package com.njuzr.eaibackend.service;

import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.njuzr.eaibackend.exception.MyException;
import com.njuzr.eaibackend.mapper.EngagementMapper;
import com.njuzr.eaibackend.mapper.serviceIpml.EngagementMapperServiceImpl;
import com.njuzr.eaibackend.po.Engagement;
import com.njuzr.eaibackend.po.User;
import com.njuzr.eaibackend.po.Assignment;
import com.njuzr.eaibackend.utils.WordExporter;
import com.njuzr.eaibackend.utils.ZipExport;
import com.njuzr.eaibackend.vo.AssignmentVO;
import com.njuzr.eaibackend.vo.EngagementVO;
import com.njuzr.eaibackend.vo.UserVO;
import com.njuzr.eaibackend.vo.StudentInfoVO;
import com.njuzr.eaibackend.vo.EngagementHistoryVO;
import freemarker.template.Configuration;
import freemarker.template.TemplateException;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.tuple.Pair;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Service;
import org.springframework.util.CollectionUtils;

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

@Slf4j
@Service
public class ExportCompositionService {

    @Autowired
    private Configuration freemarkerConfig;
    @Autowired
    private EngagementMapper engagementMapper;
    @Autowired
    private AssignmentService assignmentService;
    @Autowired
    private UserService userService;
    @Autowired
    private WordExporter wordExporter;
    @Autowired
    private EngagementMapperServiceImpl engagementMapperServiceImpl;
    @Autowired
    private com.njuzr.eaibackend.mapper.UserMapper userMapper;
    @Autowired
    private com.njuzr.eaibackend.mapper.AssignmentMapper assignmentMapper;

    public Pair<UserVO, byte[]> exportWord(Long assignmentId, Long studentId) {
        AssignmentVO assignment = assignmentService.findAssignmentById(assignmentId);
        EngagementVO engagement = assignmentService.getEngagement(studentId, assignmentId);
        UserVO user = userService.searchUsers(new Page<>(1,1), studentId, null, null, null).getRecords().get(0);

        Map<String, Object> model = buildWordInfoModel(assignment, user, engagement);

        return Pair.of(user, wordExporter.exportCompositionWord(model));

    }

    private Map<String, Object> buildWordInfoModel(AssignmentVO assignment, UserVO user, EngagementVO engagement) {
        Map<String, Object> model = new HashMap<>();
        model.put("title", assignment.getAssignmentName());
        model.put("studentName", user.getName());
        model.put("officialNumber", user.getOfficialNumber());
        model.put("assignmentName", assignment.getAssignmentName());
        model.put("date", new Date());
        model.put("content", processContent(engagement.getTextContent()));
        return model;
    }

    public byte[] exportBatchToZip(List<Long> studentIds, Long assignmentId) {
        if(assignmentId == null){
            throw MyException.create(HttpStatus.BAD_REQUEST, "assignmentId不能为空");
        }

        if (CollectionUtils.isEmpty(studentIds)) {
            List<Engagement> engagements = engagementMapperServiceImpl.getEngagementByAssignmentId(assignmentId);
            if (CollectionUtils.isEmpty(engagements)) {
                return null;
            }
            studentIds = engagements.stream()
                    .map(Engagement::getStudentId)
                    .toList();
        }
        return exportBatchToZipByStudentIds(studentIds, assignmentId);
    }

    private byte[] exportBatchToZipByStudentIds(List<Long> studentIds, Long assignmentId) {
        List<ZipExport.ZipItem> zipItems = studentIds.stream()
                .map(studentId -> {
                    try {
                        Pair<UserVO, byte[]> pair = exportWord(assignmentId, studentId);
                        UserVO student = pair.getLeft();
                        byte[] wordBytes = pair.getRight();
                        String fileName = String.format("%s_%s.%s", student.getName(), student.getOfficialNumber(), "docx");
                        return new ZipExport.ZipItem(fileName, wordBytes);
                    } catch (Exception e) {
                        log.error("exportBatchToZip failed, studentId: {}, reason: {}", studentId, e.getMessage());
                        return null;
                    }
                })
                .filter(Objects::nonNull)
                .collect(Collectors.toList());

        try {
            return ZipExport.packToZip(zipItems);
        } catch (IOException e) {
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "ZIP打包失败"+e.getMessage());
        }
    }


    public byte[] exportWordTest(Long assignmentId, Long studentId) throws IOException, TemplateException {

