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<?php
namespace App\Factories;
use App\Models\Link;
use App\Helpers\CryptoHelper;
use App\Helpers\LinkHelper;
class LinkFactory {
const MAXIMUM_LINK_LENGTH = 65535;
private static function formatLink($link_ending, $secret_ending=false) {
/**
* Given a link ending and a boolean indicating whether a secret ending is needed,
* return a link formatted with app protocol, app address, and link ending.
* @param string $link_ending
* @param boolean $secret_ending
* @return string
*/
$short_url = env('APP_PROTOCOL') . env('APP_ADDRESS') . '/' . $link_ending;
if ($secret_ending) {
$short_url .= '/' . $secret_ending;
}
return $short_url;
}
public static function createLink($long_url, $is_secret=false, $custom_ending=null, $link_ip='127.0.0.1', $creator=false, $return_object=false, $is_api=false) {
/**
* Given parameters needed to create a link, generate appropriate ending and
* return formatted link.
*
* @param string $custom_ending
* @param boolean (optional) $is_secret
* @param string (optional) $custom_ending
* @param string $link_ip
* @param string $creator
* @param bool $return_object
* @param bool $is_api
* @return string $formatted_link
*/
if (strlen($long_url) > self::MAXIMUM_LINK_LENGTH) {
// If $long_url is longer than the maximum length, then
// throw an Exception
throw new \Exception('Sorry, but your link is longer than the
maximum length allowed.');
}
$is_already_short = LinkHelper::checkIfAlreadyShortened($long_url);
if ($is_already_short) {
throw new \Exception('Sorry, but your link already
looks like a shortened URL.');
}
if (!$is_secret && (!isset($custom_ending)) && (LinkHelper::longLinkExists($long_url) !== false)) {
// if link is not specified as secret, is non-custom, and
// already exists in Polr, lookup the value and return
$existing_link = LinkHelper::longLinkExists($long_url);
return self::formatLink($existing_link);
}
if (isset($custom_ending)) {
// has custom ending
$ending_conforms = LinkHelper::validateEnding($custom_ending);
if (!$ending_conforms) {
throw new \Exception('Sorry, but custom endings
can only contain alphanumeric characters, hyphens, and underscores.');
}
$ending_in_use = LinkHelper::linkExists($custom_ending);
if ($ending_in_use) {
throw new \Exception('Sorry, but this URL ending is already in use.');
}
$link_ending = $custom_ending;
}
else {
if (env('SETTING_PSEUDORANDOM_ENDING')) {
// generate a pseudorandom ending
$link_ending = LinkHelper::findPseudoRandomEnding();
}
else {
// generate a counter-based ending or use existing ending if possible
$link_ending = LinkHelper::findSuitableEnding();
}
}
$link = new Link;
$link->short_url = $link_ending;
$link->long_url = $long_url;
$link->ip = $link_ip;
$link->is_custom = $custom_ending != null;
$link->is_api = $is_api;
if ($creator) {
// if user is logged in, save user as creator
$link->creator = $creator;
}
if ($is_secret) {
$rand_bytes_num = intval(env('POLR_SECRET_BYTES'));
$secret_key = CryptoHelper::generateRandomHex($rand_bytes_num);
$link->secret_key = $secret_key;
}
else {
$secret_key = false;
}
$link->save();
$formatted_link = self::formatLink($link_ending, $secret_key);
if ($return_object) {
return $link;
}
return $formatted_link;
}
}
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