const express = require('express');
const cors = require('cors');
const { createProxyMiddleware } = require('http-proxy-middleware');
const multer = require('multer');
const { v4: uuidv4 } = require('uuid');
const path = require('path');
const fs = require('fs');
const morgan = require('morgan');
require('dotenv').config();

// 引入自定义日志系统
const { logger } = require('./logger');

const app = express();
const PORT = process.env.PORT || 3000;

// 配置全局请求日志中间件
app.use((req, res, next) => {
  const startTime = Date.now();

  // 保存原始的res.end方法
  const originalEnd = res.end;
  res.end = function(chunk, encoding) {
    // 调用自定义日志记录
    logger.http(req, res, startTime);

    // 调用原始的res.end
    originalEnd.call(this, chunk, encoding);
  };

  next();
});

// 配置 CORS，允许前端项目的跨域请求
app.use(cors());

// --- 1. 流式对话请求代理配置 ---
app.use('/api/chat-ui/chat', (req, res, next) => {
  logger.info('Received chat request', {
    method: req.method,
    url: req.url,
    headers: {
      'content-type': req.headers['content-type'],
      'content-length': req.headers['content-length']
    }
  });

  const apiKey = process.env.ALIYUN_API_KEY;
  if (!apiKey) {
    logger.error("【错误】发送代理请求前未配置 ALIYUN_API_KEY !");
  } else {
    req.headers['authorization'] = `Bearer ${apiKey}`;
    logger.debug('Added authorization header for chat request');
  }
  next();
});

// 注意：代理中间件需要在 body-parser (express.json) 之前，不然代理会导致请求体丢失
app.use(
  '/api/chat-ui/chat',
  createProxyMiddleware({
    // 阿里云百炼由于兼容 OpenAI 格式，所以代理到此接口
    target: 'https://dashscope.aliyuncs.com/compatible-mode/v1/chat/completions',
    changeOrigin: true,
    // 去除路径前缀，确保发往阿里云的路径是纯正的 completions 路径
    pathRewrite: {
      '^/api/chat-ui/chat': '',
    },
    // 代理日志
    onProxyReq: (proxyReq, req, res) => {
      logger.info('Proxying chat request to DashScope API', {
        target: 'https://dashscope.aliyuncs.com/compatible-mode/v1/chat/completions',
        method: req.method,
        url: req.url
      });
    },
    onProxyRes: (proxyRes, req, res) => {
      logger.info('Received response from DashScope API', {
        statusCode: proxyRes.statusCode,
        headers: proxyRes.headers
      });
    },
    onError: (err, req, res) => {
      logger.error('Error occurred during proxying chat request', {
        error: err.message,
        method: req.method,
        url: req.url
      });
      res.status(500).json({ error: 'Proxy error: ' + err.message });
    }
  })
);

// --- 下面的路由专门走 Node.js 业务逻辑，因此需要解析 JSON Body ---
app.use(express.json());

// 内存中暂时存放对话数据用于 Mock
const conversationsDB = {};

// --- 2. 获取模型列表 ---
app.get('/api/chat-ui/models', (req, res) => {
  logger.info('Getting models list', {
    method: req.method,
    url: req.url,
    ip: req.ip || req.connection.remoteAddress
  });

  try {
    const models = [
      {
        id: "qwen-max",
        name: "通义千问 Max",
        description: "最强大的模型",
        maxTokens: 8192,
        provider: "Aliyun"
      },
      {
        id: "qwen-plus",
        name: "通义千问 Plus",
        description: "能力均衡",
        maxTokens: 8192,
        provider: "Aliyun"
      }
    ];

    res.json(models);
    logger.info('Successfully returned models list', { count: models.length });
  } catch (error) {
    logger.error('Error getting models list', { error: error.message });
    res.status(500).json({ error: 'Internal server error' });
  }
});

// --- 3. 获取所有对话历史 ---
app.get('/api/chat-ui/conversations', (req, res) => {
  logger.info('Getting all conversations', {
    method: req.method,
    url: req.url,
    ip: req.ip || req.connection.remoteAddress
  });

  try {
    const conversations = Object.values(conversationsDB);
    res.json(conversations);
    logger.info('Successfully returned conversations', { count: conversations.length });
  } catch (error) {
    logger.error('Error getting conversations', { error: error.message });
    res.status(500).json({ error: 'Internal server error' });
  }
});

// --- 4. 获取单个对话 ---
app.get('/api/chat-ui/conversations/:id', (req, res) => {
  const { id } = req.params;
  logger.info('Getting conversation by ID', {
    method: req.method,
    url: req.url,
    conversationId: id,
    ip: req.ip || req.connection.remoteAddress
  });

  try {
    const conversation = conversationsDB[id];
    if (conversation) {
      res.json(conversation);
      logger.info('Successfully returned conversation', { conversationId: id });
    } else {
      res.status(404).json({ error: '对话不存在' });
      logger.warn('Conversation not found', { conversationId: id });
    }
  } catch (error) {
    logger.error('Error getting conversation by ID', {
      conversationId: id,
      error: error.message
    });
    res.status(500).json({ error: 'Internal server error' });
  }
});

