package com.njuzr.eaibackend.service.impl;

import com.alibaba.fastjson2.JSONObject;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.njuzr.eaibackend.dto.AssignmentDTO;
import com.njuzr.eaibackend.dto.AssignmentQueryDTO;
import com.njuzr.eaibackend.dto.AssignmentUpdateDTO;
import com.njuzr.eaibackend.dto.CorrectDTO;
import com.njuzr.eaibackend.enums.AssignmentCompletionStatus;
import com.njuzr.eaibackend.enums.AssignmentStatus;
import com.njuzr.eaibackend.enums.Role;
import com.njuzr.eaibackend.exception.MyException;
import com.njuzr.eaibackend.mapper.*;
import com.njuzr.eaibackend.po.*;
import com.njuzr.eaibackend.po.Class;
import com.njuzr.eaibackend.service.AssignmentService;
import com.njuzr.eaibackend.service.ClassService;
import com.njuzr.eaibackend.service.TextAnalysisService;
import com.njuzr.eaibackend.utils.*;
import com.njuzr.eaibackend.vo.*;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeanUtils;
import org.springframework.cache.annotation.CacheEvict;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;
import java.util.*;
import java.util.function.Function;
import java.util.stream.Collectors;

/**
 * @author: Leonezhurui
 * @Date: 2024/3/15 - 00:40
 * @Package: EAI-Backend
 */

@Slf4j
@Service
public class AssignmentServiceImpl implements AssignmentService {

    private final AssignmentMapper assignmentMapper;

    private final CourseMapper courseMapper;

    private final StudentAssignmentMapper studentAssignmentMapper;

    private final UserMapper userMapper;

    private final ClassService classService;
    private final OssUtil ossUtil;

    private final FileUtil fileUtil = new FileUtil();

    private final TextAnalysisService textAnalysisService;

    public AssignmentServiceImpl(AssignmentMapper assignmentMapper,
                                 CourseMapper courseMapper,
                                 StudentAssignmentMapper studentAssignmentMapper,
                                 UserMapper userMapper,
                                 OssUtil ossUtil,
                                 CourseServiceImpl courseServiceImpl,
                                 CourseStudentMapper courseStudentMapper,
                                 ClassService classService,
                                 TextAnalysisService textAnalysisService) {
        this.assignmentMapper = assignmentMapper;
        this.courseMapper = courseMapper;
        this.studentAssignmentMapper = studentAssignmentMapper;
        this.userMapper = userMapper;
        this.ossUtil = ossUtil;
        this.textAnalysisService = textAnalysisService;
        this.classService = classService;
    }

    @Override
    public AssignmentVO createAssignment(MyUserDetails user, Long courseId, AssignmentDTO assignmentDTO) {
        Course course = courseMapper.selectById(courseId);
        if (course == null)
            throw MyException.create(HttpStatus.BAD_REQUEST, "课程不存在");


        if (user.getRole() != Role.ADMIN) {
            List<String> teacherIds = Collections.singletonList(Optional.ofNullable(course.getTeacherIds())
                    .orElse(Collections.emptyList().toString()));
            String userIdStr = String.valueOf(user.getId());
            boolean hasTeacherId = teacherIds.contains(userIdStr);
            boolean pidMatches = Objects.equals(course.getTeacherPid(), user.getPid());
            if (!hasTeacherId && !pidMatches) {
                throw MyException.create(HttpStatus.BAD_REQUEST, "无权限创建");
            }
        }

        Assignment target = convertToPO(assignmentDTO);
        target.setCourseId(courseId);
        target.setTeacherId(user.getId());
        target.setEngageNumber(0);
        target.setCorrectNumber(0);
        // TODO:权宜之计
//        target.setTeacherId(Long.valueOf(user.getPid()));
        target.setCreateTime(new Date());

        try {
            int code = assignmentMapper.insert(target);
            if (code == 0)
                throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "创建作业失败");
        } catch (Exception e) {
            log.error(e.getMessage());
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "创建作业失败");
        }
        return convertToVO(target);
    }


    @Override
//    @Cacheable(value = "assignmentInfo", key = "'assignment_' + #assignmentId")
    public AssignmentVO findAssignmentById(Long assignmentId) {
        QueryWrapper<Assignment> wrapper = new QueryWrapper<>();
        wrapper.eq("assignment_id", assignmentId);
        Assignment res = assignmentMapper.selectOne(wrapper);
        log.info("数据库查询作业：{}", assignmentId);
        if (res == null)
            throw MyException.create(HttpStatus.BAD_REQUEST, "作业不存在");
        return convertToVO(res);
    }

