/// <summary>
        /// Will log the matching employee in if he isn't already, and start the time management.
        /// If the matching employee is logged in, he will be logged out, and the total hours will be updated thereafter.
        /// </summary>
        public async void LoginOrLogout()
        {
            if (MainViewModel.OpenDbConnection)
            {
                PersistencyService.GetDataLoggedIn(_viewModel.LoggedInEmployees);
            }

            var employees       = _viewModel.EmployeesInDb.ToList();
            var matcingEmployee = employees.Find(e => e.EmployeeId.ToString() == _viewModel.LoginOrLogoutBox);

            var matchingLoggedInEmployee = _viewModel.LoggedInEmployees.Find(e => e.EmployeeId.ToString() == _viewModel.LoginOrLogoutBox);


            //If user IS NOT logged in, he will be logged in:
            if (matcingEmployee != null && matchingLoggedInEmployee == null)
            {
                matcingEmployee.LastLogin = DateTime.Now;
                LastLoggedIn = matcingEmployee;
                if (LastLoggedIn.TotalHours > new TimeSpan(24, 59, 59))
                {
                    LastLoggedIn.TotalHours = new TimeSpan(10, 35, 28);                                                     //Due to unknown unresponsiveness if the employees TotalHours-property is above 24 hours.
                }
                _viewModel.DatabaseTable.Clear();
                _viewModel.DatabaseTable.Add(LastLoggedIn);

                if (!MainViewModel.OpenDbConnection)
                {
                    return;
                }

                PersistencyService.PostDataLoggedIn(matcingEmployee); //Posted to logged in employees database.

                PersistencyService.PutData(matcingEmployee);          //Updates logintime for the employee on the shown employee list.

                DanxMainPage.CloseCanvases();
                DanxMainPage.MainScreenLoginCanvas.Visibility = Visibility.Visible;
                if (matcingEmployee.GetType() == typeof(AdminEmp))
                {
                    DanxMainPage.AdminToolsCanvas.Visibility = Visibility.Visible;
                }
                else
                {
                    DanxMainPage.AdminToolsCanvas.Visibility = Visibility.Collapsed;
                }
            }
            //If user IS logged in, he will be logged out:
            else if (matchingLoggedInEmployee != null)
            {
                _employeeToLogout = matchingLoggedInEmployee;
                UpdateLogoutTime();
                UpdateTotalHours();
                _employeeToLogout = null;
                if (!MainViewModel.OpenDbConnection)
                {
                    return;
                }

                PersistencyService.DeleteDataLoggedIn(matchingLoggedInEmployee); //Removing logged out employee from logged in table.

                DanxMainPage.CloseCanvases();
                DanxMainPage.MainScreenCanvas.Visibility = Visibility.Visible;

                var hoursWorkedFormat = String.Format(_hoursWorked.Hours + ":" + _hoursWorked.Minutes + ":" + _hoursWorked.Seconds);

                //Goodbye message
                DanxMainPage.UiWelcomeMessage.Text =
                    "                            Goodbye!\n          You have worked for " + hoursWorkedFormat + " today.";
                await Task.Delay(8000);

                DanxMainPage.UiWelcomeMessage.Text =
                    "                            Welcome!\nInsert worker-id in one of the boxes above.";
            }

            //If a wrong user id is entered:
            else
            {
                try
                {
                    throw new ArgumentException("Please enter a valid employee id."); //Unittest purposes
                }
                catch (ArgumentException)
                {
                    var errorMsg = new MessageDialog("Please enter a valid employee id.", "Error");
                    if (MainViewModel.OpenDbConnection)
                    {
                        errorMsg.ShowAsync();                               //Unittest purposes
                    }
                }
            }
        }