package nju.seec.helper.service.impl;

import nju.seec.helper.aspect.auth.LoginUser;
import nju.seec.helper.dao.ChooseDAO;
import nju.seec.helper.dao.CourseDAO;
import nju.seec.helper.dao.NoticeDAO;
import nju.seec.helper.dto.notice.NoticeDTO;
import nju.seec.helper.entity.Course;
import nju.seec.helper.entity.Notice;
import nju.seec.helper.enums.ExceptionType;
import nju.seec.helper.enums.MessageType;
import nju.seec.helper.exception.HelperException;
import nju.seec.helper.service.MessageService;
import nju.seec.helper.service.NoticeService;
import nju.seec.helper.vo.NoticeVO;
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.Set;

/**
 * @author cst
 */
@Service
public class NoticeServiceImpl implements NoticeService {
    private final CourseDAO courseDAO;
    private final ChooseDAO chooseDAO;
    private final NoticeDAO noticeDAO;

    private final MessageService messageService;

    public NoticeServiceImpl(CourseDAO courseDAO, ChooseDAO chooseDAO, NoticeDAO noticeDAO, MessageService messageService) {
        this.courseDAO = courseDAO;
        this.chooseDAO = chooseDAO;
        this.noticeDAO = noticeDAO;
        this.messageService = messageService;
    }

    @Transactional(rollbackFor = Exception.class)
    @Override
    public NoticeVO createNotice(LoginUser user, NoticeDTO noticeDTO) {
        Course course = courseDAO.findCourseById(noticeDTO.getCourseId());

        Notice notice = new Notice()
                .setCourseId(noticeDTO.getCourseId())
                .setTeacherId(user.getId())
                .setTitle(noticeDTO.getTitle())
                .setContent(noticeDTO.getContent());

        if (!existsAddAuth(user, notice)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权创建该公告");
        }

        Set<Long> studentIds = chooseDAO.findStudentIdsByCourseId(noticeDTO.getCourseId());
        messageService.createMessage(studentIds, MessageType.NOTICE_NEW, String.format("[%s] 发布了新公告", course.getName()), course.getId());
        return new NoticeVO(noticeDAO.save(notice));
    }

    @Transactional(rollbackFor = Exception.class)
    @Override
    public NoticeVO modifyNotice(LoginUser user, Long noticeId, NoticeDTO noticeDTO) {
        Notice notice = noticeDAO.findNoticeById(noticeId);

        if (!existsUpdateAuth(user, notice)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权修改该公告");
        }

        return new NoticeVO(
                noticeDAO.save(
                        notice.setTitle(noticeDTO.getTitle())
                                .setContent(noticeDTO.getContent())
                )
        );
    }

    @Transactional(readOnly = true)
    @Override
    public Page<NoticeVO> getNoticesByCourse(LoginUser user, Long courseId, String key, Pageable pageable) {
        return noticeDAO.findByCourseIdAndKey(courseId, key, pageable).map(NoticeVO::new);
    }

    @Transactional(rollbackFor = Exception.class)
    @Override
    public void deleteNotice(LoginUser user, Long noticeId) {
        Notice notice = noticeDAO.findNoticeById(noticeId);
        if (!existsDelAuth(user, notice)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权删除该公告");
        }
        noticeDAO.delete(notice);
        messageService.deleteMessages(noticeId, MessageType.NOTICE_NEW);
    }

    @Transactional(readOnly = true)
    @Override
    public NoticeVO getOneNotice(LoginUser user, Long noticeId) {
        return new NoticeVO(noticeDAO.findNoticeById(noticeId));
    }

    @Override
    public boolean existsAddAuth(LoginUser user, Notice notice) {
        return courseDAO.findCourseById(notice.getCourseId()).getTeacher().getId().equals(user.getId());
    }

    @Override
    public boolean existsDelAuth(LoginUser user, Notice notice) {
        return notice.getTeacherId().equals(user.getId());
    }

    @Override
    public boolean existsUpdateAuth(LoginUser user, Notice notice) {
        return notice.getTeacherId().equals(user.getId());
    }

    @Override
    public boolean existsGetAuth(LoginUser user, Notice notice) {
        return true;
    }
}