+sub is_user_used_for_task_server {
+  my ($self, $user) = @_;
+
+  return undef if !$user;
+  return join ', ', sort_by { lc } map { $_->name } @{ SL::DB::Manager::AuthClient->get_all(where => [ task_server_user_id => $user->id ]) };
+}
+
+sub check_database_superuser_privileges {
+  my ($self, %params) = @_;
+
+  my %dbconnect_form = %{ $::form };
+  my %result         = (
+    username => $dbconnect_form{dbuser},
+    password => $dbconnect_form{dbpasswd},
+  );
+
+  my $check_privileges = sub {
+    my $dbh = SL::DBConnect->connect($dbconnect_form{dbconnect}, $result{username}, $result{password}, SL::DBConnect->get_options);
+    return (error => $::locale->text('The credentials (username & password) for connecting database are wrong.')) if !$dbh;
+
+    my $is_superuser = SL::DBUtils::role_is_superuser($dbh, $result{username});
+
+    $dbh->disconnect;
+
+    return (have_privileges => $is_superuser);
+  };
+
+  User::dbconnect_vars(\%dbconnect_form, $dbconnect_form{dbdefault});
+
+  %result = (
+    %result,
+    $check_privileges->(),
+  );
+
+  if (!$result{have_privileges}) {
+    $result{username} = $::form->{database_superuser_user};
+    $result{password} = $::form->{database_superuser_password};
+
+    if ($::form->{database_superuser_user}) {
+      %result = (
+        %result,
+        $check_privileges->(),
+      );
+    }
+  }
+
+  if ($result{have_privileges}) {
+    $::auth->set_session_value(database_superuser_username => $result{username}, database_superuser_password => $result{password});
+    return %result;
+  }
+
+  $::auth->delete_session_value(qw(database_superuser_username database_superuser_password));
+
+  return ()                                                                            if !$::form->{database_superuser_user} && $params{no_credentials_not_an_error};
+  return (%result, error => $::locale->text('No superuser credentials were entered.')) if !$::form->{database_superuser_user};
+  return %result                                                                       if $result{error};
+  return (%result, error => $::locale->text('The database user \'#1\' does not have superuser privileges.', $result{username}));
+}
+