use strict;
use warnings;

use Tk;
use Tk::Table;
use Tk::Entry;
use Tk::Label;

use constant kRows => 3;
use constant kCols => 3;

main (); # Use a main sub to ensure that there are no global variabless


sub main {
    my $mw = new MainWindow;

    $mw->Label (
        -text       => "Enter any character",
        -foreground => "red",
        -font       => "verdanafont 10 bold"
    )->pack (-side => "top");

    my $table_frame = $mw->Frame ()->pack (-padx => "10");

    my $table = $table_frame->Table (
        -columns      => kCols,
        -rows         => kRows,
        -scrollbars   => "o",
        -fixedrows    => 1,
        -fixedcolumns => 1,
        -relief       => 'raised',
        -pady         => "20",
        -takefocus    => "0"
    );
    my $press = $mw->Button (
        -text    => "Press Me",
        -command => [\&PressMe, $mw, $table], # pass parameters into callback
        -font    => "verdanafont 10 bold",
        -state   => 'disabled',
        )->pack (
        -side  => "left",
        -padx  => "5",
        -ipadx => "5"
        );
    my $filled = 0;

    for my $col (0 .. kCols - 1) {
        my $tmp_label = $table_frame->Label (-text => "$col")->pack ();
        $table->put (0, $col, $tmp_label);
    }
    for my $row (0 .. kRows - 1) {
        for my $col (0 .. kCols - 1) {
            my $ent1 = $table->Entry (
                -font     => "verdana 10",
                -validate => 'key',
                # Pass button widget and a ref to $filled into callback. Need a
                # ref because we manipulate $filled in the callback
                -vcmd     => [\&onEdit, $press, \$filled],
            )->pack (-ipady => "15");
            $table->put ($row, $col, $ent1);
        }
    }
    $table->pack ();

    MainLoop;
}


sub onEdit {
    my ($button, $filled, $new, $edit, $current, $idx, $type) = @_;
    return 1 if $new eq $current;

    if (length $new && !length $current) {
        ++$$filled;
    } elsif (!length $new && length $current) {
        --$$filled;
    }

    if ($$filled == kRows * kCols) {
        $button->configure (-state => 'normal');
    } else {
        $button->configure (-state => 'disabled');
    }
    return 1;
}


sub PressMe {
    my ($mw, $table) = @_;
    my $message = "alphanumeric entered";

Outer: for my $row (0 .. kRows - 1) {
        for my $col (0 .. kCols - 1) {
            my $name = $table->get ($row, $col);
            my $val = $name->get ();

            next if $val =~ m/^[a-z0-9]+$/i;
            $message =
                  "Bad entry ($val) in row "
                . ($row + 1)
                . ", column "
                . ($col + 1);
            last Outer;
        }
    }

    my $response = $mw->messageBox (
        -type    => "ok",
        -message => $message,
        -icon    => "info",
        -title   => "info!!"
    );
}