#!/usr/bin/env perl

use strict;
use warnings;

use Tk;
use IO::Socket;

my $mw = MainWindow->new;

my $control_F = $mw->Frame()->pack(-side => 'bottom');

my $out_F = $mw->Frame()->pack(-side => 'top', -fill => 'both', -expand => 1);
my $out_T = $out_F->Scrolled('Text', -scrollbars => 'osoe', -wrap => 'none');
$out_T->pack(-fill => 'both', -expand => 1);

my $out_win = $out_T;
my $delay = 100;
my ($client, $tid);

my @button_pack_opts = (-side => 'left', -padx => 10);

$control_F->Button(-text => 'Start Server',
    -command => [\&start_server, \$client]
)->pack(@button_pack_opts);

$control_F->Button(-text => 'Start Listening',
    -command => [\&start_listen, \$mw, \$client, \$tid, \$delay, \$out_win]
)->pack(@button_pack_opts);

$control_F->Button(-text => 'Stop Listening',
    -command => [\&stop_listen, \$out_win, \$tid]
)->pack(@button_pack_opts);

$control_F->Button(-text => 'Quit',
    -command => sub { exit }
)->pack(@button_pack_opts);

MainLoop;

sub start_server {
    my ($client_ref) = @_;

    my $server = IO::Socket::INET::->new(
        Proto     => 'tcp',
        LocalPort => 55555,
        Listen    => SOMAXCONN,
        Reuse     => 1
    ) or die "Server can't start: $!";

    $$client_ref = $server->accept();
    $$client_ref->autoflush;

    return;
}

sub start_listen {
    my ($mw_ref, $client_ref, $tid_ref, $delay_ref, $out_ref) = @_;

    $$tid_ref = $$mw_ref->repeat(
        $$delay_ref => [\&read_client, $mw_ref, $client_ref, $out_ref] 
    );

    return;
}

sub stop_listen {
    my ($out_ref, $tid_ref) = @_;

    my $times_format = "(Usr: %d, Sys: %d, ChUsr: %d, ChSys: %d)\n";
    $$out_ref->insert(end => sprintf $times_format => times);
    $$out_ref->yview('end');
    $$tid_ref->cancel;

    return;
}

sub read_client {
    my ($mw_ref, $client_ref, $out_ref) = @_;

    $$mw_ref->fileevent($$client_ref, 'readable', sub {
        if (defined(my $read = readline *$$client_ref)) {
            $$out_ref->insert(end => $read);
            $$out_ref->yview('end');
        }
        else {
            $$mw_ref->fileevent($$client_ref, 'readable', '');
        }
    });

    return;
}