var util = require('util');

var Command = require('./command.js');
var Packets = require('../packets/index.js');
var ClientConstants = require('../constants/client.js');
var ClientHandshake = require('./client_handshake.js');
var CharsetToEncoding = require('../constants/charset_encodings.js');

function ChangeUser(options, callback) {
  this.onResult = callback;
  this.user = options.user;
  this.password = options.password;
  this.database = options.database;
  this.passwordSha1 = options.passwordSha1;
  this.charsetNumber = options.charsetNumber;
  this.currentConfig = options.currentConfig;
  Command.call(this);
}
util.inherits(ChangeUser, Command);

ChangeUser.prototype.handshakeResult =
  ClientHandshake.prototype.handshakeResult;
ChangeUser.prototype.calculateNativePasswordAuthToken =
  ClientHandshake.prototype.calculateNativePasswordAuthToken;

ChangeUser.prototype.start = function(packet, connection) {
  var packet = new Packets.ChangeUser({
    flags: connection.config.clientFlags,
    user: this.user,
    database: this.database,
    charsetNumber: this.charsetNumber,
    password: this.password,
    passwordSha1: this.passwordSha1,
    authPluginData1: connection._handshakePacket.authPluginData1,
    authPluginData2: connection._handshakePacket.authPluginData2
  });
  this.currentConfig.user = this.user;
  this.currentConfig.password = this.password;
  this.currentConfig.database = this.database;
  this.currentConfig.charsetNumber = this.charsetNumber;
  connection.clientEncoding = CharsetToEncoding[this.charsetNumber];
  // reset prepared statements cache as all statements become invalid after changeUser
  connection._statements.reset();
  connection.writePacket(packet.toPacket());
  return ChangeUser.prototype.handshakeResult;
};

module.exports = ChangeUser;