package nju.seec.helper.service.impl;

import nju.seec.helper.dao.*;
import nju.seec.helper.dto.QuestionStudentAnswerDTO;
import nju.seec.helper.entity.*;
import nju.seec.helper.service.QuizService;
import nju.seec.helper.util.BokUtil;
import nju.seec.helper.util.enums.ExceptionType;
import nju.seec.helper.util.enums.QuizState;
import nju.seec.helper.util.enums.SlideState;
import nju.seec.helper.util.enums.UserType;
import nju.seec.helper.util.exception.HelperException;
import nju.seec.helper.vo.quiz.BaseQuestionVO;
import nju.seec.helper.vo.quiz.QuizResultVO;
import nju.seec.helper.vo.quiz.QuizVO;
import org.springframework.beans.factory.annotation.Autowired;
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.util.Assert;

import java.util.*;
import java.util.stream.Collectors;

@Service
public class QuizServiceImpl implements QuizService {
    private final SlideDAO slideDAO;
    private final QuizDAO quizDAO;
    private final QuizStudentAnswerDAO quizStudentAnswerDAO;
    private final ChooseDAO chooseDAO;
    private final CourseDAO courseDAO;
    private final UserDAO userDAO;
    private final BokUtil bokUtil;

    @Autowired
    public QuizServiceImpl(SlideDAO slideDAO, QuizDAO quizDAO, QuizStudentAnswerDAO quizStudentAnswerDAO, ChooseDAO chooseDAO, CourseDAO courseDAO, UserDAO userDAO, BokUtil bokUtil) {
        this.slideDAO = slideDAO;
        this.quizDAO = quizDAO;
        this.quizStudentAnswerDAO = quizStudentAnswerDAO;
        this.chooseDAO = chooseDAO;
        this.courseDAO = courseDAO;
        this.userDAO = userDAO;
        this.bokUtil = bokUtil;
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Quiz createQuiz(String name, Long uid, SlideState quizTime,
                           Long slideId, List<String> questions){
        User teacher =new User();
        teacher.setId(uid);
        Slide slide = slideDAO.findSlideById(slideId);
        Course course = new Course();
        course.setId(slide.getCourseId());
        Quiz quiz = new Quiz();

        quiz.setCourse(course);
        quiz.setName(name);
        quiz.setQuestions(questions);
        quiz.setQuizTime(quizTime);
        quiz.setSlide(slide);
        quiz.setTeacher(teacher);

        checkQuizState(quiz,slide);

        quiz=quizDAO.saveAndFlush(quiz);
        return quiz;
    }
    @Override
    public String deleteQuiz(Long quizId) {
        Quiz quiz =quizDAO.findQuizById(quizId);
        if(quiz.getState()!=QuizState.NOT_STARTED){throw HelperException.of(ExceptionType.FORBIDDEN,"不能删除已经开始的测试！");}
        quizDAO.delete(quiz);
        return "delete success";
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Quiz modifyQuiz(Long quizId, String name, List<String> questions, SlideState quizTime, String slideId) {

        Quiz quiz =quizDAO.findQuizById(quizId);
        if(quiz.getState()!=QuizState.NOT_STARTED){throw HelperException.of(ExceptionType.FORBIDDEN,"不能修改已经开始的测试！");}
        if(name!=null) {
            quiz.setName(name);
        }
        if(questions!=null) {
            quiz.setQuestions(questions);
        }
        if(quizTime!=null) {
            quiz.setQuizTime(quizTime);
            checkQuizState(quiz,quiz.getSlide());
        }
        return quizDAO.saveAndFlush(quiz);

    }

    @Override
    public Page<Quiz> getAllBasicQuizByUser(Pageable pageable, QuizState state, Long uid) {
        User user=userDAO.findUserById(uid);
        //todo: 这里写的太狗屎了，可以用重写sql或者用实例查询
        if(user.getType().equals(UserType.STUDENT)){
            final Set<Long> courseIdsByStudentId = chooseDAO.findCourseIdsByStudentId(uid);
            final Set<Course> collect = courseIdsByStudentId.stream().map(i -> {
                Course c = new Course();
                c.setId(i);
                return c;
            }).collect(Collectors.toSet());
            if(state!=null){
                return quizDAO.findAllByCourseInAndState(collect,state,pageable);
            }else{
                return quizDAO.findAllByCourseIn(collect,pageable);
            }
        }else{
            if(state!=null){
                return quizDAO.findByTeacherAndState(user,state,pageable);
            }else{
                return quizDAO.findByTeacher(user,pageable);
            }

