use IO::Select;
use IO::Socket;

my $listen_port = 8080;  # we proxy for many clients on this port
my $scs_port    = 8181;  # and talk to a single connection on this port

my $DEBUG = 1;

my $lsn = new IO::Socket::INET(
            Listen => 1, 
            LocalPort => $listen_port 
) or die $!;

# make a single connection to some server
my $sock = IO::Socket::INET->new(   
            PeerAddr => 'localhost',
            PeerPort => $scs_port,
            Proto    => 'tcp'
) or die $!;

my $client = new IO::Select( $lsn );
my $server = new IO::Select( $sock );

my ($count, $data, $buffer);

while( my @ready = $client->can_read) {
    for my $fh (@ready) {
        if($fh == $lsn) {
            # Create a new socket to handle more conns
            $count++;
            $DEBUG && warn "Accepted new socket $count\n";
            my $new = $lsn->accept;
            $client->add($new);     # register it with IO::Select
        }
        else {
            # Process socket
            $DEBUG && warn "Proxy getting data\n";
            $data = '';
            $data .= $buffer while sysread( $fh, $buffer, 1 ) and $buffer ne "\n";
            $DEBUG && warn "Proxy got: $data\n";
            if ( ! $data or $data =~ m/exit/i ) {
                remove_handle( $client, $fh );
            }
            else {
                # act as a proxy for this client to the SCS
                $DEBUG && warn "Writing to server\n";
                die "Can't write to server!\n" unless $server->can_write;
                syswrite( $sock, "$data\n" );  
                $DEBUG && warn "Reading from server\n";
                die "Can't read from server!\n" unless $server->can_read; 
                $data = '';
                $data .= $buffer while sysread( $sock, $buffer, 1 ) and $buffer ne "\n";
                $DEBUG && warn "Writing back to client\n";
                if ( $client->can_write ) { 
                    syswrite( $fh, "$data\n" );
                }
                else {
                    $DEBUG && warn "Can't write data back to client\n";
                    remove_handle( $client, $fh );
                }
                #syswrite( $fh, "Hello $data\n" );  # is we want a simple server
            }
        }
    }
}

sub remove_handle {
    my ( $client, $fh ) = @_;
    $DEBUG && warn "Removing client!\n";
    syswrite( $fh, "Sayonara!\n" ) if $client->can_write;
    $client->remove($fh);
    $fh->close;
    $count--;
}