Populate Grid Data repeater subfields with clones of all Card Layouts

card_grid_data.php

<?php
/**
 * Helper function to extract the Card Data field from the Card Grid field group
 */
function get_grid_data_field() {
	$card_grid_field_group = acf_get_field_group('group_card_grid');
	if (!$card_grid_field_group) {
		return;
	}

	$card_grid_fields = acf_get_fields($card_grid_field_group['ID']);
	$grid_data_field = array_filter($card_grid_fields, function($f) {
		return $f['key'] === 'field_card_grid_data';
	});

	return array_pop($grid_data_field);
}

/**
 * Returns an array describing a field that is a clone of the specified
 * field group, ready to use in the Card Data repeater’s sub fields
 */
function get_card_layout_clone($card_layout_field_group) {
	if (!$card_layout_field_group) {
		return false;
	}

	$grid_data_field = get_grid_data_field();
	if (!$grid_data_field) {
		return false;
	}

	$base_group_key = str_replace('group_', '', $card_layout_field_group['key']);
	$name = sprintf('_%s_fields', $base_group_key);

	return [
		'menu_order'        => 0,
		'key'               => sprintf('field_%s', uniqid()),
		'label'             => '',
		'name'              => $name,
		'_name'             => '',
		'type'              => 'clone',
		'instructions'      => '',
		'required'          => 0,
		'conditional_logic' => [
			[
				[
					'field'    => 'field_card_grid_style',
					'operator' => '==',
					'value'    => $base_group_key,
				],
			],
		],
		'parent'            => $grid_data_field['ID'],
		'wrapper'           => [
			'width' => '',
			'class' => '',
			'id'    => '',
		],
		'clone'             => [sprintf('group_%s', $base_group_key)],
		'display'           => 'group',
		'layout'            => 'block',
		'required'          => 0,
		'prefix_label'      => 0,
		'prefix_name'       => 0,
	];
}

/**
 * When saving a field group, sync the Card Grid > Card Data field with
 * the list of Card Layouts
 */
add_action('acf/update_field_group', function($field_group) {
	$grid_data_field = get_grid_data_field();
	$card_layouts = get_card_layouts();

	$existing_card_layouts = implode(',', array_map(function($l) {
		return $l['key'];
	}, $card_layouts));

	$active_card_layouts = implode(',', array_map(function($f) {
		return $f['clone'][0];
	}, $grid_data_field['sub_fields']));

	//DONT UPDATE if the lists already match, or this will loop forever
	if ($active_card_layouts === $existing_card_layouts) {
		return;
	}

	write_log('GRID DATA FIELD BEFORE:');
	write_log($grid_data_field);

	$new_grid_data_field = array_merge($grid_data_field, [
		'sub_fields' => array_map('get_card_layout_clone', $card_layouts),
	]);

	write_log('GRID DATA FIELD TO SAVE:');
	write_log($new_grid_data_field);

	acf_update_field($new_grid_data_field);
});