        }

    }

    @Override
    public List<QuizResultVO> getQuizResult(Long quizId) {
        Assert.notNull(quizId,"错误的测试！");
        final Quiz quiz = quizDAO.findQuizById(quizId);
        if(quiz.getState()!=QuizState.CLOSED){throw new RuntimeException("测试未关闭,无法得到测试结果");}
        List<QuizResultVO> retList=new ArrayList<>();
        final List<StudentScore> studentScoreList = quiz.getStudentScore();
        Map<Long,List<QuizStudentAnswer>> idQuizStudentAnswerMap=new HashMap<>();
        for(QuizStudentAnswer qsa:quizStudentAnswerDAO.findAllByQuiz(quiz)){
            idQuizStudentAnswerMap.computeIfAbsent(qsa.getStudent().getId(), k -> new ArrayList<>());
            idQuizStudentAnswerMap.get(qsa.getStudent().getId()).add(qsa);
        }
        for(StudentScore studentScore:studentScoreList){
            final User student = studentScore.getStudent();
            final List<QuizStudentAnswer> list = idQuizStudentAnswerMap.get(student.getId());
            retList.add(new QuizResultVO(studentScore,student,list));
        }
        return retList;
    }

    @Override
    public void modifySlideState(Slide slide) {
        final List<Quiz> quizzes = quizDAO.findAllBySlide(slide);
        quizzes.forEach(quiz->checkQuizState(quiz,slide));
    }

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Integer upStudentAnswer(Long quizId, Long uid, List<QuestionStudentAnswerDTO> answers) {
        Assert.notNull(quizId,"错误的测试！");
        final Quiz quiz = quizDAO.findQuizById(quizId);
        if(quiz.getState()!=QuizState.ONGOING){throw HelperException.of(ExceptionType.FORBIDDEN,"不能提交尚未开始的作业！");}
        User student =new User();student.setId(uid);
        Set<QuizStudentAnswer> quizAnswers = quizStudentAnswerDAO.findByStudentAndQuiz(student,quiz);
        Set<String> questionIdSet = new HashSet<>(quiz.getQuestions());
        Map<String,QuizStudentAnswer> qsaMap=new HashMap<>(questionIdSet.size());
        for(QuizStudentAnswer qsa: quizAnswers){
            qsaMap.put(qsa.getQuestionId(),qsa);
        }
        //确定被更新或者新建的学生答案提交
        List<QuizStudentAnswer> quizStudentAnswers=new ArrayList<>();
        for(QuestionStudentAnswerDTO studentAnswer:answers){
            String id = studentAnswer.getQuestionId();
            String answer = studentAnswer.getStudentAnswer().toString();
            if(!questionIdSet.contains(id)){break;}
            if(qsaMap.get(id)!=null){
                if(qsaMap.get(id).getStudentAnswer().equals(answer)){
                    continue;
                }
                qsaMap.get(id).setStudentAnswer(answer);
                System.out.println(answer);
                quizStudentAnswers.add(qsaMap.get(id));
            }else {
                QuizStudentAnswer qsa=QuizStudentAnswer.builder()
                        .questionId(id).quiz(quiz).student(student).studentAnswer(answer)
                        .build();
                quizStudentAnswers.add(qsa);
            }

        }
        Integer savedNum=quizStudentAnswers.size();
        quizStudentAnswerDAO.saveAll(quizStudentAnswers);
        return savedNum;
    }

    @Override
    public Page<Quiz> getAllBasicQuizBySlide(Long slideId, Pageable pageable, QuizState state, Long uid) {
        Assert.notNull(slideId,"错误的幻灯片！");
        Slide slide=new Slide();
        slide.setId(slideId);
        if(state!=null) {
            return quizDAO.findAllBySlideAndState(slide, state, pageable);
        }
        else {
            return quizDAO.findAllBySlide(slide, pageable);
        }
    }
    @Override
    @Transactional(rollbackFor = Exception.class)
    public QuizState checkQuizState(Quiz quiz, Slide slide) {
        int quizTime = quiz.getQuizTime().getNum();
        int slideTime = slide.getState().getNum();
        if (quiz.getId() == null){
            //未持久化的quiz
            quiz.setState(slideTime < quizTime ? QuizState.NOT_STARTED : QuizState.ONGOING);
        }
        else {
            //持久化后，不仅仅需要推进状态，还需要判分，保存等步骤
            if (slideTime < quizTime) {
                if(quiz.getState().equals(QuizState.NOT_STARTED)){return QuizState.NOT_STARTED;}
                //未开始
                quiz.setState(QuizState.NOT_STARTED);
            } else if (slideTime == quizTime) {
                if(quiz.getState().equals(QuizState.ONGOING)){return QuizState.ONGOING;}
                quiz.setState(QuizState.ONGOING);
            } else {
                if(quiz.getState().equals(QuizState.CLOSED)){return QuizState.CLOSED;}
                quiz.setState(QuizState.CLOSED);
                Set<QuizStudentAnswer> quizAnswers = quizStudentAnswerDAO.findAllByQuiz(quiz);
                final Set<Long> studentIds = chooseDAO.findStudentIdsByCourseId(slide.getCourseId());
                Student2QuestionId2Answer triadMap = new Student2QuestionId2Answer(studentIds, quiz.getQuestions().size());
                //将已经作答的学生答案加入
                for (QuizStudentAnswer answers : quizAnswers) {
                    triadMap.addAnswer(answers);
                }
                //生成未作答的学生答案
                triadMap.fullAnswer(quiz);
                //检查答案，赋分
                triadMap.checkAnswerAndFullPass(bokUtil.bokFindByIdIn(quiz.getQuestions()), quiz);
                //保存现场
                quizStudentAnswerDAO.saveAll(triadMap.getAll());
            }

