package nju.seec.helper.service.impl;

import com.google.common.collect.ImmutableSet;
import com.google.common.io.Files;
import lombok.SneakyThrows;
import nju.seec.helper.aspect.auth.LoginUser;
import nju.seec.helper.dao.ChooseDAO;
import nju.seec.helper.dao.CourseDAO;
import nju.seec.helper.dao.SlideDAO;
import nju.seec.helper.dao.UserDAO;
import nju.seec.helper.dto.slide.SlideDTO;
import nju.seec.helper.dto.slide.SlideFileDTO;
import nju.seec.helper.dto.slide.SlideStateDTO;
import nju.seec.helper.entity.Course;
import nju.seec.helper.entity.Slide;
import nju.seec.helper.enums.ExceptionType;
import nju.seec.helper.enums.MessageType;
import nju.seec.helper.enums.SlideState;
import nju.seec.helper.exception.HelperException;
import nju.seec.helper.service.CourseService;
import nju.seec.helper.service.MessageService;
import nju.seec.helper.service.QuizService;
import nju.seec.helper.service.SlideService;
import nju.seec.helper.service.util.OssObjectUrlUtils;
import nju.seec.helper.util.OssUtils;
import nju.seec.helper.util.file.FileInfo;
import nju.seec.helper.util.file.FileUtils;
import nju.seec.helper.vo.SlideVO;
import org.springframework.dao.DataIntegrityViolationException;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.util.Set;

/**
 * @author cst
 */
@Service
public class SlideServiceImpl implements SlideService {
    private static final String SLIDE_STORE_DIR = "slide";

    private final CourseDAO courseDAO;
    private final SlideDAO slideDAO;
    private final ChooseDAO chooseDAO;
    private final UserDAO userDAO;

    private final OssUtils ossUtils;
    private final OssObjectUrlUtils ossObjectUrlUtils;

    private final QuizService quizService;
    private final MessageService messageService;
    private final CourseService courseService;

    public SlideServiceImpl(CourseDAO courseDAO, SlideDAO slideDAO, ChooseDAO chooseDAO, UserDAO userDAO, OssUtils ossUtils, OssObjectUrlUtils ossObjectUrlUtils, QuizService quizService, MessageService messageService, CourseService courseService) {
        this.courseDAO = courseDAO;
        this.slideDAO = slideDAO;
        this.chooseDAO = chooseDAO;
        this.userDAO = userDAO;
        this.ossUtils = ossUtils;
        this.ossObjectUrlUtils = ossObjectUrlUtils;
        this.quizService = quizService;
        this.messageService = messageService;
        this.courseService = courseService;
    }


    @Transactional(rollbackFor = Exception.class)
    @SneakyThrows
    @Override
    public SlideVO createSlide(LoginUser teacher, SlideDTO slideDTO) {
        Course course = courseDAO.findCourseById(slideDTO.getCourseId());

        Slide slide = new Slide()
                .setCourse(course)
                .setTeacher(userDAO.findUserById(teacher.getId()))
                .setName(slideDTO.getName())
                .setState(slideDTO.getState());

        if (!existsAddAuth(teacher, slide)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权创建该课件");
        }

        try {
            MultipartFile file = slideDTO.getFile();
            FileInfo fileInfo = getFileInfo(file);
            slide.setPages(fileInfo.getPages());
            slide.setObjectName("temp");
            slide = slideDAO.save(slide);

            String objectName = getObjectName(slide.getId(), slide.getName(), fileInfo.getExtension());
            slide.setObjectName(objectName);
            slide = slideDAO.save(slide);

            ossUtils.upload(objectName, file.getInputStream());

            return new SlideVO(slide);
        } catch (DataIntegrityViolationException e) {
            throw HelperException.of(ExceptionType.CONFLICT, "创建失败，请检查课件信息是否正确且不与已有课件冲突");
        }
    }

    @Transactional(rollbackFor = Exception.class)
    @Override
    public SlideVO modifySlide(LoginUser user, Long slideId, SlideDTO slideDTO) {
        Slide slide = slideDAO.findSlideById(slideId);

        if (!existsUpdateAuth(user, slide)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权修改该课件");
        }

        try {
            slide.setName(slideDTO.getName());
            String oldObjectName = slide.getObjectName();
            String newObjectName = getObjectName(slide.getId(), slide.getName(), Files.getFileExtension(oldObjectName));
            slide.setObjectName(newObjectName);
            slide = slideDAO.save(slide);

            if (!oldObjectName.equals(newObjectName)) {
                ossUtils.copy(oldObjectName, newObjectName);
                ossUtils.delete(oldObjectName);
            }

            return new SlideVO(slide);
        } catch (DataIntegrityViolationException e) {
            throw HelperException.of(ExceptionType.CONFLICT, "修改失败，请检查课件信息是否正确且不与已有课件冲突");
        }
    }

