<?php
/**************************************************
 *             Kody kreskowe - EAN-8              *
 **************************************************
 * Wersja: 1.0                                    *
 * Autor: Jacek Kowalski (http://jacekk.info)     *
 *                                                *
 * Utwór rozprowadzany na licencji                *
 * http://creativecommons.org/licenses/by-nc/2.5/ *
 **************************************************/

$len = strlen($_GET['kod']);
if(trim($_GET['kod'], '0123456789')!='' OR $len!=(7 OR 8)) {
	echo 'Znaki inne niż cyfry lub błędna długość ('.$len.')';
	die();
}

$kod = str_split(substr($_GET['kod'], 0, 7));
$now = 3;
foreach($kod as $val) {
	if($now==1) {
		$sum += $val;
		$now = 3;
	}
	else
	{
		$sum += $val*3;
		$now = 1;
	}
}
$sum = (10-($sum%10))%10;

if($len==7) {
	$_GET['kod'] .= $sum;
}
elseif(substr($_GET['kod'], -1)!=$sum) {
	echo 'Błędna suma kontrolna';
	die();
}

$kol = array(
	'0' => array('A', 'A', 'A', 'A', 'A', 'A'),
	'1' => array('A', 'A', 'B', 'A', 'B', 'B'),
	'2' => array('A', 'A', 'B', 'B', 'A', 'B'),
	'3' => array('A', 'A', 'B', 'B', 'B', 'A'),
	'4' => array('A', 'B', 'A', 'A', 'B', 'B'),
	'5' => array('A', 'B', 'B', 'A', 'A', 'B'),
	'6' => array('A', 'B', 'B', 'B', 'A', 'A'),
	'7' => array('A', 'B', 'A', 'B', 'A', 'B'),
	'8' => array('A', 'B', 'A', 'B', 'B', 'A'),
	'9' => array('A', 'B', 'B', 'A', 'B', 'A')
);

$code = array(
	'start' => '101',
	'lewa' => array(
		'A' => array(
			'0' => '0001101',
			'1' => '0011001',
			'2' => '0010011',
			'3' => '0111101',
			'4' => '0100011',
			'5' => '0110001',
			'6' => '0101111',
			'7' => '0111011',
			'8' => '0110111',
			'9' => '0001011'
		),
		'B' => array(
			'0' => '0100111',
			'1' => '0110011',
			'2' => '0011011',
			'3' => '0100001',
			'4' => '0011101',
			'5' => '0111001',
			'6' => '0000101',
			'7' => '0010001',
			'8' => '0001001',
			'9' => '0010111'
		)
	),
	'srodek' => '01010',
	'prawa' => array(
		'0' => '1110010',
		'1' => '1100110',
		'2' => '1101100',
		'3' => '1000010',
		'4' => '1011100',
		'5' => '1001110',
		'6' => '1010000',
		'7' => '1000100',
		'8' => '1001000',
		'9' => '1110100'
	),
	'stop' => '101'
);


function gen_binary($kod, $strona, $sys) {
	global $code, $kol;

	$kod = str_split($kod);
	$ret = '';
	if($strona==0) {
		foreach($kod as $key => $val) {
			$ret .= $code['lewa'][$kol[$sys][$key]][$val];
		}
	}
	else
	{
		foreach($kod as $val) {
			$ret .= $code['prawa'][$val];
		}
	}
	return $ret;
}
function print_code($kod, $img) {
	global $b, $w, $now;

	$kod = str_split($kod);
	foreach($kod as $val) {
		if($val==1) {
			imageline($img, $now, 0, $now, 40, $b);
		}
		$now++;
	}
}

$sys = substr($_GET['kod'], 0, 1);
$lewa = substr($_GET['kod'], 0, 4);
$prawa = substr($_GET['kod'], 4);

$i = imagecreate(67, 40);
$w = imagecolorallocate($i, 255, 255, 255);
$b = imagecolorallocate($i, 0, 0, 0);

print_code($code['start'].gen_binary($lewa, 0, $sys).$code['srodek'].gen_binary($prawa, 1, $sys).$code['stop'], $i);

header('Content-type: image/gif');
imagegif($i);
?>