From 8b6854764459d9025c140c346a58a428634da33d Mon Sep 17 00:00:00 2001
From: Aadhavan Srinivasan <aadhavan@twomorecents.org>
Date: Fri, 9 Jun 2023 20:03:30 -0500
Subject: [PATCH] Added code to generate a random GLink if the user doesn't
 submit one

---
 result.php | 86 ++++++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 68 insertions(+), 18 deletions(-)

diff --git a/result.php b/result.php
index 3ed85d0..25f7fb0 100644
--- a/result.php
+++ b/result.php
@@ -1,8 +1,36 @@
 <?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;
 
-$cluster = Cassandra::cluster()->build();
+$cluster = Cassandra::cluster()->withPersistentSessions(true)->build();
 $keyspace = 'glink';
 
 $url = $_GET["url"];
@@ -13,36 +41,58 @@ if (($matches == 0) || ($matches == false)) {
 }
 
 $shortlink = $_GET["glink"];
-$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;
-}
 
+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 = $session->prepare('INSERT INTO data (id, url, shortlink, when_created) VALUES (?,?,?,toTimestamp(now()))');
+$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)));
 
-$statement = $session->prepare('SELECT url,shortlink FROM data WHERE id=?');
-$options = array('arguments' => array($rand_num));
-$result = $session->execute($statement,$options);
-
 //$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', $row['url'],$row['shortlink']);
-	}
-}
+//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');
 
 ?>