Issue #9166: Detect JSON Feed URLs when subscribing via the API (#9167)

* feat(api): Add detection of JSON feed when subscribing via the Google Reader API.

* Added self to CREDITS.md

* Rather than making a network request, use heuristics based on the URL string to determine if the feed URL likely points to a JSON feed.

* Minor syntax preference and comment reduction

* Minor syntax

---------

Co-authored-by: Alexandre Alapetite <alexandre@alapetite.fr>

CREDITS.md

@@ -146,6 +146,7 @@ People are sorted by name so please keep this order.
 * [jlefler](https://github.com/jlefler): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:jlefler)
 * [Joe Stump](https://github.com/joestump): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:joestump), [Web](http://stu.mp)
 * [Joel Garcia](https://github.com/joelchrono12): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:joelchrono12), [Web](https://joelchrono12.xyz)
+* [John Brayton](https://github.com/jbrayton): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:jbrayton), [Web](https://www.virtualsanity.com)
 * [Jonas Östanbäck](https://github.com/cez81): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:cez81)
 * [Jordi Garcia](https://github.com/jgtorcal): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:jgtorcal)
 * [Joris Kinable](https://github.com/jkinable): [contributions](https://github.com/FreshRSS/FreshRSS/pulls?q=is:pr+author:jkinable)

p/api/greader.php

@@ -451,7 +451,8 @@ final class GReaderAPI {
 						if ($feedId <= 0) {
 							$http_auth = '';
 							try {
-								FreshRSS_feed_Controller::addFeed($streamUrl, $title, $addCatId, '', $http_auth);
+								$kind = self::detectFeedKind($streamUrl);
+								FreshRSS_feed_Controller::addFeed($streamUrl, $title, $addCatId, '', $http_auth, [], $kind);
 								continue 2;
 							} catch (Exception $e) {
 								Minz_Log::error('subscriptionEdit error subscribe: ' . $e->getMessage(), API_LOG);
@@ -482,13 +483,23 @@ final class GReaderAPI {
 		exit('OK');
 	}
 
+	/**
+	 * Guess the kind of feed (RSS/ATOM vs. JSON) based on URL.
+	 * The Google Reader API does not provide any way for the client to specify the feed format.
+	 */
+	private static function detectFeedKind(string $url): int {
+		return preg_match('/(?:\b|_)json(?:\b|_)/i', $url) === 1
+			? FreshRSS_Feed::KIND_JSONFEED
+			: FreshRSS_Feed::KIND_RSS;
+	}
+
 	private static function quickadd(string $url): never {
 		try {
 			$url = htmlspecialchars($url, ENT_COMPAT, 'UTF-8');
 			if (str_starts_with($url, 'feed/')) {
 				$url = substr($url, 5);
 			}
-			$feed = FreshRSS_feed_Controller::addFeed($url);
+			$feed = FreshRSS_feed_Controller::addFeed($url, kind: self::detectFeedKind($url));
 			exit(json_encode([
 					'numResults' => 1,
 					'query' => $feed->url(),