import mysql from "mysql2";
import config from "../config/index.js";
import * as log4js from "../log4js.js";

const pool = mysql.createPool({
  host: config.mysql.host,
  port: config.mysql.port,
  user: config.mysql.user,
  password: config.mysql.password,
  database: config.mysql.database,
  connectionLimit: 10,
  // 不在启动时立即建立连接，等第一次查询时再连接
  waitForConnections: true,
  enableKeepAlive: true,
  keepAliveInitialDelay: 10000,
});

// 监听连接错误，避免未处理的 Promise rejection 导致进程崩溃
pool.on('connection', (connection) => {
  log4js.mysql.info(`MySQL 连接建立 [id=${connection.threadId}] ${config.mysql.host}:${config.mysql.port}`);
});
pool.on('error', (err) => {
  log4js.mysql.error('MySQL 连接池错误:', err.message);
});

const promisePool = pool.promise();

// 健康检查：启动时 ping 一次数据库，失败只警告不崩溃
promisePool.query('SELECT 1').then(() => {
  log4js.mysql.info(`MySQL 连接成功 ${config.mysql.host}:${config.mysql.port}/${config.mysql.database}`);
}).catch((err) => {
  log4js.mysql.warn(`MySQL 连接失败（服务仍将继续运行）: ${err.message}`);
});

export default promisePool;