#! /usr/bin/perl
##

use ExtUtils::testlib;
use Curses;


sub fatal {
    clrtobot(0, 0);
    addstr(0, 0, "@_\n");
    refresh();
    sleep 2;
    exit 1;
}



sub driveForm($$) {
    my ($fwin, $form) = @_;

    while (1) {
        my $ch = getch($fwin);
        if ($ch == KEY_UP) {
            form_driver($form, REQ_PREV_FIELD);
        }  elsif ($ch == KEY_DOWN or $ch eq "\t" or
                  $ch eq "\r" or $ch eq "\n") {
            form_driver($form, REQ_NEXT_FIELD);
        } elsif ($ch == KEY_LEFT) {
            form_driver($form, REQ_LEFT_CHAR);
        } elsif ($ch == KEY_RIGHT) {
            form_driver($form, REQ_RIGHT_CHAR);
        } elsif ($ch == KEY_NPAGE) {
            form_driver($form, REQ_NEXT_PAGE);
        } elsif ($ch == KEY_PPAGE) {
            form_driver($form, REQ_PREV_PAGE);
        }  elsif ($ch == KEY_DC or ord($ch) == 8 or ord($ch) == 127) {
            form_driver($form, REQ_DEL_PREV);
        } elsif ($ch == KEY_F(1)) {
            last;
        } elsif ($ch =~ /^\S$/) {
            form_driver($form, ord($ch));
        } else {
            beep();
        }
    }
}



sub makeFields() {

    my $flist = [
                 [ 'L', 0,  0,  0,  8, "Form"        ],
                 [ 'L', 0,  0,  2,  0, "First Name"  ],
                 [ 'F', 1, 15,  2, 12, "F Name"      ],
                 [ 'L', 0,  0,  3,  0, "Last Name"   ],
                 [ 'F', 1, 15,  3, 12, "L Name"      ],
                 [ 'L', 0,  0,  5,  8, "Form (pt 2)" ],
                 [ 'L', 0,  0,  7,  0, "# Tuits"     ],
                 [ 'F', 1,  5,  7, 12, "Tuits"       ],
                 [ 'L', 0,  0,  8,  0, "# Bleems"    ],
                 [ 'F', 1,  5,  8, 12, "Bleems"      ]
                 ];

    my @fl;

    foreach my $F (@$flist) {
        my $field;
            # This is a Perl reference to a scalar number variable.  The
            # number is the numerical equivalent (cast) of the C pointer to the
            # executable-Curses FIELD object.  The reference is blessed into
            # package "Curses::Field", but don't confuse it with a Perl
            # object.

        if ($F->[0] eq 'L') {
            $field = new_field(1, length($F->[5]), $F->[3], $F->[4], 0, 0);
            if ($field eq '') {
                fatal("new_field $F->[5] failed");
            }
            set_field_buffer($field, 0, $F->[5]);
            field_opts_off($field, O_ACTIVE);
            field_opts_off($field, O_EDIT);
        } elsif ($F->[0] eq 'F') {
            $field = new_field($F->[1], $F->[2], $F->[3], $F->[4], 0, 0);
            if ($field eq '') {
                fatal("new_field $F->[5] failed");
            }
            if ($F->[5] eq "Tuits") {
                set_field_buffer($field, 0, $F->[5]);
            }
            set_field_back($field, A_UNDERLINE);
        }

        push(@fl, $field);
    }
    return @fl;
}



sub makeForm(@) {
    
    my @fl = @_;

    my @pack;
    foreach $fieldR (@fl) {
        push(@pack, $ {$fieldR});
    }
    push(@pack, 0);

    # new_form()'s argument is a list of fields.  Its form is amazingly
    # complex:

    # The argument is a string whose ASCII encoding is an array of C
    # pointers.  Each pointer is to a FIELD object of the
    # executable-Curses library, except the last is NULL to mark the
    # end of the list.  For example, assume there are two fields and
    # the executable-Curses library represents them with FIELD objects
    # whose addresses (pointers) are 0x11223344 and 0x0004080C.  The
    # argument to Curses::new_form() is a 12 character string whose
    # ASCII encoding is 0x112233440004080C00000000 .

    # Maybe some day we can provide an alternative where there is an
    # actual Perl field object class and the argument is a reference to
    # a Perl list of them.

    my $form = new_form(pack('L!*', @pack));
    if ($form eq '') {
        fatal("new_form failed");
    }
    return $form;
}



sub demo() {

    noecho();

    eval { new_form() };
    if ($@ =~ m{not defined by your vendor}) {
        print STDERR "Curses was not compiled with form function.\n";
        exit 1;
    }

    my @fl = makeFields();

    my $form = makeForm(@fl);

    my $rows;
    my $cols;

    scale_form($form, $rows, $cols);

    my $fwin = newwin($rows + 2, $cols + 4, 4, 0);
    my $fsub = derwin($fwin, $rows, $cols, 1, 2);

    set_form_win($form, $fwin);
    set_form_sub($form, $fsub);

    box($fwin, 0, 0);
    keypad($fwin, 1);

    post_form($form);

    addstr(0, 0, "Use KEY_UP/KEY_DOWN/KEY_PPAGE/KEY_NPAGE to navigate");
    addstr(1, 0, "Press 'ENTER' to select item, or 'F1' to exit");
    addstr(2, 0, "Other alphanumeric characters will enter data");
    refresh();

    driveForm($fwin, $form);

    unpost_form($form);
    delwin($fwin);
    free_form($form);
    map { free_field($_) } @fl;
}



##############################################################################
#                    MAINLINE
##############################################################################

initscr();

# The eval makes sure if it croaks, we have a chance to restore the
# terminal.

eval { demo() };

endwin();

if ($@) {
    print STDERR "Failed.  $@\n";
    exit(1);
}

exit(0);