const express = require('express');
const { v4: uuidv4 } = require('uuid');
const { optionalAuth } = require('../middleware/auth');
const conversionService = require('../services/conversionService');
const ConversionTask = require('../models/ConversionTask');
const File = require('../models/File');

const router = express.Router();

/**
 * @route   POST /api/convert/start
 * @desc    开始一个新的文件转换任务
 * @access  Private (optional)
 */
router.post('/start', optionalAuth, async (req, res, next) => {
  try {
    const { fileId, outputFormat, options = {} } = req.body;

    if (!fileId || !outputFormat) {
      return res.status(400).json({ success: false, message: '缺少必要参数：fileId和outputFormat' });
    }

    // 验证文件是否存在
    const file = await File.findOne({ fileId });
    if (!file) {
      return res.status(404).json({ success: false, message: '文件未找到' });
    }

    // 创建转换任务
    const task = await ConversionTask.create({
      taskId: uuidv4(),
      fileId,
      outputFormat,
      options,
      userId: req.user?.userId || null,
      sourceFile: {
        name: file.fileName,
        size: file.size,
        type: file.mimeType
      }
    });

    // 异步开始转换，不阻塞响应
    conversionService.startConversion(task.taskId);

    res.status(202).json({
      success: true,
      message: '转换任务已创建',
      data: {
        taskId: task.taskId,
        status: task.status,
        progress: task.progress
      }
    });

  } catch (error) {
    next(error);
  }
});

/**
 * @route   GET /api/convert/status/:taskId
 * @desc    查询转换任务的状态
 * @access  Public
 */
router.get('/status/:taskId', async (req, res, next) => {
  try {
    const { taskId } = req.params;
    const task = await ConversionTask.findOne({ taskId }).lean();

    if (!task) {
      return res.status(404).json({ success: false, message: '转换任务未找到' });
    }

    res.json({ success: true, data: task });

  } catch (error) {
    next(error);
  }
});

/**
 * @route   GET /api/convert/result/:taskId
 * @desc    获取转换任务的结果
 * @access  Public
 */
router.get('/result/:taskId', async (req, res, next) => {
  try {
    const { taskId } = req.params;
    const task = await ConversionTask.findOne({ taskId }).lean();

    if (!task) {
      return res.status(404).json({ success: false, message: '转换任务未找到' });
    }

    if (task.status !== 'completed') {
      return res.status(400).json({ success: false, message: '转换尚未完成' });
    }

    res.json({
      success: true,
      data: {
        taskId: task.taskId,
        resultUrl: task.resultFile.downloadUrl,
        fileName: task.resultFile.fileName,
        fileSize: task.resultFile.fileSize
      }
    });

  } catch (error) {
    next(error);
  }
});

/**
 * @route   POST /api/convert/batch
 * @desc    开始批量转换任务
 * @access  Private (optional)
 */
router.post('/batch', optionalAuth, async (req, res, next) => {
  try {
    const { fileIds, outputFormat, options = {} } = req.body;

    if (!fileIds || !Array.isArray(fileIds) || fileIds.length === 0) {
      return res.status(400).json({ success: false, message: '请提供要转换的文件ID列表' });
    }

    if (fileIds.length > 10) {
      return res.status(400).json({ success: false, message: '批量转换最多支持10个文件' });
    }

    const batchId = uuidv4();
    const createdTasks = [];

    for (const fileId of fileIds) {
      const file = await File.findOne({ fileId });
      if (file) {
        const task = await ConversionTask.create({
          taskId: uuidv4(),
          batchId,
          fileId,
          outputFormat,
          options,
          userId: req.user?.userId || null,
          sourceFile: {
            name: file.fileName,
            size: file.size,
            type: file.mimeType
          }
        });
        createdTasks.push(task);
        // 异步开始转换
        conversionService.startConversion(task.taskId);
      }
    }

    res.status(202).json({
      success: true,
      message: '批量转换任务已创建',
      data: {
        batchId,
        taskCount: createdTasks.length,
        tasks: createdTasks.map(t => ({ taskId: t.taskId, status: t.status }))
      }
    });

  } catch (error) {
    next(error);
  }
});

/**
 * @route   POST /api/convert/cancel/:taskId
 * @desc    取消一个正在进行的转换任务
 * @access  Private (optional)
 */
router.post('/cancel/:taskId', optionalAuth, async (req, res, next) => {
  try {
    const { taskId } = req.params;
    const task = await ConversionTask.findOne({ taskId });

    if (!task) {
      return res.status(404).json({ success: false, message: '转换任务未找到' });
    }

    // 权限检查：确保用户只能取消自己的任务
    if (task.userId && (!req.user || task.userId !== req.user.userId)) {
        return res.status(403).json({ success: false, message: '无权操作此任务' });
    }

    await task.cancel();

    res.json({ success: true, message: '转换任务已取消' });

  } catch (error) {
    next(error);
  }
});

module.exports = router;