Add a capability for the reference API and expose the regex to clients

Signed-off-by: Joas Schilling <coding@schilljs.com>

lib/private/OCS/CoreCapabilities.php

 
 use OCP\Capabilities\ICapability;
 use OCP\IConfig;
+use OCP\IURLGenerator;
 
 /**
  * Class Capabilities
 			'core' => [
 				'pollinterval' => $this->config->getSystemValue('pollinterval', 60),
 				'webdav-root' => $this->config->getSystemValue('webdav-root', 'remote.php/webdav'),
-			]
+				'reference-api' => true,
+				'reference-regex' => IURLGenerator::URL_REGEX_NO_MODIFIERS,
+			],
 		];
 	}
 }

lib/public/IURLGenerator.php

 	 *
 	 * @since 25.0.0
 	 */
-	public const URL_REGEX = '/(\s|\n|^)(https?:\/\/)((?:[-A-Z0-9+_]+\.)+[-A-Z]+(?:\/[-A-Z0-9+&@#%?=~_|!:,.;()]*)*)(\s|\n|$)/mi';
+	public const URL_REGEX = '/' . self::URL_REGEX_NO_MODIFIERS . '/mi';
+
+	/**
+	 * Regex for matching http(s) urls (without modifiers for client compatibility)
+	 *
+	 * This is a copy of the frontend regex in core/src/OCP/comments.js, make sure to adjust both when changing
+	 *
+	 * @since 25.0.0
+	 */
+	public const URL_REGEX_NO_MODIFIERS = '(\s|\n|^)(https?:\/\/)((?:[-A-Z0-9+_]+\.)+[-A-Z]+(?:\/[-A-Z0-9+&@#%?=~_|!:,.;()]*)*)(\s|\n|$)';
 
 	/**
 	 * Returns the URL for a route