import { createPool } from 'mariadb';
import fs from 'fs';
import path from 'path';

function loadDatabaseConfig() {
  const envPath = path.join(process.cwd(), '.env');
  if (fs.existsSync(envPath)) {
    const envContent = fs.readFileSync(envPath, 'utf-8');
    const lines = envContent.split('\n');
    
    for (const line of lines) {
      const trimmedLine = line.trim();
      if (trimmedLine.startsWith('DATABASE_URL=')) {
        const url = trimmedLine.substring('DATABASE_URL='.length).replace(/^"|"$/g, '');
        
        // 解析URL
        const parts = url.split('://')[1].split('@');
        const auth = parts[0].split(':');
        const hostAndDb = parts[1].split('/');
        const hostAndPort = hostAndDb[0].split(':');
        
        return {
          user: auth[0],
          password: auth[1],
          host: hostAndPort[0],
          port: parseInt(hostAndPort[1]),
          database: hostAndDb[1]
        };
      }
    }
  }
  
  return {
    host: '192.168.111.111',
    port: 3306,
    user: 'root',
    password: 'fullstack',
    database: 'iboard'
  };
}

let pool;

async function initPool() {
  if (!pool) {
    const config = loadDatabaseConfig();
    pool = createPool({
      host: config.host,
      port: config.port,
      user: config.user,
      password: config.password,
      database: config.database,
      connectionLimit: 5
    });
  }
  return pool;
}

export default async function handler(req, res) {
  try {
    await initPool();
    
    // 获取查询参数
    const { startDate, endDate, limit = 30 } = req.query;
    
    let query = 'SELECT date, centerPrice FROM econ_ExchangeRate WHERE currency = ? ORDER BY date DESC';
    const params = ['USD/CNY'];
    
    if (startDate && endDate) {
      query = 'SELECT date, centerPrice FROM econ_ExchangeRate WHERE currency = ? AND date BETWEEN ? AND ? ORDER BY date DESC';
      params.push(startDate, endDate);
    }
    
    const result = await pool.query(query, params);
    
    // 限制返回数量
    const limitedResult = result.slice(0, parseInt(limit));
    
    // 反转顺序，使日期从早到晚
    const sortedResult = limitedResult.reverse();
    
    // 格式化数据
    const formattedData = sortedResult.map(row => ({
      date: row.date instanceof Date ? row.date.toISOString().split('T')[0] : row.date,
      rate: parseFloat(row.centerPrice)
    }));
    
    res.status(200).json({
      success: true,
      data: formattedData,
      total: result.length
    });
  } catch (error) {
    console.error('获取汇率数据失败:', error.message);
    res.status(500).json({
      success: false,
      message: '获取汇率数据失败',
      error: error.message
    });
  } finally {
    // 不关闭连接池，保持连接池打开以提高性能
    // 如果需要关闭连接池，应该在关闭后将 pool 变量设置为 null
    // if (pool) {
    //   await pool.end();
    //   pool = null;
    // }
  }
}