        String assignmentName = "My Favorite Season";
        String content = "My favorite season is autumn. The weather is cool and comfortable, and the leaves turn golden, making the scenery beautiful. I enjoy walking in the park and listening to the sound of rustling leaves. Autumn is also a harvest season, with fruits like apples and pears ripe for picking.\n" +
                "During this season, my family often goes hiking or has picnics. The Mid-Autumn Festival, when we eat mooncakes and admire the full moon, is my favorite holiday. Autumn reminds me of warmth and joy.\n" +
                "In short, autumn is not only pleasant but also full of happy memories. That’s why I love it most.";

        Map<String, Object> model = new HashMap<>();
        model.put("title", "title_"+assignmentName);
        model.put("studentName", "柏琪");
        model.put("assignmentName", assignmentName);
        model.put("date", new Date());
        model.put("content", content.replaceAll("\n", "<br/>"));

        return wordExporter.exportCompositionWord(model);
    }

    private String processContent(String content) {
        return content.replaceAll("\n", "<br/>");
    }

    public byte[] downloadClassAssignments(Long classId) {
        // 获取班级信息
        com.njuzr.eaibackend.po.Class cls = classService.getClassById(classId);
        if (cls == null) {
            throw MyException.create(HttpStatus.BAD_REQUEST, "班级不存在");
        }

        // 获取班级所有学生
        List<StudentInfoVO> students = classService.getStudentsByClassId(classId);
        if (students.isEmpty()) {
            throw MyException.create(HttpStatus.BAD_REQUEST, "班级无学生");
        }

        // 获取班级对应的课程ID
        Long courseId = cls.getCourseId();
        if (courseId == null) {
            throw MyException.create(HttpStatus.BAD_REQUEST, "班级未关联课程");
        }

        // 获取课程的所有作业
        List<Assignment> courseAssignments = assignmentMapper.selectByCourseId(courseId);
        if (courseAssignments.isEmpty()) {
            throw MyException.create(HttpStatus.BAD_REQUEST, "课程无作业");
        }

        // 生成ZIP文件
        try {
            List<ZipExport.ZipItem> zipItems = new ArrayList<>();
            for (StudentInfoVO student : students) {
                String officialNumber = student.getOfficialNumber();
                User user = userMapper.selectOne(new QueryWrapper<User>().eq("official_number", officialNumber));
                if (user == null) {
                    continue;
                }
                Long studentId = user.getId();
                
                for (Assignment assignment : courseAssignments) {
                    Long assignmentId = assignment.getAssignmentId();
                    String assignmentDir = assignment.getAssignmentName() + "/";
                    String studentDir = assignmentDir + user.getOfficialNumber() + "_" + user.getName() + "/";
                    try {
                        List<EngagementHistoryVO> historyList = assignmentService.getEngagementHistory(studentId, assignmentId);
                        for (EngagementHistoryVO history : historyList) {
                            Map<String, Object> model = new HashMap<>();
                            model.put("title", assignment.getAssignmentName());
                            model.put("studentName", user.getName());
                            model.put("officialNumber", user.getOfficialNumber());
                            model.put("assignmentName", assignment.getAssignmentName());
                            model.put("date", history.getSubmitTime());
                            model.put("content", processContent(history.getTextContent()));
                            
                            byte[] wordBytes = wordExporter.exportCompositionWord(model);
                            String fileName = studentDir + user.getOfficialNumber() + "_" + user.getName() + "_版本" + history.getVersion() + ".docx";
                            zipItems.add(new ZipExport.ZipItem(fileName, wordBytes));
                        }
                    } catch (Exception e) {
                        log.warn("学生 {} 未提交作业 {}，跳过", studentId, assignmentId);
                    }
                }
            }
            return ZipExport.packToZip(zipItems);
        } catch (IOException e) {
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "ZIP打包失败" + e.getMessage());
        }
    }

    public byte[] downloadAssignmentSubmissions(Long assignmentId) {
        AssignmentVO assignment = assignmentService.findAssignmentById(assignmentId);
        if (assignment == null) {
            throw MyException.create(HttpStatus.BAD_REQUEST, "作业不存在");
        }