// --- 5. 保存或更新对话 ---
app.post('/api/chat-ui/conversations', (req, res) => {
  logger.info('Creating or updating conversation', {
    method: req.method,
    url: req.url,
    body: {
      hasId: !!req.body.id,
      title: req.body.title
    },
    ip: req.ip || req.connection.remoteAddress
  });

  try {
    const data = req.body;
    if(!data.id) {
      data.id = uuidv4();
      logger.debug('Generated new conversation ID', { conversationId: data.id });
    }

    conversationsDB[data.id] = data;
    res.json(data);
    logger.info('Successfully saved conversation', { conversationId: data.id });
  } catch (error) {
    logger.error('Error saving conversation', { error: error.message });
    res.status(500).json({ error: 'Internal server error' });
  }
});

// --- 6. 删除对话 ---
app.delete('/api/chat-ui/conversations/:id', (req, res) => {
  const { id } = req.params;
  logger.info('Deleting conversation', {
    method: req.method,
    url: req.url,
    conversationId: id,
    ip: req.ip || req.connection.remoteAddress
  });

  try {
    if (conversationsDB[id]) {
      delete conversationsDB[id];
      res.json({ success: true, message: "删除成功" });
      logger.info('Successfully deleted conversation', { conversationId: id });
    } else {
      res.status(404).json({ error: '对话不存在' });
      logger.warn('Attempted to delete non-existent conversation', { conversationId: id });
    }
  } catch (error) {
    logger.error('Error deleting conversation', {
      conversationId: id,
      error: error.message
    });
    res.status(500).json({ error: 'Internal server error' });
  }
});

// 为了存储上传文件而建立临时目录
const uploadDir = path.join(__dirname, 'uploads');
if (!fs.existsSync(uploadDir)) {
  fs.mkdirSync(uploadDir);
  logger.info('Created uploads directory', { path: uploadDir });
}

// 配置文件上传
const storage = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, uploadDir);
  },
  filename: function (req, file, cb) {
    const uniqueSuffix = Date.now() + '-' + Math.round(Math.random() * 1E9);
    cb(null, uniqueSuffix + '-' + file.originalname);
  }
});
const upload = multer({ storage: storage });

// 提供静态文件访问支持
app.use('/uploads', express.static(uploadDir));

// --- 7. 上传文件 ---
app.post('/api/chat-ui/upload', upload.single('file'), (req, res) => {
  logger.info('Processing file upload', {
    method: req.method,
    url: req.url,
    originalFilename: req.file ? req.file.originalname : 'none',
    mimetype: req.file ? req.file.mimetype : 'none',
    size: req.file ? req.file.size : 'none',
    ip: req.ip || req.connection.remoteAddress
  });

  if (!req.file) {
    const errorMsg = '没有文件上传';
    logger.warn(errorMsg, {
      method: req.method,
      url: req.url
    });
    return res.status(400).json({ error: errorMsg });
  }

  try {
    // 返回供前端使用和访问的 URL
    const response = {
      url: `http://localhost:${PORT}/uploads/${req.file.filename}`,
      name: req.file.originalname,
      size: req.file.size,
      mimeType: req.file.mimetype
    };

    res.json(response);
    logger.info('Successfully uploaded file', {
      filename: req.file.filename,
      originalName: req.file.originalname,
      url: response.url,
      size: req.file.size
    });
  } catch (error) {
    logger.error('Error processing file upload', {
      originalFilename: req.file.originalname,
      error: error.message
    });
    res.status(500).json({ error: 'File upload processing failed' });
  }
});

// --- 8. 停止生成 ---
app.post(['/api/chat-ui/stop', '/api/chat-ui/stop/:id'], (req, res) => {
  const id = req.params.id;
  logger.info('Stop generation request received', {
    method: req.method,
    url: req.url,
    messageId: id,
    ip: req.ip || req.connection.remoteAddress
  });

  try {
    res.json({ success: true, message: "已发出停止指令" });
    logger.info('Stop generation request processed', { messageId: id });
  } catch (error) {
    logger.error('Error processing stop generation request', {
      messageId: id,
      error: error.message
    });
    res.status(500).json({ error: 'Internal server error' });
  }
});

// 其他所有路由返回404
app.use((req, res) => {
  logger.warn('Route not found', {
    method: req.method,
    url: req.url,
    ip: req.ip || req.connection.remoteAddress
  });
  res.status(404).json({ error: 'Endpoint not found' });
});

app.listen(PORT, () => {
  logger.info('Server started successfully', {
    port: PORT,
    timestamp: new Date().toISOString()
  });

  console.log('====================================');
  console.log(`本地代理服务器已启动，监听端口: ${PORT}`);
  console.log('====================================');
  if (!process.env.ALIYUN_API_KEY) {
      console.log('⚠️ 警告: 未在 .env 文件中检测到 ALIYUN_API_KEY!');
      console.log('请在 server/.env 中添加您的百炼 API Key。');
  } else {
      console.log('✅ 检测到了 API Key。');
      logger.info('API Key detected in environment');
  }
});