    @Transactional(rollbackFor = Exception.class)
    @Override
    public void modifySlideState(LoginUser user, Long slideId, SlideStateDTO slideStateDTO) {
        Slide slide = slideDAO.findSlideById(slideId);

        if (!existsUpdateAuth(user, slide)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权修改该课件状态");
        }

        slide.setState(slideStateDTO.getState());
        slide = slideDAO.save(slide);

        // 增加通知
        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());
        }

        // 修改Slide状态同时推进quiz状态
        quizService.modifyQuizState(slide);
    }

    @Transactional(rollbackFor = Exception.class)
    @SneakyThrows
    @Override
    public void modifySlideFile(LoginUser user, Long slideId, SlideFileDTO slideFileDTO) {
        Slide slide = slideDAO.findSlideById(slideId);

        if (!existsUpdateAuth(user, slide)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权修改该课件文件");
        }

        MultipartFile file = slideFileDTO.getFile();
        FileInfo fileInfo = getFileInfo(file);
        slide.setPages(fileInfo.getPages());

        String oldObjectName = slide.getObjectName();
        String newObjectName = getObjectName(slide.getId(), slide.getName(), fileInfo.getExtension());
        slide.setObjectName(newObjectName);
        slideDAO.save(slide);

        ossUtils.upload(newObjectName, file.getInputStream());
        if (!oldObjectName.equals(newObjectName)) {
            ossUtils.delete(oldObjectName);
        }
    }

    @Transactional(rollbackFor = Exception.class)
    @Override
    public void deleteSlide(LoginUser user, Long slideId) {
        Slide slide = slideDAO.findSlideById(slideId);

        if (!existsDelAuth(user, slide)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权删除该课件");
        }

        slide.setDeleteAt(System.currentTimeMillis());
        slideDAO.save(slide);
    }

    @SneakyThrows
    private FileInfo getFileInfo(MultipartFile file) {
        return FileUtils.getFileInfo(file);
    }

    private String getObjectName(Long slideId, String slideName, String extension) {
        return SLIDE_STORE_DIR + File.separator + slideId + File.separator + slideName + "." + extension;
    }

    @Transactional(readOnly = true)
    @Override
    public Page<SlideVO> teacherGetSlides(LoginUser teacher, String key, Pageable pageable) {
        return slideDAO.findByTeacherAndNameContains(userDAO.findUserById(teacher.getId()), key, pageable).map(SlideVO::new);
    }

    private static final Set<SlideState> STATES_NOT_GET_BY_STUDENT_SET = ImmutableSet.of(SlideState.DRAFT);

    @Transactional(readOnly = true)
    @Override
    public Page<SlideVO> getSlidesByCourse(LoginUser user, Long courseId, String key, Pageable pageable) {
        Course course = courseDAO.findCourseById(courseId);

        if (!courseService.existsGetAuth(user, course)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权访问该课程的课件");
        }

        switch (user.getType()) {
            case TEACHER:
                return slideDAO.findByCourseAndNameContains(course, key, pageable).map(SlideVO::new);
            case STUDENT:
                return slideDAO.findByCourseAndStateNotInAndNameContains(course, STATES_NOT_GET_BY_STUDENT_SET, key, pageable).map(SlideVO::new);
            default:
                return Page.empty();
        }
    }

    @Transactional(readOnly = true)
    @Override
    public String getSlideUrl(LoginUser user, Long slideId) {
        Slide slide = slideDAO.findSlideById(slideId);

        if (!existsGetAuth(user, slide)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权获取该课件的链接");
        }

        return ossObjectUrlUtils.getUrl(slide.getObjectName());
    }

    @Transactional(readOnly = true)
    @Override
    public SlideVO getOneSlide(LoginUser user, Long slideId) {
        Slide slide = slideDAO.findSlideById(slideId);

        if (!existsGetAuth(user, slide)) {
            throw HelperException.of(ExceptionType.FORBIDDEN, "您无权访问该课件");
        }

        return new SlideVO(slide);
    }

    @Override
    public boolean existsAddAuth(LoginUser user, Slide slide) {
        return slide.getCourse().getTeacher().getId().equals(user.getId());
    }

    @Override
    public boolean existsDelAuth(LoginUser user, Slide slide) {
        return slide.getTeacher().getId().equals(user.getId());
    }

    @Override
    public boolean existsUpdateAuth(LoginUser user, Slide slide) {
        return slide.getTeacher().getId().equals(user.getId());
    }

    @Override
    public boolean existsGetAuth(LoginUser user, Slide slide) {
        return courseService.existsGetAuth(user, courseDAO.findCourseById(slide.getCourse().getId()));
    }
}