const mysql = require('mysql')

class MySQLPool {
  constructor () {
    this._user = ''
    this._password = ''
    this._host = ''
    this._port = 3306
    this._database = ''
    this._socketPath = ''
    this._pool = null
    this.autoclose = false
    this._useSocket = false
  }

  createPool () {
    let json = {
      connectionLimit: 30,
      user: this._user,
      password: this._password,
      host: this._host,
      port: this._port,
      socketPath: this._socketPath
    }
    if (this._useSocket) {
      delete json.host
      delete json.port
    } else {
      delete json.socketPath
    }
    this._pool = mysql.createPool(json)
  }

  async getConn () {
    return new Promise((resolve, reject) => {
      this._pool.getConnection((err, conn) => {
        if (err) return reject(err)
        return resolve(conn)
      })
    })
  }

  formatQuery (query, arg) {
    return mysql.format(query, arg)
  }

  escape (val) {
    return mysql.escape(val)
  }

  recordPage (rows, page, maxPage) {
    if (!page || !isFinite(page) || page < 1) page = 1

    let totalPage = Math.ceil(rows / maxPage)

    let prevPage = page - 1
    let nextPage = page + 1

    if (prevPage < 1) prevPage = 1
    if (nextPage > totalPage) nextPage = totalPage

    let recStart = (page - 1) * maxPage + 1
    let recEnd = (recStart + maxPage - 1)
    if (recEnd > rows) recEnd = rows

    let json = {
      recStart,
      recEnd,
      total: rows,
      prevPage,
      nextPage,
      totalPage,
      page
    }

    return json
  }

  set user (str) { this._user = str }
  set host (str) { this._host = str }
  set password (str) { this._password = str }
  set port (str) { this._port = str }
  set database (str) { this._database = str }
}

// let Pool = ((opts) => {
//     let defOpts = {
//         user: 'root',
//         pass: '',
//         host: 'localhost',
//         port: 3306,
//         socket: '/var/lib/mysql/mysql.sock',
//         useSocket: false
//     }

//     let opt = {
//         user: opts.user || defOpts.user,
//         pass: opts.pass || defOpts.pass,
//         host: opts.host || defOpts.host,
//         port: opts.port || defOpts.port,
//         socket: opts.socket || defOpts.socket,
//         useSocket: opts.useSocket || defOpts.useSocket
//     };

//     let pool = new MySQLPool();

//     pool._host = opt.host;
//     pool._password = opt.pass;
//     pool._port = opt.port;
//     pool._user = opt.user;
//     pool._socket = opt.socket;
//     pool._useSocket = opt.useSocket;

//     pool.createPool();
//     return pool
// })()

module.exports = new MySQLPool()