The array of additional arguments. Please see the $defaults array below.
	 */
	public static function add( $message, $type = '', $args = [] ) {

		static $uniq_id = 0;

		$defaults = [
			'dismiss' => self::DISMISS_NONE, // Dismissible level: one of the self::DISMISS_* const. By default notice is not dismissible.
			'slug'    => '',                 // Slug. Should be unique if dismissible is not equal self::DISMISS_NONE.
			'autop'   => true,               // `false` if not needed to pass message through wpautop().
			'class'   => '',                 // Additional CSS class.
		];

		$args = wp_parse_args( $args, $defaults );

		$dismissible = (int) $args['dismiss'];
		$dismissible = $dismissible > self::DISMISS_USER ? self::DISMISS_USER : $dismissible;

		$class  = $dismissible > self::DISMISS_NONE ? ' is-dismissible' : '';
		$global = ( $dismissible === self::DISMISS_GLOBAL ) ? 'global-' : '';
		$slug   = sanitize_key( $args['slug'] );

		++$uniq_id;

		$uniq_id += ( $uniq_id === (int) $slug ) ? 1 : 0;

		$id      = 'wpforms-notice-' . $global;
		$id     .= empty( $slug ) ? $uniq_id : $slug;
		$type    = ! empty( $type ) ? 'notice-' . esc_attr( sanitize_key( $type ) ) : '';
		$class   = empty( $args['class'] ) ? $class : $class . ' ' . esc_attr( sanitize_key( $args['class'] ) );
		$message = $args['autop'] ? wpautop( $message ) : $message;
		$notice  = sprintf(
			'<div class="notice wpforms-notice %s%s" id="%s">%s</div>',
			esc_attr( $type ),
			esc_attr( $class ),
			esc_attr( $id ),
			$message
		);

		if ( empty( $slug ) ) {
			wpforms()->get( 'notice' )->notices[] = $notice;
		} else {
			wpforms()->get( 'notice' )->notices[ $slug ] = $notice;
		}
	}

	/**
	 * Add info notice.
	 *
	 * @since 1.6.7.1
	 *
	 * @param string $message Message to display.
	 * @param array  $args    Array of additional arguments. Details in the self::add() method.
	 */
	public static function info( $message, $args = [] ) {

		self::add( $message, 'info', $args );
	}

	/**
	 * Add error notice.
	 *
	 * @since 1.6.7.1
	 *
	 * @param string $message Message to display.
	 * @param array  $args    Array of additional arguments. Details in the self::add() method.
	 */
	public static function error( $message, $args = [] ) {

		self::add( $message, 'error', $args );
	}

	/**
	 * Add success notice.
	 *
	 * @since 1.6.7.1
	 *
	 * @param string $message Message to display.
	 * @param array  $args    Array of additional arguments. Details in the self::add() method.
	 */
	public static function success( $message, $args = [] ) {

		self::add( $message, 'success', $args );
	}

	/**
	 * Add warning notice.
	 *
	 * @since 1.6.7.1
	 *
	 * @param string $message Message to display.
	 * @param array  $args    Array of additional arguments. Details in the self::add() method.
	 */
	public static function warning( $message, $args = [] ) {

		self::add( $message, 'warning', $args );
	}

	/**
	 * AJAX routine that updates dismissed notices meta data.
	 *
	 * @since 1.6.7.1
	 */
	public function dismiss_ajax() {

		// Run a security check.
		check_ajax_referer( 'wpforms-admin', 'nonce' );

		// Sanitize POST data.
		$post = array_map( 'sanitize_key', wp_unslash( $_POST ) );

		// Update notices meta data.
		if ( strpos( $post['id'], 'global-' ) !== false ) {

			// Check for permissions.
			if ( ! wpforms_current_user_can() ) {
				wp_send_json_error();
			}

			$notices = $this->dismiss_global( $post['id'] );
			$level   = self::DISMISS_GLOBAL;

		} else {

			$notices = $this->dismiss_user( $post['id'] );
			$level   = self::DISMISS_USER;
		}

		/**
		 * Allows developers to apply additional logic to the dismissing notice process.
		 * Executes after updating option or user meta (according to the notice level).
		 *
		 * @since 1.6.7.1
		 *
		 * @param string  $notice_id Notice ID (slug).
		 * @param integer $level     Notice level.
		 * @param array   $notices   Dismissed notices.
		 */
		do_action( 'wpforms_admin_notice_dismiss_ajax', $post['id'], $level, $notices );

		if ( ! wpforms_debug() ) {
			wp_send_json_success();
		}

		wp_send_json_success(
			[
				'id'      => $post['id'],
				'time'    => time(),
				'level'   => $level,
				'notices' => $notices,
			]
		);
	}

	/**
	 * AJAX sub-routine that updates dismissed notices option.
	 *
	 * @since 1.6.7.1
	 *
	 * @param string $id Notice Id.
	 *
	 * @return array Notices.
	 */
	private function dismiss_global( $id ) {

		$id             = str_replace( 'global-', '', $id );
		$notices        = get_option( 'wpforms_admin_notices', [] );
		$notices[ $id ] = [
			'time'      => time(),
			'dismissed' => true,
		];

		update_option( 'wpforms_admin_notices', $notices, true );

		return $notices;
	}

	/**
	 *  AJAX sub-routine that updates dismissed notices user meta.
	 *
	 * @since 1.6.7.1
	 *
	 * @param string $id Notice Id.
	 *
	 * @return array Notices.
	 */
	private function dismiss_user( $id ) {

		$user_id        = get_current_user_id();
		$notices        = get_user_meta( $user_id, 'wpforms_admin_notices', true );
		$notices        = ! is_array( $notices ) ? [] : $notices;
		$notices[ $id ] = [
			'time'      => time(),
			'dismissed' => true,
		];

		update_user_meta( $user_id, 'wpforms_admin_notices', $notices );

		return $notices;
	}
}