<?php

function gen_base62_rand_shortlink($len) {
	$rand_bytes = random_bytes(intval(($len * 2) / 3));
        $rand_string = base64_encode($rand_bytes);
	$rand_string = str_replace("+","",$rand_string);
        $rand_string = str_replace("/","",$rand_string);
        $rand_string = str_replace("=","",$rand_string);

	if (mb_strlen($rand_string) < $len) {
		$curlen = mb_strlen($rand_string);
		$rand_string = $rand_string . gen_rand_shortlink($len - $curlen);
	}

	return $rand_string;
}

function gen_rand_shortlink($len) {
	$to_return = '';
	$possible_chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
	while (mb_strlen($to_return) < $len) {
		$to_return = $to_return . $possible_chars[rand(0, mb_strlen($possible_chars)-1)];
	}

	return $to_return;

}


ini_set('display_errors', 1);
use Casssandra;

$cluster = Cassandra::cluster()->withPersistentSessions(true)->build();
$keyspace = 'glink';

$url = $_GET["url"];
$matches = preg_match('/^http(s)*:\\/\\/[a-zA-Z0-9\\-]+(\\.[a-zA-Z0-9\\-]+)+$/',$url);
if (($matches == 0) || ($matches == false)) {
	printf("The URL entered was invalid. Please try again.");
	return;
}

$shortlink = $_GET["glink"];

if ($shortlink != '') {
	$matches_shortlink = preg_match('/^[a-zA-Z]+$/',$shortlink);
	if (($matches_shortlink == 0) || ($matches_shortlink == false)) {
	        printf("The GLink entered was invalid. The GLink can only contain letters. Please try again.");
	        return;
	}
} else {
	/* generate a random shortlink */
	gen_shortlink:
		$rand_string = gen_rand_shortlink(6);  /* the function is defined at the start of this file */
		$shortlink = $rand_string;

		/* Check if shortlink is already taken by querying the database */
		$statement = $session->prepare('SELECT url FROM data WHERE id=?');
		$result = $session->execute($statement,array('arguments' => array($shortlink)));

		if ($result->count() != 0) {
			goto gen_shortlink;
		}

}

$session = $cluster->connect($keyspace);

//$statement = new Cassandra\SimpleStatement('SELECT name FROM data WHERE id=5');

$statement = $session->prepare('SELECT url FROM data WHERE shortlink=? ALLOW FILTERING');
$options = array('arguments' => array($shortlink));
$result = $session->execute($statement,$options);

if ($result->count() != 0) {
	printf('That GLink is already taken. Please try another one.');
	exit;
}

$rand_num = rand(0,99999999);

$statement = $session->prepare('INSERT INTO data (id, url, shortlink, when_created) VALUES (?,?,?,toTimestamp(now())) USING TTL 20');
$result = $session->execute($statement,array('arguments' => array($rand_num,$url,$shortlink)));

//$stringRepresentation= json_encode($result[0]);

//printf("%s\n\n\n",$stringRepresentation);

//foreach($result as $row) {
//	if (is_null($row)) {
//		printf('Unsuccessful');
//	} else {
		printf('Successful: The URL you entered was: %s and your GLink is: https://glink.zip/%s', $url,$shortlink);
//	}
//}
//printf('Done');

?>