const db = require('../db/index')
const multer = require('multer')
const fs = require('fs')
const {
  importQuestionsByFile
} = require('./stb')

const sanitizeInput = {
  toPositiveInt: (value, defaultValue) => {
    const num = parseInt(value)
    return (num > 0) ? num : defaultValue
  },
  escapeSearch: (str) => {
    if (!str) return ''
     return str.replace(/[<>&"']/g, '')
  }
}

const storage = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, './uploads')
  },
  filename: function (req, file, cb) {
    cb(null, Date.now() + '-' + file.originalname)
  }
})

// 文件类型过滤
const fileFilter = (req, file, cb) => {
  if (
    file.mimetype === 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet' || // xlsx
    file.mimetype === 'application/vnd.openxmlformats-officedocument.wordprocessingml.document' || // docx
    file.mimetype === 'text/plain'
  ) {
    cb(null, true)
  } else {
    cb(new Error('不支持的文件类型'), false)
  }
}

const upload = multer({
  storage: storage,
  fileFilter: fileFilter
})

// 上传试卷
exports.uploadPaper = [
  upload.single('file'),
  async (req, res) => {
    try {
      if (!req.file) {
        return res.json({
          status: 1,
          message: '请选择文件'
        })
      }

      const filePath = req.file.path
      await importQuestionsByFile(filePath)
      fs.unlinkSync(filePath)

      res.json({
        status: 0,
        message: '上传成功'
      })

    } catch (error) {
      if (req.file && req.file.path) {
        fs.unlinkSync(req.file.path)
      }

      res.json({
        status: 1,
        message: '上传失败',
        error: error.message,
        format: {
          excel: "必须包含列：'题目', '选项A', '选项B', '选项C', '选项D', '答案'",
          word: `格式示例：
                      题目1：问题内容
                      A. 选项A内容
                      B. 选项B内容
                      C. 选项C内容
                      D. 选项D内容
                      答案：A

                      题目2：...`,
                                txt: `格式示：
                      ���题内容
                      A. 选项A内容
                      B. 选项B内容
                      C. 选项C内容
                      D. 选项D内容
                      答案：A

                      下一道题...`
        }
      })
    }
  }
]

// 获取试卷列表
exports.getList = async (req, res) => {
  try {
    const [papers] = await db.promise().query('SELECT * FROM paper');
    const papersWithCount = papers.map(paper => ({
      ...paper,
      topic_count: JSON.parse(paper.TopicsId || '[]').length
    }));

    res.json({ success: true, data: papersWithCount });
  } catch (error) {
    console.error('获取试卷列表失败:', error);
    res.status(500).json({ success: false, message: '获取试卷列表失败' });
  }
}

// 获取指定试卷的题目列表
exports.getPaperQuestions = async (req, res) => {
  try {
    const { paperId, page = 1, pageSize = 10 } = req.body;

    if (!paperId) {
      return res.status(400).json({ success: false, message: '无效的试卷ID' });
    }

    const sanitizedPaperId = sanitizeInput.toPositiveInt(paperId, 0);
    const sanitizedPage = sanitizeInput.toPositiveInt(page, 1);
    const sanitizedPageSize = sanitizeInput.toPositiveInt(pageSize, 10);
    const limitedPageSize = Math.min(sanitizedPageSize, 100);
    const offset = (sanitizedPage - 1) * limitedPageSize;

    const [papers] = await db.promise().query('SELECT * FROM paper WHERE id = ?', [sanitizedPaperId]);
    if (papers.length === 0) {
      return res.status(404).json({ success: false, message: '试卷不存在' });
    }

    const topicIds = JSON.parse(papers[0].TopicsId || '[]');
    const total = topicIds.length;

    const pagedTopicIds = topicIds.slice(offset, offset + limitedPageSize);

    if (pagedTopicIds.length === 0) {
      return res.json({
        success: true,
        data: {
          list: [],
          pagination: {
            current: sanitizedPage,
            pageSize: limitedPageSize,
            total
          }
        }
      });
    }

