var Sequence        = require('./Sequence');
var Util            = require('util');
var Packets         = require('../packets');
var Auth            = require('../Auth');
var ClientConstants = require('../constants/client');

module.exports = Handshake;
Util.inherits(Handshake, Sequence);
function Handshake(options, callback) {
  Sequence.call(this, options, callback);

  options = options || {};

  this._config                        = options.config;
  this._handshakeInitializationPacket = null;
}

Handshake.prototype.determinePacket = function determinePacket(firstByte, parser) {
  if (firstByte === 0xff) {
    return Packets.ErrorPacket;
  }

  if (!this._handshakeInitializationPacket) {
    return Packets.HandshakeInitializationPacket;
  }

  if (firstByte === 0xfe) {
    return (parser.packetLength() === 1)
      ? Packets.UseOldPasswordPacket
      : Packets.AuthSwitchRequestPacket;
  }

  return undefined;
};

Handshake.prototype['AuthSwitchRequestPacket'] = function (packet) {
  if (packet.authMethodName === 'mysql_native_password') {
    var challenge = packet.authMethodData.slice(0, 20);

    this.emit('packet', new Packets.AuthSwitchResponsePacket({
      data: Auth.token(this._config.password, challenge)
    }));
  } else {
    var err = new Error(
      'MySQL is requesting the ' + packet.authMethodName + ' authentication method, which is not supported.'
    );

    err.code = 'UNSUPPORTED_AUTH_METHOD';
    err.fatal = true;

    this.end(err);
  }
};

Handshake.prototype['HandshakeInitializationPacket'] = function(packet) {
  this._handshakeInitializationPacket = packet;

  this._config.protocol41 = packet.protocol41;

  var serverSSLSupport = packet.serverCapabilities1 & ClientConstants.CLIENT_SSL;

  if (this._config.ssl) {
    if (!serverSSLSupport) {
      var err = new Error('Server does not support secure connection');

      err.code = 'HANDSHAKE_NO_SSL_SUPPORT';
      err.fatal = true;

      this.end(err);
      return;
    }

    this._config.clientFlags |= ClientConstants.CLIENT_SSL;
    this.emit('packet', new Packets.SSLRequestPacket({
      clientFlags   : this._config.clientFlags,
      maxPacketSize : this._config.maxPacketSize,
      charsetNumber : this._config.charsetNumber
    }));
    this.emit('start-tls');
  } else {
    this._sendCredentials();
  }
};

Handshake.prototype._tlsUpgradeCompleteHandler = function() {
  this._sendCredentials();
};

Handshake.prototype._sendCredentials = function() {
  var packet = this._handshakeInitializationPacket;
  this.emit('packet', new Packets.ClientAuthenticationPacket({
    clientFlags   : this._config.clientFlags,
    maxPacketSize : this._config.maxPacketSize,
    charsetNumber : this._config.charsetNumber,
    user          : this._config.user,
    database      : this._config.database,
    protocol41    : packet.protocol41,
    scrambleBuff  : (packet.protocol41)
      ? Auth.token(this._config.password, packet.scrambleBuff())
      : Auth.scramble323(packet.scrambleBuff(), this._config.password)
  }));
};

Handshake.prototype['UseOldPasswordPacket'] = function() {
  if (!this._config.insecureAuth) {
    var err = new Error(
      'MySQL server is requesting the old and insecure pre-4.1 auth mechanism. ' +
      'Upgrade the user password or use the {insecureAuth: true} option.'
    );

    err.code = 'HANDSHAKE_INSECURE_AUTH';
    err.fatal = true;

    this.end(err);
    return;
  }

  this.emit('packet', new Packets.OldPasswordPacket({
    scrambleBuff: Auth.scramble323(this._handshakeInitializationPacket.scrambleBuff(), this._config.password)
  }));
};

Handshake.prototype['ErrorPacket'] = function(packet) {
  var err = this._packetToError(packet, true);
  err.fatal = true;
  this.end(err);
};