    @Override
    public IPage<AssignmentVO> findAssignmentPage(Page<Assignment> page, AssignmentQueryDTO assignmentQueryDTO) {
        log.info("作业查询服务：{}", assignmentQueryDTO);
        QueryWrapper<Assignment> wrapper = new QueryWrapper<>();

        if (assignmentQueryDTO.getAssignmentId() != null) { // assignmentId直接判断是否相等
            // TODO 检测assignmentId是否正确
            wrapper.eq("assignmentId", assignmentQueryDTO.getAssignmentId());
        }
        if (assignmentQueryDTO.getTeacherId() != null) { // teacherId直接匹配
            wrapper.eq("teacher_id", assignmentQueryDTO.getTeacherId());
        }
        if (assignmentQueryDTO.getCourseId() != null) { // teacherId直接匹配
            wrapper.eq("course_id", assignmentQueryDTO.getCourseId());
        }
        if (assignmentQueryDTO.getAssignmentName() != null) { // 模糊匹配作业名字
            wrapper.like("assignment_name", assignmentQueryDTO.getAssignmentName());
        }

        if(assignmentQueryDTO.getType() != null){
            wrapper.eq("type",assignmentQueryDTO.getType());
        }
        if (assignmentQueryDTO.getStatus() != null) {
            AssignmentStatus status = assignmentQueryDTO.getStatus();
            if (status == AssignmentStatus.NOT_STARTED) {
                wrapper.gt("start_time", LocalDateTime.now()); // 意思是start_time > now()
            } else if (status == AssignmentStatus.PROCEEDING) {
                wrapper.le("start_time", LocalDateTime.now())
                        .ge("end_time", LocalDateTime.now());
            } else {
                wrapper.lt("end_time", LocalDateTime.now());
            }
        }
        IPage<Assignment> assignments = assignmentMapper.selectPage(page, wrapper);

        return PageMapperUtil.convert(assignments, this::convertToVO);
    }


    @Override
    @CacheEvict(value = "assignmentInfo", key = "'assignment_' + #assignmentId")
    public AssignmentVO updateAssignment(MyUserDetails user, Long assignmentId, AssignmentUpdateDTO assignmentUpdateDTO) {
        Assignment target = assignmentMapper.selectById(assignmentId);
        if (!Objects.equals(target.getTeacherId(), user.getId()) && !Objects.equals(target.getTeacherPid(), user.getPid()))
            throw MyException.create(HttpStatus.BAD_REQUEST, "无权限更新");

        Assignment ope = convertToPO(assignmentUpdateDTO);
        ope.setAssignmentId(assignmentId);
        try {
            int code = assignmentMapper.updateById(ope);
            if (code == 0)
                throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "服务器更新失败");
        } catch (Exception e) {
            log.error(e.getMessage());
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "服务器更新失败");
        }

        return convertToVO(assignmentMapper.selectById(assignmentId));
    }


    /**
     * 教师删除作业
     */
    @Override
    @Transactional
    @CacheEvict(value = "assignmentInfo", key = "'assignment_' + #assignmentId")
    public void deleteById(Long teacherId, Long assignmentId) {
        Assignment target = assignmentMapper.selectById(assignmentId);
        if (!Objects.equals(target.getTeacherId(), teacherId))
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "无权限删除");

        try {
            List<Engagement> engagements = studentAssignmentMapper.findEngagementByAssignmentId(assignmentId);
            for(Engagement engagement : engagements) {
                studentAssignmentMapper.delete(engagement.getStudentId(), assignmentId);
            }
            int code = assignmentMapper.deleteById(assignmentId);
            if (code == 0) {
                throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "删除作业错误");
            }
        } catch (Exception e) {
            log.error(e.getMessage());
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "删除作业错误");
        }

    }


    @Override
    public void engageAssignment(Long studentId, Long assignmentId) {
        if(studentAssignmentMapper.findEngagementByStudentIdAndAssignmentId(studentId, assignmentId) != null){
            return;
        }


        // 1创建Engagement实体类，初始化基本信息
        Engagement engagement = new Engagement();
        engagement.setStudentId(studentId);
        engagement.setAssignmentId(assignmentId);
        engagement.setVersion(1); // 设置这是version
        engagement.setStatus(AssignmentCompletionStatus.NOT_SUBMITTED); // 已经进入到页面编辑，但是还没有提交

