#!/usr/local/bin/perl

use IO::Socket;
use Time::localtime;

$port = 7654;
$maxspoj = SOMAXCONN;

sub calc {
	my $oper = shift;
	my $op1 = shift;
	my $op2 = shift;

	if ($oper eq "+") {
		$vysl = $op1 + $op2;
	} elsif ($oper eq "-") {
		$vysl = $op1 - $op2;
	} elsif ($oper eq "*") {
		$vysl = $op1 * $op2;
	} elsif ($oper eq "/") {
		$vysl = $op1 / $op2;
	} else {
		$vysl = "ERR";
	}
	return $vysl;
}
	

$server = IO::Socket::INET->new(Proto=>"tcp", LocalPort=>$port, Listen=>$maxspoj, Reuse=>1)
	or die "Nelze vytvorit server.\n\n";

print "\nSER: [",ctime,"] Inicializace.\nPort: $port.\nMax. spojeni: $maxspoj\n";
binmode(STDOUT);

sub REAPER {
	$waitpid = wait;
	$SIG{CHLD} = \&REAPER;
#	print "Reaped $waitpid" . ($? ? " with exit $?" : '');
}

$SIG{CHLD} = \&REAPER;

while ($klient = $server->accept) {
	print "SER: [",ctime,"] Socket klienta vytvoren.\n";
	$klient->autoflush(1);
	
	if (($pid = fork) == 0) {
		# ocekava se pozadavek ve forme "CALC klientID x[+-*/]y"
		@poz = split(' ',<$klient>);
		$prefix = $poz[0];
		$klID = $poz[1];
		$vyraz = $poz[2];
		print "SER: [",ctime," $klID] FORK: Zacatek.\n";

		# platny prefix? reaguj jen na CALC!
		if ($prefix eq "CALC" &&
		    $vyraz !~ /^$/) {
			$vyraz =~ /(.+)([\+\-\*\/])(.+)/;
			$op1 = $1;
			$oper = $2;
			$op2 = $3;
			print "SER: [",ctime," $klID] Pozadavek: $op1 $oper $op2\n";

			sleep(5);
			$vysl = calc($oper,$op1,$op2);
			print "SER: [",ctime," $klID] Vysledek: $vysl. Odesilam klientovi.\n";
			print $klient "RSLT $vysl \n";
		} else {
			# Spatny pozadavek	
			print "SER: [",ctime," $klID] Zaslan spatny pozadavek. Odesilam chybovou zpravu.\n";
			print $klient "RSLT ERR \n";
		}
		print "SER: [",ctime," $klID] Zaviram socket klienta.\n";
		close $klient;
#		print "SER: [",ctime," $klID] Zaviram socket serveru.\n";
#		close $server;
		die "SER: [",ctime," $klID] FORK: Konec.";
	} else {
		close $klient;
	}
}

print "SER: [",ctime,"] Zaviram socket serveru a konec.\n\n\n";
close $server;