use strict;
use warnings;
use IO::Select;
use IO::Socket;

$|=1;
$SIG{INT}=\&exit_genchars;

my $time_zone_inc=10;
my %sock_client_hash;
my $cc=48;

    my $server_sock = new IO::Socket::INET(
        Listen => 1,LocalPort => 19,Reuse=> 1
    );
    my $sel = new IO::Select( $server_sock  );
    my @ready;
    while($server_sock) {
        @ready = $sel->can_read(0.0001);
        foreach my $socket (@ready) {
            if($socket == $server_sock ) {
                new_socket($socket);
            }else{
                if(defined ($socket)) {
                    close_socket($socket);
                }
            }
        }
        my @wready = $sel->can_write(0.0001);
        my $wsocket;
        foreach $wsocket (@wready) {
            gen_chars($wsocket);
        }
    }

sub new_socket {
    my $newclientsock=shift;
    $newclientsock = $server_sock ->accept;
    $sel->add($newclientsock);
    my ($ip,$peer_port)=sock_attrs($newclientsock);
    $sock_client_hash{$newclientsock->fileno}{ip}=$ip;
    $sock_client_hash{$newclientsock->fileno}{port}=$peer_port;
    my $fileNo=$newclientsock->fileno;
    log_event("New Client connected -> FileNo($fileNo) $ip:$peer_port\n");
}

sub gen_chars {
    my($wrs) = $_[0];
     if($cc==58) {
         $cc=65;
     }elsif($cc==91) {
         $cc=97;
     }elsif($cc==123) {
         $cc=48;
     } 
     $wrs->send(chr($cc)) or close_socket($wrs);
     $cc++;
}

sub close_socket {
    my $socket=$_[0];
    my $sock_ip=$sock_client_hash{$socket->fileno}{ip};
    my $sock_peer_port=$sock_client_hash{$socket->fileno}{port};
    my $fileNo=$socket->fileno;
    log_event("Unable to write to -> FileNo($fileNo) $sock_ip:$sock_peer_port\n");
    if(defined ($socket)) {
        $sel->remove($socket);
        $socket->close;
        log_event("Removed socket -> FileNo($fileNo) $sock_ip:$sock_peer_port\n");
    }
}

sub sock_attrs {
     my $socket=$_[0];
     my $ip=$socket->peerhost;
     my $port=$socket->peerport;
     return $ip,$port;
}

sub log_event {
    my $msg=shift;
    my $gmTime=rTime();
    print "$gmTime -> $msg";
}
   
sub rTime {
    my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday)
        = gmtime(time);
    my $militaryTime=($hour)+$time_zone_inc;
    my $m;
    my $s;
    if($militaryTime>24) {
        $militaryTime=$militaryTime-24;
    }
    $militaryTime=$hour;
    if(length($min)==1) {
        $m="0".$min;
        $min=$m;
    }
    if(length($sec)==1) {
        $s="0".$sec;
        $sec=$s;
    }
    my $roundedTime="$militaryTime:$min:$sec";
    return $roundedTime;
}

sub exit_genchars {
    log_event("Exit called\n");
    exit(0);
}