function allow_admin_svg_uploads($file_types)
{
	if (!current_user_can('administrator'))
	{
		return $file_types;
	}
	$file_types['svg'] = 'image/svg+xml';
	return $file_types;
}
add_filter('upload_mimes', 'allow_admin_svg_uploads');

function mytheme_handle_current_year_shortcode()
{
	$year = date('Y');
	return $year;
}

add_shortcode('mytheme_current_year', 'mytheme_handle_current_year_shortcode');

define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);

add_filter('auto_core_update_send_email', '__return_false');
add_filter('auto_theme_update_send_email', '__return_false');
add_filter('auto_plugin_update_send_email', '__return_false');

//Increase the login session expiration time (by default, it's 2 days, or 14 days if you checked "Remember me")
function extend_wordpress_login_sessions($seconds, $user_id, $remember)
{
	if ($remember)
	{
		$expiration = 90 * 24 * 60 * 60; //Extend remembered sessions to 90 days
	}
	
	else
	{
		$expiration = 15 * 24 * 60 * 60; //Extend non-remembered sessions to 15 days
	}

	return $expiration;
}

add_filter('auth_cookie_expiration', 'extend_wordpress_login_sessions', 99, 3);

function get_sorted_categories($taxonomy, $meta_key_to_sort_by, $parent_category_id = 0, $indent_level = 0, &$nested_categories_array = null)
{
    if ($nested_categories_array === null)
    {
        $nested_categories_array = [];
    }

    $categories = get_categories
    (
        [
            'parent' => $parent_category_id,
            'hide_empty' => false,
            'taxonomy' => $taxonomy,
        ]
    );

    usort($categories, function($a, $b) use ($meta_key_to_sort_by)
    {
        $order_a = intval(get_term_meta($a->term_id, $meta_key_to_sort_by, true));
        $order_b = intval(get_term_meta($b->term_id, $meta_key_to_sort_by, true));
        return $order_a - $order_b;
    });

    foreach ($categories as $category)
    {
        $category_id = $category ?-> term_id;
        $category_name = $category ?-> name;
        $category_slug = $category ?-> slug;
        $category_count = $category ?-> count;
        $category_permalink = get_category_link($category_id);

        $nested_categories_array[] =
        [
            'category_id' => $category_id,
            'category_name' => $category_name,
            'category_slug' => $category_slug,
            'category_permalink' => $category_permalink,
            'category_count' => $category_count,
            'indent_level' => $indent_level,
        ];

        get_sorted_categories($taxonomy, $meta_key_to_sort_by, $category_id, $indent_level + 1, $nested_categories_array);
    }

    return $nested_categories_array;
}

$nested_audio_categories = get_sorted_categories('food_category', 'food_order');


Example of a returned array:

array (
  0 => 
  array (
    'category_id' => 183,
    'category_name' => 'Foods',
    'category_slug' => 'foods',
    'category_permalink' => 'https://example.com/food-category/foods/',
    'category_count' => 2,
    'indent_level' => 0,
  ),
  1 => 
  array (
    'category_id' => 15,
    'category_name' => 'Italian',
    'category_slug' => 'italian',
    'category_permalink' => 'https://example.com/food-category/italian/',
    'category_count' => 698,
    'indent_level' => 1,
  ),
  2 => 
  array (
    'category_id' => 28,
    'category_name' => 'Pizza',
    'category_slug' => 'pizza',
    'category_permalink' => 'https://example.com/food-category/pizza/',
    'category_count' => 477,
    'indent_level' => 2,
  ),
  3 => 
  array (
    'category_id' => 29,
    'category_name' => 'Japanese',
    'category_slug' => 'japanese',
    'category_permalink' => 'https://example.com/food-category/japanese/',
    'category_count' => 165,
    'indent_level' => 1,
  ),

function mysite_get_foobar_ajax()
{
	$response =	[
					'status'		=> 'success',
					'text_message'	=> 'The foobar was successful.',
					'html_message'	=> '<p class="success-message">The foobar was successful.</p>',
				];
	echo json_encode($response);
	wp_die();
}

add_action('wp_ajax_mysite_get_foobar_ajax', 'mysite_get_foobar_ajax');

?>


<script>
let form_data = new FormData();
form_data.append('action', 'mysite_get_foobar_ajax');

fetch('/wp-admin/admin-ajax.php', {method: 'POST', headers: {}, body: form_data})
.then
(
	response => response.json()
)
.then
(
	data =>
	{
		console.log(data);
		
		if (data.status === 'success')
		{
			alert(data.text_message);
		}
		
		else if (data.status === 'error')
		{
			alert(data.text_message);
		}
		
		else
		{
			throw 'Unexpected response status';
		}
	}
)
.catch(error =>
{
	console.log(error);
	alert('An unknown error occured.');
});
</script>

<form action="/" style="margin-bottom: 80px;">
	<input type="text" class="homepage-search" name="s" placeholder="Search the website...">
</form>

/*
* Plugin Name: Custom Foobar Plugin
* Description: Our custom foobar plugin
* Version: 1.0
* Author: Author
* Author URI: https://www.example.com
*/

function handle_foobar_shortcode($original_shortcode_attributes)
{
	$attributes = shortcode_atts([
									'lorem'	=> null,
								],
								$original_shortcode_attributes);
	
	$lorem = $attributes['lorem'] ?? null;
	
	if ($attributes['lorem'] !== 'ipsum')
	{
		return '<p>Error: Unexpected value for "lorem" attribute (expected "ipsum").</p>';
	}
	
	$output_html = '<p>The shortcode works!</p>';
	
	return $output_html;
}

add_shortcode('foobar', 'handle_foobar_shortcode');

$debug_tags = array();

add_action('all', function ($tag)
{
    global $debug_tags;
    if (in_array($tag, $debug_tags))
	{
        return;
    }
    echo "<pre>" . $tag . "</pre>";
    $debug_tags[] = $tag;
});