        Assignment assignment = assignmentMapper.selectById(assignmentId);
        assignment.setEngageNumber(assignment.getEngageNumber() + 1);


//        // 2通过FileUtil创建一个空的docx文件
//        InputStream inputStream = fileUtil.createEmptyDocx();
//
//        String filePath = assignmentId + "_" + studentId + ".docx";
//        // 3通过OssUtil工具类上传空文件，注意给其命名为`assignmentId/studentId.docx`，并得到文件链接
//        String fileName = ossUtil.uploadEnduringFile(inputStream, filePath);
//        engagement.setFileUrl(fileName);

        try {
            int code = studentAssignmentMapper.insert(engagement);
            int code1 = assignmentMapper.updateById(assignment);
            if (code == 0 || code1 == 0)
                throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "参加作业失败");
        } catch (Exception e) {
            log.error(e.getMessage());
//            ossUtil.deleteFile(filePath);
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "参加作业失败");
        }
    }


    /**
     * 根据两个外键，搜索学生参与作业的情况（需要在mysql中设置索引）
     *
     * @param studentId
     * @param assignmentId
     * @return
     */
    @Override
    public EngagementVO getEngagement(Long studentId, Long assignmentId) {
        Engagement engagement = studentAssignmentMapper.findEngagementByStudentIdAndAssignmentId(studentId, assignmentId);
        if (engagement == null)
            throw MyException.create(HttpStatus.BAD_REQUEST, "参与作业情况不存在");
        return convertToVO(engagement);
    }


    // 返回顺序： 先是未批改的，然后是批改的按照成绩从高到低返回
    @Override
    public IPage<EngagementVO> findEngagementPage(Page<Engagement> page, Long assignmentId) {
        IPage<Engagement> engagements = studentAssignmentMapper.findEngagementByAssignmentId(page, assignmentId);
        return PageMapperUtil.convert(engagements, this::convertToVO);
    }




    @Override
    public EngagementDetailVO getDetailEngagement(Long studentId, Long assignmentId) {
        // 1 获取用户详细信息
        User student = userMapper.selectById(studentId);
        if (student == null)
            throw MyException.create(HttpStatus.BAD_REQUEST, "学生不存在");

        // 2 获取作业详细信息
        Assignment assignment = assignmentMapper.selectById(assignmentId);
        if (assignment == null)
            throw MyException.create(HttpStatus.BAD_REQUEST, "作业不存在");

        // 3 获取作业参与详细信息
        Engagement engagement = studentAssignmentMapper.findEngagementByStudentIdAndAssignmentId(studentId, assignmentId);
        if (engagement == null)
            throw MyException.create(HttpStatus.BAD_REQUEST, "参与作业情况不存在");


        EngagementDetailVO detailVO = ModelMapperUtil.map(engagement, EngagementDetailVO.class);
        detailVO.setUserVO(ModelMapperUtil.map(student, UserVO.class));
        detailVO.setAssignmentVO(convertToVO(assignment));
//        detailVO.setFileKey(assignmentId + "_" + studentId + "_" + engagement.getVersion());

        log.info("请求到详细信息：" + detailVO);

        return detailVO;
    }

    /**
     * 作业提交，更新文件版本和作业状态
     *
     * @param studentId
     * @param assignmentId
     */
    @Override
    public void engagementSubmit(Long studentId, Long assignmentId) {
        Engagement engagement = studentAssignmentMapper.findEngagementByStudentIdAndAssignmentId(studentId, assignmentId);
        if (engagement == null)
            throw MyException.create(HttpStatus.BAD_REQUEST, "参与作业情况不存在");
        int originalVersion = engagement.getVersion();
        engagement.setVersion(originalVersion + 1);
        engagement.setStatus(AssignmentCompletionStatus.SUBMITTED);
        try {
            int code = studentAssignmentMapper.updateById(engagement);
            if (code == 0)
                throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "更新文件版本失败");
        } catch (Exception e) {
            log.error(e.getMessage());
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "更新文件版本失败");
        }
    }