    // 查询题目详情
    const [topics] = await db.promise().query(
      'SELECT * FROM topics WHERE id IN (?)',
      [pagedTopicIds]
    );

    const orderedTopics = pagedTopicIds.map(id =>
      topics.find(topic => topic.id === id)
    ).filter(Boolean);

    res.json({
      success: true,
      data: {
        list: orderedTopics,
        pagination: {
          current: sanitizedPage,
          pageSize: limitedPageSize,
          total
        }
      }
    });
  } catch (error) {
    console.error('获取试卷题目失败:', error);
    res.status(500).json({ success: false, message: '获取试卷题目失败' });
  }
}

//  获取试卷详情
exports.getPaperDetail = async (req, res) => {
  try {
    console.log('Received body:', req.body);

    if (!paperId) {
      return res.status(400).json({ success: false, message: '无效的试卷ID' });
    }

    const sanitizedPaperId = sanitizeInput.toPositiveInt(paperId, 0);
    const sanitizedPage = sanitizeInput.toPositiveInt(page, 1);
    const sanitizedPageSize = sanitizeInput.toPositiveInt(pageSize, 10);
    const limitedPageSize = Math.min(sanitizedPageSize, 100);
    const offset = (sanitizedPage - 1) * limitedPageSize;

    const [papers] = await db.promise().query('SELECT * FROM paper WHERE id = ?', [sanitizedPaperId]);
    if (papers.length === 0) {
      return res.status(404).json({ success: false, message: '试卷不存在' });
    }

    const topicIds = JSON.parse(papers[0].TopicsId || '[]');
    const total = topicIds.length;

    const pagedTopicIds = topicIds.slice(offset, offset + limitedPageSize);

    let topics = [];
    if (pagedTopicIds.length > 0) {
      const [topicsResult] = await db.promise().query(
        'SELECT * FROM topics WHERE id IN (?)',
        [pagedTopicIds]
      );
      topics = pagedTopicIds.map(id =>
        topicsResult.find(topic => topic.id === id)
      ).filter(Boolean);
    }

    res.json({
      success: true,
      data: {
        ...papers[0],
        topics: {
          list: topics,
          pagination: {
            current: sanitizedPage,
            pageSize: limitedPageSize,
            total
          }
        }
      }
    });
  } catch (error) {
    console.error('获取试卷详情失败:', error);
    res.status(500).json({ success: false, message: '获取试卷详情失败' });
  }
}

// 搜索题目
exports.searchTopics = async (req, res) => {
  try {
    let { keyword, page = 1, pageSize = 10 } = req.query;

    keyword = sanitizeInput.escapeSearch(keyword);
    if (!keyword) {
      return res.status(400).json({ success: false, message: '请提供有效的搜索关键词' });
    }

    page = sanitizeInput.toPositiveInt(page, 1);
    pageSize = Math.min(sanitizeInput.toPositiveInt(pageSize, 10), 100);
    const offset = (page - 1) * pageSize;

    const [countResult] = await db.promise().query(
      'SELECT COUNT(*) as total FROM topics WHERE title LIKE ?',
      [`%${keyword}%`]
    );
    const total = countResult[0].total;

    const [topics] = await db.promise().query(
      `SELECT t.*,
        (SELECT title FROM paper WHERE JSON_CONTAINS(TopicsId, CAST(t.id AS JSON))) as paper_title
       FROM topics t
       WHERE t.title LIKE ?
       LIMIT ?, ?`,
      [`%${keyword}%`, offset, pageSize]
    );

    res.json({
      success: true,
      data: {
        list: topics,
        pagination: {
          current: page,
          pageSize,
          total
        }
      }
    });
  } catch (error) {
    console.error('搜索题目失败:', error);
    res.status(500).json({ success: false, message: '搜索题目失败' });
  }
}