// Cancel customer booking based on Seat selection
private void btnCancelBooking(object sender, EventArgs e)
{
// clear messages
lblMessages.Text = "";
// it only needs the seat selection. if not empty, REMOVE IT!
try
{
string row = lstBoxRow.SelectedItem.ToString();
string seat = lstBoxSeat.SelectedItem.ToString();
string seatSelection = row + seat;
// if seat is not occupied, present message
if (AirplaneService.SeatStatus(seatSelection))
{
lblMessages.Text = "Selected seat is empty.";
ResetSelection(); // unselect and clears everything
return; // forces the end of the method.
}
// at this point, removal of seat is possible.
string warningMessage = "The removal of a customer will enforce the first name, if any, " +
"on the waitlist to take it's place and cannot be undone.\r\n" +
"Do you want to proceed?";
DialogResult result = MessageBox.Show(warningMessage, "Cancel Booking", MessageBoxButtons.YesNo);
// user confirm he wants to proceed
if (result == DialogResult.Yes)
{
AirplaneService.UnassignSeat(seatSelection);
// get the first element of the waitlist.
if (WaitlistService.HasNext())
{
// Dequeue element and put on the txtName
txtName.Text = WaitlistService.RemoveFromTheWaitlist();
// Assign the customer to the seat.
btnBookSeat(sender, e);
}
btnShowWaitingList(sender, e);
btnShowAllSeats(sender, e);
ResetSelection();
}
else
{
// clear form entirely
ResetSelection();
}
}
// NRE is caused by the lstBoxRow and Seat. It means that seat was not properly selected.
catch (NullReferenceException)
{
lblMessages.Text += "Select a seat first";
}
}