        Long courseId = assignment.getCourseId();
        List<com.njuzr.eaibackend.po.Class> courseClasses = classService.select(courseId);
        if (courseClasses.isEmpty()) {
            throw MyException.create(HttpStatus.BAD_REQUEST, "课程无班级");
        }

        try {
            List<ZipExport.ZipItem> zipItems = new ArrayList<>();
            
            for (com.njuzr.eaibackend.po.Class cls : courseClasses) {
                String className = cls.getClassName();
                String classDir = className + "/";
                
                List<StudentInfoVO> students = classService.getStudentsByClassId(cls.getClassId());
                for (StudentInfoVO student : students) {
                    String officialNumber = student.getOfficialNumber();
                    User user = userMapper.selectOne(new QueryWrapper<User>().eq("official_number", officialNumber));
                    if (user == null) continue;
                    
                    Long studentId = user.getId();
                    String studentDir = classDir + user.getOfficialNumber() + "_" + user.getName() + "/";
                    
                    List<EngagementHistoryVO> historyList = assignmentService.getEngagementHistory(studentId, assignmentId);
                    for (EngagementHistoryVO history : historyList) {
                        Map<String, Object> model = new HashMap<>();
                        model.put("title", assignment.getAssignmentName());
                        model.put("studentName", user.getName());
                        model.put("officialNumber", user.getOfficialNumber());
                        model.put("assignmentName", assignment.getAssignmentName());
                        model.put("date", history.getSubmitTime());
                        model.put("content", processContent(history.getTextContent()));
                        
                        byte[] wordBytes = wordExporter.exportCompositionWord(model);
                        String fileName = studentDir + user.getOfficialNumber() + "_" + user.getName() + "_版本" + history.getVersion() + ".docx";
                        zipItems.add(new ZipExport.ZipItem(fileName, wordBytes));
                    }
                }
            }
            return ZipExport.packToZip(zipItems);
        } catch (IOException e) {
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "ZIP打包失败" + e.getMessage());
        }
    }

    public byte[] downloadClassAssignment(Long classId, Long assignmentId) {
        com.njuzr.eaibackend.po.Class cls = classService.getClassById(classId);
        if (cls == null) {
            throw MyException.create(HttpStatus.BAD_REQUEST, "班级不存在");
        }
        
        AssignmentVO assignment = assignmentService.findAssignmentById(assignmentId);
        if (assignment == null) {
            throw MyException.create(HttpStatus.BAD_REQUEST, "作业不存在");
        }
        
        String folderName = cls.getClassName() + "_" + assignment.getAssignmentName();
        String folderDir = folderName + "/";
        
        List<StudentInfoVO> students = classService.getStudentsByClassId(classId);
        if (students.isEmpty()) {
            throw MyException.create(HttpStatus.BAD_REQUEST, "班级无学生");
        }
        
        try {
            List<ZipExport.ZipItem> zipItems = new ArrayList<>();
            
            for (StudentInfoVO student : students) {
                String officialNumber = student.getOfficialNumber();
                User user = userMapper.selectOne(new QueryWrapper<User>().eq("official_number", officialNumber));
                if (user == null) continue;
                
                Long studentId = user.getId();
                String studentDir = folderDir + user.getOfficialNumber() + "_" + user.getName() + "/";
                
                List<EngagementHistoryVO> historyList = assignmentService.getEngagementHistory(studentId, assignmentId);
                for (EngagementHistoryVO history : historyList) {
                    Map<String, Object> model = new HashMap<>();
                    model.put("title", assignment.getAssignmentName());
                    model.put("studentName", user.getName());
                    model.put("officialNumber", user.getOfficialNumber());
                    model.put("assignmentName", assignment.getAssignmentName());
                    model.put("date", history.getSubmitTime());
                    model.put("content", processContent(history.getTextContent()));
                    
                    byte[] wordBytes = wordExporter.exportCompositionWord(model);
                    String fileName = studentDir + user.getOfficialNumber() + "_" + user.getName() + "_版本" + history.getVersion() + ".docx";
                    zipItems.add(new ZipExport.ZipItem(fileName, wordBytes));
                }
            }
            return ZipExport.packToZip(zipItems);
        } catch (IOException e) {
            throw MyException.create(HttpStatus.INTERNAL_SERVER_ERROR, "ZIP打包失败" + e.getMessage());
        }
    }

    // 需要注入 ClassService
    @Autowired
    private ClassService classService;

}