#!/usr/bin/perl

use strict;
use warnings;
use diagnostics;

use Tk;
use Tk::Text;
use IO::Socket;

my ( $ip_addr, $line, $sock, $afterid, $cancel );

my $mw = new MainWindow;

# Put a Frame in it/give it a label
my $frm_name = $mw->Frame();
my $lab = $frm_name->Label( -text => "Enter IP address:port" );

# We need entry boxes for IP address:socket & a button to start running.
my $ent1    = $frm_name->Entry();
my $but     = $mw->Button( -text => "Start", -command => \&start );
my $stopbut = $mw->Button( -text => "Stop", -command => \&stop );

# Create a window for Display and Input.

my $textarea = $mw->Frame();          #creating another frame
my $txt      = $textarea->Scrolled(
    'Text',
    -width      => 80,
    -height     => 10,
    -scrollbars => 'osoe'
);
$lab->grid( -row => 1, -column => 1 );
$ent1->grid( -row => 1, -column => 2 );
$frm_name->grid( -row => 1, -column => 1, -columnspan => 2 );

$but->grid( -row => 4, -column => 1 );
$stopbut->grid( -row => 4, -column => 2 );
$txt->grid( -row => 1, -column => 1 );

$textarea->grid( -row => 5, -column => 1, -columnspan => 2 );

MainLoop;

sub start {
    return if defined $afterid;
    $cancel  = 0;
    $ip_addr = $ent1->get();
    print STDOUT "addr: $ip_addr\n";

    $sock = new IO::Socket::INET(
        PeerAddr => $ip_addr,
        PeerPort => '5000',
        Proto    => 'tcp',
    );
    die "Could not create socket: $! \n" unless $sock;

    $afterid = $mw->after(
        100,
        sub {
            while ( defined( $line = <$sock> ) ) {
                $line =~ s/\015\012/\n/;
                $txt->insert( 'end', $line );
                $txt->see('end');
                $mw->update;
                last if $cancel;
            }
        }
    );
}

sub stop {
    return unless $afterid;
    $cancel = 1;
    $afterid->cancel;
    undef $afterid;
    close $sock;
    undef $sock;
}