/**
 * 游戏区服动态数据库连接工具
 *
 * 游戏每个区服对应独立的数据库 mir_actor_s{serverId}
 * 该模块根据 serverId 动态创建连接池（带缓存，同一区服复用连接）
 *
 * 使用示例：
 *   import getGameDB from '../mysql/gameDB.js'
 *   const db = getGameDB(1)
 *   const [rows] = await db.query('SELECT ...')
 */

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

// 连接池缓存，避免对同一区服重复创建
const poolCache = new Map()

/**
 * 获取指定区服的 MySQL 连接池（Promise 包装）
 * @param {number} serverId  区服 ID
 * @returns {import('mysql2/promise').Pool}
 */
export default function getGameDB(serverId) {
  const dbName = `mir_actor_s${serverId}`
  if (poolCache.has(dbName)) return poolCache.get(dbName)

  const pool = mysql.createPool({
    host: config.game.dbHost || config.mysql.host,
    port: config.game.dbPort || config.mysql.port,
    user: config.game.dbUser || config.mysql.user,
    password: config.game.dbPassword || config.mysql.password,
    database: dbName,
    connectionLimit: 5,
    waitForConnections: true,
  })

  pool.on('error', (err) => {
    log4js.mysql.error(`[${dbName}] 连接池错误:`, err.message)
  })

  const promisePool = pool.promise()
  poolCache.set(dbName, promisePool)
  return promisePool
}