fixup! implement IButtonWidget and IIconWidget

lib/Controller/ViewController.php

@@ -23,6 +23,7 @@
  */
 namespace OCA\Calendar\Controller;
 
+use InvalidArgumentException;
 use OCA\Calendar\Service\Appointments\AppointmentConfigService;
 use OCP\App\IAppManager;
 use OCP\AppFramework\Controller;
@@ -151,13 +152,20 @@ private function getView(string $view): string {
 	}
 
 	/**
+	 * @NoAdminRequired
 	 * @NoCSRFRequired
 	 *
 	 * This function makes the colour dots work for mobile widgets
 	 *
-	 * Returns an SVG with size32x32
+	 * Returns an SVG with size32x32 if the hex colour is valid
+	 *
+	 * @param string $color - url encoded HEX colour
+	 * @return DataDownloadResponse
 	 */
-	public function getCalendarDotSvg(string $color) {
+	public function getCalendarDotSvg(string $color): DataDownloadResponse {
+		if (!preg_match('/^#[a-f0-9]{6}$/i', urldecode($color))) {
+			throw new InvalidArgumentException('Not a HEX colour');
+		}
 		$svg = '<svg height="32" width="32" viewBox="0 0 32 32" xmlns="http://www.w3.org/2000/svg"><rect width="100%" height="100%" fill="' . urldecode($color) . '"/></svg>';
 		$response = new DataDownloadResponse($svg, "$color.svg", 'svg+xml');
 		$response->cacheFor(31536000);