program flight;
uses crt;

var
reservation : array[1..3,1..15] of string[20];
choice : char;
save : text;
fexists : boolean;


procedure FileExists(filename: string);

begin
{$I-}
Assign(save, filename);
Reset(save);
Close(save);
{$I+}
fexists := (IOResult = 0) and (filename <> '');

end;


procedure add;
var y,z:integer;

begin
clrscr;
writeln;
writeln;
write ('Add a reservation for which flight? (1,2, or 3) --->  ');
readln (y);
writeln;
writeln;
z := 0;
repeat
z := z + 1;
until (reservation[y,z] = '') or (z = 16);
if z <> 16 then begin
writeln ('Reservation #',z,' on fight #',y,' : ');
write ('Name : ');
readln (reservation[y,z]);
end else begin
writeln ('This flight is full!!');
write ('Do you want to erase all of it''s reservations? (Y or N)');
repeat
choice := upcase(readkey);
until (choice = 'Y') or (choice = 'N');
if choice = 'Y' then for z := 1 to 15 do reservation[y,z] := '';
end;

end;


procedure view_all;
var
z,y,b : integer;

begin

clrscr;
writeln;
for y := 1 to 3 do begin

b := 0;
repeat
b := b + 1;
until (reservation[y,b] = '') or (b = 16);

for z := 1 to b - 1 do writeln ('Flight #',y,', reservation #',z,' : ',reservation[y,z]);
writeln;
writeln ('You have ',16 - b,' reservations left open in this flight');
writeln;
writeln;
writeln ('--More--');
readkey;
clrscr;
writeln;
end;

end;


procedure view_one;
var y,z,b:integer;

begin

clrscr;
writeln;
writeln;
write ('What flight do you want to look at? --->  ');
readln (y);
writeln;
writeln;

b := 0;
repeat
b := b + 1
until (reservation[y,b] = '') or (b = 16);

for z := 1 to b - 1 do writeln ('Flight #',y,', reservation #',z,' : ',reservation[y,z]);
writeln;
writeln ('You have ',16 - b,' reservations left open in this flight');
readkey;

end;


Procedure save_data;
var x,y : integer;
begin
clrscr;
writeln;
writeln;
if fexists then begin
writeln ('You already have a saved data file. Are you sure you want to over write it?');
write ('(Y or N)');
repeat
choice := upcase(readkey);
until (choice = 'Y') or (choice = 'N');
end;
if (fexists = false) or (choice = 'Y') then begin
rewrite(save);
for x := 1 to 3 do
for y := 1 to 15 do writeln (save,reservation[x,y]);
close(save);
fexists := true;
writeln;
writeln ('Data Saved');
choice := readkey;
end;
end;


procedure load_data;
var x,y : integer;
begin

clrscr;
writeln;
writeln;
if fexists then begin
writeln ('Are you sure you want to load your saved data? (all current data will be lost)');
write ('(Y or N)');
repeat
choice := upcase(readkey);
until (choice = 'Y') or (choice = 'N');
if choice = 'Y' then begin
reset (save);
for x := 1 to 3 do
for y := 1 to 15 do readln (save,reservation[x,y]);
close (save);
writeln;
writeln ('Data Loaded');
end;
end else writeln ('You have no saved data to load');

choice := readkey;

end;


begin

repeat

fileexists('flight.$$$');

clrscr;
gotoxy (25,4);
writeln ('Fast-Flight Airlines reservations');
gotoxy (25,6);
write ('-----------------------');
gotoxy (25,7);
write ('Main Menu');
gotoxy (25,8);
write ('-----------------------');
gotoxy (25,11);
write ('[L]oad a set of saved data');
gotoxy (25,12);
write ('[S]ave current data');
gotoxy (25,13);
write ('[A]dd a reservation');
gotoxy (25,14);
write ('View [O]ne reservation');
gotoxy (25,15);
write ('[V]iew all reservations');
gotoxy (25,16);
write ('[Q]uit');
gotoxy (25,18);
write ('Please enter a letter : ');
choice := upcase(readkey);

case choice of
'A' : add;
'O' : view_one;
'V' : view_all;
'S' : save_data;
'L' : load_data;
end;


until choice = 'Q';
end.