comment) {
        Integer topNumber = comment.getTopNumber();
        comment.setTopNumber(0);
        if (topNumber != 0) {
            commentDAO.saveAll(
                    commentDAO.findBySlideIdAndPageNumberAndTopNumberGreaterThan(comment.getSlideId(), comment.getPageNumber(), topNumber)
                            .parallelStream()
                            .peek(topComment -> topComment.setTopNumber(topComment.getTopNumber() - 1))
                            .collect(Collectors.toList())
            );
        }
    }

    @Override
    public boolean existsAddAuth(LoginUser user, Comment comment) {
        return true;
    }

    @Override
    public boolean existsDelAuth(LoginUser user, Comment comment) {
        return comment.getUser().getId().equals(user.getId());
    }

    @Override
    public boolean existsUpdateAuth(LoginUser user, Comment comment) {
        return comment.getUser().getId().equals(user.getId())
                || slideDAO.findSlideById(comment.getSlideId()).getTeacher().getId().equals(user.getId());
    }

    @Override
    public boolean existsGetAuth(LoginUser user, Comment comment) {
        return comment.getShow()
                || comment.getUser().getId().equals(user.getId());
    }
}