public static function init() {
		// Rating posts.
		add_filter( 'comments_open', array( __CLASS__, 'comments_open' ), 10, 2 );
		add_filter( 'preprocess_comment', array( __CLASS__, 'check_comment_rating' ), 0 );
		add_action( 'comment_post', array( __CLASS__, 'add_comment_rating' ), 1 );
		add_action( 'comment_moderation_recipients', array( __CLASS__, 'comment_moderation_recipients' ), 10, 2 );

		// Clear transients.
		add_action( 'wp_update_comment_count', array( __CLASS__, 'clear_transients' ) );

		// Secure order notes.
		add_filter( 'comments_clauses', array( __CLASS__, 'exclude_order_comments' ), 10, 1 );
		add_filter( 'comment_feed_where', array( __CLASS__, 'exclude_order_comments_from_feed_where' ) );

		// Secure webhook comments.
		add_filter( 'comments_clauses', array( __CLASS__, 'exclude_webhook_comments' ), 10, 1 );
		add_filter( 'comment_feed_where', array( __CLASS__, 'exclude_webhook_comments_from_feed_where' ) );

		// Count comments.
		add_filter( 'wp_count_comments', array( __CLASS__, 'wp_count_comments' ), 10, 2 );

		// Delete comments count cache whenever there is a new comment or a comment status changes.
		add_action( 'wp_insert_comment', array( __CLASS__, 'delete_comments_count_cache' ) );
		add_action( 'wp_set_comment_status', array( __CLASS__, 'delete_comments_count_cache' ) );

		// Support avatars for `review` comment type.
		add_filter( 'get_avatar_comment_types', array( __CLASS__, 'add_avatar_for_review_comment_type' ) );

		// Review of verified purchase.
		add_action( 'comment_post', array( __CLASS__, 'add_comment_purchase_verification' ) );

		// Set comment type.
		add_action( 'preprocess_comment', array( __CLASS__, 'update_comment_type' ), 1 );
	}