    /**
     * 作业暂存，更新文件版本，不修改作业状态
     *
     * @param studentId
     * @param assignmentId
     */
    @Override
    public void engagementStage(Long studentId, Long assignmentId, JSONObject jsonObject) {
        Engagement engagement = studentAssignmentMapper.findEngagementByStudentIdAndAssignmentId(studentId, assignmentId);
        if (engagement == null)
            throw MyException.create(HttpStatus.BAD_REQUEST, "参与作业情况不存在");
        int originalVersion = engagement.getVersion();
        String quillContent = jsonObject.getString("quillContent");
        String textContent = jsonObject.getString("textContent");
        String htmlContent = jsonObject.getString("htmlContent");
        engagement.setVersion(originalVersion + 1);
        engagement.setQuillContent(quillContent);
        engagement.setTextContent(textContent);
        engagement.setHtmlContent(htmlContent);
        try {
            int code = studentAssignmentMapper.updateById(engagement);
            if (code == 0)
                throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "更新文件版本失败");
            // 异步启动文本分析，不影响主流程返回速度
            try {
                textAnalysisService.analyzeAndSaveTextContentAsync(studentId, assignmentId);
                log.info("已启动异步文本分析 - studentId: {}, assignmentId: {}", studentId, assignmentId);
            } catch (Exception e) {
                log.error("启动异步文本分析失败 - studentId: {}, assignmentId: {}, error: {}",
                        studentId, assignmentId, e.getMessage());
                // 不抛出异常，避免影响主流程
            }
        } catch (Exception e) {
            log.error(e.getMessage());
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "更新文件版本失败");
        }
    }

    @Override
    public void engagementCorrect(Long teacherId, Long studentId, Long assignmentId, CorrectDTO correctDTO) {
        Engagement engagement = studentAssignmentMapper.findEngagementByStudentIdAndAssignmentId(studentId, assignmentId);
        if (engagement == null)
            throw MyException.create(HttpStatus.BAD_REQUEST, "参与作业情况不存在");

        Assignment assignment = assignmentMapper.selectById(assignmentId);
        if (assignment == null)
            throw MyException.create(HttpStatus.BAD_REQUEST, "作业不存在");

        if (!Objects.equals(assignment.getTeacherId(), teacherId))
            throw MyException.create(HttpStatus.BAD_REQUEST, "无权限批改");

        if(engagement.getStatus() != AssignmentCompletionStatus.CORRECTED){
            assignment.setCorrectNumber(assignment.getCorrectNumber() + 1);
            engagement.setStatus(AssignmentCompletionStatus.CORRECTED);
        }
        engagement.setScore(correctDTO.getScore());
        engagement.setRemark(correctDTO.getRemark());
        try {
            int code = studentAssignmentMapper.updateById(engagement);
            int code1 = assignmentMapper.updateById(assignment);
            if (code == 0 || code1 == 0)
                throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "批改作业失败");
        } catch (Exception e) {
            log.error(e.getMessage());
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "批改作业失败");
        }

    }

    @Override
    public long getNextStudentId(Long assignmentId, Long studentId) {
        List<Engagement> allRecords = studentAssignmentMapper.selectList(
                new QueryWrapper<Engagement>()
                        .eq("assignment_id", assignmentId)
                // 可以在此添加其他查询条件
        );
        // 对记录进行排序：status为4或6的记录排到最后，其他记录保持原始顺序
        List<Engagement> sortedList = allRecords.stream()
                .sorted(Comparator.comparing(
                        e -> e.getStatus() == AssignmentCompletionStatus.PUBLISHED ||
                                e.getStatus() == AssignmentCompletionStatus.CORRECTED
                )).toList();

        int currentIndex = -1;
        for (int i = 0; i < sortedList.size(); i++) {
            if (sortedList.get(i).getStudentId().equals(studentId)) {
                currentIndex = i;
                break;
            }
        }
        if (currentIndex == allRecords.size() - 1 || currentIndex == -1) {
            return sortedList.get(0).getStudentId();
        }

        return sortedList.get(currentIndex + 1).getStudentId();
    }

    @Override
    public EngageNumberVo getEngageNumber(Long assignmentId) {
        Assignment assignment = assignmentMapper.selectById(assignmentId);
        if(assignment == null){
            throw MyException.create(HttpStatus.BAD_REQUEST, "作业不存在");
        }
        if(assignment.getEngageNumber() != null && assignment.getCorrectNumber() != null){
            return new EngageNumberVo(assignment.getEngageNumber(), assignment.getCorrectNumber());
        } else {
            throw MyException.create(HttpStatus.BAD_REQUEST, "未建立作业统计");
        }
    }

    private Assignment convertToPO(AssignmentDTO assignmentDTO) {
        Assignment assignment = new Assignment();
        BeanUtils.copyProperties(assignmentDTO, assignment);
        if (assignmentDTO.getAttachments() != null)
            assignment.setAttachments(ConvertUtil.listToString(assignmentDTO.getAttachments()));
        return assignment;
    }

