private void AddGuestButton_Click(object sender, EventArgs e)
        {
            if (FirstNameTextBox.Text == "" || LastNameTextBox.Text == "")
            {
                WarningLabel.DissapearAfterSeconds(3);

                foreach (Control control in GuestCreationPanel.Controls)
                {
                    if (control is TextBox && control.Text == "")
                    {
                        (control as CampingTextBox).Flicker();
                    }
                }
            }
            else
            {
                Guest guest = DAL.Instance.CreateGuest(FirstNameTextBox.Text, LastNameTextBox.Text, DateOfBirthPicker.Value);
                guests.Add(guest);
                ListViewItem item = new ListViewItem(new string[] { guest.GetFullName(), guest.Age.ToString() });
                this.CurrentGuests.Items.Add(item);

                FirstNameTextBox.Text   = "";
                LastNameTextBox.Text    = "";
                DateOfBirthPicker.Value = DateTime.Today.AddYears(-DAL.Instance.AverageAge);
            }
        }
 private void CustomerIsGuest_CheckedChanged(object sender, EventArgs e)
 {
     if (CustomerIsGuest.Checked)
     {
         customerAsGuest = DAL.Instance.CreateGuest(customer.FirstName, customer.LastName, customer.DateOfBirth);
         ListViewItem item = new ListViewItem(new string[] { customerAsGuest.GetFullName() + " 👑", customerAsGuest.Age.ToString() });
         this.CurrentGuests.Items.Insert(0, item);
         guests.Add(customerAsGuest);
     }
     else
     {
         guests.Remove(customerAsGuest);
         customerAsGuest.Remove();
         customerAsGuest = null;
         this.CurrentGuests.Items.RemoveAt(0);
     }
 }