            quizDAO.save(quiz);
        }
        return quiz.getState();
    }
    @Override
    public QuizState checkQuizState(Long quizId, Long slideId){
        Quiz quiz=quizDAO.findQuizById(quizId);
        Slide slide=slideDAO.findSlideById(slideId);
        return checkQuizState(quiz,slide);
    }
    private class Student2QuestionId2Answer {
        Map<Long,Map<String,QuizStudentAnswer>> student2QuestionId2Answer;
        Student2QuestionId2Answer(Set<Long> studentIds, Integer quizQuestionSize) {
            student2QuestionId2Answer =new LinkedHashMap<>(studentIds.size());
            for(Long studentId:studentIds){
                Map<String,QuizStudentAnswer> questionId2Answer= new LinkedHashMap<>(quizQuestionSize);
                student2QuestionId2Answer.put(studentId,questionId2Answer);
            }
        }
        void addAnswer(QuizStudentAnswer answers){
            Map<String, QuizStudentAnswer> stringQuizStudentAnswerMap = student2QuestionId2Answer.get(answers.getStudent().getId());
            if(stringQuizStudentAnswerMap==null){
                return ;
            }
            stringQuizStudentAnswerMap.put(answers.getQuestionId(),answers);
        }
        void fullAnswer(Quiz quiz){
            List<String> questions=quiz.getQuestions();
            student2QuestionId2Answer.forEach((studentId, map)->{
                if(questions.size()!=map.size()){
                    for(String questionId:questions){
                        if(map.get(questionId)==null){
                            User student =new User();student.setId(studentId);
                            QuizStudentAnswer qsa=QuizStudentAnswer.builder()
                                    .questionId(questionId).quiz(quiz).student(student)
                                    .build();
                            map.put(questionId,qsa);
                        }
                    }
                }
            });
        }
        void checkAnswerAndFullPass(List<BaseQuestionVO> questionVos, Quiz quiz){
            if(quiz.getStudentScore()==null){quiz.setStudentScore(new ArrayList<>(student2QuestionId2Answer.size()));}
            student2QuestionId2Answer.forEach((studentId, map)->{
                int passCount=0;
                for(BaseQuestionVO vo:questionVos){
                    final String studentAnswer = map.get(vo.getQuestionId()).getStudentAnswer();
                    boolean pass=vo.checkAnswer(studentAnswer);
                    if(pass){passCount++;}
                    map.get(vo.getQuestionId()).setPass(pass);
                }
                Double score = (100.0*passCount)/questionVos.size();
                User student =new User();student.setId(studentId);
                StudentScore studentScore=new StudentScore();
                studentScore.setQuizId(quiz.getId());
                studentScore.setScore(Long.valueOf(Math.round(score)).intValue());
                studentScore.setStudent(student);
                quiz.getStudentScore().add(studentScore);
            });
        }
        List<QuizStudentAnswer> getAll(){
            List<QuizStudentAnswer> list=new ArrayList<>();
            for(Long sid: student2QuestionId2Answer.keySet()){
                list.addAll(student2QuestionId2Answer.get(sid).values());
            }
            return list;
        }
    }
    @Override
    public QuizVO combineQuiz(Long quizId){
        Assert.notNull(quizId,"错误的测试！");
        final Quiz quizById = quizDAO.findQuizById(quizId);
        final List<BaseQuestionVO> questionVoS = bokUtil.bokFindByIdIn(quizById.getQuestions());
        return new QuizVO(quizById,questionVoS);
    }
    @Override
    public QuizVO combineQuizWithAnswer(Long quizId, Long uid,UserType userType){
        Assert.notNull(quizId,"错误的测试！");
        final Quiz quizById = quizDAO.findQuizById(quizId);
        User student =new User();
        student.setId(uid);

        if(userType==null||userType.equals(UserType.TEACHER)){
            //向老师展示
            List<BaseQuestionVO> questionVoS = bokUtil.bokFindByIdIn(quizById.getQuestions());
            return new QuizVO(quizById,questionVoS);
        }
        if(quizById.getState().equals(QuizState.NOT_STARTED)){
            //未开始看不到题目
            return new QuizVO(quizById);
        }

        List<BaseQuestionVO> questionVos = bokUtil.bokFindByIdIn(quizById.getQuestions());
        final Set<QuizStudentAnswer> quizAnswers = quizStudentAnswerDAO.findByStudentAndQuiz(student,quizById);
        Map<String,QuizStudentAnswer> qsaMap=new HashMap<>(quizAnswers.size());
        for(QuizStudentAnswer qsa: quizAnswers){
            qsaMap.put(qsa.getQuestionId(),qsa);
        }
        for(BaseQuestionVO vo:questionVos){
            if(qsaMap.get(vo.getQuestionId())!=null){
                vo.exAddAnswer(qsaMap.get(vo.getQuestionId()));
            }
        }

        return new QuizVO(quizById,questionVos);
    }


}