Ajax handler for saving a widget.

function wp_ajax_save_widget() {
	global $wp_registered_widgets, $wp_registered_widget_controls, $wp_registered_widget_updates;

	check_ajax_referer( 'save-sidebar-widgets', 'savewidgets' );

	if ( ! current_user_can( 'edit_theme_options' ) || ! isset( $_POST['id_base'] ) ) {
		wp_die( -1 );
	}

	unset( $_POST['savewidgets'], $_POST['action'] );

	/**
	 * Fires early when editing the widgets displayed in sidebars.
	 *
	 * @since 2.8.0
	 */
	do_action( 'load-widgets.php' ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores

	/**
	 * Fires early when editing the widgets displayed in sidebars.
	 *
	 * @since 2.8.0
	 */
	do_action( 'widgets.php' ); // phpcs:ignore WordPress.NamingConventions.ValidHookName.UseUnderscores

	/** This action is documented in wp-admin/widgets.php */
	do_action( 'sidebar_admin_setup' );

	$id_base      = wp_unslash( $_POST['id_base'] );
	$widget_id    = wp_unslash( $_POST['widget-id'] );
	$sidebar_id   = $_POST['sidebar'];
	$multi_number = ! empty( $_POST['multi_number'] ) ? (int) $_POST['multi_number'] : 0;
	$settings     = isset( $_POST[ 'widget-' . $id_base ] ) && is_array( $_POST[ 'widget-' . $id_base ] ) ? $_POST[ 'widget-' . $id_base ] : false;
	$error        = '
' . __( 'An error has occurred. Please reload the page and try again.' ) . '
';

	$sidebars = wp_get_sidebars_widgets();
	$sidebar  = isset( $sidebars[ $sidebar_id ] ) ? $sidebars[ $sidebar_id ] : array();

	// Delete.
	if ( isset( $_POST['delete_widget'] ) && $_POST['delete_widget'] ) {

		if ( ! isset( $wp_registered_widgets[ $widget_id ] ) ) {
			wp_die( $error );
		}

		$sidebar = array_diff( $sidebar, array( $widget_id ) );
		$_POST   = array(
			'sidebar'            => $sidebar_id,
			'widget-' . $id_base => array(),
			'the-widget-id'      => $widget_id,
			'delete_widget'      => '1',
		);

		/** This action is documented in wp-admin/widgets.php */
		do_action( 'delete_widget', $widget_id, $sidebar_id, $id_base );

	} elseif ( $settings && preg_match( '/__i__|%i%/', key( $settings ) ) ) {
		if ( ! $multi_number ) {
			wp_die( $error );
		}

		$_POST[ 'widget-' . $id_base ] = array( $multi_number => reset( $settings ) );
		$widget_id                     = $id_base . '-' . $multi_number;
		$sidebar[]                     = $widget_id;
	}
	$_POST['widget-id'] = $sidebar;

	foreach ( (array) $wp_registered_widget_updates as $name => $control ) {

		if ( $name == $id_base ) {
			if ( ! is_callable( $control['callback'] ) ) {
				continue;
			}

			ob_start();
				call_user_func_array( $control['callback'], $control['params'] );
			ob_end_clean();
			break;
		}
	}

	if ( isset( $_POST['delete_widget'] ) && $_POST['delete_widget'] ) {
		$sidebars[ $sidebar_id ] = $sidebar;
		wp_set_sidebars_widgets( $sidebars );
		echo "deleted:$widget_id";
		wp_die();
	}

	if ( ! empty( $_POST['add_new'] ) ) {
		wp_die();
	}

	$form = $wp_registered_widget_controls[ $widget_id ];
	if ( $form ) {
		call_user_func_array( $form['callback'], $form['params'] );
	}

	wp_die();
}