Holiday snow: do not display on p2 (#40519)

* Holiday snow: do not display on p2

Follow-up to #40478

The snowstorm library we use to display falling snow is not compatible with p2s. Let's consequently not offer the option to turn on snow on p2s.

* changelog

Author: jeherve

projects/packages/jetpack-mu-wpcom/changelog/update-snow-p2s

@@ -0,0 +1,4 @@
+Significance: patch
+Type: fixed
+
+Holiday Snow: do not display on p2s.

projects/packages/jetpack-mu-wpcom/src/features/holiday-snow/class-holiday-snow.php

@@ -47,6 +47,18 @@ public static function is_snow_season() {
 		return apply_filters( 'jetpack_is_holiday_snow_season', $is_snow_season );
 	}
 
+	/**
+	 * Check if the site uses p2.
+	 * p2 is currently not compatible with Holiday Snow.
+	 * This covers both P2 and P2020 themes.
+	 *
+	 * @return bool
+	 */
+	private static function is_p2() {
+		return str_contains( get_stylesheet(), 'pub/p2' )
+			|| function_exists( '\WPForTeams\is_wpforteams_site' ) && is_wpforteams_site( get_current_blog_id() );
+	}
+
 	/**
 	 * Check if the snow is enabled.
 	 *
@@ -62,7 +74,7 @@ public static function is_snow_enabled() {
 	 * @return void
 	 */
 	public static function init() {
-		if ( ! self::is_snow_season() ) {
+		if ( ! self::is_snow_season() || self::is_p2() ) {
 			return;
 		}