    private Assignment convertToPO(AssignmentUpdateDTO assignmentDTO) {
        Assignment assignment = new Assignment();
        BeanUtils.copyProperties(assignmentDTO, assignment);
        if (assignmentDTO.getAttachments() != null)
            assignment.setAttachments(ConvertUtil.listToString(assignmentDTO.getAttachments()));
        return assignment;
    }

    private AssignmentVO convertToVO(Assignment assignment) {
        AssignmentVO res = new AssignmentVO();
        BeanUtils.copyProperties(assignment, res);
        if (assignment.getAttachments() != null)
            res.setAttachments(ConvertUtil.stringToList(assignment.getAttachments(), String::valueOf));
        res.setStatus(calculateStatus(res.getStartTime(), res.getEndTime()));
        // 组装老师姓名
        res.setTeacherName(userMapper.selectNameById(assignment.getTeacherId()));
        return res;
    }

    private EngagementVO convertToVO(Engagement engagement) {
        EngagementVO res = ModelMapperUtil.map(engagement, EngagementVO.class);
        // 组装文件key
//        res.setFileKey(res.getAssignmentId() + "_" + res.getStudentId() + "_" + res.getVersion());
        // 组装学生姓名
        String studentName = userMapper.selectNameById(engagement.getStudentId());
        res.setStudentName(studentName);
        return res;
    }

    private AssignmentStatus calculateStatus(Date startTime, Date endTime) {
        Date now = new Date();
        if (now.before(startTime)) {
            return AssignmentStatus.NOT_STARTED;
        } else if (now.after(endTime)) {
            return AssignmentStatus.FINISHED;
        } else {
            return AssignmentStatus.PROCEEDING;
        }
    }



    @Override
    public List<StudentAssignmentStatusVO> getStudentsAssignmentStatus(Long classId, Long assignmentId) {
        // 1. 验证班级和作业存在性
        Assignment assignment = assignmentMapper.selectById(assignmentId);
        if (assignment == null) {
            throw new RuntimeException("作业不存在");  // 建议替换为项目自定义异常
        }

        // 2. 获取班级所有学生（从class_student表）
        List<StudentInfoVO> classStudents = classService.getStudentsByClassId(classId);
        if (classStudents.isEmpty()) {
            return Collections.emptyList();
        }

        // 3. 提取学号列表，查询对应的用户ID（users表）
        List<String> officialNumbers = classStudents.stream()
                .map(StudentInfoVO::getOfficialNumber)
                .collect(Collectors.toList());

        List<User> users = userMapper.selectUserIdByOfficialNumbers(officialNumbers);
        Map<String, Long> officialNumberToUserIdMap = users.stream()
                .collect(Collectors.toMap(
                        User::getOfficialNumber,
                        User::getId
                ));

        // 4. 查询这些学生的作业提交情况（student_assignment表）
        List<Long> studentIds = new ArrayList<>(officialNumberToUserIdMap.values());
        List<StudentAssignment> studentAssignments = studentAssignmentMapper.findByAssignmentIdAndStudentIds(assignmentId, studentIds);

        // 5. 构建学生ID到作业情况的映射
        Map<Long, StudentAssignment> studentIdToAssignmentMap = studentAssignments.stream()
                .collect(Collectors.toMap(
                        StudentAssignment::getStudentId,
                        Function.identity()
                ));

        // 6. 组装返回结果
        return classStudents.stream()
                .map(student -> {
                    StudentAssignmentStatusVO vo = new StudentAssignmentStatusVO();
                    vo.setOfficialNumber(student.getOfficialNumber());
                    vo.setStuName(student.getStuName());

                    // 设置学生ID
                    Long studentId = officialNumberToUserIdMap.get(student.getOfficialNumber());
                    vo.setStudentId(studentId);

                    // 设置状态和成绩
                    StudentAssignment studentAssignment = studentIdToAssignmentMap.get(studentId);
                    if (studentAssignment == null) {
                        // 未参与作业，按未提交处理
                        vo.setStatus(AssignmentCompletionStatus.NOT_SUBMITTED);
                        vo.setScore(0);
                    } else {
                        // 转换状态为枚举
                        vo.setStatus(AssignmentCompletionStatus.fromValue(studentAssignment.getStatus()));
                        // 处理成绩（BigDecimal转Integer，未批改为0）
                        vo.setScore(studentAssignment.getScore() != null ?
                                studentAssignment.getScore().intValue() : 0);
                    }
                    return vo;
                })
                .collect(Collectors.toList());
    }
}