*
	 * @param array $args The hook parameters.
	 * @return array The expanded hook parameters.
	 */
	public function expand_wp_insert_comment( $args ) {
		return array( $args[0], $this->filter_comment( $args[1] ) );
	}

	/**
	 * Filter a comment object to the fields we need.
	 *
	 * @access public
	 *
	 * @param \WP_Comment $comment The unfiltered comment object.
	 * @return \WP_Comment Filtered comment object.
	 */
	public function filter_comment( $comment ) {
		/**
		 * Filters whether to prevent sending comment data to .com
		 *
		 * Passing true to the filter will prevent the comment data from being sent
		 * to the WordPress.com.
		 * Instead we pass data that will still enable us to do a checksum against the
		 * Jetpacks data but will prevent us from displaying the data on in the API as well as
		 * other services.
		 *
		 * @since 4.2.0
		 *
		 * @param boolean false prevent post data from bing synced to WordPress.com
		 * @param mixed $comment WP_COMMENT object
		 */
		if ( apply_filters( 'jetpack_sync_prevent_sending_comment_data', false, $comment ) ) {
			$blocked_comment                   = new \stdClass();
			$blocked_comment->comment_ID       = $comment->comment_ID;
			$blocked_comment->comment_date     = $comment->comment_date;
			$blocked_comment->comment_date_gmt = $comment->comment_date_gmt;
			$blocked_comment->comment_approved = 'jetpack_sync_blocked';
			return $blocked_comment;
		}

		return $comment;
	}

	/**
	 * Whether a certain comment meta key is whitelisted for sync.
	 *
	 * @access public
	 *
	 * @param string $meta_key Comment meta key.
	 * @return boolean Whether the meta key is whitelisted.
	 */
	public function is_whitelisted_comment_meta( $meta_key ) {
		return in_array( $meta_key, Settings::get_setting( 'comment_meta_whitelist' ), true );
	}

	/**
	 * Handler for filtering out non-whitelisted comment meta.
	 *
	 * @access public
	 *
	 * @param array $args Hook args.
	 * @return array|boolean False if not whitelisted, the original hook args otherwise.
	 */
	public function filter_meta( $args ) {
		if ( $this->is_comment_type_allowed( $args[1] ) && $this->is_whitelisted_comment_meta( $args[2] ) ) {
			return $args;
		}

		return false;
	}

	/**
	 * Expand the comment IDs to comment objects and meta before being serialized and sent to the server.
	 *
	 * @access public
	 *
	 * @param array $args The hook parameters.
	 * @return array The expanded hook parameters.
	 */
	public function expand_comment_ids( $args ) {
		list( $comment_ids, $previous_interval_end ) = $args;
		$comments                                    = get_comments(
			array(
				'include_unapproved' => true,
				'comment__in'        => $comment_ids,
				'orderby'            => 'comment_ID',
				'order'              => 'DESC',
			)
		);

		return array(
			$comments,
			$this->get_metadata( $comment_ids, 'comment', Settings::get_setting( 'comment_meta_whitelist' ) ),
			$previous_interval_end,
		);
	}
}