module.exports.attach = function (scServer, socket) {
  var tokenExpiresInSeconds = 10 * 60;
  var tokenRenewalIntervalInMilliseconds = Math.round(
    1000 * tokenExpiresInSeconds / 3
  );

  // Keep renewing the token (if there is one) at a predefined interval to make
  // sure that it doesn't expire while the connection is active.
  var renewAuthTokenInterval = setInterval(function () {
    var currentToken = socket.getAuthToken();
    if (currentToken) {
      currentToken.exp = Math.round(Date.now() / 1000) + tokenExpiresInSeconds;
      socket.setAuthToken(currentToken);
    }
  }, tokenRenewalIntervalInMilliseconds);

  socket.once('disconnect', function () {
    clearInterval(renewAuthTokenInterval);
  });

  var validateLoginDetails = function (loginDetails, respond) {
    scServer.thinky.r.table('User')
    .filter({username: loginDetails.username})
    .run(function (err, results) {
      if (results && results[0] && results[0].password === loginDetails.password) {
        var token = {
          username: loginDetails.username
        };
        socket.setAuthToken(token, {expiresIn: tokenExpiresInSeconds});
        respond();
      } else {
        // This is not really an error.
        // We are simply rejecting the login - So we will
        // leave the first (error) argument as null.
        respond(null, 'Invalid username or password');
      }
    });
  };

  socket.on('login', validateLoginDetails);
};