#! /usr/bin/perl -w
# server0.pl

use strict;
use Socket;
my $port = shift || 7890;
my $proto = getprotobyname('tcp');
socket(SERVER, PF_INET, SOCK_STREAM, $proto) or die "socket: $!";
setsockopt(SERVER, SOL_SOCKET, SO_REUSEADDR, 1) or die "setsock: $!";
my $paddr = sockaddr_in($port, INADDR_ANY);
bind(SERVER, $paddr) or die "bind: $!";
listen(SERVER, SOMAXCONN) or die "listen: $!";
print "SERVER started on port $port \n";

my $client_addr;
my $calc=0;
my @data;

while ($client_addr = accept(CLIENT, SERVER)) 
{
        my $old_fh = select(CLIENT);
	$| = 1;
	select($old_fh);

print "New connection established.\n";
print "Requesting data...\n";
print CLIENT "OK\n";
print "OK sent!\n";

        while ($calc == 0)
        {
        print "reading...\n";
	$calc = <CLIENT>;
        }
                print "Data: \n";
                print $calc;
                @data = split(/(\+|\*|\/|\-)/,$calc);
                if ($data[1] eq "+")
                {
                	print CLIENT $data[0]+$data[2];
                }
                if ($data[1] eq "-")
                {
                	print CLIENT $data[0]-$data[2];
                }
                if ($data[1] eq "*")
                {
                	print CLIENT $data[0]*$data[2];
                }
                if ($data[1] eq "/")
                {
                	print CLIENT $data[0]/$data[2];
                }

close CLIENT;
print "--END--";
exit;
}